Preparation and characterization of NiAl–TiC–TiB2 intermetallic matrix composite coatings by atmospheric plasma spraying of SHS powders

Abstract

NiAl–TiC–TiB2 intermetallic matrix composite coatings with various TiC–TiB2 contents were fabricated by depositing self-propagating high-temperature synthesized (SHS) NiAl–TiC–TiB2 powders using atmospheric plasma spraying (APS) technique. The preparation process was carefully investigated and the effects of TiC–TiB2 contents on the physical and chemical properties of the composite coating were studied. Results indicate that SHS synthesized NiAl–TiC–TiB2 intermetallic matrix materials show high purity. The TiC–TiB2 particles are well dispersed in the NiAl matrix. There is no obvious oxidation in the composite coating during the APS process. With an increase in TiC–TiB2 contents, the hardness of NiAl–TiC–TiB2 composite coating is increased, while the thermal expansion coefficient (TEC) of the coating is decreased. NiAl–TiC–TiB2 intermetallic matrix composite coating with moderate TiC–TiB2 content shows the best corrosion resistance. Few TiC–TiB2 particles in NiAl promote the formation of the continuous Al2O3 film without destroying the integrity of the film improving the corrosion resistance of the coating.