铁基粉末冶金材料渗硼强化的干滑动高温摩擦磨损行为

High temperature dry sliding wear behavior of boriding strengthened Fe-based powder metallurgy material

通过固体粉末渗硼法直接烧结铁基粉末冶金材料,制备具有渗硼层的试样。将铁基粉末冶金材料在850、950和1050℃渗硼处理3、5和10 h,采用光学显微镜及扫描电镜观察了渗硼层的形貌,测定了渗硼层的厚度;用X射线衍射仪分析了渗硼层的物相组成;用Rockwell-C粘附性试验评估渗硼层与基体的粘合强度质量。使用HT-1000型高温摩擦磨损试验机测试了试样的摩擦磨损性能。结果表明,在850℃及950℃下渗硼形成单相Fe2B,而FeB+Fe2B双相渗硼层在1050℃下生成。粘附性试验与高温磨损试验均表明,在950℃下渗硼5 h的试样的渗层与基体结合最为紧密,抗磨损及抗氧化的能力最强。高温摩擦磨损试验中,微裂纹引起的分层剥落及氧化磨损是渗硼试样主要的磨损机制,未渗硼试样出现严重的的氧化和塑性变形。

Fe-based powder metallurgy material having boronizing layer was prepared with directly sintering at 850,950 and 1050 ℃ for 3,5 and 10 h respectively by pack powder boriding method. The morphology and the thickness of the boronizing layer were observed and measured by metallographic microscope and scanning electron microscope,and the phase composition of the boronizing layer was analyzed by X-ray diffractometer. The bond strength of the boronizing layer to the substrate was evaluated by Rockwell-C adhesion test. The friction and wear performance of the specimens was measured by HT-1000 high temperature friction and wear tester. The results show that single-phase Fe2B is formed by boronizing at 850 ℃ and 950 ℃,while dual-phase( FeB + Fe2B) boronizing layer is formed at 1050 ℃ . Both the adhesion test and the high-temperature wear test results show that the layer of the specimen borided at 950 ℃ for 5 h is the most tightly bonded to the substrate,with the highest resistance to wear and oxidation. In the high-temperature friction and wear experiment,the fatigue spalling and oxidative wear caused by microcracks are the main wear mechanisms of the boronizing specimens,while the un-boronizing specimens show severe oxidation and plastic deformation.