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利用高功率光纤激光熔覆设备,在Q235A钢表面制备了CaF_2/Ni60复合涂层。采用着色渗透探伤法研究了激光扫描速度和CaF_2对涂层的裂纹敏感性的影响,并利用显微硬度计和摩擦磨损机考察了CaF_2对复合涂层显微硬度和耐磨性能的影响。结果表明,激光扫描速度和CaF_2与涂层裂纹敏感性密切相关,随着扫描速度的增大,涂层表面裂纹敏感性增大;随着CaF_2比例的增加,熔覆层表面的裂纹数量先减少后增加,当w(CaF_2)=6.0%时,激光熔覆层表面未出现裂纹;CaF_2粉末改善了熔池的流动性,使组织分布较均匀,显微硬度波动性减小,当w(CaF_2)=6.0%时,涂层平均硬度为875 HV0.3,约为基体硬度的5.3倍。Q235A基体的平均体积磨损量是Ni60+6.0%CaF_2涂层的4.7倍,提高了涂层的耐磨性。
CaF_2 / Ni60 composite coating was prepared on the surface of Q235A steel with high power fiber laser cladding equipment. The effects of laser scanning speed and CaF_2 on the crack susceptibility of the coating were studied by the color penetrant test. The effect of CaF_2 on the microhardness and wear resistance of the coating was also investigated by using microhardness tester and friction and wear tester. The results show that the laser scanning speed and CaF 2 are closely related to the crack susceptibility of the coating. With the increase of the scanning speed, the surface crack sensitivity of the coating increases. With the increase of CaF 2 ratio, the number of cracks on the coating surface decreases (CaF 2) = 6.0%, no cracks appeared on the surface of laser cladding layer. CaF 2 powder improved the fluidity of the molten pool, the distribution of microstructure was more uniform and the fluctuation of microhardness was less. ) = 6.0%, the average hardness of the coating is 875 HV0.3, about 5.3 times the hardness of the matrix. The average volumetric wear of Q235A matrix was 4.7 times that of Ni60 + 6.0% CaF 2 coating, which improved the abrasion resistance of the coating.