Abstract

The effect of the carbon content on the kinetics of spark plasma sintering of nanopowder and submicron powder of WC–10% Co compositions was studied. Free carbon in the graphite form was introduced into nanopowders and submicron powders by mixing. The activation energy of solid-phase sintering at isothermal holding and continuous heating was determined. It is shown that increase in the carbon content leads to decrease in the volume fraction of the η phase and shift of the shrinkage curve into the region of low temperatures. It is established that an increase in the carbon content does not have a significant effect on the sintering activation energy of nanopowders and submicron powders in the region of “average” heating temperatures, the value of which is close to the activation energy of grain boundary diffusion in cobalt. It is shown that an increase in the carbon content leads to a significant decrease in the activation energy of consolidation of WC–Co powders in the region of “high” sintering temperatures owing to a decrease in the concentration of tungsten atoms in the γ phase based on cobalt. The sintering kinetics of fine-grained WC–Co alloys is limited by the rate of Coble diffusion creep of cobalt.

中文翻译：

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WC-10％Co超细晶硬质合金火花等离子体烧结动力学。

摘要

研究了碳含量对WC-10％Co组成的纳米粉末和亚微米粉末的火花等离子体烧结动力学的影响。通过混合将石墨形式的游离碳引入纳米粉末和亚微米粉末中。确定了等温保温和连续加热下固相烧结的活化能。已经表明，碳含量的增加导致η相的体积分数减小，并且收缩曲线向低温区域移动。已经确定，在“平均”加热温度范围内，碳含量的增加对纳米粉末和亚微米粉末的烧结活化能没有显着影响，其值接近晶界扩散的活化能。在钴。结果表明，由于“γ”相中钨原子浓度的降低，碳含量的增加导致“高”烧结温度区域WC-Co粉末固结的活化能大大降低。在钴上。细晶粒WC-Co合金的烧结动力学受到钴的Coble扩散蠕变速率的限制。