Effect of Powder Particle Size and Spray Parameters on the Ni/Al Reaction During Plasma Spraying of Ni-Al Composite Powders

It was known for long that Ni-Al composite powders can be used to deposit self-bonding coating as a bond coat common ceramic coatings due the exothermic reaction between Ni and Al. However, it found with commercial large particle size, is difficult ignite self-propagating Al form intermetallics by plasma spraying. In this study, powder particles of different sizes were prepare intermetallics-based The dependencies microstructure on size spray parameters investigated. phase composition, microstructure, porosity oxide content characterized x-ray diffraction, scanning electron microscope image analyzing. results show dominant factor controlling formation during When larger than about 50 ?m are used, forming aluminide cannot complete even heating flame generated at high arc power. when smaller less completely occur rapidly in spraying, contributing droplets highest temperature development effect. positive relationship molten droplet tensile adhesive strength resultant recognized confirm contribution or cohesive strength.