Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5439069 | Ceramics International | 2017 | 28 Pages |
Abstract
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)10W12O41â7H2O 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 Ã
and c=2.83Â Ã
. Free carbon in WC:nC composites forms agglomerates of carbon “nano-onions” of spherical or multi-layered tubular shapes.
Keywords
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
Vladimir N. Krasil'nikov, Ðvgenii V. Polyakov, Nikolai Ð. Khlebnikov, Nadezda V. Tarakina, Ðikhail V. Kuznetsov,