Si3N4-hBN陶瓷复合材料与Fe-B合金配副的摩擦学特性研究

利用MMU-5G销-盘式端面磨损试验机考察Si3N4-hBN陶瓷复合材料与Fe-B合金配副分别在干摩擦和水润滑条件下的摩擦磨损性能,分别采用扫描电子显微镜( SEM)、激光扫描显微镜(LSM)、X光电子能谱(XPS)、X射线能谱(EDS)和X射线衍射(XRD)分析摩擦面及磨屑的形貌与物质组成.结果表明,hBN的加入未能有效地改善Si3N4-hBN/Fe-B合金摩擦副的摩擦学性能,干摩擦条件下,Si3N4-hBN摩擦表面微凸体与Fe-B合金中的硬质相Fe2B发生碰撞而导致脆性断裂和剥落,发生磨粒磨损,摩擦因数均高于0.9,磨损率均高于10-5 mm3/ (N·m)数量级；水润滑条件下,由于水流带走了磨屑,避免磨粒磨损的发生,为Si3N4-hBN摩擦表面发生化学抛光提供条件,化学抛光使销、盘试样的摩擦表面变得光滑,从而获得较为优异的摩擦学性能.

Study on the Tribological Characteristics of Si3N4-hBN Ceramic Materials Sliding against Fe-B Alloy

The tribological behaviors of Si3N4-hBN composites sliding on Fe-B alloy without lubrication and with water lubrication were studied on a MMU-5G type pin-on-disc wear tester.The results show that the addition of hBN to Si3N4 can not effectively improve the tribological characteristics of Si3N4-hBN/Fe-B alloy sliding pairs.The materials and worn surfaces as well as wear debris were characterized by means of scanning electron microscopy(SEM)and X-ray diffraction(XRD),and the worn surfaces were analyzed by using X-ray diffraction spectroscopy(EDS),laser scanning microscopy(LSM)and X-ray photoelectron spectroscopy(XPS).The analysis indicates that,without lubrication,the wear of Si3N4-hBN composites is resulted from cracking and fracture,while the hard phase Fe2B in Fe-B alloy spall off during the wear test.This results in the abrasive wear,high friction coefficients(>0.9)and high wear coefficients(>1×10-5 mm3/(N·m)).With water lubrication,the wear debris is carried away from wear surfaces by water stream,and the abrasive wear is avoided.The wear surfaces become smooth due to the chemical removal of micro-asperities on Si3N4-hBN surface caused by successive oxidation and hydrolysis of Si3N4 and hBN.As a result,excellent tribological characteristics of Si3N4-hBN/Fe-B alloy pairs are obtained.