Plasma Synthesis of Tungsten Carbide Nanopowder from Ammonium Paratungstate

Abstract

A thermal plasma process has been applied to the synthesis of nanosized tungsten carbide powder with ammonium paratungstate (APT) as the precursor. The reduction and carburization of vaporized APT produced nanosized tungsten carbide (WC1−x) powder, which sometimes contained a small amount of W2C phase. The effects of reactant gas composition, plasma torch power, the flow rate of plasma gas, and the addition of secondary plasma gas (H2) on the product composition and particle size were investigated. The produced tungsten carbide (WC1−x) powder was <20 nm in particle size. The synthesized powders were also subjected to a hydrogen heat treatment to fully carburize the WC1−x and W2C phases to the WC phase as well as to remove excess carbon. Finally, WC powder of particle size <100 nm was obtained.

Nanostructured tungsten carbides by thermochemical processing

“…In a recent report, Zhu et al [23], have demonstrated low temperature carburization of W at 890-1030 • C by a new technique combining mechanical milling and dielectric barrier discharge plasma. Other routes like plasma enhanced chemical vapor deposition, ion arc exchange method, high-frequency induction combustion and plasma synthesis from ammonium paratungstate [24][25][26][27] have also been reported for the synthesis of tungsten carbide. Many of these studies have shown that the synthesis of either pure nano-WC or W 2 C in bulk quantity is difficult as both these phases along with WC 1−x and W tend to evolve under similar conditions.…”

Novel Crystal Growth of In Situ WC in Selective Laser‐Melted W–C–Ni Ternary System

“…Tungsten carbide (WC), as a typical refractory metal carbide, has been widely used in the metal machining, molds, and mineral industries because of the excellent properties such as high chemical inertness, low coefficient of thermal expansion, high hardness, and high wear/corrosion resistance . Normally, the Co is taken as the traditional binder element for WC and some other transition metals such as Ni and Fe act as alternatives .…”

Porous Tungsten Carbide Nanoplates Derived from Tungsten Trioxide Nanoplates

“…[1][2][3] For electrocatalytical applications, high surface areas and good dispersibility are essential requirements. To achieve this purpose, many groups have developed various methods to prepare nanoscale WC nanocrystals, including WC nanoparticles on support, 4-6 free-standing WC nanoparticles, 7,8 mesoporous WC nanochains, 9 WC nanofibers, 10 WC nanorods and nanopatelets, 11 hollow WC microspheres, 12 three-dimensionally ordered macroporous WC, 13 hierarchical WC micro/nanocrystals, 14 and inverse opal WC nanostructures. 15 However, morphology-controlled synthesis of lowdimensional tungsten carbide nanostructures (e.g., nanoplates) with high surface areas and high redispersibility is still a harsh challenge.…”