Copper fabrication

Secondary Recovery. Metal returning from the store of metal in use is referred to as old scrap, in contrast with scrap generated within the copper fabrication process, which is called new scrap (see Recycling). In 1990 the amount of the U.S. copper supply derived from old scrap was 24% of the total copper consumed. About 40% of old scrap is used for producing refined copper most of the remainder is used in the production of brass and bronze ingots (see Copper alloys). About 75% of new scrap is consumed by brass mills, with most of the remainder used in the production of refined copper. Some estimates suggest that as much as 60% of the copper produced is ultimately recycled for reuse. Old scrap combined with new scrap from fabricating plants accounts for about 40% of the metallic input to domestic copper furnaces. 

Fig. 5. Single mixer and micromixer array in nickel on copper fabricated by LIGA technique and housing. Channel width 40 pm, Materials Nickel on copper, silver and titanium diboride. The silver and nickel-on-copper micromixers were realized by electroforming, the titanium diboride micromixer was fabricated by die sinking with LIGA electrodes...

Tin—lead coatings (10—60 wt % tin) can be applied by hot-dipping or electrode position to steel and copper fabricated articles and sheet. A special product is teme plate used for roofing and flashings, automobile fuel tanks and fittings, air filters, mufflers, and general uses such as covers, lids, drawers, cabinets, consoles for instruments, and for radio and television equipment. Teme plate is low carbon steel, coated by a hot-dip process with an alloy of tin and lead, commonly about 7—25 wt % tin, remainder lead. Electroplating is another possibility. 

Just as baffling is the presence of pseudomorphs after feathers in conjunction with spaced weft twined fabric and fine yams yet, no interworking of feathers into either fabric or yam structures could be ascertained. The significance of the feathers is pertinent here. Their position only on the underside of the plate near its center may mean that the feathers were placed there for a special mortuary purpose and bear no relation to the fabric. On the other hand, the pseudomorphs after feathers could be part of one of the fabrics, surviving only because of their association with the copper. Fabric, feathers, and copper plate may be parts of ceremonial garb. The ornaments were not placed next to the skeleton, but rather they were beneath its remains and separated from it by soil fill. Church (18) also points out the presence of textiles or preserved textiles adhering to copper plates found on chest or loins of human remains in the Ohio Hopewell finds. She does not mention feathers as part of the plate-textile finds. Scholtz (12) has found feathers used in yams recovered from the Ozark Bluff shelters, but the manipulation of the feathers appears to be closer to the Etowah fabric No. 1145 than to the feather pseudomorphs of Tunacunnhee. 

Surface mercuiy usually is in the metallic form. Simple washing of the surface can be very effective. High-pressure water can remove mercury quickly splash containment is necessary. Steel and rubber-lined pipework can be retorted or cleaned with HCI/CI2 or NaOH/H2C>2. These solutions oxidize the metal to the soluble Hg +. Heavily contaminated steel will sweat mercury. Lott [19] points out that broken concrete from a cell room floor also can sweat mercury if allowed to stand overnight. Components should be stored with this in mind. Liquid droplets can be collected. The storage area should be ventilated because of evaporation of the mercury. Buswork and copper fabrications are protected by surface films and usually are not seriously contaminated with mercury. Surface washing is good practice before recycle. Copper braid or flexible strips can be more heavily contaminated and require treatment in a mercury distillation oven. 

Electrically Conducting Fibers. FlectricaHy conducting fibers are useful in blends with fibers of other types to achieve antistatic properties in apparel fabrics and carpets. The process developed by Nippon Sanmo Dyeing Co., for example, is reportedly used by Asahi in Casbmilon 2.2 dtex (2 den) staple fibers. Courtaulds claims a flame-resistant electrically conductive fiber produced by reaction with guanadine and treatment with copper sulfide (97). 

Technological History (26,54—61). As a first approach, there are three groups of components supports, paint media, and pigments. The support is the substrate upon which the paint layers are laid down. This can be a specially prepared area on a wall for a wall painting, a wooden panel as in a panel painting, or a fabric in canvas paintings. Paper is a prevalent support in Oriental painting. Other supports are encountered less frequently, eg, metal panels such as copper sheet. 

The cell head is fabricated from a 2.54-cm steel plate and has separate compartments for fluorine and hydrogen. The oudet-gas manifolds, hydrogen fluoride feed and purge lines, and electrical connections are on top of the head. The gas separation skirt is made of Monel. An insulating gasket maintains the seal between the tank and the head. The anode assembly consists of 32 carbon blades bolted onto a copper bar, each of which contains three copper conductor posts. The cathode assembly consists of three vertical, 0.6-cm parallel steep plates. The plates surround the anode assembly and are supported by three steel posts which also serve as conductors. 

Only lead alloys containing copper below 0.08% have practical appHcations. Lead sheet, pipe, cable sheathing, wine, and fabricated products are produced from lead—copper alloys having copper contents near the eutectic composition. Lead—copper alloys in the range 0.03—0.08 wt % copper are covered by many specifications ASTM B29-92 (7), QQL 171 (United States), BS 334, HP2 Type 11 (Canada), DIN 1719 (Germany), and AS 1812 (Austraha). 

Skiving is a variant in which the base metal surface oxides are mechanically removed foUowed immediately by pressure rolling of a precious metal or alloy strip. This is commonly used for inlays for electrical contacts and for jewelry fabrication. The common inlay materials include gold, silver, copper, brass, and solder. No heat is needed, and the coating is appHed only to designated areas so there is Htde waste (3,50). 

Copper Sulfide—Cadmium Sulfide. This thin-film solar cell was used in early aerospace experiments dating back to 1955. The Cu S band gap is ca 1.2 eV. Various methods of fabricating thin-film solar cells from Cu S/CdS materials exist. The most common method is based on a simple process of serially overcoating a metal substrate, eg, copper (16). The substrate first is coated with zinc which serves as an ohmic contact between the copper and a 30-p.m thick, vapor-deposited layer of polycrystaUine CdS. A layer is then formed on the CdS base by dipping the unit into hot cuprous chloride, followed by heat-treating it in air. A heterojunction then exists between the CdS and Cu S layers. 

Copper-based thermal stabilizers are also effective photostabilizers for nylon. They can be added before polymerization, or the soluble salts (eg, CuSO can be appHed to fibers as part of the finish or to fabrics as post-treatments. The effectiveness of the copper salt—alkah haUde system added to prepolymer in retarding phototendering and photoyeUowing of the resulting spun yam is illustrated in Figure 5. 

Toluhydroquinone and methyl / fX butyUiydroquinone provide improved resin color retention 2,5-di-/-butyIhydroquinone also moderates the cure rate of the resin. Quaternary ammonium compounds, such as benzyl trimethyl ammonium hydroxide, are effective stabilizers in combination with hydroquinones and also produce beneficial improvements in color when promoted with cobalt octoate. Copper naphthenate is an active stabilizer at levels of 10 ppm at higher levels (150 ppm) it infiuences the cure rate. Tertiary butylcatechol (TBC) is a popular stabilizer used by fabricators to adjust room temperature gelation characteristics. 

Some fabrication processes, such as continuous panel processes, are mn at elevated temperatures to improve productivity. Dual-catalyst systems are commonly used to initiate a controlled rapid gel and then a fast cure to complete the cross-linking reaction. Cumene hydroperoxide initiated at 50°C with benzyl trimethyl ammonium hydroxide and copper naphthenate in combination with tert-huty octoate are preferred for panel products. Other heat-initiated catalysts, such as lauroyl peroxide and tert-huty perbenzoate, are optional systems. Eor higher temperature mol ding processes such as pultmsion or matched metal die mol ding at temperatures of 150°C, dual-catalyst systems are usually employed based on /-butyl perbenzoate and 2,5-dimethyl-2,5-di-2-ethyIhexanoylperoxy-hexane (Table 6). 

The bellows is formed from a length of thin-walled tubing by extmsion in a die. The metals used in the constmction of the bellows must be ductile enough for reasonably easy fabrication and have a high resistance to fatigue failure. Materials commonly used are brass, bronze, beryllium copper, alloys of nickel and copper, steel, and Monel (5). 

Textiles. Sorbitol sequesters iron and copper ions in strongly alkaline textile bleaching or scouring solutions (see Textiles). In compositions for conferring permanent wash-and-wear properties on cotton fabrics, sorbitol is a scavenger for unreacted formaldehyde (252) and a plasticizer in sod-resistant and sod-release finishes (253). 

Molten tin wets and adheres readily to clean iron, steel, copper, and copper-base alloys, and the coating is bright. It provides protection against oxidation of the coated metal and aids in subsequent fabrication because it is ductile and solderable. Tin coatings can be appHed to most metals by electro deposition (see Electroplating). 

Tin is used in various industrial appHcations as cast and wrought forms obtained by rolling, drawing, extmsion, atomizing, and casting tinplate, ie, low carbon steel sheet or strip roUed to 0.15—0.25 mm thick and thinly coated with pure tin tin coatings and tin alloy coatings appHed to fabricated articles (as opposed to sheet or strip) of steel, cast iron, copper, copper-base alloys, and aluminum tin alloys and tin compounds. 

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