【作者】 王钰；

【导师】 周小平；

【作者基本信息】 湖北工业大学 ， 材料加工工程， 2009， 硕士

【摘要】 反应喷涂是目前制备陶瓷/金属涂层的一项新技术,它是自蔓延高温合成与热喷涂技术相结合而发展起来的。其最大特点是,涂层中的陶瓷相不是预先加入到喷涂原料中,而是喷涂粉末在飞行过程中经历一系列放热反应而获得的。获得的陶瓷相分布均匀,粒度小,不存在陶瓷/金属结合界面污染问题,涂层的性能好,并且工序简单、经济。本文基于反应喷涂原理,以FeB、Mo、Fe等粉末为原料,采用反应火焰喷涂在钢表面合成Mo2FeB2金属陶瓷涂层;以Fe、Al粉末为原料喷涂,形成Fe-Al金属间化合物作为粘结底层。用扫描电镜、能谱仪、X射线衍射仪和硬度计分析了不同热处理温度和粘结底层含铝量不同对涂层显微组织和界面结构的影响,研究了涂层的形成机制。用粘结拉伸法,测量了粘结底层与钢基体间的结合强度。比较了三元硼化物基金属陶瓷涂层试样和钢基体的耐磨性,并分析涂层的耐磨机理。用Uddeholm法对三元硼化物基金属陶瓷涂层试样和钢基体进行热疲劳试验,分析和对比有涂层试样和无涂层试样的表面热疲劳裂纹形貌,探讨涂层的热疲劳机理。从上述试验结果得出以下结论:经过反应火焰喷涂后,在钢基体表面生成三元硼化物基金属陶瓷涂层,其组织为Mo2FeB2+α-Fe;喷涂所得的粘结底层组织为Fe3Al+FeAl,属于金属间化合物,其作用是起到过渡连接实现三元硼化物基金属陶瓷涂层与钢基体的满意结合。三元硼化物(Mo2FeB2)硬质相是在喷涂过程中发生原位反应形成的,所以其形成与热处理工艺无关;热处理有利于粘结底层中的Fe、Al转化为金属间化合物。粘结底层与钢基体间产生冶金结合和扩散结合界面,随着热处理温度升高,结合强度先升后降,在550℃时达到最大,为36MPa。三元硼化物基金属陶瓷涂层的显微硬度值达到1400HV 0. 1,粘结底层的显微硬度在800HV 0. 1左右,高于钢基体表面的显微硬度。涂层的耐磨性高于高速钢,是由于表面的Mo2FeB2硬质相具有较高的硬度。三元硼化物基金属陶瓷涂层的抗热疲劳性能大于钢基体,是由于涂层中含有Ni、Mo、Cr等合金元素,具有较强的抗氧化能力。更多还原

【Abstract】 Reactive spraying is a new technology of the preparation of ceramic/metal coating. It is combined and developed with SHS and the technology of the thermal spraying. Its greatest feature is that the ceramics of the coating rather than adding to the spraying of raw materials, but obtained in the process of a series of the exothermic reaction which the spraying powders experienced during flight. Use this method can obtain ceramics the distribute equally and size small. And this is no ceramic/metal interface pollution problem, and the performance of the coating is good. The process is easy and economic.In this dissertation, based on the principle of the reaction spraying, using reaction flame spraying to synthesis Mo2FeB2 metal ceramic coating with the powders of FeB、Mo、Fe as raw materials on the surface of steel. And use the powders of Fe、Al as raw materials to format the Fe-Al intermetallic compounds as the bottom bonding. The effect of the different heat processing temperatures and the different amount of Al on microstructures of the coating and interface morphology are analyzed by SEM、EDS、XRD and hardness tester. The mechanism of their formation was studied. Using bonding tensile test method, the bonding strength between coating and substrate was measured. Wear resistance of the ternary boride based ceramic coating was compared with the substrate, and wear mechanism of the coating was analyzed. Thermal fatigue test of the ternary boride based ceramic coating sample was conducted by the Uddeholm method. An approach to mechanism of the thermal fatigues formation of the coating was performed. Form above mentioned experimental results of the fallowing can be concluded:The coating from ternary boride cermet has microstructure of Mo2FeB2+α-Fe after the reaction flame spraying. The ternary boride based ceramic coating can be formatted on the steel substrate surface. The microstructure of the bottom bonding is Fe3Al+FeAl.They belong to the intermetallic compound, and the role is to play a transition connection between the ternary boride based ceramic coating and steel substrate to a satisfaction combination.The ternary boride (Mo2FeB2) hard phase are formatted in the reaction spray processing, and the formation has nothing to do with the heat processing; The heat processing do good harm to the translation of the Fe、Al of the bottom bonding to the intermetallic compound.The bonding strength on the bottom bonding and steel substrate leads to metallurgical bonding and diffusion bonded. The bond strength increase first and down with the increase of the temperature of heat process. And go to the max 36MPa at the temperature of 550℃.The micro-hardness of the ternary boride based ceramic coating is 1400HV 0. 1, the bottom bonding is 800HV 0. 1.The wear resistance of the coating is higher than the high-speed steel. Because there are many hard phases (Mo2FeB2) on the surface, and the hard phases have a high hardness. The termal fatigue of the coating is higher than the surface of the steel. Because it contains the alloying element of Ni、Mo、Cr. They have strong antioxidant capacity.更多还原