球磨制备Mo-B-Co-Cr热喷涂复合粉体研究

目的通过机械球磨加粘结破碎法制备可用于超音速火焰喷涂制备MoB-CoCr涂层的Mo-B-Co-Cr复合粉末。方法通过机械球磨加粘结破碎法制备m(MoB):m(CoCr)分别为1:1、2:1和3:1复合粉末,研究所制备的三种复合粉末的组织形貌及物相,并将所制备的m(Mo B):m(CoCr)=1:1复合粉末进行超音速火焰喷涂实验制备MoB-CoCr涂层,研究所制备涂层的组织结构。采用扫描电子显微镜观察粉末和涂层的形貌,通过X-射线衍射仪分析复合粉末的物相,通过图像法测量涂层的平均孔隙率和厚度。结果制备的三种复合粉末各相之间结合良好,组织形态呈近球形。经过X-射线衍射发现,三种复合粉末中未发现杂质及氧化现象,复合粉末的物相主要为Mo、Co和Cr三相,随着MoB质量比的增加,复合粉末中Mo相的峰值逐渐增高。通过对m(MoB):m(CoCr)=1:1复合粉末进行超音速火焰喷涂技术制备涂层,发现所制备的MoB-CoCr涂层形态呈典型的层状结构,涂层组织致密性较好,且涂层各相间及涂层与基体界面结合良好。结论采用机械球磨加粘结破碎法可制备近似球形的Mo-B-Co-Cr复合粉末,通过超音速火焰喷涂技术可成功制备组织结构较好的MoB-CoCr涂层。

Mo-B-Co-Cr Composite Powder Prepared by Ball Milling for HVOF Coating Deposition

The work aims to prepare three kinds of Mo-B-Co-Cr composite powder in the method of mechanical milling + cementation and fragmentation, and also MoB-CoCr coating in the method of high velocity oxygen fuel (HVOF). Three kinds of Mo-B-Co-Cr composite powder with mass ratio (m(MoB):m(CoCr)) of 1:1, 2:1 and 3:1 were prepared in the method of mechanical milling+cementation and fragmentation. Microstructure and phases of the powder as-prepared were studied. MoB-CoCr coating was prepared by applying HVOF experiment to Mo-B-Co-Cr composite powder as-prepared with mass ratio of 1:1, and microstructure of the coating was also studied. Microstructure of the composite powder and coating were observed with scanning electron microscope (SEM). Phases of the composite powder was analyzed with X-ray diffractometer (XRD). Mean porosity and thickness of the coating were measured in image method. Each phase in the composite powder bonded well, morphology of the composite powder was subglobular. No impurities or oxidation phenomenon was found in the process of X-ray diffraction. The phases of the (three kinds of) composite powder were mainly Mo, Co and Cr. As the mass ratio of MoB increased, peak value of Mo phase in the composite powder increased gradually. The MoB-CoCr coating prepared by applying HVOF to the composite powder with m(MoB):m(CoCr)=1:1 exhibited typical lamellar structure, and the coating had good compactness, and bonding of all phases in the coating or interface between coating and substrate was good. Subglobular Mo-B-Co-Cr composite powder can be fabricated by ball milling in the method of mechanical milling + cementation and fragmentation, and MoB-CoCr coating with good microstructure can be successfully prepared in HVOF method.