WC对金刚石钻头镍基钎料胎体性能的影响

Impact of WC on diamond bit's matrix performance with nickel-based brazing material

在Ni-Cr-B-Si基钎料中添加WC,添加量(质量分数)不超过30%。对胎体材料的硬度、抗弯强度和耐磨性进行测定,用扫描电镜观察胎体的表面形貌,并对不同区域进行能谱分析。结果表明,随w(WC)增加,胎体材料的硬度和耐磨性先增大后减小,在w(WC)为20%时,硬度达到最大值(123.8 HRB),耐磨性最好,磨损量为0.221 g。抗弯强度随w(WC)增加先缓慢下降,w(WC)超过20%后急剧下降。抗弯强度在1 080～1 220 MPa之间,完全满足钻头对胎体抗弯强度的要求(抗弯强度值≥700 MPa)。胎体中WC颗粒由原始尺寸45～50μm减小到5μm以下,含WC的胎体材料出现较多的孔洞,钎焊层致密性下降。能谱分析表明,胎体材料中W元素与C元素没有同时出现,由此推断WC发生了相的转变;黑色区域为Ni、Fe、O的富集区,生成Ni与Fe的氧化物。

Research was made on addition of WC powder to Ni-Cr-B-Si alloy, the mass fraction of WC does not exceed 30%. The hardness, bending strength and wear resistance of matrix materials were investigated. Both morphology of wear surfaces worn by sand paper and elements distribution at different area were analyzed with SEM and EDX, respectively. The study results show that the hardness and wear resistance of matrix material increase at first with WC content increasing then decrease when the content of WC exceeds 20%. While bending strength declines slowly at first stage with WC powder adding within the content as 20% and goes down rapidly when the content exceeded 20%. Microanalysis shows that the dimension of WC particle decreases from 45-50μm as its original size to 5 μm following. The composite WC matrix material was composed of series black holes, the alloy densification goes down. EDX analysis indicates that the W element is not distributed in accordance with C element. It can be conclude that the phase transformation occurred in WC. Ni, Fe and O elements congregates in the black holes, may create oxide of Ni or Fe.