【摘要】 鉴于采用传统的球磨法很难制备出WC平均晶粒度(d_WC)超过8μm的特超粗晶硬质合金，本文采用两种规格（??5.5 mm和??10.5 mm,长径比均为1.5∶1）的棒状研磨体结合不同的湿磨时间（使湿磨强度保持在只混合而不过度破碎的程度）,成功制备出d_WC大于8μm的特超粗晶硬质合金，并对其微观组织和物理力学性能进行了分析。结果表明：大棒研磨体对物料的破碎及混合效果均不如小棒；随着小棒研磨体质量的增加及湿磨时间的延长，合金的孔隙度、Co相均匀性均得到明显改善，但d_WC逐渐降低。随着d_WC降低，合金的硬度和强度值升高，而热导率及断裂韧性值降低。在研磨体为小棒、湿磨时间为12 h,或者研磨体为大棒、湿磨时间为20 h的条件下，可以制备出孔隙度达A02B00水平且d_WC≥8μm的特超粗晶硬质合金，其硬度值保持在900 HV₅₀左右，抗弯强度值超过1 800 MPa,热导率超过140 W/（m·K）,最大断裂韧性值为21.6 MPa·m^1/2。相较于超粗晶硬质合金，特超粗晶硬质合金对裂纹的产生及其扩展表现出更好的抑制和阻碍作用，断裂韧性更优。更多还原

【Abstract】 In view of the fact that it is difficult to prepare ultra-coarse grain cemented carbides with WC average grain size(d_WC) greater than 8 μm by traditional ball milling method, this paper adopted two specifications（??5.5 mm and ??10.5 mm, aspect ratio 1.5∶1） of rod-shaped grinding media combined with di-fferent wet grinding time, so that the wet grinding strength can maintain at the degree of only mixing without excessive crushing, and the ultra-coarse-grained cemented carbides with d_WC greater than 8 μm were successfully prepared.Their microstructure and physical and mechanical properties were then analyzed.The results show that the crushing and mixing effect of the large rod grinding media on the material is inferior to that of the small rod.With the increase of the small rod grinding media mass and the wet grinding time, the porosity and Co phase uniformity of the alloy are obviously improved, but the d_WC decreases gradually.With the decrease of d_WC,the hardness and strength of the alloy increase, while the thermal conductivity and the fracture toughness decrease.The ultra-coarse-grained cemented carbide with porosity of A02B00 level and d_WC of ≥8 μm can be prepared under the conditions of small rod and wet grinding time of 12 h or large rod and wet grinding time of 20 h.The hardness value is maintained at about 900 HV₅₀,the bending strength value exceeds 1 800 MPa, the thermal conductivity exceeds 140 W/（m·K）,and the maximum fracture toughness value is 21.6 MPa·m^1/2.Compared with super-coarse-grained cemented carbide, ultra-coarse-grained cemented carbide shows better inhibition and hindrance to the generation and propagation of cracks, along with superior fracture toughness.更多还原