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Spark Plasma Sintering of WC–10Co Nanopowders with Various Carbon Content Obtained by Plasma-Chemical Synthesis
Inorganic Materials: Applied Research Pub Date : 2021-04-20 , DOI: 10.1134/s207511332102009x
Yu. V. Blagoveshchenskiy , N. V. Isaeva , E. A. Lantsev , M. S. Boldin , V. N. Chuvil’deev , A. V. Nokhrin , A. A. Murashov , P. V. Andreev , K. E. Smetanina , N. V. Malekhonova , A. V. Terentev

Abstract

Features of high-speed sintering of WC–Co nanopowders with various contents of excess carbon (colloidal graphite) were studied. Powders were obtained in a process that included plasma-chemical and low-temperature syntheses and a chemical-metallurgical method of applying ultrathin cobalt layers by precipitation from a solution of salts. Powder materials were consolidated by high-speed spark plasma sintering. It was found that an increase in the concentration of free carbon (colloidal graphite) has the greatest effect on the shrinkage and the sintering rate at the stage of intense shrinkage of WC–Co nanopowders. It was revealed that the process of nanopowder compaction at the intense shrinkage stage is determined by the intensity of the plastic flow and the intensity of diffusion along the boundaries of cobalt grains. It was shown that the mechanism of plastic deformation of the cobalt-based γ phase corresponds to the Coble diffusion creep. It was found that an increase in carbon content lowers the activation energy at the stage of intense shrinkage and does not significantly affect the activation energy at stage III of sintering, where the shrinkage intensity is observed to decrease. It was shown that a decrease in the sintering activation energy is due to a decrease in the tungsten concentration in the γ phase.



中文翻译:

通过等离子化学合成获得具有不同碳含量的WC-10Co纳米粉的火花等离子烧结

摘要

研究了不同含量的过量碳(胶态石墨)对WC-Co纳米粉的高速烧结特性。通过包括等离子体化学和低温合成以及通过从盐溶液中沉淀来施加超薄钴层的化学冶金方法的过程获得粉末。粉末材料通过高速火花等离子体烧结进行固结。结果发现,在WC-Co纳米粉体的剧烈收缩阶段,游离碳(胶体石墨)浓度的增加对收缩率和烧结速率影响最大。结果表明,纳米粉末在强收缩阶段的压缩过程是由塑性流动的强度和沿钴晶粒边界的扩散强度决定的。结果表明,钴基γ相的塑性变形机制与Coble扩散蠕变相对应。已经发现,碳含量的增加降低了剧烈收缩阶段的活化能,并且没有显着影响烧结阶段III的活化能,在该阶段观察到收缩强度降低。结果表明,烧结活化能的降低是由于γ相中钨浓度的降低。

更新日期:2021-04-20
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