Precursor synthesis and properties of nanodispersed tungsten carbide and nanocomposites WC:nC

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• 作者：Vladimir N. Krasil&rsquo ; nikov^a ; Еvgenii V. Polyakov^a ; Nikolai А. Khlebnikov^a ; ^b ; ^{NA.Khlebnikov@urfu.ru} ; Nadezda V. Tarakina^a ; ^c ; Мikhail V. Kuznetsov^a
• 关键词：Carbon ; Composites ; Tungsten carbides
• 刊名：Ceramics International
• 出版年：2017
• 出版时间：1 April 2017
• 年：2017
• 卷：43
• 期：5
• 页码：4131-4138
• 全文大小：3665 K
• 卷排序：43

文摘

Nanoscale tungsten carbide (WC) and WC:nC nanocomposites have been synthesized by the precursor method. The precursor, obtained in the form of a glassy mass by thermal treatment of a mixture of (NH4)10W12O41∙7H2O and glycerol, was heated in inert gaseous atmosphere up to 1050–1100 °C. The concentration of chemically active carbon in the precursor and nanocomposites depends on the W/C ratio in the initial mixture. At W/C=1/3 pure tungsten carbide is formed; at W/C>1/3 composites of WC and free carbon (WC:nC) are formed. Heating of the precursor with W/C=1/6 up to 1100 °C in helium atmosphere results in the formation of carbon-encapsulated tungsten carbide nanoparticles. An increase in the precursor-heating rate leads to the formation of chain-like structures. Each chain consists of hexagonal WC grains with unit cell parameters a=2.93 Å and c=2.83 Å. Free carbon in WC:nC composites forms agglomerates of carbon “nano-onions” of spherical or multi-layered tubular shapes.