Barium Chromate as a Solid Lubricant for Nickel Aluminum

Ni ₃Al matrix composites with various BaCrO ₄ 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 BaCrO ₄ was absent but BaAl ₂O ₄ formed in the composite during the fabrication process. The low wear rate was attributed to the oxidative layer consisting of NiO and BaCrO ₄ that re-formed on the worn surface, which effectively protects the sliding surface from wear at high temperatures. On the whole, BaCrO ₄ can act as a solid lubricant for Ni ₃Al intermetallics at high temperatures.