双尺度结构WC-6%Co硬质合金球磨工艺研究

Study on Ball Milling Process of Bimodal-grained WC-6%Co Cemented Carbides

以粒度分别为2.4μm和0.9μm的粗细WC和Co为原料,采用常规球磨和真空烧结制备了双尺度结构WC-6%Co硬质合金。利用XRD、SEM观察合金的物相变化及微观组织形貌,并通过对比分析密度、硬度、矫顽磁力、抗弯强度和断裂韧性等研究了球磨工艺对合金综合力学性能的影响。结果表明,随着球磨时间和球料比的增加,WC晶粒逐渐长大,合金的(0001)基面百分比例显著增加,同时(1010)棱柱面比例降低。且相比于球磨时间,增加球料比更能破碎和活化细WC颗粒。预磨24 h、球料比4∶1及混合球磨24 h、球料比2∶1球磨条件下制备的合金综合性能达到最佳,其密度、硬度、矫顽磁力均较优异,抗弯强度最高达到3 250 MPa,同时断裂韧性为11.5 MPa·m^(1/2)。

Using WC with particle size of 0.9 μm and 2.4 μm and Co as raw materials, the bimodal-grained WC-6%Co cemented carbides were fabricated by conventional roller ball milling and following vacuum sintering.The phase change and microstructure morphology of alloys were observed by XRD and SEM,and the effect of ball milling on the comprehensive mechanical properties of the alloy was studied by comparing the density, hardness, coercive force, bending strength and fracture toughness.The results show that with the increase of milling time and ball-to-powder ratio, WC grains gradually grow up, the percentage of(0001) basal plane of the alloy significantly increases, and the ratio of (1010) prism plane decreases.Compared with the ball milling time, increasing the ball-to-powder ratio can break and activate the fine WC particles.The comprehensive properties of the alloy prepared by pre-milling for 24 h with ball-to-powder ratio of 4∶1 and mixed ball milling for 24 h with ball-to-powder ratio of 2∶1 are the best, its density, hardness and coercive force are excellent, the bending strength is up to 3 250 MPa, and the fracture toughness reaches 11.5 MPa·m^(1/2).