利用激光熔覆技术在TC4钛合金表面制备钴基/氧化石墨烯(GO)复合熔覆层,保持扫描速度V1=6 mm/s,送粉速率V2=1.2 r/min,光斑直径D=4 mm不变,设置4组功率P1=1000 W、P2=1300 W、P3=1600 W、P4=1900 W,研究了激光功率对钴基/GO复合熔覆层微观组织及力学性能的影响。结果表明:熔覆层中主要包含TiC、Co2Ti、γ-Co、α-Ti和Cr3C2相,GO在低功率下与TC4基体原位生成TiC,同时与半固态的Co2Ti组织共同作用,GO在高功率下迅速分解,熔覆层成分主要为Co2Ti组织。当激光功率为P2=1300 W时熔覆效果最佳,成形组织均匀,与TC4基体呈冶金结合,熔覆层硬度高达1100 HV0.2,几乎是基体硬度390 HV0.2的2.82倍。

In this study, a cobalt-based/graphene oxide (GO) composite coating has been fabricated on the surface of the TC4 substrate/titanium alloy via laser cladding. The scanning speed of V₁=6 mm/s, feeding rate of V₂=1.2 r/min, and spot diameter of D=4 mm remain constant, and four different laser power settings of P₁ =1000 W, P₂=1300 W, P₃=1600 W, and P₄=1900 W are selected to investigate the effect of laser power on the microstructure and mechanical properties of the cobalt-based/GO composite coating. The results prove that the cladding layer mainly comprises the TiC, Co₂Ti, γ-Co, α-Ti, and Cr₃C₂ phases. GO reacted with the TC4 matrix under the reaction of low power to in situ composites TiC. Furthermore, it interacts with the semi-solid Co₂Ti structure and decomposes rapidly under a high-power reaction, mainly generating the Co₂Ti structure. When the laser power is P₂=1300 W, the cladding effect is optimal and the forming structure is uniform; subsequently, the cladding cobalt-based/GO coating is metallurgically bonded to the TC4 substrate. The microhardness of the cladding layer is 1100 HV0.2, which is 2.82 times that of the matrix having a microhardness of 390 HV0.2.