分别采用机械球磨法和球磨-超声-冷冻干燥法制备WC-6Co-GO/Al2O3混合粉末,并通过冷压成形-烧结制备块体硬质合金,研究混粉工艺和GO/Al2O3复合粒子含量对混合粉末的分散性以及合金的微观形貌、致密度和力学性能的影响。结果表明：超声-冷冻干燥可以有效地解决GO/Al2O3复合粒子的团聚问题,获得细小均匀的粉末颗粒。采用球磨-超声-冷冻干燥法混粉时,所制备的GO/Al2O3复合粒子质量分数为0.15%的硬质合金中,复合粒子均匀分布在WC晶粒间使细化晶粒的效果较显著,而且合金的相对密度较高,合金的强度提高至2 723.6 MPa,比普通机械球磨的合金提高约600 MPa,硬度(HV30)和断裂韧性分别提高约200.0和1.0 MPa∙m1/2。
The mixed powders of WC-6Co-GO/Al2O3 were prepared by mechanical ball milling method and ball milling-ultrasonic-freeze-drying method, respectively, and the bulk cemented carbide was prepared by cold press forming-sintering. The effects of the mixing process and the content of GO/Al2O3 composite particles on the dispersion of the mixed powders and the microscopic morphology, density and mechanical properties of the alloy were studied. The results show that ultrasonic freeze-drying can effectively solve the agglomeration problem of GO/Al2O3 composite particles and obtain fine uniform powder particles. In the prepared cemented carbide with the mass fraction of GO/Al2O3 composite particles of 0.15% when mixing powder by ball milling-ultrasonic- freeze-drying method, the composite particles are uniformly distributed among the WC grains to make the effect of refining the grains more significant, and the relative density of the alloy is higher, and the strength of the alloy increases to 2 723.6 MPa, which is about 600 MPa higher than that of the alloy with ordinary mechanical ball milling, and the hardness (HV30) and toughness also increase by about 200.0 and 1.0 MPa∙m1/2, respectively.
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