电火花沉积WC-4Co复合层界面行为

摘要

Submicron WC-4Co cemented carbide material was deposited on the surface of cast steel by electro-spark deposition (ESD), the electro-spark deposition coating was prepared. The behavior of interface between the coating and the substrate was studied by SEM and XRD. The surface wettability, the forming mechanism of phase, microstructure, element distribution of deposition, bonding mechanism of interface and microhardness of the coating were investigated. The results show that microano and amorphous coating with high melting-point is produced on the surface of cast steel by ESD. The coating consists of Fe 3 W 3 C, Co 3 W 3 C,Si 2 W and Fe 2 C phases. The coating is well metallurgical bonded with the cast steel roll substrate. The microstructure of the transition layer is a structure of fine columnar crystals and equiaxed crystals. The extra-fine structure hard Si2W and Fe2C phases distribute dispersedly in Fe3W3C and Co3W3C deposition. The coating is usually more than 20 µm thick. The average microhardness of the coating is 1803. 2 HV. These fine and dispersed hard phases can greatly improve the hardness of coating.%采用新型电火花沉积设备，将亚微米WC-4Co陶瓷硬质合金材料沉积在铸钢材料上，制备电火花沉积合金涂层，利用SEM和XRD等技术研究沉积层与基体间的界面行为，分析沉积层的表面润湿性、物相形成机理、微观组织结构、界面元素分布、界面结合机理和显微硬度变化等。结果表明：电火花沉积技术可以在金属基体表面制造出微纳米非晶高熔点强化层。铸钢表面沉积层主要由Fe3W3C、Co3W3C、Si2W和Fe2C 等相组成；沉积层与基体呈冶金结合，过渡层中出现一些柱状晶和等轴晶的组织结构，沉积层中细小的Fe2C和Si2W等硬质相颗粒弥散分布于Fe 3 W 3 C和Co 3 W 3 C沉积层上。沉积层的厚度大于20µm，沉积层的平均显微硬度为1803.2 HV，细小弥散分布的硬质相是沉积层硬度提高的主要因素。