摘要
采用加压氢气还原和固相合金化技术,以BaF2.CaF2共晶、Cr3C2颗粒为核心,制备了NiCr合金包覆的NiCr/Cr3C2-BaF2.CaF2复合粉末,采用大气等离子喷涂技术制备相应涂层.采用扫描电子显微镜、X射线衍射和SRV摩擦磨损试验机等分析测试技术,研究了涂层组成、结构以及从室温到500℃涂层的摩擦磨损性能.研究结果表明:研制的NiCr/Cr3C2-BaF2.CaF2复合涂层是一种性能优良的高温自润滑耐磨涂层,表面包覆的致密NiCr层抑制了喷涂过程中颗粒的氧化、脱碳和烧蚀,涂层的显微硬度和结合强度较高;涂层在室温下的摩擦系数为0.74±0.02,随温度升高摩擦系数逐渐降低,500℃时降低为0.38±0.03,涂层和对偶球Si3N4的磨损率与室温相比显著下降.摩擦机理研究发现,高温下BaF2.CaF2共晶软化,导致涂层剪切强度比室温时明显变低,在摩擦表面形成了连续的BaF2.CaF2润滑膜.
BaF2·CaF2 eutectic and Cr3C2 composite powders coated with NiCr alloy were prepared with the technology of hydrogen reduction hydrothermal process combined with a solid state alloying. NiCr/Cr3C2 -BaF2 · CaF2 coating was produced by atmospheric plasma spray （APS） using the prepared powders. The mierostructure and phase compositions of the powders as well as the deposited coating were analyzed by SEM and XRD, while the friction and wear behavior of the coatings from room temperature to 500℃ were evaluated using a SRV high temperature tribometer. The NiCr/Cr3 C2 - BaF2 · CaF2 composite coating exhibited excellent wear - resistant performance by high temperature selflubrication with high microhardness and cohesive strength. Oxidation, decarburization and ablation of Cr3C2 - BaF2 · CaF2 during spray were avoided due to the protection by NiCr layer. The friction coefficient of the coating, 0.74 ± 0.02 at room temperature, gradually decreased with the increase of temperature, a small value of 0.38 ± 0.03 was achieved as temperature up to 500℃ , which led to a significant decrease of wear rates of both of the coating and the Si3N4 ball. BaF2 · CaF2 eutectie underwent a transition with decrease of shear strength at high temperature fi＇om brittle to plastic state, which resulted in the formation on a continuous lubricating layer in the wear track at 500℃.
出处
《摩擦学学报》
EI
CAS
CSCD
北大核心
2009年第1期68-74,共7页
Tribology
