Thermophysical Properties of Platinum-Copper Alloys
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BOTH copper and platinum have distinct characteristics. Copper is a versatile metal of reddish-brown color and well-known transition metal. The intrinsic properties of copper such as excellent electrical and thermal conductivity, high reflectivity, malleability, and ductility make it a good material choice for a wide range of industrial applications such as jewelry, coinage, decorative elements in architecture, electrical and electronic devices, contact paths on electrical circuit boards, capacitor components, and plating. It is resistant to weak acids, but will dissolve in strong acids. Copper resists atmospheric corrosion better than iron does. Copper, after silver, is as an excellent conductor of electricity.[1] On the other hand, platinum is a precious metal and belongs to the group of platinum metals. Pure platinum is a high density silvery-whitish lustrous ductile metal with low electrical resistivity and comparatively low thermal conductivity. Its crystal structure is facecentered-cubic (fcc). It is shiny, forge, and workable, and occurs in the crust of the earth with a frequency of approximately 0.001 parts per million (ppm). Platinum is attacked neither by oxygen nor by water and is insoluble in all acids with the exception of aqua regia or melted alkalis. Platinum is employed as material in large areas of SHAHID MEHMOOD, Assistant Professor, is with the Physics Department, Air University, E9 Sector Air complex, Islamabad, Pakistan. GERNOT POTTLACHER, Head of the Laboratory, is with the Institute of Experimental Physics, Technical University Graz, Petersgasse 16, 8010 Graz, Austria. Contact e-mail: pottlacher@ tugraz.at ULRICH E. KLOTZ, Head of the Laboratory, is with the Research Institute Precious Metals & Metals Chemistry, Katharinenstrasse 17, 73525 Schwaebisch Gmuend, Germany. Manuscript submitted October 5, 2011. Article published online October 17, 2012 METALLURGICAL AND MATERIALS TRANSACTIONS A
the thermodynamic temperature scale ITS-90 in platinum resistance thermometers. Platinum is used in many fields such as in weights and standard measures and in the electronic industry for electric contacts, which can be exposed to high temperatures; its alloys are commonly used in jewelry.[2] Pt-Cu alloys are mostly used in jewelry, and their thermophysical properties are required to improve the casting process of such alloys. Platinum-copper alloy systems offer several general purpose jewelry alloys for machining and for hand-working applications. Casting, however, can be difficult with some copper-containing alloys.[3] Platinum jewelry is usually produced by investment casting starting from wax models. However, platinum is much more difficult to cast than other jewelry alloys such as silver or gold because of its high melting temperature, large shrinkage during freezing, low thermal conductivity, high surface tension, and high viscosity. As a result, casters are confronted with relatively high reject rates. Hence, to resolve these difficulties, a detailed study of thermophysical properties of solid and liqu
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