点焊电极表面电火花沉积TiB_2涂层的特征

在CuCrZr电极表面通过电火花振动沉积制备了TiB_2功能涂层,测试了功能涂层的显微形貌、物相、硬度以及界面元素分布.试验表明,TiB_2涂层电极具有典型的电火花涂层结构,存在明显的元素互扩散,表明功能层与基体之间为冶金结合.但TiB_2涂层结构不致密,存在裂纹和孔洞,硬度较低.随着电火花电容和电压的增加.涂层的硬度降低.元素扩散和涂层氧化的加剧,是导致涂层硬度降低的主要原因.由于基体Cu的气化、脆性剥落和熔敷棒的切削作用,沉积TiB_2后基体质量反而降低.高电压下电火花沉积以及预涂敷Ni,都会导致基体质量降低更多.

Characteristics of TiB_2 coating on surface of copper electrode prepared by electrospark deposition

TiB_2 functional coating was prepared on surface of CuCrZr electrode by electrospark deposition(ESD). Microstructure, phases, elements distribution and hardness of the coating were examined, respectively. The results indicate that the microstructure of TiB_2 coating is a typical one for ESD. The elements inter-diffusion at the interface demonstrates the metallurgical bonding between the coating and substrate. The nickel precoated TiB_2 coating is not dense and pores and crack is observed. Diffusion of elements titanium and copper and oxidation of TiB_2 become severe as the voltage and capacitance increase, which leads to hardness of the coating at high voltage and capacitance decreases. The mass of the electrodes after cladding with TiB_2 decreases as the pulse energy increases with the voltage increasing. Evaporating of copper and flaking of TiB_2 coating play the most important roles in the mass loss of the electrodes. Cutting of TiB_2 bar with high hardness to CuCrZr electrode rotated with high speed and pre-coated nickel are also responsible for the mass loss of the electrodes.