原位生成TaC颗粒增强镍基激光熔覆层

利用激光熔覆技术,在A3钢表面制备出了原位生成TaC颗粒强化的镍基复合涂层。使用金相显微镜、扫描电镜(SEM)、电子能谱(EDS)和X射线衍射(XRD)仪对熔覆层进行了显微组织和物相分析,并测试了熔覆层显微硬度及摩擦性能。结果表明,在适当的工艺条件下,激光熔覆制备原位生成TaC颗粒增强镍基复合涂层成形良好、表面光滑,涂层与基体呈现良好的冶金结合。熔覆层组织由原位生成的TaC颗粒相 Cr3C2与γ(Cr-Ni-Fe-C)的枝状共晶相 γ(Cr-Ni-Fe-C)基体组成。由于TaC颗粒强化相的形成及其均匀弥散分布,既提高了涂层中的强化相比例,又细化了组织,使得TaC/Ni60激光熔覆层具有高的硬度(平均硬度HV0.31100),与纯Ni60熔覆层相比,耐磨性提高4倍。

Investigation on In-Situ Synthesis of TaC Particulate Reinforced Ni-Based Composite Coatings by Laser Cladding

TaC particulate reinforced Ni-based composite coating has been successfully in situ synthesized by laser cladding on steel A3 substrate by prior to pasting. The microstructural and metallographic analyses were performed by a scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The microhardness and wear-resistance of the coatings have been investigated. It is indicated that good finish and in situ synthesized TaC particulate reinforced composite coatings can be achieved employing a proper amount of (Ta2O5+C)-doping under suitable processing parameters, and that the excellent bonding between the coating and substrate is ensured by the strong metallurgical interface. Both particles in which in-situ synthesized TaC and acicular dendrite consisted of Cr3C2 and γ(Cr-Ni-Fe-C) are homogenously dispread in the γ(Cr-Ni-Fe-C) matrix . Because of the generation of TaC particle and its homogeneous distribution, the proportion of the reinforcements in the coatings is enlarged and the grain is refined. Thus, the coatings give the excellent wear resistance (high average hardness of HV0.31100) which is five times as high as that of pure Ni60 coatings.