Ni3Al Matrix Composite with Lubricious Tungstate at High Temperatures

Ni3Al–Ag–BaF2/CaF2–W composites were fabricated by the powder metallurgy route, and their tribological properties over a wide temperature range, starting from room temperature up to 800 °C, were investigated. The Ni3Al matrix composite with 15 wt% BaF2/CaF2 exhibited a favorable friction coefficient (range 0.3–0.4) and wear rate (0.2–6.2 × 10−4mm3 N−1 m−1). The formation of BaWO4 and CaWO4 with lubricity on the worn surface due to a tribo-chemical reaction at high temperatures provided excellent lubricating properties. The low friction coefficient over a broad temperature range could be attributed to the synergistic effect of Ag, BaF2/CaF2, BaWO4, and CaWO4.