等离子喷涂制备NiCoCrAlY/BaF_2/CaF_2/C/Y自润滑涂层及其高温摩擦性能

Fabrication and High Temperature Tribological Properties of Plasma Sprayed NiCoCrAlY/BaF_2/CaF_2/C/Y Self-lubricating Coatings

通过等离子喷涂技术制备润滑相BaF2∶CaF2∶C比分别为3.1∶1.9∶7和15.5∶9.5∶4.9的两种NiCoCrAlY/BaF2/CaF2/C/Y复合涂层,研究了所选固体润滑剂在高温摩擦中对涂层润滑性能和机械性能的影响,分析BaF2/CaF2/C的综合作用,在500℃和800℃时分别对涂层进行高温摩擦试验。结果表明:500℃时,摩擦面比较粗糙,涂层的摩擦因数较高,磨损较为严重,表现出明显的剥落现象;800℃时,涂层表面没有BaF2/CaF2/C等润滑相的存在,发生了摩擦化学反应,摩擦表面生成了一层光滑致密的氧化膜,并存在一定程度的材料转移现象。经过X射线衍射(XRD)分析表明,在高温和摩擦的共同作用下,涂层表面有BaCrO4生成,摩擦因数最低可达0.268,对应的磨损量为0.351 6mm3,有效降低了涂层的摩擦和磨损。在涂层的性能测试中,各润滑相之间的协同作用较好。

Two types of NiCoCrAlY/BaF2/CaF2/C/Y self-lubricating coatings were deposited by plasma spraying,whose rates of BaF2/CaF2/C are 3.1∶1.9∶7and 15.5∶9.5∶4.9,and the effect of multi-lubricants on tribological properties was investigated at 500 ℃ and 800 ℃.The synergetic effects of BaF2,CaF2 and graphite on the tribological characteristics were analyzed.The friction test was carried out on a CMS band high temperature tribometer.At 500 ℃,the worn surfaces were unpolished,and coatings had high friction coefficients and severe wear,with obvious phenomenon of spalling.However,at 800 ℃,no phases of BaF2/CaF2/C existed,friction chemical reactions happened,worn surfaces were covered with a compact oxidation film,and some glaze film partially transferred to the counterface.X-ray diffraction（XRD）analysis show that the new phase of BaCrO4 are formed in the composites under the effect of high-temperature and friction,the lowest friction coefficient is 0.268,and the wear volume is 0.3516 mm^3,which decreased the frication and wear of the coatings.The synergetic effect of the solid-lubricants plays an important lubricanting role during the tests at the high temperature.