Copper is a chemical element with the symbol Cu (from Latin: cuprum) and atomic number 29. It is a ductilemetal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish. It is used as a conductor of heat and electricity, a building material, and a constituent of various metal alloys.HP Pavilion DV4 Battery
The metal and its alloys have been used for thousands of years. In the Roman era, copper was principally mined on Cyprus, hence the origin of the name of the metal as ?yprium (metal of Cyprus), later shortened to ?uprum. Its compounds are commonly encountered as copper(II) salts,HP Pavilion DV4-1000 Battery
which often impart blue or green colors to minerals such as turquoise and have been widely used historically as pigments. Architectural structures built with copper corrode to give green verdigris (or patina).Decorative art prominently features copper, both by itself and as part of pigments.HP Pavilion DV4-1000EA Battery
Copper(II) ions are water-soluble, where they function at low concentration as bacteriostatic substances, fungicides, and wood preservatives. In sufficient amounts, they are poisonous to higher organisms; at lower concentrations it is an essential trace nutrient to all higher plant and animal life. The main areas where copper is found in animals are tissues, liver, muscle and bone.HP Pavilion DV4-1000ET Battery
Copper, silver and gold are in group 11 of the periodic table, and they share certain attributes: they have one s-orbital electron on top of a filled d-electron shell and are characterized by high ductility and electrical conductivity. The filled d-shells in these elements do not contribute much to the interatomic interactions, which are dominated by the s-electrons through metallic bonds.HP Pavilion DV4-1001 Battery
Contrary to metals with incomplete d-shells, metallic bonds in copper are lacking a covalentcharacter and are relatively weak. This explains the low hardness and high ductility of single crystals of copper.At the macroscopic scale, introduction of extended defects to the crystal lattice, such as grain boundaries, hinders flow of the material under applied stress thereby increasing its hardness.HP Pavilion DV4-1001AX Battery
For this reason, copper is usually supplied in a fine-grainedpolycrystalline form, which has greater strength than monocrystalline forms.
The low hardness of copper partly explains its high electrical (59.6×106 S/m) and thus also high thermal conductivity, which are the second highest among pure metals at room temperature.HP Pavilion DV4-1001TU Battery
This is because the resistivity to electron transport in metals at room temperature mostly originates from scattering of electrons on thermal vibrations of the lattice, which are relatively weak for a soft metal. The maximum permissible current density of copper in open air is approximately 3.1×106 A/m2 of cross-sectional area, above which it begins to heat excessively.HP Pavilion DV4-1001TX Battery
As with other metals, if copper is placed against another metal, galvanic corrosion will occur.
Together with osmium (bluish), and gold (yellow), copper is one of only three elemental metals with a natural color other than gray or silver. Pure copper is orange-red and acquires a reddishtarnish when exposed to air.HP Pavilion DV4-1002 Battery
The characteristic color of copper results from the electronic transitions between the filled 3d and half-empty 4s atomic shells – the energy difference between these shells is such that it corresponds to orange light. The same mechanism accounts for the yellow color of gold.HP Pavilion DV4-1002AX Battery
Copper forms a rich variety of compounds with oxidation states +1 and +2, which are often calledcuprous and cupric, respectively.It does not react with water, but it slowly reacts with atmospheric oxygen forming a layer of brown-black copper oxide.HP Pavilion DV4-1002TU Battery
In contrast to the oxidation of iron by wet air, this oxide layer stops the further, bulk corrosion. A green layer of verdigris (copper carbonate) can often be seen on old copper constructions, such as the Statue of Liberty, the largest copper statue in the world build using repoussé and chasing.HP Pavilion DV4-1002TX Battery
Hydrogen sulfides and sulfides react with copper to form various copper sulfides on the surface. In the latter case, the copper corrodes, as is seen when copper is exposed to air containing sulfur compounds. Oxygen-containing ammonia solutions give water-soluble complexes with copper,HP Pavilion DV4-1003AX Battery
as do oxygen and hydrochloric acid to form copper chlorides and acidified hydrogen peroxide to form copper(II) salts. Copper(II) chloride and copper comproportionate to form copper(I) chloride.
There are 29 isotopes of copper. 63Cu and 65Cu are stable, with 63Cu comprising approximately 69% of naturally occurring copper; they both have a spin of 3/2.HP Pavilion DV4-1003TU Battery
The other isotopes are radioactive, with the most stable being 67Cu with a half-lifeof 61.83 hours.Seven metastable isotopes have been characterized, with 68mCu the longest-lived with a half-life of 3.8 minutes. Isotopes with a mass number above 64 decay by ?-, whereas those with a mass number below 64 decay by ?+. 64Cu, which has a half-life of 12.7 hours, decays both ways.HP Pavilion DV4-1003TX Battery
62Cu and 64Cu have significant applications. 64Cu is a radiocontrast for X-ray imaging, and complexed with a chelate can be used for treating cancer. 62Cu is used in 62Cu-PTSM that is a radioactive tracer for positron emission tomography.HP Pavilion DV4-1004AX Battery
Copper can be found as either native copper or as part of minerals. Native copper is a polycrystal, with the largest described single crystal measuring 4.4×3.2×3.2 cm. The largest mass of elemental copper weighed 420 tonnes and was found in 1857 on the Keweenaw Peninsula inMichigan, US.HP Pavilion DV4-1004TU Battery
There are many examples of copper-containing minerals: chalcopyrite and chalcocite are copper sulfides, azurite and malachite are copper carbonates and cuprite is a copper oxide. Copper is present in the Earth's crust at a concentration of about 50 parts per million (ppm), and is also synthesized in massive stars.HP Pavilion DV4-1004TX Battery
Most copper is mined or extracted as copper sulfides from large open pit mines in porphyry copper deposits that contain 0.4 to 1.0% copper. Examples include Chuquicamata in Chile,Bingham Canyon Mine in Utah, United States and El Chino Mine in New Mexico, United States.HP Pavilion DV4-1005TX Battery
According to the British Geological Survey, in 2005, Chile was the top mine producer of copper with at least one-third world share followed by the United States, Indonesia and Peru. The amount of copper in use is increasing and the quantity available is barely sufficient to allow all countries to reach developed world levels of usage.HP Pavilion DV4-1006TX Battery
Copper has been in use at least 10,000 years, but more than 95% of all copper ever mined andsmelted has been extracted since 1900. As with many natural resources, the total amount of copper on Earth is vast (around 1014 tons just in the top kilometer of Earth's crust, or about 5 million years worth at the current rate of extraction).HP Pavilion DV4-1007TX Battery
However, only a tiny fraction of these reserves is economically viable, given present-day prices and technologies. Various estimates of existing copper reserves available for mining vary from 25 years to 60 years, depending on core assumptions such as the growth rate.HP Pavilion DV4-1008TX Battery
Recycling is a major source of copper in the modern world. Because of these and other factors, the future of copper production and supply is the subject of much debate, including the concept of Peak copper, analogue to Peak Oil.
The price of copper has historically been unstable, and it quintupled from the 60-year low of US$0.60/lb (US$1.32/kg) in June 1999 to US$3.75 per pound (US$8.27/kg) in May 2006.HP Pavilion DV4-1009TX Battery
It dropped to US$2.40/lb (US$5.29/kg) in February 2007, then rebounded to US$3.50/lb (US$7.71/kg) in April 2007. In February 2009, weakening global demand and a steep fall in commodity prices since the previous year's highs left copper prices at US$1.51/lb.HP Pavilion DV4-1010TX Battery
The concentration of copper in ores averages only 0.6%, and most commercial ores are sulfides, especially chalcopyrite (CuFeS2) and to a lesser extent chalcocite (Cu2S). These minerals are concentrated from crushed ores to the level of 10–15% copper by froth flotation or bioleaching.HP Pavilion DV4-1011TX Battery
Heating this material with silica in flash smelting removes much of the iron as slag. The process exploits the greater ease of converting iron sulfides into its oxides, which in turn react with the silica to form the silicate slag, which floats on top of the heated mass.HP Pavilion DV4-1012TX Battery
The resulting copper matte consisting of Cu2S is then roasted to convert all sulfides into oxides:
2 Cu2S + 3 O2 ? 2 Cu2O + 2 SO2
The cuprous oxide is converted to blister copper upon heating:HP Pavilion DV4-1013TX Battery
2 Cu2O ? 4 Cu + O2
This step exploits the relatively easy reduction of copper oxides to copper metal. Natural gas is blown across the blister to remove most of the remaining oxygen andelectrorefining is performed on the resulting material to produce pure copper:
Cu2+ + 2 e–? CuHP Pavilion DV4-1014NR Battery
Copper, like aluminium, is 100% recyclable without any loss of quality whether in a raw state or contained in a manufactured product. In volume, copper is the third most recycled metal after iron and aluminium. It is estimated that 80% of the copper ever mined is still in use today.HP Pavilion DV4-1014TX Battery
According to the International Resource Panel's Metal Stocks in Society report, the global per capita stock of Copper in use in society is 35–55 kg. Much of this is in more-developed countries (140–300 kg per capita) rather than less-developed countries (30–40 kg per capita).HP Pavilion DV4-1015TX Battery
The process of recycling copper follows roughly the same steps as is used to extract copper, but requires fewer steps. High purity scrap copper is melted in a furnace and then reduced and cast into billets and ingots; lower purity scrap is refined by electroplating in a bath of sulfuric acid.HP Pavilion DV4-1015TX Battery
As for other elements, the simplest compounds of copper are binary compounds, i.e. those containing only two elements. The principal ones are the oxides, sulfides and halides. Both cuprous and cupric oxides are known.HP Pavilion DV4-1016TX Battery
Among the numerous copper sulfides, important examples include copper(I) sulfide and copper(II) sulfide.
The cuprous halides with chlorine, bromine, and iodine are known, as are the cupric halides with fluorine, chlorine, and bromine. Attempts to prepare copper(II) iodide give cuprous iodide and iodine.HP Pavilion DV4-1017TX Battery
2 Cu2+ + 4 I? ? 2 CuI + I2
Copper, like all metals, forms coordination complexes with ligands. In aqueous solution, copper(II) exists as [Cu(H2O)6]2+. This complex exhibits the fastest water exchange rate (speed of water ligands attaching and detaching) for any transition metal aquo complex.HP Pavilion DV4-1018TX Battery
Adding aqueoussodium hydroxide causes the precipitation of light blue solid copper(II) hydroxide. A simplified equation is:
Cu2+ + 2 OH? ? Cu(OH)2
Aqueous ammonia results in the same precipitate. Upon adding excess ammonia, the precipitate dissolves, formingtetraamminecopper(II):HP Pavilion DV4-1019TX Battery
Cu(H2O)4(OH)2 + 4 NH3 ? [Cu(H2O)2(NH3)4]2+ + 2 H2O + 2 OH?
Many other oxyanions form complexes; these include copper(II) acetate, copper(II) nitrate, and copper(II) carbonate. Copper(II) sulfate forms a blue crystalline pentahydrate, which is the most familiar copper compound in the laboratory. It is used in afungicide called the Bordeaux mixture.HP Pavilion DV4-1020TX Battery
Polyols, compounds containing more than one alcohol functional group, generally interact with cupric salts. For example, copper salts are used to test for reducing sugars. Specifically, usingBenedict's reagent and Fehling's solution the presence of the sugar is signaled by a color change from blue Cu(II) to reddish copper(I) oxide.HP Pavilion DV4-1020US Battery
Schweizer's reagent and related complexes with ethylenediamine and other aminesdissolve cellulose. Amino acids form very stable chelate complexes with copper(II). Many wet-chemical tests for copper ions exist, one involving potassium ferrocyanide, which gives a brown precipitate with copper(II) salts.HP Pavilion DV4-1021TX Battery
Compounds that contain a carbon-copper bond are known as organocopper compounds. They are very reactive towards oxygen to form copper(I) oxide and have many uses in chemistry.HP Pavilion DV4-1022TX Battery
They are synthesized by treating copper(I) compounds with Grignard reagents, terminal alkynes or organolithium reagents; in particular, the last reaction described produces a Gilman reagent. These can undergo substitution with alkyl halides to form coupling products; as such, they are important in the field of organic synthesis.HP Pavilion DV4-1023TX Battery
Copper(I) acetylide is highly shock-sensitive but is an intermediate in reactions such as the Cadiot-Chodkiewicz coupling and theSonogashira coupling. Conjugate addition to enones and carbocupration of alkynes can also be achieved with organocopper compounds.HP Pavilion DV4-1024TX Battery
Copper(I) forms a variety of weak complexes with alkenes and carbon monoxide, especially in the presence of amine ligands.
Copper(III) and copper(IV)
Complexes of copper(III) are frequent intermediates in reactions of organocopper compounds. Dicopper oxo complexes also feature copper(III).HP Pavilion DV4-1025TX Battery
Fluoride ligands, being highly basic, stabilize metal ions in high oxidation states; indeed, representative copper(III) and copper(IV) complex are fluorides. These include K3CuF6 and Cs2CuF6. With di- and tripeptides, purple-colored complexes of copper(III) have been observed, this high oxidation state being stabilized by the deprotonatedamide ligands.HP Pavilion DV4-1026TX Battery
Copper occurs naturally as native copper and was known to some of the oldest civilizations on record. It has a history of use that is at least 10,000 years old, and estimates of its discovery place it at 9000 BC in the Middle East; a copper pendant was found in northern Iraq that dates to 8700 BC.HP Pavilion DV4-1027TX Battery
There is evidence that gold and iron were the only metals used by humans before copper. Copper smelting was invented locally in several different places. It was probably discovered independently in China before 2800 BC, in Central America perhaps around 600 AD, and in West Africa about the 9th or 10th century AD.HP Pavilion DV4-1028TX Battery
Investment casting was invented in 4500–4000 BC in Southeast Asia and carbon dating has established mining at Alderley Edge in Cheshire, UK at 2280 to 1890 BC. Ötzi the Iceman, a male dated from 3300–3200 BC, was found with an axe with a copper head 99.7% pure; high levels of arsenic in his hair suggest his involvement in copper smelting.HP Pavilion DV4-1028US Battery
Experience with copper has assisted the development of other metals; in particular, copper smelting led to the discovery of iron smelting. Production in the Old Copper Complex in Michigan and Wisconsin is dated between 6000 and 3000 BC.HP Pavilion DV4-1029TX Battery
Alloying of copper with zinc or tin to make brass and bronze was practiced soon after the discovery of copper. Bronze artifacts from Sumerian cities and Egyptianartifacts of copper and bronze alloys date to 3000 BC. The Bronze Age was from 2500 BC to 600 BC when usage of bronze was widespread in Europe;HP Pavilion DV4-1030EE Battery
the transition between the Neolithic period and the Bronze Age is termed the Chalcolithic period (copper-stone), with copper tools being used with stone tools. Brass was known to the Greeks, but became a significant supplement to bronze during the Roman Empire.HP Pavilion DV4-1030EI Battery
Antiquity and Middle Ages
In Greece, copper was known by the name chalkos (??????). It was an important resource for the Romans, Greeks and other ancient peoples. In Roman times, it was known as aes Cyprium, aes being the generic Latin term for copper alloys and Cyprium from Cyprus, where much copper was mined.HP Pavilion DV4-1030EJ Battery
The phrase was simplified to cuprum, hence the English copper. Aphrodite and Venus represented copper in mythology and alchemy, due to its lustrous beauty, its ancient use in producing mirrors, and its association with Cyprus, which was sacred to the goddess.HP Pavilion DV4-1030EN Battery
The seven heavenly bodies known to the ancients were associated with the seven metals known in antiquity, and Venus was assigned to copper.
Britain's first use of brass occurred around the 3rd–2nd century BC. In North America, copper mining began with marginal workings by Native Americans.HP Pavilion DV4-1030TX Battery
Native copper is known to have been extracted from sites on Isle Royale with primitive stone tools between 800 and 1600.Copper metallurgy was flourishing in South America, particularly in Peru around 1000 AD; it proceeded at a much slower rate on other continents.HP Pavilion DV4-1031TX Battery
Copper burial ornamentals from the 15th century have been uncovered, but the metal's commercial production did not start until the early 20th century.
The cultural role of copper has been important, particularly in currency. Romans in the 6th through 3rd centuries BC used copper lumps as money.HP Pavilion DV4-1032TX Battery
At first, the copper itself was valued, but gradually the shape and look of the copper became more important. Julius Caesar had his own coins made from brass, whileOctavianus Augustus Caesar's coins were made from Cu-Pb-Sn alloys. With an estimated annual output of around 15,000 t,HP Pavilion DV4-1033TX Battery
Roman copper mining and smelting activitiesreached a scale unsurpassed until the time of the Industrial Revolution; the provinces most intensely mined were those of Hispania, Cyprus and in Central Europe.
The gates of the Temple of Jerusalem used Corinthian bronze made by depletion gilding. It was most prevalent in Alexandria, where alchemy is thought to have begun.HP Pavilion DV4-1034TX Battery
In ancient India, copper was used in the holistic medical science Ayurveda for surgical instruments and other medical equipment. Ancient Egyptians (~2400 BC) used copper for sterilizing wounds and drinking water, and later on for headaches, burns, and itching.HP Pavilion DV4-1035LA Battery
The Baghdad Battery, with copper cylinders soldered to lead, dates back to 248 BC to AD 226 and resembles a galvanic cell, leading people to believe this was the first battery; the claim has not been verified.
The Great Copper Mountain was a mine in Falun, Sweden, that operated from the 10th century to 1992.HP Pavilion DV4-1035TX Battery
It produced two thirds of Europe's copper demand in the 17th century and helped fund many of Sweden's wars during that time. It was referred to as the nation's treasury; Sweden had a copper backed currency.
The uses of copper in art were not limited to currency: it was used by Renaissance sculptors, in pre-photographic technology known as the daguerreotype, and the Statue of Liberty.HP Pavilion DV4-1036TX Battery
Copper plating and copper sheathing for ships' hulls was widespread; the ships of Christopher Columbus were among the earliest to have this feature. The Norddeutsche Affinerie in Hamburg was the first modern electroplating plant starting its production in 1876.HP Pavilion DV4-1037TX Battery
The German scientist Gottfried Osann invented powder metallurgy in 1830 while determining the metal's atomic mass; around then it was discovered that the amount and type of alloying element (e.g. tin) to copper would affect bell tones. Flash smelting was developed by Outokumpu in Finland and first applied atHarjavalta in 1949;HP Pavilion DV4-1038TX Battery
the energy-efficient process accounts for 50% of the world’s primary copper production.
The Intergovernmental Council of Copper Exporting Countries, formed in 1967 with Chile, Peru, Zaire and Zambia, played a similar role for copper as OPEC does for oil. It never achieved the same influence, particularly because the second-largest producer, the United States, was never a member; it was dissolved in 1988.HP Pavilion DV4-1039TX Battery
The major applications of copper are in electrical wires (60%), roofing and plumbing (20%) and industrial machinery (15%). Copper is mostly used as a metal, but when a higher hardness is required it is combined with other elements to make an alloy (5% of total use) such as brass and bronze.HP Pavilion DV4-1040EE Battery
A small part of copper supply is used in production of compounds for nutritional supplements and fungicides in agriculture. Machining of copper is possible, although it is usually necessary to use an alloy for intricate parts to get good machinability characteristics.HP Pavilion DV4-1040EI Battery
Electronics and related devices
The electrical properties of copper are exploited in copper wires and devices such aselectromagnets. Integrated circuits and printed circuit boards increasingly feature copper in place of aluminium because of its superior electrical conductivity (see Copper interconnectfor main article);HP Pavilion DV4-1040TX Battery
heat sinks and heat exchangers use copper as a result of its superior heat dissipation capacity to aluminium. Vacuum tubes, cathode ray tubes, and the magnetrons in microwave ovens use copper, as do wave guides for microwave radiation.
Architecture and industry
Because of the waterproof nature of copper, it has been used as the roofing material of many buildings since ancient times.HP Pavilion DV4-1041TX Battery
The green color on these buildings is due to a long-term chemical reaction: copper is first oxidized to copper(II) oxide, then to cuprous and cupric sulfide and finally to copper(II) carbonate, also called verdigris, which is highly corrosion-resistant. The copper used in this application is phosphorus deoxidized copper (Cu-DHP).HP Pavilion DV4-1042TX Battery
Lightning rods use copper as a means to divert electric current throughout the ground instead of destroying the main structure.Copper has excellent brazing and solderingproperties and can be welded; the best results are obtained with gas metal arc welding.HP Pavilion DV4-1043TX Battery
Copper in alloys
Numerous copper alloys exist, many with important uses. Brass is an alloy of copper and zinc and bronze usually refers to copper-tin alloys, but can refer to any alloy of copper such as aluminium bronze. Copper is one of the most important constituents ofcarat silver and gold alloys and carat solders used in the jewelry industry, modifying the color, hardness and melting point of the resulting alloys.HP Pavilion DV4-1044TX Battery
The alloy of copper and nickel, called cupronickel, is used in low-denomination statuary coins, often for the outer cladding. The US 5-cent coin called nickel consists of 75% copper and 25% nickel and has a homogeneous composition. The 90% copper/10% nickel alloy is remarkable by its resistance to corrosion and is used in various parts being exposed to seawater.HP Pavilion DV4-1045TX Battery
Alloys of copper with aluminium (about 7%) have a pleasant golden color and are used in decorations. Copper alloys with tin are part of lead-free solders.
Copper-alloy touch surfaces have natural intrinsic properties to destroy a wide range of microorganismsHP Pavilion DV4-1046TX Battery
(e.g., E. coli O157:H7,methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus, Clostridium difficile, influenza A virus, adenovirus, andfungi). Some 355 copper alloys were proven to kill more than 99.9% of disease-causing bacteria within just two hours when cleaned regularly.HP Pavilion DV4-1047TX Battery
The United States Environmental Protection Agency (EPA) has approved the registrations of these copper alloys as “antimicrobial materials with public health benefits," which allows manufacturers to legally make claims as to the positive public health benefits of products made with registered antimicrobial copper alloys.HP Pavilion DV4-1048TX Battery
In addition, the EPA has approved a long list of antimicrobial copper products made from these alloys, such as bedrails, handrails, over-bed tables, sinks, faucets,door knobs, toilet hardware, computer keyboards, health club equipment, shopping cart handles, etc. (for a comprehensive list of products, see: Antimicrobial copper-alloy touch surfaces#Approved products).HP Pavilion DV4-1049TX Battery
Copper doorknobs are used by hospitals to reduce the transfer of disease, and Legionnaires' disease is suppressed by copper tubing in plumbing systems. Antimicrobial copper alloy products are now being installed in healthcare facilities in the U.K., Ireland, Japan, Korea, France, Denmark, and Brazil and in the subway transit system in Santiago,HP Pavilion DV4-1050 Battery
Chile, where copper-zinc alloy handrails will be installed in some 30 stations between 2011–2014.
Copper has long been used as a biostatic surface to line parts of ships to protect against barnacles and mussels. It was originally used pure, but has since been superseded by Muntz metal.HP Pavilion DV4-1050EE Battery
Bacteria will not grow on a copper surface because it is biostatic. Similarly, as discussed in copper alloys in aquaculture, copper alloys have become important netting materials in the aquaculture industry for the fact that they are antimicrobial and prevent biofouling even in extreme conditions and have strong structural and corrosion-resistant properties in marine environments.HP Pavilion DV4-1050EL Battery
Copper compounds in liquid form are used as a wood preservative, particularly in treating original portion of structures during restoration of damage due to dry rot. Together with zinc, copper wires may be placed over non-conductive roofing materials to discourage the growth of moss.HP Pavilion DV4-1050EP Battery
Textile fibers use copper to create antimicrobial protective fabrics, as do ceramic glazes, stained glass and musical instruments. Electroplating commonly uses copper as a base for other metals such as nickel.
Copper is one of three metals, along with lead and silver, used in a museum materials testing procedure called the Oddy test. In this procedure, copper is used to detect chlorides, oxides, and sulfur compounds.HP Pavilion DV4-1050ER Battery
Copper is also commonly found in jewelry, and folklore states that copper bracelets relieve arthritis symptoms, though this is not proven.
Copper proteins have diverse roles in biological electron transport and oxygen transportation, processes that exploit the easy interconversion of Cu(I) and Cu(II).HP Pavilion DV4-1050TX Battery
The biological role for copper commenced with the appearance of oxygen in earth's atmosphere. The protein hemocyanin is the oxygen carrier in most mollusks and some arthropods such as the horseshoe crab(Limulus polyphemus). Because hemocyanin is blue, these organisms have blue blood, not the red blood found in organisms that rely on hemoglobin for this purpose.HP Pavilion DV4-1051 Battery
Structurally related to hemocyanin are the laccases and tyrosinases. Instead of reversibly binding oxygen, these proteins hydroxylate substrates, illustrated by their role in the formation of lacquers.
Copper is also a component of other proteins associated with the processing of oxygen.HP Pavilion DV4-1051TX Battery
In cytochrome c oxidase, which is required for aerobic respiration, copper and iron cooperate in the reduction of oxygen. Copper is also found in many superoxide dismutases, proteins that detoxify superoxides, by converting it (by disproportionation) to oxygen and hydrogen peroxide:HP Pavilion DV4-1052 Battery
2 HO2 ? H2O2 + O2
Several copper proteins, such as the "blue copper proteins", do not interact directly with substrates, hence they are not enzymes. These proteins relay electrons by the process called electron transfer.HP Pavilion DV4-1052TX Battery
Copper is an essential trace element in plants and animals, but not some microorganisms. The human body contains copper at a level of about 1.4 to 2.1 mg per kg of body mass. Stated differently, the RDA for copper in normal healthy adults is quoted as 0.97 mg/day and as 3.0 mg/day.HP Pavilion DV4-1053 Battery
Copper is absorbed in the gut, then transported to the liver bound to albumin. It enters the bloodstream via the plasma protein called ceruloplasmin, where its metabolism is controlled, and is excreted in bile.
Because of its role in facilitating iron uptake, copper deficiency can produce anemia-like symptoms,HP Pavilion DV4-1053TX Battery
neutropenia, bone abnormalities, hypopigmentation, impaired growth, increased incidence of infections, osteoporosis, and abnormalities in glucose and cholesterol metabolism. Conversely, an accumulation of copper in body tissues causes Wilson's disease.HP Pavilion DV4-1054TX Battery
Severe deficiency can be found by testing for low plasma or serum copper levels, low ceruloplasmin, and low red blood cell superoxide dismutase levels; these are not sensitive to marginal copper status. The "cytochrome c oxidase activity of leucocytes and platelets" has been stated as another factor in deficiency, but the results have not been confirmed by replication.HP Pavilion DV4-1055TX Battery
Numerous antimicrobial efficacy studies have been conducted in the past 10 years regarding copper’s efficacy to destroy a wide range of bacteria, as well asinfluenza A virus, adenovirus, and fungi.HP Pavilion DV4-1070 Battery
Extensive EPA-sanctioned tests using Good Laboratory Practices have found that when cleaned regularly, some 355 different EPA-registered antimicrobial copper alloy surfaces:
- Continuously reduce bacterial contamination, achieving 99.9% reduction within two hours of exposure;HP Pavilion DV4-1070EE Battery
- Kill greater than 99.9% of Gram-negative and Gram-positive bacteria within two hours of exposure;
- Deliver continuous and ongoing antibacterial action, remaining effective in killing greater than 99.9% of bacteria within two hours;HP Pavilion DV4-1070EF Battery
- Kill greater than 99.9% of bacteria within two hours, and continue to kill 99% of bacteria even after repeated contamination;
- Help inhibit the buildup and growth of bacteria within two hours of exposure between routine cleaning and sanitizing steps.HP Pavilion DV4-1070ER Battery
- Testing demonstrates effective antibacterial activity against E. coli O157:H7, methicillin-resistant Staphylococcus aureus(MRSA), Staphylococcus Epidermidis,Enterobacter aerogenes, and Pseudomonas aeruginosa.
Several of the aforementioned bacteria are responsible for a large portion of the nearly two million hospital-acquired infections contracted each year in the United States.HP Pavilion DV4-1070ES Battery
Gram quantities of various copper salts have been taken in suicide attempts and produced acute copper toxicity in humans, possibly due to redox cycling and the generation of reactive oxygen species that damage DNA. Corresponding amounts of copper salts (30 mg/kg) are toxic in animals.HP Pavilion DV4-1080EI Battery
A minimum dietary value for healthy growth in rabbits has been reported to be at least 3 ppm in the diet. However, higher concentrations of copper (100 ppm, 200 ppm, or 500 ppm) in the diet of rabbits may favorably influence feed conversion efficiency, growth rates, and carcass dressing percentages.HP Pavilion DV4-1080EO Battery
Chronic copper toxicity does not normally occur in humans because of transport systems that regulate absorption and excretion. Autosomal recessive mutations in copper transport proteins can disable these systems, leading to Wilson's disease with copper accumulation and cirrhosis of the liver in persons who have inherited two defective genes.HP Pavilion DV4-1080ES Battery
Electroplating is a plating process in which metal ions in a solution are moved by an electric field to coat an electrode. The process uses electrical current to reduce cations of a desired material from a solution and coat a conductive object with a thin layer of the material, such as a metal.HP Pavilion DV4-1090EO Battery
Electroplating is primarily used for depositing a layer of material to bestow a desired property (e.g., abrasion and wear resistance, corrosion protection, lubricity, aesthetic qualities, etc.) to a surface that otherwise lacks that property. Another application uses electroplating to build up thickness on undersized parts.HP Pavilion DV4-1090ES Battery
The process used in electroplating is called electrodeposition. It is analogous to a galvanic cell acting in reverse. The part to be plated is the cathode of the circuit. In one technique, the anode is made of the metal to be plated on the part. Both components are immersed in a solution called an electrolyte containing one or more dissolved metal salts as well as other ionsthat permit the flow of electricity.HP Pavilion DV4-1100 Battery
A power supply supplies a direct current to the anode, oxidizing the metal atoms that comprise it and allowing them to dissolve in the solution. At the cathode, the dissolved metal ions in the electrolyte solution are reduced at the interface between the solution and the cathode, such that they "plate out" onto the cathode.HP Pavilion DV4-1100EA Battery
The rate at which the anode is dissolved is equal to the rate at which the cathode is plated, vis-a-vis the current flowing through the circuit. In this manner, the ions in the electrolyte bath are continuously replenished by the anode.
Other electroplating processes may use a non-consumable anode such as lead. In these techniques, ions of the metal to be plated must be periodically replenished in the bath as they are drawn out of the solution.HP Pavilion DV4-1101 Battery
The anode and cathode in the electroplating cell are both connected to an external supply of direct current — a battery or, more commonly, a rectifier. The anode is connected to the positive terminal of the supply, and the cathode (article to be plated) is connected to the negative terminal.HP Pavilion DV4-1101TU Battery
When the external power supply is switched on, the metal at the anode is oxidized from the zero valence state to form cations with a positive charge. These cations associate with the anions in the solution. The cations are reduced at the cathode to deposit in the metallic, zero valence state.HP Pavilion DV4-1101TX Battery
For example, in an acid solution, copper is oxidized at the anode to Cu2+ by losing two electrons. The Cu2+ associates with the anion SO42- in the solution to form copper sulfate. At the cathode, the Cu2+ is reduced to metallic copper by gaining two electrons. The result is the effective transfer of copper from the anode source to a plate covering the cathode.HP Pavilion DV4-1102 Battery
The plating is most commonly a single metallic element, not an alloy. However, some alloys can be electrodeposited, notably brassand solder.
Many plating baths include cyanides of other metals (e.g., potassium cyanide) in addition to cyanides of the metal to be deposited.HP Pavilion DV4-1102TU Battery
These free cyanides facilitate anode corrosion, help to maintain a constant metal ion level and contribute to conductivity. Additionally, non-metal chemicals such as carbonates and phosphates may be added to increase conductivity.
When plating is not desired on certain areas of the substrate, stop-offs are applied to prevent the bath from coming in contact with the substrate.HP Pavilion DV4-1102TX Battery
Typical stop-offs include tape, foil, lacquers, and waxes.
Initially, a special plating deposit called a "strike" or "flash" may be used to form a very thin (typically less than 0.1 micrometer thick) plating with high quality and good adherence to the substrate.HP Pavilion DV4-1103TU Battery
This serves as a foundation for subsequent plating processes. A strike uses a high current density and a bath with a low ion concentration. The process is slow, so more efficient plating processes are used once the desired strike thickness is obtained.
The striking method is also used in combination with the plating of different metals.HP Pavilion DV4-1103TX Battery
If it is desirable to plate one type of deposit onto a metal to improve corrosion resistance but this metal has inherently poor adhesion to the substrate, a strike can be first deposited that is compatible with both. One example of this situation is the poor adhesion of electrolytic nickel on zinc alloys, in which case a copper strike is used, which has good adherence to both.HP Pavilion DV4-1104TU Battery
A closely related process is brush electroplating, in which localized areas or entire items are plated using a brush saturated with plating solution.HP Pavilion DV4-1104TX Battery
The brush, typically a stainless steel body wrapped with a cloth material that both holds the plating solution and prevents direct contact with the item being plated, is connected to the positive side of a low voltage direct-current power source, and the item to be plated connected to the negative. HP Pavilion DV4-1105EF Battery
The operator dips the brush in plating solution then applies it to the item, moving the brush continually to get an even distribution of the plating material. Brush electroplating has several advantages over tank plating, including portability, ability to plate items that for some reason cannot be tank platedHP Pavilion DV4-1105EM Battery
(one application was the plating of portions of very large decorative support columns in a building restoration), low or no masking requirements, and comparatively low plating solution volume requirements. Disadvantages compared to tank plating can include greater operator involvement (tank plating can frequently be done with minimal attention), and inability to achieve as great a plate thickness.HP Pavilion DV4-1105TU Battery
Usually an electrolytic cell (consisting of two electrodes, electrolyte, and external source of current) is used for electrodeposition. In contrast, an electroless deposition process uses only one electrode and no external source of electric current.HP Pavilion DV4-1105TX Battery
However, the solution for the electroless process needs to contain a reducing agent so that the electrode reaction has the form:
In principle any water-based reducer can be used although the redox potential of the reducer half-cell must be high enough to overcome the energy barriers inherent in liquid chemistry.HP Pavilion DV4-1106EE Battery
Electroless nickel plating uses hypophosphite as the reducer while plating of other metals like silver, gold and copper typically use low molecular weight aldehydes.
A major benefit of this approach over electroplating is that power sources and plating baths are not needed, reducing the cost of production.HP Pavilion DV4-1106EM Battery
The technique can also plate diverse shapes and types of surface. The downside is that the plating process is usually slower and cannot create such thick plates of metal. As a consequence of these characteristics, electroless deposition is quite common in the decorative arts.HP Pavilion DV4-1106TX Battery
Cleanliness is essential to successful electroplating, since molecular layers of oil can prevent adhesion of the coating. ASTM B322 is a standard guide for cleaning metals prior to electroplating. Cleaning processes include solvent cleaning, hot alkaline detergent cleaning, electro-cleaning, and acid treatment etc.HP Pavilion DV4-1107TX Battery
The most common industrial test for cleanliness is the waterbreak test, in which the surface is thoroughly rinsed and held vertical. Hydrophobic contaminants such as oils cause the water to bead and break up, allowing the water to drain rapidly. Perfectly clean metal surfaces are hydrophilic and will retain an unbroken sheet of water that does not bead up or drain off.HP Pavilion DV4-1108TX Battery
ASTM F22 describes a version of this test. This test does not detect hydrophilic contaminants, but the electroplating process can displace these easily since the solutions are water-based. Surfactants such as soap reduce the sensitivity of the test and must be thoroughly rinsed off.HP Pavilion DV4-1109TX Battery
An example of a mechanical change is a change in tensile strength or surfacehardness which is a required attribute in tooling industry.
Although it is not confirmed, the Parthian Battery may have been the first system used for electroplating.HP Pavilion DV4-1110TX Battery
Modern electrochemistry was invented by Italian chemist Luigi V. Brugnatelli in 1805. Brugnatelli used his colleague Alessandro Volta's invention of five years earlier, the voltaic pile, to facilitate the first electrodeposition. Brugnatelli's inventions were suppressed by the French Academy of Sciences and did not become used in general industry for the following thirty years.HP Pavilion DV4-1111TX Battery
By 1839, scientists in Britain and Russia had independently devised metal deposition processes similar to Brugnatelli's for the copper electroplating of printing press plates.
Boris Jacobi in Russia not only rediscovered galvanoplastics, but developed electrotyping andgalvanoplastic sculpture.HP Pavilion DV4-1112TX Battery
Galvanoplactics quickly came into fashion in Russia, with such people as inventor Peter Bagration, scientist Heinrich Lenz and science fiction author Vladimir Odoyevsky all contributing to further development of the technology. Among the most notorious cases of electroplating usage in mid-19th century Russia were gigantic galvanoplastic sculptures of St.HP Pavilion DV4-1113TX Battery
Isaac's Cathedral in Saint Petersburg and gold-electroplated dome of theCathedral of Christ the Saviour in Moscow, the tallest Orthodox church in the world.
Soon after, John Wright of Birmingham, England discovered that potassium cyanide was a suitableelectrolyte for gold and silver electroplating.HP Pavilion DV4-1114NR Battery
Wright's associates, George Elkington and Henry Elkington were awarded the first patents for electroplating in 1840. These two then founded the electroplating industry in Birmingham from where it spread around the world.
The Norddeutsche Affinerie in Hamburg was the first modern electroplating plant starting its production in 1876.HP Pavilion DV4-1114TX Battery
As the science of electrochemistry grew, its relationship to the electroplating process became understood and other types of non-decorative metal electroplating processes were developed. Commercial electroplating of nickel, brass, tin, and zinc were developed by the 1850s.HP Pavilion DV4-1115EF Battery
Electroplating baths and equipment based on the patents of the Elkingtons were scaled up to accommodate the plating of numerous large scale objects and for specific manufacturing and engineering applications.
The plating industry received a big boost from the advent of the development of electric generators in the late 19th century.HP Pavilion DV4-1115TX Battery
With the higher currents, available metal machine components, hardware, and automotive parts requiring corrosion protection and enhanced wear properties, along with better appearance, could be processed in bulk.
The two World Wars and the growing aviation industry gave impetus to further developments and refinements including such processes as hard chromium plating,HP Pavilion DV4-1116TX Battery
bronzealloy plating, sulfamate nickel plating, along with numerous other plating processes. Plating equipment evolved from manually operated tar-lined wooden tanks to automated equipment, capable of processing thousands of kilograms per hour of parts.HP Pavilion DV4-1117CA Battery
One of the American physicist Richard Feynman's first projects was to develop technology for electroplating metal onto plastic. Feynman developed the original idea of his friend into a successful invention, allowing his employer (and friend) to keep commercial promises he had made but could not have fulfilled otherwise.HP Pavilion DV4-1117TX Battery
Electroplating is a useful process process. It is widely used in industry for coating metal objects with a thin layer of a different metal. The layer of metal deposited has some desired property, which metal of the object lacks. For example chromium plating is done on many objects such as car parts, bath taps, kitchen gas burners, wheel rims and many others.HP Pavilion DV4-1118CA Battery
The Hull cell is a type of test cell used to qualitatively check the condition of an electroplating bath. It allows for optimization for current density range, optimization of additive concentration, recognition of impurity effects and indication of macro-throwing power capability.HP Pavilion DV4-1118TX Battery
The Hull cell replicates the plating bath on a lab scale. It is filled with a sample of the plating solution, an appropriate anode which is connected to a rectifier. The "work" is replaced with a hull cell test panel that will be plated to show the "health" of the bath.
The Hull cell is a trapezoidal container that holds 267 ml of solution.HP Pavilion DV4-1119TX Battery
This shape allows one to place the test panel on an angle to the anode. As a result, the deposit is plated at different current densities which can be measured with a hull cell ruler. The solution volume allows for a quantitative optimization of additive concentration: 1 gram addition to 267 mL is equivalent to 0.5 oz/gal in the plating tank.HP Pavilion DV4-1120BR Battery
Erosion corrosion, also known as impingement damage, is the combined effect of corrosion and erosion caused by rapid flowing turbulent water. It is probably the second most common cause of copper tube failures behind Type 1 pitting which is also known as Cold Water Pitting of Copper Tube.HP Pavilion DV4-1120TX Battery
Copper water tubes
Copper tubes have been used to distribute drinking water within buildings for many years, and hundreds of miles are installed throughout Europe every year. The long life of copper when exposed to natural waters is a result of its thermodynamic stability,HP Pavilion DV4-1120US Battery
its high resistance to reacting with the environment, and the formation of insoluble corrosion products that insulate the metal from the environment. The corrosion rate of copper in most drinkable waters is less than 2.5 µm/year, at this rate a 15 mm tube with a wall thickness of 0.7 mm would last for about 280 years.HP Pavilion DV4-1121BR Battery
In some soft waters the general corrosion rate may increase to 12.5 µm/year, but even at this rate it would take over 50 years to perforate the same tube.
If the general water speed or the degree of local turbulence in an installation is high, the protective film that would normally be formed on a copper tube as a result of slight initial corrosion, may be torn off the surface locally,HP Pavilion DV4-1121CA Battery
permitting further corrosion to take place at that point. If this process continues it can produce deep localised attack of the type known as erosion-corrosion or impingement damage. The actual attack on the metal is by the corrosive action of the water to which it is exposed while the erosive factor is the mechanical removal of the corrosion product from the surface.HP Pavilion DV4-1121TX Battery
Impingement attack produces highly characteristic water-swept pits, which are often horseshoe shaped, or it can produce broader areas of attack. The leading edge of the pit is frequently undercut by the swirling action of the water. Usually, the surface of the metal within the pits or areas of attack is smooth and carries no substantial corrosion product.HP Pavilion DV4-1122TX Battery
Erosion-corrosion is known to occur in pumped-circulation hot water distribution systems, and even in cold water distribution systems, if the water velocities are too high. The factors influencing the attack include the chemical character of the water passing through the system,HP Pavilion DV4-1123LA Battery
the temperature, the average water velocity in the system and the presence of any local features likely to induce turbulence in the water stream.
It is unusual for the general water velocity in a system to be so high that impingement attack occurs throughout the whole of the copper pipework.HP Pavilion DV4-1123TX Battery
More commonly, the velocity is just sufficiently low for satisfactory protective films to be formed and to remain in position on most of the system, with impingement damage more likely to occur where there is an abrupt change in the direction of water flow giving rise to a high degree of turbulence, such as at tee pieces and elbow fittings.HP Pavilion DV4-1123US Battery
It is not generally realised how great an effect small obstructions can have on the flow pattern of water in a pipe-work system and the extent to which they can induce turbulence and cause corrosion-erosion. For example, it is most important, as far as possible, to ensure that copper tubes cut with a tube cutter are deburred before making the joint.HP Pavilion DV4-1124LA Battery
Also a gap between the tube end and the stop in the fitting, due to the tube not having been cut to the correct length and fully inserted into the socket of the fitting, can also induce turbulence in the water stream.
The rate of impingement attack on copper also depends to some extent on the temperature of the water.HP Pavilion DV4-1124NR Battery
The maximum velocities for fresh waters at different temperatures recommended in Sweden are given in the table below. These figures are for aerated waters of pH not less than about 7.
Recommended Maximum Water Velocities at Different Temperatures for Copper (m/s)HP Pavilion DV4-1124TX Battery
§ These velocities give a risk of impingement attack and are acceptable only for small bore connections to taps, flushing cisterns etc., through which water flow is intermittent.
BS 6700 gives the following maximum water velocities although it does note that these are currently under investigation and the velocities specified will be amended if the results of this investigation so require.HP Pavilion DV4-1125BR Battery
The minimum water speed at which copper pipes suffer impingement attack depends also to some extent on water composition. Aggressive waters that tend to be cupro-solvent are the most likely to give rise to impingement attack. Installations in large buildings where flow rates may be high and water is in continuous circulation are much more susceptible to attack than ordinary domestic installations.HP Pavilion DV4-1125LA Battery
A high mineral content or a pH below 7 is likely to increase the possibility of corrosion-erosion occurring while a positive Langelier Index and consequent tendency to deposit a calcium carbonate scale is generally beneficial. The presence or absence of colloidal organic matter is also probably of some importance.HP Pavilion DV4-1125NR Battery
Remedial measures for impingement attack include modifications to the system to reduce the average water velocity, e.g. by using larger diameter tubes or, if appropriate, to lower the pump speed, and/or to redesign the part of the installation concerned to eliminate the cause of local turbulence, e.g. by using slow or swept bends and tee fittings rather than elbows and square tees.HP Pavilion DV4-1125TX Battery
It is important to minimise the possibility of any local turbulence occurring by ensuring that the ends of tubes cut with a tube cutter are deburred and that the tubes are inserted fully to the stops in the fitting before the joints are made, as referred to earlier in this section.HP Pavilion DV4-1126LA Battery
In some cases, where the above approaches are not possible, the length of copper tube affected can sometimes be replaced by materials more resistant to corrosion-erosion, e.g. 90/10 copper-nickel (BS Designation CN102) using appropriate fittings, or stainless steel to BS 4127:1994.HP Pavilion DV4-1126TX Battery
Cold water pitting of copper tube occurs in only a minority of installations. Copper water tubes are usually guaranteed by the manufacturer against manufacturing defects for a period of 50 years. The vast majority of copper systems far exceed this time period but a small minority may fail after a comparatively short time.HP Pavilion DV4-1127LA Battery
The majority of failures seen are the result of poor installation or operation of the water system. The most common failure seen in the last 20 years is pitting corrosion in cold water tubes, also known as Type 1 pitting. These failures are usually the result of poor commissioning practice although a significant number are initiated by flux left in the bore after assembly of soldered joints.HP Pavilion DV4-1127TX Battery
Prior to about 1970 the most common cause of Type 1 pitting was carbon films left in the bore by the manufacturing process.
Research and manufacturing improvements in the 1960s virtually eliminated carbon as a cause of pitting with the introduction of a clause in the 1971 edition of BS 2871 requiring tube bores to be free of deleterious films.HP Pavilion DV4-1128TX Battery
Despite this, carbon is still regularly blamed for tube failures without proper investigation.
Copper water tubes
Copper tubes have been used to distribute potable water within building for many years and hundreds of miles are installed throughout Europe every year.HP Pavilion DV4-1129LA Battery
The long life of copper when exposed to natural waters is a result of its thermodynamic stability, its high resistance to reacting with the environment, and the formation of insoluble corrosion products that insulate the metal from the environment.HP Pavilion DV4-1129TX Battery
The corrosion rate of copper in most potable waters is less than 25 µm/year, at this rate a 15 mm tube with a wall thickness of 0.7 mm would last for about 280 years. In some soft waters the general corrosion rate may increase to 125 µm/year, but even at this rate it would take over 50 years to perforate the same tube.HP Pavilion DV4-1130BR Battery
Despite the reliability of copper and copper alloys, in some cold hard waters pits may form in the bore of a tube. If these pits form, failure times can be expected between 6 months and 2 years from initiation. The mechanism that leads to the pitting of copper in cold hard waters is complex,HP Pavilion DV4-1130TX Battery
it requires a water with a specific chemistry that is capable of supporting pit growth and a mechanism for the initiation of the pits.
The pits that penetrate the bore are usually covered in a hard pale green nodule of copper sulfate and copper hydroxide salts.HP Pavilion DV4-1131BR Battery
If the nodule is removed a hemispherical pit is revealed filled with coarse crystals of red cuprous oxide and green cuprous chloride. The pits are often referred to as Type 1 pits and the form of attack as Type 1 pitting.
The characteristics capable of supporting Type 1 pits were determined empirically by Lucey after examining the compositions of waters in which the pitting behaviour was known.HP Pavilion DV4-1131TX Battery
They should be cold, less than 30°C, hard or moderately hard, 170 to 300 mg/l carbonate hardness, and organically pure. Organically pure waters usually originate from deep wells, or boreholes. Surface waters from rivers or lakes contain naturally occurring organic compounds that inhibit the formation of Type 1 pits,HP Pavilion DV4-1132TX Battery
unless a deflocculation treatment has been carried out that removes organic material. Type 1 pitting is relatively uncommon in North America and this may be a result of the lower population density allowing a significant proportion of the potable water to be obtained from surface derived sources.HP Pavilion DV4-1133TX Battery
In addition to being cold hard and organically pure, the water needs a specific chemistry. The effect of the water chemistry can be empirically determined though use of the Pitting Propensity Rating (PPR) a number that takes into account the sulfate, chloride, nitrate and sodium ion concentrations of the water as well as its acidity or pH.HP Pavilion DV4-1134TX Battery
A water with a positive PPR has been shown to be capable of propagating Type 1 pits.
Many waters in both the UK and Europe are capable of supporting Type 1 pitting but no problems will be experienced unless a pit is initiated in the wall of the tube.HP Pavilion DV4-1135BR Battery
When a copper tube is initially filled with a hard water salts deposit on the wall and the copper slowly reacts with the water producing a thin protective layer of mixed corrosion products and hardness scale. If any pitting of the tube is to occur then this film must be locally disrupted. There are three mechanisms that allow the disruption of the protective deposits.HP Pavilion DV4-1135EE Battery
The most well known, although now the least common, is the presence of carbon films on the bore. Stagnation and flux residues are the most common initiation mechanisms that have led to Type 1 pitting failures in the last ten years.
Copper tubes are made from the large billets of copper that are gradually worked and drawn down to the required size.HP Pavilion DV4-1135EI Battery
As the tubes are drawn they are heat treated to produce the correct mechanical properties. The organic oils and greases used to lubricate the tubes during the drawing processes are broken down during the heat treatment and gradually coat the tube with a film of carbon.HP Pavilion DV4-1135TX Battery
If the carbon is left in the bore of the tube then it disrupts the formation of the protective scale and allows the initiation of pits in the wall. The presence of deleterious films, such as carbon, has been prohibited by the British Standards in copper tubes since 1969.HP Pavilion DV4-1136BR Battery
All copper tubes for water service are treated, usually by grit blasting or acid pickling, to remove any films produced during manufacture with the result that Type 1 pitting initiated by carbon films is now very rare.
If water is left to stand in a tube for an extended period, the chemical characteristics of the water change as the mixed scale and corrosion products are deposited.HP Pavilion DV4-1136TX Battery
In addition any loose scale that is not well adhered to the wall will not be flushed away and air dissolved in the water will form bubbles, producing air pockets. These processes can lead to a number of problems mainly on horizontal tube runs. Particles of scale that do not adhere to the walls and are not washed away tend to fall into the bottom of the tube producing a coarse porous deposit.HP Pavilion DV4-1137TX Battery
Air pockets that develop in horizontal runs disrupt the formation of protective scales in two areas. The water lines at the sides and the air space at the top of the tube.
In each of the areas that the scale has been disrupted there is the possibility of the initiation of Type 1 pitting. Once pitting has initiated,HP Pavilion DV4-1138TX Battery
then even after the tube has been put back into service, the pit will continue to develop until the wall has perforated. This form of attack is often associated with the commissioning of a system. Once a system has been commissioned it should be either put immediately into service or drained down and dried by flushing with compressed air otherwise pitting may initiate.HP Pavilion DV4-1139TX Battery
If either of these options is not possible then the system should be flushed though regularly until it is put into use.
In plumbing systems fluxes are used to keep the mating surfaces clean during soldering operations. The fluxes often consist of corrosive chemicals such as ammonium chloride and zinc chloride in a binder such as petroleum jelly.HP Pavilion DV4-1140EK Battery
If too much flux is applied to the joint then the excess will melt and run down the bore of a vertical tube or pool in the bottom of a horizontal tube. Where the bore of the tube is covered in a layer of flux it may be locally protected from corrosion but at the edges of the flux pits often initiate.HP Pavilion DV4-1140GO Battery
If the tube is put into service in a water that supports Type 1 pitting then these pits will develop and eventually perforate the sides of the tube.
In most cases Type 1 pitting can be avoided by good working practices. Always use tubes that have been manufactured to BS EN 1057.HP Pavilion DV4-1140TX Battery
Tubes greater than 10 mm indiameter made to this standard will always be marked the number of the standard, the nominal size, wall thickness and temper of the tube, the manufacturer’s identification mark and the date of production at least every 600 mm. Tubes less than 10 mm in diameter will be similarly marked at each end.HP Pavilion DV4-1141TX Battery
Once a system has been commissioned it should be either put immediately into service or drained down and dried. If either of these options is not possible then the system should be flushed though regularly until it is put into use. It should not be left to stand for more than a week. At present stagnation is the most common cause of Type 1 pitting.HP Pavilion DV4-1142TX Battery
Flux should be used sparingly. A small quantity should be painted over the areas to be joined and any excess removed after the joint has been made. Some fluxes are marked as water-soluble but under some circumstances they are not removed before pitting has initiated.HP Pavilion DV4-1143GO Battery
Metal theft is the theft of metal items on a very large scale. These thefts usually increase when worldwide prices for scrap metal rise. In recent years, prices for metals have risen dramatically due to rapid industrialization in India and China. The metals most commonly stolen are copper, aluminium, brass, and bronze.HP Pavilion DV4-1143TX Battery
Other researchers have defined metal theft more specifically as "the theft of items for the value of their constituent metals." The defining characteristic of metal theft (besides being limited to items containing or made entirely from metal) is the motivation for the theft.HP Pavilion DV4-1144TX Battery
Whereas items are generally stolen for theirintrinsic value (e.g., stealing an iPod for its value as an iPod), items stolen in metal theft are stolen for their more or less extrinsic value as raw material or commodities. Items stolen in metal theft are ultimately scrapped, or recycled, to provide material for making new products.HP Pavilion DV4-1144US Battery
Motivations for theft
Scrap metal has drastically increased in price over recent years. In 2001, it sold for $77 a ton, increasing to $300/ton by 2004. In 2008, it hit nearly $500/ton. Some elected officials and law enforcement officials have concluded that many metal thefts are by drug addicts stealing metal in order to fund their addictions.HP Pavilion DV4-1145BR Battery
Some officials believe that most of these drug-related metal thefts are caused by methamphetamine users, however, this varies by the location the metal is being stolen. Regardless of the reason, developing nations such as China, India, and South Korea are ever-fueling the demand for it.HP Pavilion DV4-1145GO Battery
In the fourth quarter of 2008, however, world market prices for metals like copper, aluminium, and platinum dropped steeply. Although there is anecdotal evidence that this price decrease has led to fewer metal thefts, strong empirical research on the exact nature of relationship between commodity prices and metal thefts is still lacking.HP Pavilion DV4-1145TX Battery
Some have argued that the "genie is out of the bottle" now and drops in commodity prices will not result in corresponding drops in thefts. In fact, it is possible that thefts may actually increase to compensate for the loss in value.
Metal theft in South Africa is rampant, with an estimated of R5 billion per annum lost due to the theft.HP Pavilion DV4-1146TX Battery
The stolen metal ranges from copper cables, piping, bolts to manhole covers. The theft continuously disrupts and degrades services, such as the power supply provided by Eskom and the telecommunication services by Telkom. Eskom estimated that the theft has costed the company about R25 million per annum,HP Pavilion DV4-1147CL Battery
with incidents increasing from 446 incidents in 2005; 1,059 in 2007 and 1,914 in 2008. The theft has cost Telkom R863 million (April 2007 - January 2008 period). Despite the minimal copper reserve South Africa has, as much as 3000 tonnes of copper leave Cape Town harbour every month.HP Pavilion DV4-1147TX Battery
Aside from the economic impact, the theft also
The Non-Ferrous Crime Combatting Committee (NFCCC) has been formed specifically to combat this type of crime in the country.HP Pavilion DV4-1148TX Battery
In Australia, copper wiring, believed to be stolen from a variety of locations including rail tracks, power stations and scrap metal depots, was destined for the Asian black market.
From July to September 2005, a gang of thieves in Brunei dismantled and stole parts from more than 60 power substations in that country, including copper earthing cables and aluminum doors. It is apparently being sold as scrap metal.HP Pavilion DV4-1149TX Battery
The thefts are ongoing.In Quebec, during May 2006, thieves stole sections of copper roofing, gutters and wiring from four Quebec city churches, two being St. Charles de Limoilou and St. Francois d'Assise. The thieves were discovered in action on their third night, whereupon they fled.HP Pavilion DV4-1150BR Battery
High copper prices are believed to be the reason for the thefts. Repairs were expected to cost more than $40,000.
In October 2010, a 400 pound bronze bell was stolen in Shelburne County, Nova Scotia. Thieves removed the bell from a monument in Roseway Cemetery.HP Pavilion DV4-1150EO Battery
The bell was part of the Roseway United Memorial Church, built in 1912, until it was demolished in 1993. It was recovered in a Halifax-area scrapyard October 6.
327 bronze markers stolen from Theresienstadt concentration camp cemetery in mid-April 2008, with 700 more stolen the next week.HP Pavilion DV4-1150EP Battery
A scrap metal dealer was arrested on April 18, 2008. He intended to melt them down for their copper.
In February 2006, near the German city of Weimar, thieves dismantled and carted away some 5 kilometres (3 mi) of disused rail track, causing at least 200,000 euros worth of damage.HP Pavilion DV4-1150ER Battery
In Haiti, after the 2010 Haiti earthquake, some looters were reported to be removing rebar from the concrete of collapsed buildings in order to sell it. Others hacked up downed power lines.
In Japan, there were 5,700 metal theft reported cases in 2007 in locations as far apart as Shizuoka, Hiroshima and Okinawa.HP Pavilion DV4-1150ES Battery
On the 11th of January, 2011 an ICE train derailed near the Dutch city of Zevenaar. The cause of the accident was the theft of 300 meters of copper cable. Nobody was harmed.
In 2001, thieves in Khabarovsk Krai stole electric and telephone lines leading to military bases there. A small bridge was stolen in Russia in 2007, when a man chopped up its 5-meter span and hauled it away.HP Pavilion DV4-1150TX Battery
In Ukraine, statues, wires, sewage hatches, and even a museum-exhibit steam locomotive have been stolen for sale as scrap. In February 2004, thieves in western Ukraine dismantled and stole an 11 m long, one-tonne steel bridge that spanned the river Svalyavka.HP Pavilion DV4-1151TX Battery
In September 2009, smugglers attempted to make off with 25 tons of radioactive scrap metal from the Chernobyl Exclusion Zone. The Security Service of Ukraine caught them.
Significant rises in metal theft were observed during 2006-2007 in the UK,especially in North West England, where metal theft is still on the rise as of 2008.HP Pavilion DV4-1152TX Battery
Police Review have said that metal theft is now the fastest growing crime in the UK (for 2008) with the annual damage to industry estimated at £360m.
In the UK, the British Metals Recycling Association is working with authorities such as the Association of Chief Police Officers and the British Transport Police to halt the problem of metal being stolen from its members' sites and to identify stolen materials.HP Pavilion DV4-1153TX Battery
Roofs, manhole covers, statues etc. have all been increasingly targeted recently due to the rising cost of metal. Most of the time metal is sold for scrap but occasionally used by the thieves themselves. There have been many stories of metal theft;HP Pavilion DV4-1154TX Battery
a bronze statue of former Olympic champion Steve Ovett disappeared fromPreston Park in Brighton and church bells in Devon were stolen by thieves. A statue made by Henry Moore was stolen from a museum in 2006 and believed to have been melted down for scrap.HP Pavilion DV4-1155SE Battery
Churches, especially older churches, suffer as 'lead theft' from church (and other) roofs is on the rise, although some police do not take it seriously. In late 2011 the police began a number of crackdowns on metal theft, the largest in South Yorkshire resulting in at least 22 arrests and the seizure of amateur smelting equipment.HP Pavilion DV4-1155TX Battery
Cities across the United States have become targets for metal thieves. Manhole cover thefts have increased dramatically between 2007 and 2008, with Philadelphia as one of the hardest hit targets. Other cities dealing with this trend include Chicago, Greensboro, NC, and Long Beach, CA.HP Pavilion DV4-1156TX Battery
Copper wire thefts are also becoming increasingly common in the U.S. With copper prices at $3.70 a pound as of June 2007, compared to $0.60 a pound in 2002, people are increasingly stealing copper wire from telephone and power company assets.HP Pavilion DV4-1157TX Battery
Gangs have been created, a black market for copper wire has emerged, and men even have been killed in power plants while trying to obtain copper wire. Other sources of stolen copper include railroad signal lines, grounding bars at electric substations, and even a 3000 pound bell stolen from a Buddhist temple in Tacoma, Washington, which was later recovered.HP Pavilion DV4-1158TX Battery
For example, Georgia, like many other states, has seen enough copper crime that a special task force has been created to fight it. The Metro Atlanta Copper Task Force is led by the Atlanta Police Department and involves police and recyclers from surrounding metro areas, Georgia Power, and the Fulton County DA’s office.HP Pavilion DV4-1159TX Battery
Many states around the nation have passed – or are exploring – legislation to combat the problem. A new Georgia law took effect in July 2007 making it a crime to knowingly buy stolen metal. It allows prosecutors to prosecute for the actual cost of returning property to original conditions, as many of these thefts dramatically hurt the surrounding property value.HP Pavilion DV4-1160ES Battery
All in all, there is a nationwide movement towards education and cooperation between local prosecutors, police departments, and scrap metal dealers about problems of and solutions for metal theft.
In response to the growing concerns and the lack of hard numbers on these crimes in Indianapolis,HP Pavilion DV4-1160TX Battery
IN, the Indianapolis Metropolitan Police Department (IMPD) and the University of Indianapolis Community Research Center (CRC) began in 2008 a collaborative effort to collect data on metal thefts. The Indianapolis Metal Theft Project gathers and analyzes a wide variety of data to provide a clearer understanding of the incidence,HP Pavilion DV4-1161TX Battery
types, costs, and impacts of metal theft in Indianapolis in order to inform and implement strategies to reduce these crimes and their impacts.
The Department of Justice's Office of Community-Oriented Policing and the Center for Problem-Oriented Policing published its 58th problem-solving guide in 2010 directed towards Theft of Scrap Metal.HP Pavilion DV4-1162TX Battery
The author of the guide, Brandon Kooi, Ph.D., provides a review of the problem in the U.S. and internationally, followed by a number of suggested responses and what to consider in those responses.
The International Association of Property Crime Investigators presents the annual National Metal Theft Investigation Seminar uniting law enforcement and corporate security to share, learn and network to combat metal theft.HP Pavilion DV4-1163TX Battery
The Institute of Scrap Recycling Industries is one of the groups backing these educational efforts throughout the country. As the nation’s trade association for the scrap recycling industry, ISRI provides members and community leaders with resources that they can use when facing the issue.HP Pavilion DV4-1164TX Battery
They have also teamed with theNational Crime Prevention Council (known for McGruff the Crime Dog and the “Take a Bite Out of Crime” slogan) in an effort to team with law enforcement and crime prevention organizations to fight and solve this problem, and have established a theft alert system that these groups can use.HP Pavilion DV4-1165TX Battery
ISRI and the National Crime Prevention Council offer a number of tips for how to fight and prevent metal theft, including requiring photo ID and license plate information for every transaction, training employees on identifying stolen goods, and keeping good records that might be useful later.HP Pavilion DV4-1166CA Battery
In 2011, Officer Mandy Curfiss, a police officer on the reality television series Police Women of Cincinnati stated that theft of copper items for their copper content was common in Cincinnati.
Operation Tremor is a joint operation between British Transport Police,HP Pavilion DV4-1166TX Battery
Lancashire Constabulary and Network Rail to combat thieves who have been stealing copper boilers and piping and taking copper cables from train tracks, which can disable signalling equipment and safety devices. Some of the wire is used to carry information for automatic signalling and safety equipment .HP Pavilion DV4-1167TX Battery
The police circulated pictures of known thieves to scrap metal merchants and taxi drivers after a dramatic rise in thefts from railway property and homes. Part of the blame was put on the rise in price of copper which had tripled in the three years leading to 2006.
Equipment used in targeting offenders included CCTV and Automatic Number Plate Recognition (ANPR).HP Pavilion DV4-1168TX Battery
The operation launched in December 2006 highlights a growing problem which is affecting the whole national rail network.
Smelting is a form of extractive metallurgy; its main use is to produce a metal from its ore. This includes iron extraction fromiron ore, and copper extraction and other base metals from their ores.HP Pavilion DV4-1169TX Battery
Smelting uses heat and a chemical reducing agent to change the oxidation state of the metal ore; the reducing agent is commonly a source of carbon such as coke, or in earlier timescharcoal. The carbon or carbon monoxide derived from it removes oxygen from the ore to leave the metal.HP Pavilion DV4-1180BR Battery
The carbon is thus oxidized in two stages, producing first carbon monoxide and then carbon dioxide. As most ores are impure, it is often necessary to use flux, such as limestone, to remove the accompanying rock gangue as slag.
Plants for the electrolytic reduction of aluminium are also generally referred to as smelters. HP Pavilion DV4-1190BR Battery
These do not melt aluminum oxide but instead dissolve it in aluminum fluoride. They normally use carbon electrodes, and conversion of carbon to carbon dioxide provides an important part of deoxydation energy, rest of energy being provided by electricity, but novel smelter designs use electrodes that are not consumed in the process. The end product is molten aluminum.HP Pavilion DV4-1190EA Battery,HP Pavilion DV4-1190EJ Battery,HP Pavilion DV4-1190EL Battery,HP Pavilion DV4-1198ER Battery