Session BB9.2

3:45 PM BB9.2
THERMAL CONDUCTIVITY OF LOW PRESSURE PLASMA SPRAYED METAL COATINGS. Kendall J. Hollis, Richard G. Castro, Los Alamos National Laboratory, Materials Science and Technology Div, Los Alamos, NM.

The effect of plasma spray processing conditions on the thermal conductivity of metallic coatings was investigated. Conditions varied were the starting powder impurity concentration, powder atomization method, plasma torch secondary gas additions, and the deposit substrate temperature. Flash thermal diffusivity measurements of coatings sprayed under the various conditions were collected. Powder impurity, secondary gas addition, and substrate temperature were found to have significant effects on the coating thermal diffusivity. Chemical analysis, optical microscopy, SEM, TEM, mechanical properties testing, and finite-element heat-transfer modeling were used to explain the changes in thermal properties. Porosity and impurity content were found to be largely responsible for the losses in coating thermal conductivity. The coatings investigated had from 60% to 98% of the theoretical thermal conductivity of the bulk material.