纳米石墨改性ZM5镁合金微弧氧化陶瓷层摩擦磨损性能

摘要

Micro-arc oxidation(MAO) ceramic coating of ZM5 alloy was prepared in the silicate electrolyte system with nano-graphite particle. The micro morphology, chemical and phase composition were investigated by SEM, EDS and XRD. At room temperature, the tribological properties of coatings were evaluated by a ball -on-disc wear test machine. The results show that the MAO ceramic coating with nano-graphite is composed by Mg2SiO4 , MgO, Mg, and C. Graphite disperses in the coating through mechanical effect and shows antifriction effect. The volume friction rate of the MAO ceramic coating with nano-graphite is 9. 19 ×10-5 mm3/Nm under the load of 4. 9 N. It is one-fourteenth of that of ZM5 substrate and one-third of that of MAO ceramic coating without graphite. The volume friction rate of the MAO ceramic coating with nano-graphite is 1. 44 × 10-1 mm3/Nm under the load of 9. 8 N. It is one-eighth of that of ZM5 substrate and two-fifth of that of the MAO ceramic coating without graphite. The wear resistance of ZM5 substrate increases dramatically because of the MAO ceramic coating with nano-graphite. The wear mechanism of the MAO ceramic coating with nano -graphite is fatigue wear from the fatigue spalling morphology.%添加纳米石墨颗粒的硅酸盐溶液中制备ZM5合金微弧氧化陶瓷层,利用SEM、EDS和XRD分析了涂层的微观形貌、成分及物相组成,用球-盘干磨损试验对涂层的室温摩擦磨损行为进行研究.结果表明,纳米石墨改性微弧氧化陶瓷层主要由Mg2SiO4、少量的MgO、Mg和C相组成,石墨以机械形式分散于陶瓷层中并起到减摩作用.4.9N载荷下体积磨损率为9.19×10-5 mm3/Nm,是无石墨微弧氧化陶瓷层的1/3,ZM5基体的1/14;9.8 N载荷下体积磨损率为1.44×10-4 mm3/Nm,是无石墨微弧氧化陶瓷层的2/5,ZM5基体的1/8,与无石墨微弧氧化陶瓷层相比显著提高了镁合金基体的耐磨性,且其室温干摩擦磨损机理为疲劳磨损,磨痕呈疲劳剥落形貌.