【作者】 李明；

【导师】 周小平；

【作者基本信息】 湖北工业大学 ， 材料加工工程， 2012， 硕士

【摘要】 在铝合金表面制备复相陶瓷涂层是提高铝合金耐磨性的一种方法。等离子喷涂制备Al₂O₃-TiB₂复相涂层的方法是将混合粉末机械合金化后，利用等离子喷涂在基体表面原位合成复相涂层。它的显著优点是陶瓷相颗粒较小，分布均匀，强化效果好。本文重点研究铝合金表面反应喷涂制备Al₂O₃-TiB₂复相涂层喷涂粉末特性、反应喷涂制备Al₂O₃-TiB₂复相涂层工艺和涂层形成机理。用X射线衍射仪、扫描电镜分析了机械合金化后混合粉末的物相组成，比较了不同机械合金化时间混合粉末的变化，以及对喷涂所得涂层成分的影响。由于混合粉末熔点差异较大，采用氧-乙炔火焰喷涂（低温条件）和等离子喷涂（高温条件）两种喷涂方法，研究不同温度、喷涂距离及添加粘结剂对涂层组织、涂层和基体间结合强度、涂层致密度的影响，研究反应喷涂、复相涂层的形成机理；在此基础上优化出最佳的反应喷涂制备、复相涂层的成分配比及喷涂工艺并测定了涂层的显微硬度。从上述试验结果得出以下结论：未球磨的混合粉末进行喷涂，所得涂层中只含有Al，TiO2，B₂O和B₂O₃，无Al₂O₃和TiB₂相，说明在喷涂过程中没有反应发生；球磨后的混合粉末喷涂可以得到含Al₂O₃和TiB₂的复相涂层。两种喷涂方法都可得到含Al₂O₃和TiB₂相的涂层。氧-乙炔火焰喷涂得到的复相涂层中Al₂O₃及TiB₂颗粒较少，等离子喷涂得到的涂层中Al₂O₃及TiB₂颗粒较多，但涂层的致密度差，自身结合强度不高。喷涂反应发生在混合粉末喷涂飞行过程中，喷涂的最佳距离为350mm。在混合粉末中添加Al粉作为粘结剂，添加20%粘结剂的涂层结合效果好，Al₂O₃及TiB₂颗粒分布均匀，涂层致密度高。复相涂层最佳制备方案为等离子喷涂含20%粘结剂的球磨粉末，所得涂层最高显微硬度可达1300HV_0.1。更多还原

【Abstract】 Prepared multiphase ceramic coatings on the surface of aluminum alloy is a way toimprove wear resistance of aluminum alloy. In this work, the mixed powders wereprepared by mechanical alloying,and the Al₂O₃-TiB₂composite coating was obtainedby plasma spraying.The major excellences exist in small ceramic phase particles, evenlydistributed and high bonding strength in coating.In this dissertation, characteristics with spraying powder,prepared process andformation mechanism of Al₂O₃-TiB₂composite coating were studied.The influences ofmechanical alloying and spraying temperature on the phase constituent andmicrostructure of the composite were analyzed by X-ray diffractometry（XRD） andscanning electron microscopy（SEM）.The oxygen-acetylene flame spraying （lowtemperature） and plasma spraying （high-temperature conditions） were used to obtainedcoatings because mixture melting points of powders were different. The affect of spraytemperature, spray distance and binder for microstructures and properties of thepreparated coating was analysed. From above mentioned experimental results thefallowing can be concluded:There are only Al,TiO₂,B₂O and B₂O₃phases in coating was obtained withunmilled mixed powder by flame spraying.Therefore,no reaction has been happen insparying.It is found that coating obtained with milled powder by flame spraying andplasma spraying results in an Al₂O₃and TiB₂phase,which was confirmed by XRDmeasurements.The coating obtained by flame spraying has little hard particles of Al₂O₃and TiB₂,and the bonding strength of coating obtained by plasma spraying was low.The spray reactions of mixed powder had take place during flight course, and the bestspray distance was350mm.Through the analysis of SEM，coating without binder wasdiscontinuous and difference density; coating with20%binder has a good bondingeffect and grains of Al₂O₃and TiB₂well-distributed. The maximum microhardness ofcoating was1300HV0.1。更多还原