扫描速度对激光熔覆TC4-Ni包B4C复合涂层组织与性能的影响

Effect of scanning speed on microstructure and properties of TC4-Ni package B4C composite coating prepared by laser cladding

采用激光熔覆技术,在钛合金表面制备了TC4-20wt%Ni包B4C涂层,利用SEM、XRD、EDS对熔覆层的宏观形貌和微观组织进行分析。试验表明,原位生成的Ti C、Ti B、Ti B2和Ti2N均匀分布在α-Ti基体中,且在涂层中保留有未熔的B4C颗粒。随着扫描速度的增加,涂层稀释率变大,未熔的B4C数量增多,板条状Ti B数量与尺寸减小,细枝状Ti B2增多。涂层的硬度与摩擦因数都随扫描速度的增大而提高,扫描速度为10 mm/s时,熔覆层的平均硬度最高为851 HV0.3,较基材相比提升了2-3倍,摩擦因数稳定在0.74-0.78;在同等试验条件下,当扫描速度为8 mm/s时,涂层的磨损量仅为基材的25%。

TC4-20wt%Ni package B4C composite coating was prepared on the surface of TC4 alloy by laser cladding technology.The macromorphology and microstructure of the cladding layer were analyzed by using of SEM,XRD and EDS.The experiment results show that the insitu generated Ti C,Ti B,Ti B2and Ti2N are uniformly distributed in theα-Ti matrix,and the unmelted B4C particles are retained in the coating.With the increase of scanning speed,the dilution rate of the coating increases,the amount of unmelted B4C increases,the amount and size of the lath-like Ti B decreases,the amount of the twig-like Ti B2increases.The hardness and friction coefficient of the coating are enhanced with the increase of the scanning speed.When the scanning speed is 10 mm/s,the average hardness of the cladding layer is851 HV0.3,which is 2-3 times higher than that of the substrate,and the friction coefficient is stable at 0.74-0.78.When the scanning speed is 8 mm/s,the wear mass loss of the coating is only 25%of that of the substrate under the same experimental condition.