材料期刊网

以Ti、B4C和Cu等粉末为原料,采用自蔓延高温合成工艺制备TiC-TiB2复合材料,并通过电火花表面强化在点焊镀锌钢板用电极的表面制备TiC-TiB2复合强化层。用四探针法测量了强化层的电导率,利用SEM和XRD分析了强化层的微观结构和物相,运用点焊实验测试了强化电极的使用寿命,初步分析了强化层对电极失效的影响。结果表明：电火花强化层致密无明显分层,强化层与基体间为牢固的冶金结合;强化层物相主要为TiB2、TiC、B2O3和Cu等,强化层中的非晶组织和组织细化使其衍射峰宽化;TiC-TiB2复合强化层的导电率可达86.53%IACS,具有良好的导电性能,适合制作点焊电极材料;强化电极的点焊寿命比无强化层电极大约提高了4倍。

TiC and TiB2 composite rod was prepared by self-propagating high-temperature synthesis with powders of B4C,Ti and Cu,and the TiC-TiB2 coating was deposited by electrical discharge hardening on surface of cupper alloy electrode used for spot welding of zinc-coated steel plate.The electrical conductivity of the composite coating was measured by the four-probe method.Microstructure and phase components of the coating were characterized by SEM and XRD,and its lifespan was examined by spot-welding test.The results show that the TiC-TiB2 composite coating is free from pore and delimitation and a few cracks are spotted in the coating and a good metallurgical bonding between the coating and the substrate is formed.Main phases of the composite coating are TiB2,TiC,B2O3 and Cu,the fine crystalline structure and non-crystalline phase in the coating make the diffraction peak widening.Measured by the four-probe method,electrical conductivity of the TiC-TiB2 composite coating reaches 86.53 %IACS and as a result,the spot-welding life of the TiC-TiB2 coated electrode is prolonged by about four times compared with that of the un-coated Cu Cr Er electrode.