DZ125表面激光熔覆TiN增强Co基复合涂层组织与耐磨性研究

Microstructure and Wear Resistance of Laser Clad TiN Reinforced Co-based Alloy Coatings on DZ125 Superalloy

采用5kW CO_2连续激光器,在DZ125高温合金表面制备了TiN增强Co基复合涂层,并对熔覆层的显微组织、相结构、显微硬度和抗磨损性能进行了研究。结果表明:激光熔覆层主要由γ-Co、TiN、TiC、(Cr,W)_(23)C_6和Co_3Ti组成;激光熔覆层与基体形成良好的冶金结合;熔覆层中弥散分布着许多大小不等的TiC、未熔TiN及其它硬质点相,大幅度提高了熔覆层的耐磨性能,耐磨性随着扫描速度的增加而提高。

Co-based composite coatings reinforced by TiN particles were prepared on DZ125 superalloy substrate by using a 5 kW CO2 laser. The microstructures and phases of the coatings were analyzed by means of scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The microhardness and wear resistance of the coatings were also tested. The results showed that the coating was mainly consisted of γ-Co, TiN, TiC, （Cr, W）22C6 and Co3 Ti respectively. And different solidification morphologies were observed, varying from the interface to the surface. The microhardness of the composite coating was enhanced prominently as compared to the substrate region, which should be attributed to the TiC, undissolved TiN and other new complicated phase. Wear tests without lubrication showed that the wear resistance of the coating was much higher than that of the substrate. And with the increase of laser scanning speed, the wear resistance of the coatings was improved notably. The abrasive mechanism of the coating was also analyzed.