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碳氫協(xié)同還原-碳化法制備納米WC粉的工藝及機理研究
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南昌大學,南昌大學

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TF123

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國家自然科學基金項目(面上項目,重點項目,重大項目)


Process and Mechanism of WC Nano-powders Prepared by Carbon-hydrogen Coreduction-carbonization Method
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Nanchang University,Nanchang University

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    摘要:

    針對傳統(tǒng)還原-碳化工藝中WC粉顆粒的長大問題,采用碳氫協(xié)同還原-碳化法制備納米級球形WC粉,研究前驅(qū)體配碳比和反應溫度對WC粉性能的影響。結(jié)果表明,WC的碳含量與前驅(qū)體的配碳比密切相關(guān),最佳配碳比(即n(C)/n(W)值)為3.6。W向WC的轉(zhuǎn)變具有結(jié)構(gòu)遺傳性,WC的平均粒徑與還原溫度和碳化溫度密切相關(guān)。隨著還原溫度由680 ℃升高至800 ℃,還原水蒸氣與碳反應生成CO和H2,顯著降低體系中水蒸氣的分壓,從而抑制中間產(chǎn)物W顆粒的揮發(fā)-沉積長大,WC的平均粒徑隨還原溫度升高而減小。碳化過程中的高溫促進WC顆粒的晶界遷移和納米W顆粒之間的燒結(jié)合并長大,WC的平均粒徑隨碳化溫度的升高而增大。n(C)/n(W)為3.6的前驅(qū)體粉末經(jīng)800 ℃還原和1100 ℃碳化后,得到平均粒徑為87.3 nm的球形WC粉。

    Abstract:

    Aim at the existing problem of the growth of WC particles in the traditional reduction and carbonization process, adopted the method of carbon-hydrogen coreduction-carbonization to prepare nano-level powders and studied the effects of the n(C)/n(W) of precursors and reaction temperature on the properties of WC. The results show that the carbon content of WC is related to the n(C)/n(W) of precursors, and the optimum molar ratio is 3.6. The average particle size of WC is closely related to reduction temperature and carbonization temperature duo to the transformation of W to WC has structural heredity. Pressure of water vapor in the system decreases due to the reaction of H2O and C with the reduction temperature increases from 680 ℃ to 800 ℃, and which inhibited the volatilization-deposition growth of W particles in hydrogen reduction process. Therefore, the average particle size of WC decreases with increasing reduction temperature. The high temperature can promote the grain boundary migration of WC particles and the combination growth of nano W particles, and the average particle size of WC increases with increasing carbonization temperature. When the n(C)/n(W) of precursor is 3.6, the average particle size of WC powders is 87.3 nm after reduction and carbonization at 800 ℃ and 1100 ℃, respectively.

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葉楠,唐建成.碳氫協(xié)同還原-碳化法制備納米WC粉的工藝及機理研究[J].稀有金屬材料與工程,2017,46(1):143~149.[Ye Nan, Tang Jiancheng. Process and Mechanism of WC Nano-powders Prepared by Carbon-hydrogen Coreduction-carbonization Method[J]. Rare Metal Materials and Engineering,2017,46(1):143~149.]
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  • 收稿日期:2016-04-05
  • 最后修改日期:2016-04-26
  • 錄用日期:2016-05-19
  • 在線發(fā)布日期: 2017-03-16
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