Abstract
FeCr matrix high-temperature self-lubricating composites reinforced by Mo, Ag, and CuO were fabricated by the powder metallurgy technique. The tribological behaviors of composites were studied at temperatures up to 800 °C. The CuO content was optimized according to the tribological results. Mo showed an obvious lubricating effect when it converted into MoO3. The bimetallic oxide system formed high-temperature solid lubricants with low shear strength. CuO reacted with MoO3 and formed CuMoO4 and Cu3Mo2O9. The composites showed an increase in the friction coefficient with the increase of CuO. However, the wear rates decreased with the increase of CuO. The critical threshold at which there was a transition of friction coefficients and wear rates from room temperature (RT) to 800 °C was 10 wt.% CuO. The Fe(Cr)-14% Mo-10.5% Ag-10% CuO composite showed the most reasonable high-temperature tribological behaviors. This was ascribed to the synergistic effects of silver, Mo, in situ formed solid lubricants (metal oxides and salt compounds), and the stable oxide film on the worn surfaces. At elevated temperatures, the dominant wear mechanism was oxidation wear.
Highlights
High-temperature wear usually leads to the loss of mechanical strength and to a decrease in the service life of mechanical parts [1,2,3]
High-temperature mechanical parts are made of nickel and cobalt matrix materials due to their excellent oxidation resistance and mechanical strength
Fe matrix material is one of the superalloys, which are widely used in many industrial fields as wear resistant mechanical parts [4,5]
Summary
High-temperature wear usually leads to the loss of mechanical strength and to a decrease in the service life of mechanical parts [1,2,3]. Ceramic matrix materials are used under some rigorous working conditions These materials have a considerable wear resistance at elevated temperatures, the cost is high. It is necessary to develop composites with a low cost, a low friction coefficient, and a high wear resistance at elevated temperatures. The excellent wear resistance of Fe matrix alloys could be achieved by adding hard ceramic particles, such as SiC, TiC, and Al2 O3 [12,13,14]. Solid lubricants work as an effective strengthening phase to reinforce the tribological properties of metal matrix composites at elevated temperatures [16,17,18]. In our previous work [22], BaF2 was used to improve the wear resistance of FeCr matrix composites as high-temperature solid lubricants.
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