Friction and Wear Behaviors of Ni-based Composites Containing Graphite/Ag2MoO4 Lubricants
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In order to improve the tribological properties of Ni-based composites, novel adaptive Ni-based composites containing multiple lubricants were prepared via a mechanical alloying and hot-press sintering technique. The phase constituents and microstructure of the composites were characterized and the tribological properties were evaluated from room temperature to 700 °C. The results showed that the Ag2MoO4 phase decomposed and new phases of Mo2C, Ag, and MoO3 formed in the sintered composites, which can be attributed to the solid state reaction of silver molybdate lubricant during the sintering process. The wear test results indicated that the Ni-based composites containing graphite and silver molybdate lubricants exhibited superior tribological properties at ambient and high temperatures. Subsequently, the Raman results demonstrated that the composition of the tribo-layers on the worn surface of the Ni-based composites was varied with increasing temperature. Combined with the wear test results, it can be proposed that the improvement of tribological properties is due to the synergistic lubricating action of silver molybdate, iron oxide, and nickel oxide. Furthermore, Raman results of the composite containing silver molybdate and silver/molybdenum trioxide lubricants revealed that the silver molybdate lubricant can reproduce easily by the direct reaction between molybdenum trioxide and silver in the agglomerate state.
KeywordsNi-based composites Multiple lubricants Synergistic lubricating action Tribological property Silver molybdate
The authors acknowledge the financial support by the National Natural Science Foundation of China (Grant No. 50972148, 51175490) and the “Hundred Talents Program” of the Chinese Academy of Sciences (Grant No. KGCX2-YW-804).
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