Characterization and comparison between APS coatings prepared from ball milled and plasma processed nickel–aluminium powders

Plasma spraying has wide range of applications which include corrosion, thermal and abrasion resistance coatings. In the present work, nickel and aluminium powders were ball milled and the same were thermal plasma processed to produce spherical nickel alumindes particles. Both ball milled and plasma processed powders were spray deposited on stainless steel (SS 304) substrate using atmospheric plasma spray technique (APS). The experiments were carried out for different plasma input power levels, torch to base distances and coating thicknesses. Microstructure, micro hardness, adhesive strength, and porosity of the coatings are reported and discussed. Effect of plasma processing parameters and plasma spheroidization of powders on coating properties has been evaluated and reported. High plasma power, low torch to base distance lead to high temperature supplied to in-flight particles which correspond to high hardness, low porosity and high adhesion. Spherical morphology and formation of nickel aluminide intermetallic were achieved by plasma spheroidization. Coatings prepared from plasma processed powders enhance the coating properties positively.