Micro-indentation and erosion properties of thermal sprayed NiAl intermetallic-based alloy coatings

This investigation reports the effect of CeO2 and Cr additives on the microstructures, micro-indentation and erosion properties of the high velocity oxy-fuel (HVOF) thermal sprayed NiAl intermetallic coatings. It has been found that the addition of CeO2 and Cr reduces the tendency of brittle peeling of NiAl intermetallic coatings during thermal spraying, presumably due to the improved wetness and bond strength of the sprayed intermetallic materials. The NiAl intermetallic coatings containing CeO2 and Cr are also featured with fewer cracks, less porosity, higher hardness, and higher elastic modulus than the pure NiAl coatings. Due to the improvement in mechanical properties and physical integrity, the NiAl intermetallic coatings containing CeO2 and Cr have exhibited significant increase in their erosion resistance compared with that of pure NiAl coatings. The possible mechanisms related to the improved microstructures, mechanical properties and erosion resistance of the NiAl intermetallic coatings containing CeO2 and Cr additives are also discussed.