Characterization of NiAl layers deposited by atmospheric plasma spray (APS)

Abstract

In this paper analyzed were the mechanical properties and microstructure of the Ni30Al coating layers deposited using atmospheric plasma spray (APS). For deposition of the coating applied was a composite Ni30wt.% Al powder, manufactured by mechanical alloying of granulation below - 180 µm. The coatings mechanical properties were analyzed by microhardness measuring with the HV0.3 method and the bond strength by tension method. For the analysis of the microstructure of the coating layers applied was the method of light and scanning electron microscopy (SEM). Microhardness tests showed that the coating has a wide range of measured values which indicate a heterogeneous multiphase lamellar microstructure of the coating, which was confirmed by metallographic examination of the layers. The multi-phase lamellar microstructure consisted of the initial solid a-Al, y-Ni solutions, formed solid b-NiAl and NiAl martensite solutions, intermetallic compounds y-Ni3Al and Ni2Al3 and the oxide y-Al2O3 phase formed by oxidation of molten Al particles. Based on these tests given was an evaluation of the quality of the coating. The results of the experiment showed that the technological process of production of composite powders significantly affects the mechanical properties and structure of the coating layers.