B_4C加入量对氩弧熔覆Ni-Cr-W合金涂层组织及耐蚀性能的影响

为改善Ni基合金涂层的组织及耐蚀性,采用氩弧熔覆技术在40Cr钢基体表面制备Ni-Cr-W基/B_4C复合涂层,主要研究了B_4C加入量对涂层显微组织、显微硬度以及耐蚀性能的影响。结果表明:合金涂层显微组织由平面晶、柱状晶和树枝状晶等组成;当B_4C含量为5%时,涂层熔覆层的组织明显发生细化;当B_4C含量超过5%时,熔覆涂层表面出现气孔和裂纹等缺陷,内部夹杂增多,涂层质量下降;B_4C的加入提高了合金涂层的硬度,当B_4C含量达到5%时表面硬度较高,达到1 027.4 HV_(0.5N),B_4C含量继续升高,硬度变化不大;B_4C的加入降低了熔覆层耐蚀性,当B_4C含量为5%时耐蚀性相比未加B_4C时的下降不多,耐蚀性较好。

Influences of B4C Content on Microstructure and Corrosion Resistance of Argon Arc Cladding Ni-Cr-W Alloy Coating

In order to improve microstructure and properties of Ni-based alloy coating,Ni-Cr-W cladding coating was prepared on 40Cr steel substrate by the argon arc cladding technique,and the microstructure,micro-hardness and corrosion resistance of the coatings containing different B4C contents were investigated.Results showed that the microstructure of the coatings was composed of planar,columnar and dendrite grains.When B4C content was 5％,the microstructure of the cladding layer was obviously refined.When the content of B4C exceeded 5％,there were porosities and cracks on the cladding layer surface and impurities in the cladding coating,indicating that the quality of the coating deteriorated.Compared with the coating without B4C,the microhardness of the coatings with different B4C contents was significantly enhanced.The coating had higher hardness value of 1 027.4 HV0.5 N with 5％ B4C.When B4C content continued to increase,the hardness changed little.The corrosion resistance of the cladding layer with B4C addition was decreased and the coating with 5％ B4C showed the better corrosion resistance than others.