Session BB3.3

9:30 AM BB3.3
MICROSTRUCTURAL AND PHYSICAL CHARACTERISTICS OF COPPER DEPOSITED BY COLD GAS-DYNAMIC SPRAYING. Robert C. McCune, Oludele O. Popoola, Eddie L. Cartwright, William T. Donlon, Ford Motor Company - Ford Research Laboratory, Dearborn, MI.

A technique for developing thick metallic layers using relatively low-temperature, high-velocity spray nozzles has been reported by Alkhimov, et al. (1990). An exploratory study of this process was subsequently undertaken by a consortium of companies organized under the National Center for Manufacturing Sciences (NCMS). This paper reports on outcomes of that program as related to the development of high-purity copper deposits produced by cold gas-dynamic spraying. The utility of thermally-sprayed copper metallizations for electrical applications is often limited by the purity of the deposit, which may be degraded by formation of oxides, voids or other inhomogeneities which are a consequence of the high temperatures used in arc, flame or plasma processes. This work reports on coatings produced from two different starting copper powders; one manufactured by direct reduction, having a large fraction of surface oxide coverage; the other produced by gas atomization, being more regular and limited in the extent of surface oxidation. The microstructural aspects of the two resulting coatings are compared at the level of optical, scanning and transmission electron microscopy. Mechanical and physical properties were obtained through use of microhardness, electrical conductivity, Young's modulus and residual stress measurements. Results of studies on the microstructural evolution and damage reduction during annealing will be presented.