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为了提高镀锌钢板用点焊电极的使用寿命,在铜电极表面涂覆过渡层Ni后沉积了TiB2涂层。通过SEM和XRD分析了Ni和TiB2涂层的物相和微观结构,并测试了其显微硬度。结果表明:由于材料具有良好的塑性,预涂覆的Ni涂层结构致密无裂纹,与基体Cu无分层;而TiB2涂层内存在裂纹和孔洞。通过过渡层Ni将TiB2涂层和基体Cu粘结起来,获得了较理想的涂层。随着电火花放电电容和电压的增加,TiB2的氧化程度增强,Cu和Ni大量扩散进入涂层表面,使TiB2/Ni涂层的硬度降低。由于TiB2良好的导电和导热性能及高的硬度,TiB2/Ni涂层电极在点焊时的塑性变形降低,寿命比无涂层电极和TiC涂层电极得到了明显提高。
In order to improve the service life of spot welding electrodes for galvanized steel sheets, a TiB2 coating was deposited on the surface of the copper electrode after the transition layer Ni was deposited. The phase and microstructure of Ni and TiB2 coatings were analyzed by SEM and XRD, and their microhardness was tested. The results show that due to the good plasticity of the material, the pre-coated Ni coating is dense and crack-free, without delaminating from the Cu substrate, while cracks and holes exist in the TiB2 coating. The TiB2 coating and the matrix Cu are bonded through the transition layer Ni to obtain the ideal coating. With the increase of EDC discharge capacity and voltage, the oxidation degree of TiB2 is enhanced, Cu and Ni diffuse into the coating surface, and the hardness of TiB2 / Ni coating is reduced. TiB2 / Ni coated electrodes have lower plastic deformation during spot welding due to their excellent electrical and thermal conductivity and higher hardness, resulting in significantly longer lifetimes than uncoated and TiC-coated electrodes.