论文部分内容阅读
利用Master S intering Curve晶粒长大方程模拟了200 nm WC-Co硬质合金固相烧结和液相烧结过程中WC晶粒的长大曲线,并与实际烧结实验相比较。烧结实验选用的WC的粒度为200 nm,采用球磨混料,经过普通模压,压制压力为200 MPa,制备出直径为20 mm、厚度为3~5 mm的压坯。烧结实验在管式炉中进行,烧结气氛为高纯氢气,加热速率为10℃.m in-1,烧结时间为10 m in。结果表明:Master S interingC ruve模型在WC-Co硬质合金烧结过程中具有很好的适用性。计算出的晶粒长大随烧结温度的变化与实际烧结实验具有很好的一致性。经过固相烧结,200 nm的WC长大到254 nm,烧结激活能为450 k.Jmol-1,但体积扩散和晶界扩散机制的区别不是很明显。经过液相烧结WC颗粒继续长大到287 nm,此时固液相的界面反应控制整个烧结过程,烧结激活能为474 k.Jmol-1。压坯烧结激活能的增加,将显著抑制在烧结过程中WC晶粒的长大。
The growth curve of WC grains in the solid-state sintering and liquid-phase sintering of 200-nm WC-Co cemented carbide was simulated by the Master S intering Curve grain growth equation and compared with the actual sintering experiment. The particle size of WC used in the sintering experiment was 200 nm. The ball mill mixture was used to make the green compact with the diameter of 20 mm and the thickness of 3 ~ 5 mm after normal compression and pressing pressure of 200 MPa. Sintering experiments were carried out in a tube furnace. The sintering atmosphere was high purity hydrogen at a heating rate of 10 ° C.m in-1 with a sintering time of 10 mins. The results show that the Master S intering C ruve model has good applicability in WC-Co cemented carbide sintering. The calculated grain growth with the sintering temperature changes with the actual sintering experiment has a good consistency. After solid-phase sintering, the WC at 200 nm grows to 254 nm and the sintering activation energy is 450 kJ-mol-1, but the difference between volume diffusion and grain boundary diffusion is not obvious. After the liquid phase sintering WC particles continue to grow to 287 nm, then the solid-liquid interface control of the entire sintering process, the activation energy of sintering 474 k.Jmol-1. The increase of sintering activation energy of green compact will significantly suppress the growth of WC grains during sintering.