Barium Chromate as a Solid Lubricant for Nickel Aluminum

Ni3Al matrix composites with various BaCrO4 contents were fabricated using a powder metallurgy technique and their tribological behavior was studied from room temperature to 800°C. The results show that at high temperature of about 800°C, the tribological properties of the composites were improved. However, it was found that BaCrO4 was absent but BaAl2O4 formed in the composite during the fabrication process. The low wear rate was attributed to the oxidative layer consisting of NiO and BaCrO4 that re-formed on the worn surface, which effectively protects the sliding surface from wear at high temperatures. On the whole, BaCrO4 can act as a solid lubricant for Ni3Al intermetallics at high temperatures.