摘要:
本文采用两步碳热还原法合成了WC-xVC复合粉，并以此为原料制备了不同Co含量的WC-Co-VC硬质合金。研究了烧结温度(1420 ℃, 1440 ℃和1460 ℃)对试样致密化过程的影响。同时，研究了Co和VC含量对WC的晶粒尺寸、以及样品的维氏硬度和断裂韧性的影响。结果表明，随着烧结温度的升高，致密度增大，当烧结温度为1460 ℃时，所有试样的致密度均大于98.5 %。此外，随着VC含量的增加，WC的平均晶粒尺寸减小，这导致样品的硬度提高，而断裂韧性降低。当VC添加量为6 wt.%时，WC-6Co硬质合金(1941 HV30)和WC-10Co硬质合金(1838 HV30)的硬度均达到最大值。在烧结温度和VC含量一定的情况下，试样的断裂韧性随着Co含量的增加而增加。
Abstract:
In this work, WC-xVC composite powders were synthesized by a two-step carbothermal reduction process, and then WC-Co-VC cemented carbides with different Co contents (6 wt.% and 10 wt.%) were prepared by using WC-xVC composite powder as raw material. The effect of sintering temperature (1420 ℃, 1440 ℃ and 1460 ℃) on the densification of samples was studied. Meanwhile, the influences of Co and VC contents on the grain size of WC as well as hardness and fracture toughness were investigated. The experimental results indicated that as the sintering temperature increased, the relative density increased, and when the temperature was 1460 ℃, the relative densities were all higher than 98.5%. With the increase of VC addition amount, the average grain size decreased, leading to an improvement in hardness, while a decrease in fracture toughness. When the VC addition amount was 6 wt.%, the hardness reached the highest values of 1941 HV30 and 1838 HV30, for the alloys with the Co content of 6 wt.% and 10 wt.%, respectively. In addition, when the sintering temperature and VC content were constant, the increase of Co content would increase the fracture toughness and reduce the hardness.
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