论文部分内容阅读
利用高温膨胀仪在氢气气氛下首次测定和研究了WC (Ni·Fe) 8%、WC VC (Ni·Fe) 8%纳米级超细晶粒 (WC平均晶粒 2 0 0～ 30 0nm)硬质合金与常规细颗粒 (WC平均晶粒≤ 1 5μm)硬质合金压坯在烧结过程中的膨胀收缩动力学曲线特征、起始收缩温度、剧烈收缩温度随温度变化的收缩速率与WC粉的总碳含量、WC粉的平均粒径以及压坯密度的关系。结果发现 ,超细晶粒硬质合金 (WC粉总碳 6 0 1% )在烧结过程中物理膨胀现象较弱 ,开始收缩温度与剧烈收缩温度均较低 ,分别为 80 0℃ ,1150℃ ,最大收缩速率高达 10 50× 10 -6mm ℃ ,常规细晶粒合金的物理膨胀严重 ,在 62 0～ 130 0℃范围内相对膨胀 1 7% ,开始收缩温度与剧烈收缩温度分别为 132 0℃和 1390℃ ,最大收缩速率为 60 0× 10 -6mm ℃ ,远低于纳米级超细晶粒合金。WC粉总碳含量增加 ,合金的开始收缩温度及剧烈收缩温度均明显降低。压坯密度提高 ,合金的最终收缩率降低。在压坯密度一定的情况下 ,随着烧结温度提高 ,合金收缩率增加。
In the hydrogen atmosphere, 8% WC (Ni · Fe) and 8% nano-scale WC VC (Ni · Fe) ultrafine grained (WC average grains 200 ~ 300 nm) hard Cemented carbide and conventional fine particles (WC average grains ≤ 15μm) Cemented carbide compact sintering sintering expansion kinetic curve characteristics, initial shrinkage temperature, shrinkage rate of severe shrinkage temperature changes with temperature and WC powder The total carbon content, the average particle size of the WC powder and the density of the green compact. The results show that the physical expansion of ultrafine-grained cemented carbide (60% of the total WC content of WC powder) during sintering is weak, and the initial and severe shrinkage temperatures are both 80 0 ℃ and 1150 ℃, respectively. The maximum shrinkage rate is as high as 10 50 × 10 -6mm ℃. The conventional fine grain alloy has severe physical expansion and relatively expands 17% at 62 0 ~ 130 0 ℃. The initial shrinkage temperature and severe shrinkage temperature are 132 0 ℃ and 1390 ℃, the maximum shrinkage rate of 60 × 10 -6mm ℃, much lower than the nano-ultra-fine grain alloy. The total carbon content of WC powder increases, and the initial shrinkage temperature and severe shrinkage temperature of the alloy decrease obviously. As the density of the green compact increases, the ultimate shrinkage of the alloy decreases. In the case of a certain density of green compact, as the sintering temperature increases, the alloy shrinkage increases.