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Rotational speed has an important influence on the performance of coating materials. The a-C:Ta composite coatings were prepared by controlling the substrate rotational speed during deposition process using PVD technique. The results showed that the coating transformed from dense structure to columnar structure. Due to the changes of deposition time and the vapor incident angle of the sputtering ions, the sp2 hybrid structure increased and the C–Ta bonds contents decreased as a function of the rotational speed, which led to the improvement of adhesion force. The average friction coefficient of the composite coatings did not fluctuate significantly for the amorphous carbon matrix and the transfer films formed during friction, while the wear rates were gradually increased. The sample at 0.5 rpm possessed the lowest wear rate, which was mainly associated with the cooperative behavior of the dense structure and the formation of TaC nanoclusters in the composite coating. [ABSTRACT FROM AUTHOR]

In this work, the friction and wear properties of layered MoAlB ceramics sliding against Al 2 O 3 and Inconel 718 alloy (Inc718) from room temperature (RT) to 800 °C were studied. The tribological behaviors of MoAlB ceramics are found to be greatly influenced by the test temperature and the counterpart. From RT to 800 °C, the MoAlB/Al 2 O 3 tribo-pairs exhibit a higher friction coefficient and wear rate compared with those of the MoAlB/Inc718 tribo-pairs. Irrespective of the laminate structure, the tribological properties of MoAlB ceramics are associated with the oxides that are induced by tribo-oxidation reactions. For the MoAlB/Al 2 O 3 tribo-pairs, abrasive wear and adhesive wear are responsible for the poor friction and wear behaviors. However, the tribo-film, which consists of oxides of Ni, Cr and Fe, can provide a good lubrication effect when MoAlB slides against Inc718. [ABSTRACT FROM AUTHOR]

Abstract: In order to lubricate ZrO2 ceramic, a series of ZrO2 matrix high-temperature self-lubricating composites were designed and prepared by hot-press technique. It was found that the ZrO2(Y2O3)–CaF2–Mo–graphite system showed a good tribological behavior at both low and high temperatures. The wear mechanism of the composite was investigated in detail. [Copyright &y& Elsevier]