超音速火焰喷涂法制备超细结构WC-Co涂层及其结构与性能表征

Fabrication of ultrafine-structured WC-Co coating by high velocity oxy-fuel spraying method and characterizations on microstructure and performance

目前WC-Co类硬质合金涂层主要采用微米级粗粉制备。本文作者以WO2.9、Co3O4和碳黑为原料,利用原位反应合成技术制备超细WC-Co复合粉。配碳量(质量分数)为17.04%时(理论配碳量为16.83%),合成的WC-12Co超细粉末中只含有WC和Co两种物相,粉末平均粒径为210 nm。团聚造粒后利用超音速火焰喷涂技术在40Cr钢表面制备超细结构的WC-12Co硬质合金涂层,涂层中WC颗粒尺寸非常均匀,平均粒径为300 nm,与Co相结合紧密。与普通商业化粉末制备的涂层相比,该涂层的致密性、硬度和耐磨性都显著提高,平均硬度达到1 300 HV0.3,比普通商业化粉末涂层的平均硬度高30%,尤其在大载荷下耐磨性能更佳,显示超细WC-Co复合粉在制备高性能硬质合金涂层方面具有突出的优势。

Current WC-Co cemented carbide coatings are mainly prepared by micro-size powders.In the present work,the ultrafine WC-Co composite powder was rapidly synthesized by the technique of in situ reactions.By controlling the carbon addition of the raw powders as 17.04% in mass fraction,the as-synthesized ultrafine WC-12Co composite powder only contains WC and Co phases,with an average particle size of 210 nm.The ultrafine structured WC-12Co cemented carbide coating was fabricated by the high velocity oxy-fuel method,using the agglomerated and sintered composite powder particles.The results indicate that the coating fabricated by the ultrafine composite powder has obviously lower porosity,30% higher hardness as up to 1300HV0.3,and better wear resistance especially in larger load than those of the coating fabricated by conventional commercial powder.The results demonstrate that the ultrafine WC-Co composite powder has superior advantages in preparing cemented carbide coatings with high performance.