High-temperature solid lubricants have shown much potential for applications to sliding parts in a large number of industrial applications, such as those encountered in the aerospace, tooling, materials-forming, auto-motive, and nuclear power industries. these composites can form silver molybdate tribo-reaction layer within wear test to keep low friction coefficients and wear rates. The Ni-based composite matrix with Cr2O3 phase offers good mechanical and anti-oxidizing properties at high temperature, and the addition of Ag2MoO4 can reduce friction and wear at moderately high temperatures (300 * 500 ℃) due to the formation and the migration of Ag coming from the dissociation of Ag2MoO4 to the surface. At high temperature, the formation of silver molybdate tribo-reaction layer is expected to be an effective mechanism for friction reduction. The friction coefficient and wear rate of the composites decrease with the increasing of temperature and Ag2MoO4 contents. The best tribological properties are obtained from NC20AM composites over the range from room temperature to 700 ℃. The worn mechanisms of composites are characterized by abrasive, micro-scuffing and plastic deformation, and the scuffing abates with the increasing of Ag2MoO4 contents and testing temperatures. The composition of the tribo-layers on the worn surfaces of the composites is varied at different temperatures. It is proposed that the synergistic lubricating effect of silver molybdate (reproduced in the rubbing process at high temperatures) and Fe oxide (transfer from disk material to the pin) formed on the worn surface are attributed to the improved tribological properties of the composites at high temperatures.
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