激光熔覆CaF_2/Ni基合金复合涂层的裂纹敏感性及力学性能研究

Research on Crack Susceptibility and Mechanical Properties of CaF_2/Ni Composite Coating by Laser Cladding

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。

CaF2/Ni composite coatings were fabricated on Q235A steelusing laser cladding. The influence of laser scanning speed and CaF2 on crack susceptibility was investigated by dye-penetrant testing method, and the microhardness and wear re sistance influenced by CaF2 were analyzed with microhardness tester and friction and wear tester. The results show thatlaser scanning speed and CaF2 is closely related to crack susceptibility. With the increase of scanning speed, surface crack susceptibility of coating increases,and with the increase of CaF2 ratio, number of surface crack of cladding layer decrease first then increase. When the content of CaF2 is 6wt%, crack does not appear on the surface of laser cladding. The CaF2 improves the liquidity of the molten pool, uniforms the tissue distribution, and decreases the volatility of microhardness, average hardness of coating with 6wt% CaF2 is 875 HV0. 3, which is 5. 3 times of substrate hardness. The average amount of wear volume of Q235A is 4.7 times of Ni60＋6%CaF2 coating, which improve the abrasion resistance of coating.