Influence of Substrate Surface Quality on Electro-Spark Alloying

Deposition of protective coatings improves the corrosion resistance and tribological behavior of the surfaces of metallic components. However, surface preparation prior to coating application increases the cost per unit area of the coating. Substrates made of St3 steel with surface roughness R_a ranging from 0.01 to 0.597 μm were prepared, including those with a layer of rust, and were subjected to electro-spark deposition of Cr–Fe–Cu coatings. The performed studies led to the conclusion that the initial surface roughness of St3 steel does not affect the nature of material deposition during the electro-spark alloying (ESA) and the structure of the deposited coatings. This is unequivocally confirmed by the data on heat resistance and tribological properties of the coatings. Electro-spark treatment can promote self-cleaning of the rust layer; however, complete elimination is not achieved, and large pores are formed in the coating. This significantly reduces the heat resistance and wear resistance of the coating.