| Abstract: | Nickel-graphite self-lubricating composites are a promising candidate to be used in turbine constructions that are usually exposed to high temperature oxidation and wear.However,the high-temperature stability of graphite as well as the effect that the oxide scale will play on the following wear process are still yet in debate.In this work,oxidation behavior of a NiCrAl-graphite composite and the subsequent friction and wear performances were studied.Results indicate that graphite is stable in the composites after oxidation at T≤ 400 ℃ for 300 h,which contributes synergistically with the thin oxide film to self-lubrication.The friction coefficient is below 0.20 and the wear rate is ～ 1.43 × 10-5 mm3 N-1 m-1.The composite has the highest friction coefficient and wear rate when it was suffered from the high temperature oxidation at 500 ℃.Once it was oxidized at 600 ℃,a glaze layer would develop during the subsequent sliding.It plays a positive role in improving tribological properties though in the absence of lubricant phase of graphite,with to be exactly the friction coefficient and wear rate reduced by 13％ and 21％,respectively,in comparison with the case of oxidation at 500 ℃. |
