快冷熔覆法原位合成大厚度铁基非晶复合涂层的研究

通过水冷提高凝固速率及降低基体金属对熔覆层的稀释,采用改进的钨极惰性气体氩弧熔覆的方法,原位制备了大厚度(1—5 mm)Fe基非晶/纳米晶复合涂层.利用X射线衍射,光学显微镜和透射电子显微镜对涂层成分和组织进行分析,并测试了涂层的显微硬度.结果表明,采用快冷熔覆的方法可以制备出含有50%以上非晶含量的非晶/纳米晶复合涂层,涂层内纳米晶颗粒表面被非晶过渡层包覆.较厚涂层的显微硬度达到1600HV_0.3,与基体为冶金连接,有良好的结合强度及耐磨性.非晶/纳米晶复合结构使得涂层与基体之间的过渡区具备较强的弹塑性,提高了涂层的抗冲击性. 最后重点讨论了微观结构和性能之间的内在联系,涂层内非晶相与纳米晶相的协同作用是造成涂层高硬度的主要原因. 关键词： 非晶 涂层 熔覆 显微硬度

Preparation of Fe-based thick amorphous composite coating by cladding with auxiliary cooling system

A thick Fe-based amorphous composite coating (1—5mm) was prepared in situ by tungsten inert gas (TIG) cladding method. The auxiliary cooling system was used to improve the solidification rate of molten alloy and decrease the dilution from the substrates. The microstructure of the composite coating was investigated by X-ray differaction, optical microscope and transmission electron microscope. In addition, the micro-hardness of the coating was also measured. The results show that the composite coating is composed of the amorphous phase and the nano-crystalline grains encapsulated by amorphous transition layer, whose content is more than 50 percent. The composite coatings have been found to have good bonding strength and high wear resistance, the maximum value of the micro-hardness is up to 1600HV_0.3. The microstructure of the transition layer with good elastic-plastic properties leads to the higher impact resistance. At last, the relations between the microstructure and micro-hardness properties were discussed in detail, and the main reason for high hardness is the cooperation of the amorphous phase and nano-crystalline phase in the composite coatings.