INVESTIGATION OF PHENOMENA INFLUENCING PROPERTIES OF PLASMA SPRAYED CERAMIC-METAL COMPOSITE DEPOSITS.

The phenomena influencing the properties of plasma sprayed ceramic-metal composite (cermet) deposits were examined. For that purpose, cermet deposits were developed by co-spraying alumina and austenitic stainless steel powders and were compared with those fabricated by spraying these powders individually. A set of particle injection and plasma spray parameters were determined by optimizing deposition efficiency of sprayed powders. The properties of the fabricated composite deposits were only partially dependent on the inherent properties of the parent materials and other factors had more dominating influence. Beside other factors, in-flight metallic particle oxidation and ceramic-metal wetting behavior were found to be the major phenomena controlling deposit properties. The in-flight particle oxidation, contributing up to 43% of the total oxide in metallic deposits, resulted in higher hardness and elastic modulus values of stainless steel deposits. The formed oxide could assist in improving the wetting behavior of stainless steel-alumina system, studied by sessile drop method. In non-wetting conditions, extensively fragmented stainless steel splats were collected on predeposited alumina causing poor interlamellar contacts and inferior deposit integrity and mechanical properties. [ABSTRACT FROM AUTHOR]