等离子喷涂WC-20Cr3C2-7Ni/8YSZ复合涂层的组织及摩擦学性能

为提高连铸机拉矫辊的服役寿命，通过等离子喷涂技术在模具钢H13表面制备不同质量比的WC-20Cr₃C₂-7Ni+8YSZ复合涂层，分析各涂层的微区组织、显微硬度、抗划伤性、耐磨性和磨损形式。结果表明，在WC-20Cr₃C₂-7Ni粉末中分别加入30wt%、50wt%的8YSZ,其复合涂层的致密性明显提高，且涂层晶粒明显得到细化；WC-20Cr₃C₂-7Ni涂层中出现WC_1-x与W相，且随着8YSZ的添加WC相的结晶强度变弱；WC-20Cr₃C₂-7Ni+30wt%8YSZ涂层平均硬度(1172 HV0.2)相对于WC-20Cr₃C₂-7Ni涂层(1152 HV0.2)并没有明显变化，WC-20Cr₃C₂-7Ni+50wt%8YSZ涂层硬度(1052 HV0.2)相对于WC-20Cr₃...

Microstructure and tribological properties of WC-20Cr3C2-7Ni/8YSZ composite coatings by plasma spraying

In order to improve the service life of the pulling and straightening roller of the continuous caster, WC-20Cr₃C₂-7Ni+8YSZ composite coatings with different mass ratios were prepared on the surface of H13 steel by plasma spraying technology, and the microstructure, microhardness, scratch resistance, wear resistance and wear form of each coating were analyzed. The results show that the compactness of the composite coating is significantly increased by adding 30wt% or 50wt% 8YSZ into the WC-20Cr₃C₂-7Ni powder, and the coating grains are obviously refined. WC_1-x and W phases appear in WC-20Cr₃C₂-7Ni coating, and the crystallization strength of WC phase weakens with the addition of 8YSZ. The average hardness of WC-20Cr₃C₂-7Ni+30wt%8YSZ coating (1172 HV0.2) is not significantly changed relative to that of WC-20Cr₃C₂-7Ni coating (1152 HV0.2), but the hardness of WC-20Cr₃C₂-7Ni+50wt%8YSZ coating (1052 HV0.2) is decreased by 8.7% compared to that of WC-20Cr₃C₂-7Ni coating. The scratch resistance performance of WC-20Cr₃C₂-7Ni coating is weaker than that of the two composite coatings. The surface morphology of friction and wear changes from a large number of shedding pits to furrows, and the wear form also changes from fatigue wear to abrasive wear. The wear rate of WC-20Cr₃C₂-7Ni+30wt%8YSZ coating is 2.3×10^-5mm³/(N·m), which is about 50% less than WC-20Cr₃C₂-7Ni and WC-20Cr₃C₂-7Ni+50wt%8YSZ coatings. The composite coatings are prepared on the surface of the straightening roll of the continuous casting machine and applied in production practice. The test data show that the surface temperature of WC-20Cr₃C₂-7Ni and the addition of 30wt% and 50wt%8YSZ coatings are reduced by 40.4 ℃, 97.2 ℃ and 127 ℃, respectively. Their working life are increased by 73.3%, 133.3% and 100%, respectively, compared with conventional pull rollers.