Characterizations of AMT-200 HVOF NiCrAlY coatings

The development of high velocity oxygen-fuel (HVOF) process shows a clear trend toward the design of a new gun in which high pressure and large power are expected in order to obtain a stable flame and a high powder feed rate for industrial applications. In this work, a new HVOF gun, AMT-200, was used to prepare NiCrAlY coatings. The influences of thermal treatment and spraying parameters, i.e. oxygen/fuel gas stoichiometric ratio and spraying distance on coating structures and properties were studied. Artificial neural networks (ANN) was implemented in this study to predict the coating structural attribute (porosity, hardness). The results show that the spraying parameters play significant roles on the structures and properties of NiCrAlY coatings. Employing optimized parameters, a dense NiCrAlY coating, with a high coating/substrate bonding strength was obtained by this system. Moreover, thermal treatment reduced significantly the coating porosity and increased greatly coating/substrate bonding strength.