共沉淀回收W-Co复合粉末的碳化机理
CARBURIZATION MECHANISM OF W-Co COMPOSITE POWDER RECYCLED BY CO-PRECIPITATION
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摘要: 共沉淀回收W-Co复合粉末的还原料在固相碳化过程中,低温下由Co3W和Co7W6向η型碳化物转化,高温(900℃以上)下由η型碳化物转化为共生的β-Co和粗晶WC,该粗晶WC是导致用这种回收料生产的合金中具有超常粗大的WC晶粒的原因。在600~1100℃由W和C直接生成和在750~1100℃由W2C和C生成细晶WC(<0.2μm)。由于低温下不存在游离态Co对W粉碳化过程的催化作用,即使在1200℃下也难以完成碳化过程。Abstract: In the process of solid phase carburization of the reduced W-Co composite powder recycled by co-precipitation was converted from Co3W and Co7W6 to η type carbides at low temperature and was converted from η type to co-grown β-Co and coarse WC crystals at high temperature (over 900℃), the coarse WC crystals were the cause of the formation of super coase. WC crystals in the alloys produced by these recycled materials. Fine WC crystals (<0. 2μm) were directly formed from W and C at 600~1100℃ and produced from W2C and C at 750~1100℃. There was no catalytical effect of free Co phase on carburization at low temperature. The carburization process could not be completed even if at 1200℃.
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Key words:
- hard alloy /
- co-precipitation recycled /
- W—Co composite powder /
- carburization
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