Zirconium carbide dispersed high Cr–Ni cast iron produced by plasma spraying

Abstract

Spray material is heated, melted, and accelerated by a high temperature flame in the plasma spraying process. Low-pressure plasma spraying can produce rapidly solidified thick materials because alloy droplets accumulate successively on the substrate, and solidify at a cooling rate in the range of 105–108ks−1. Depending on the cooling conditions of the substrate and on the alloy composition, deposits can be produced as metastable phases or extremely fine crystalline phases. Plasma spraying is an attractive method for the production of deposits with in-situ formed fine particles. In recent years, much attention has been paid to high Cr–Ni cast iron with vanadium carbide, which is attractive for use in metal molds and pump parts, due to its high wear resistance and high corrosion resistance. In the present work, high Cr–Ni cast iron alloy powder was low-pressure plasma sprayed to produce high Cr–Ni cast iron base alloy deposits with finely dispersed zirconium carbide particles. The as-sprayed deposit produced on a non-cooled substrate was composed of γFe, αFe, ZrC and Cr7C3. The fine precipitates in the as-sprayed deposit were carbide. With increasing heat treatment temperature up to 1273K, the carbide particles coarsened. The as-sprayed deposit produced on a non-cooled substrate had higher hardness than the heat-treated deposits. The wear resistance of deposit decreased with increasing heat treatment temperature. The as-sprayed deposit produced on a non-cooled substrate and heat-treated deposits had higher wear resistance than commercial stainless steel.