Gold fabrication

Franchina J. G., Lackowski W. M., Dermody D. L., Crooks R. M., Bergbreiter D. E., Sirkar K., Russell R. J., and Rishko M. V, Electrostatic immobilization of glucose oxidase in a weak acid, polyelectrolyte hyperbranched ultrathin film on gold Fabrication, characterization, and enzymatic activity, A a/. Chem., 71(15), 3133-3139,1999. 

M. Hakamada, M. Mabuchi, Mechanical strength of nanoporous gold fabricated by dealloying. Scr. Mater. 56(11), 1003-1006 (2007)... 

Schneir J, Harary H H, Dagata J A, Hansma P Kand Sonnenfeld R 1989 Scanning tunneling microscopy and fabrication of nanometer scale structure at the liquid-gold interface Scanning Microsc. 3 719... 

Gold Metal. Besides its use for monetary reserves, gold is used in the private sector principally for investment and fabrication. A breakdown by... 

Table 4. World Fabrication of Gold, Metric Tons...

The solder and ahoy market, including low melting or fusible ahoys, is a principal user of indium (see SoLDERS AND BRAZING ALLOYS). The addition of indium results in unique properties of solders such as improved corrosion and fatigue resistance, increased hardness, and compatibhity with gold substrates. To fachitate use in various appHcations, indium and its ahoys can be easily fabricated into wine, ribbon, foil, spheres, preforms, solder paste, and powder. 

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). 

Fite refining adjusts the sulfur and oxygen levels in the bhster copper and removes impurities as slag or volatile products. The fire-refined copper is sold for fabrication into end products, provided that the chemistry permits product specifications to be met. Some impurities, such as selenium and nickel, are not sufficiently removed by fire refining. If these impurities are detrimental to fabrication or end use, the copper must be electrorefined. Other impurities, such as gold, silver, selenium, and tellurium, are only recovered via electrorefining. Virtually all copper is electrorefined. 

Sheet nd Sha.pe Waxes. Sheet and shape waxes are used to produce patterns from which complete or partial dentures are cast of gold or base metal alloys. They are used to fabricate the restoration prototype directly upon a refractory investment cast. 

GoldJilloys, Wrought Type. Two types of wrought gold alloys were formerly recognized by the ADA specification no. 7 for the fabrication of orthodontic and prosthetic dental appHances, ie, type I, high-precious-metal alloys, and type II, low-precious-metal alloys (gold color). Alloys of this type are seldom used in the United States they have been replaced by stainless steels and nickel—titanium alloys. 

Alloys based on Ag—Pd have been used for a number of years and are available from most gold alloy manufacturers (148). The palladium content is 22—50 wt % silver content is from 35 to 66 wt %. Minor amounts of Zn, In, or Sn are often present to increase fluidity. Both In and Sn form intermetaUic compounds with both Pd and Ag and, therefore, some of the commercial alloys are susceptible to age hardening (149). These alloys are somewhat difficult to fabricate and require meticulous processing. They may also produce a greenish discoloration when they are fused with porcelain veneers. Nevertheless, clinical experience generally has been satisfactory, and cost is the primary criterion for use. 

Bursting discs may be fabricated of gold, silver, platinum or palladium. The recommended maximum temperatures for continuous use are 80 C for gold, 150 C for silver, 300 C for palladium and 450 C for platinum. Figure 6.6 gives bursting pressure/disc thickness data for these metals and for aluminium and nickel. 

Hild DN, Laughlin JM, Gold RE. 1989. Laundry parameters as factors in lowering methyl parathion residue in cotton polyester fabrics. Arch Environ Contam Toxicol 18 908-914. 

Laughlin J, Gold RE. 1987. The vaporization of methyl parathion from contaminated cotton fabrics. Textile Chemist and Colorist 19 39-42. 

Laughlin J, Gold RE. 1989a. Evaporative dissipation of methyl parathion from laundered protective apparel fabrics. Bull Environ Contam Toxicol 42 566-573. 

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