Abstract
Microstructure and properties of plasma sprayed cast iron coatings are closely linked to the spray conditions such as substrate temperature, chamber pressure, particle size, and spray distance. Another factor is the chemical composition of sprayed particles, which affects the physical properties such as density, viscosity, and thermal conductivity of droplets. In spraying cast iron on aluminum alloy substrate the purpose is to deposit a superior wear resistant coating as an approach to improve its wear resistance. Presence of graphite in cast iron increases the wear resistance of cast iron coating because of its self-lubricant property. Graphite grows during droplet solidification and splat cooling and thus its appearance is related to the solidification rate of the individual droplets. Alloying elements such as Al and Si in cast iron materials promote the graphite formation because they act as strong graphitizers probably by creation active nuclei for graphite growing. The aim of this paper is to examine the influence of powder chemical composition on the features and properties of sprayed cast iron splat and coating by spraying three cast iron powders of different chemical compositions on Al-Si-Cu alloy. The effect of powder chemical composition on graphite formation and microstructure was investigated. In addition, the mechanical properties such as friction, wear resistance, and microhardness of sprayed coatings with those powders were examined. The influence of chemical composition of sprayed powders on the microstructure of cast iron coatings was examined by X-ray and SEM.
