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

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.