A Novel Method for Direct Synthesis of WC-Co Nanocomposite Powder

Abstract

In this study, a novel method, termed dielectric-barrier-discharge-plasma (DBDP) assisted ball milling and low-temperature carburization, was used to synthesize WC-Co nanocomposite powder. X-ray diffraction, scanning/transmission electron microscopy, and differential scanning calorimetry were used to characterize the microstructure of powders. Starting from W, Co, and graphite powder mixtures, the DBDP-milled W-C-10Co powder exhibited a flakelike morphology with very fine lamellar structure. The WC-Co composite powder was synthesized at 1273 K (1000°C), which is much lower than the requisite temperature for the conventional carburizing method. The obtained WC-Co composite powder had a nanocomposite microstructure in which fine WC particles were bounded by homogenously distributed Co phase, and the WC crystals had a slablike morphology with a planar size of about 200 nm and <100-nm thickness. The combinational effect of the milling and the plasma in the DBDP milling caused a unique fine flakelike morphology and high-density interfaces in the W-C-10Co powder mixture, which is responsible for the reduced carburization temperature and the nanocomposite structure of WC-Co powder.

A Novel Approach to the Rapid in situ Synthesis of Tungsten Carbide Nanopowder by Plasma Milling and Carbothermal Reduction

“…Previous work by our group [ 18–20 ] demonstrated that the use of a discharge plasma allows the fabrication of highly active W–C mixtures and promotes the reaction between W and C to form WC, thus lowering the reaction temperature of carburization. In the present study, TG‐DSC analyses of the nanocomposite powders were performed as a means of comparing their carburization processes.…”

“…Material Preparation: A milling device (PBMS, South China University of Technology, China) was used to prepare the WO 3 -C nanocomposite powders, based on working principles described in the previous publications. [18][19][20] A high-voltage alternating current power supply operating at 9.8 kHz and a maximum pulse voltage of 20 kV was applied to the ball milling jar using a single dielectric barrier discharge reactor. This current produced a homogeneous non-thermal Ar gas plasma in the milling jar.…”

“…Recently, ultrafine WC grains have been synthesized via the carburization of W–C–Co nanocomposite powders activated by plasma milling (P‐milling). This process allows the carburization temperature to be reduced by 300–500 °C by promoting the mass diffusion rates of the W and C. [ 17–20 ] P‐milling has also been reported to activate V 2 O 5 –C powder mixtures and improve the deoxidation reaction while permitting much lower temperatures to be applied. [ 21 ] These improvements are attributed to the large number of clean surface contacts and surface area of the nanocomposite produced by P‐milling.…”

Fabrication of TiN-doped Ti nanocomposites with high strength and ductility by plasma-assisted ball milling and selective laser melting

“…The Ti-TiN nanocomposites were synthesized from raw atomized spherical CP-Ti powder with a diameter of about 15-53 µm (Changsha TIJO Metal Materials Co., Ltd., China) using a plasma milling device (PBMS, South China University of Technology, China). The working principle of this device has been reported previously [22][23][24][25]. In this work, mechanical ball milling was conducted during exposure to a homogeneous non-thermal N 2 gas plasma, which was generated with a pulse peak voltage of 25 kV and discharge frequency of 11.5 kHz using a single dielectric barrier discharge reactor.…”

Comparative research of plasma-assisted milling and traditional milling in synthesizing AlN

“…High-energy ball milling, utilizing mechanical energy, is a frequently used method to prepare ultrafine powders, alloys, or compounds in the solid state, and has attracted much attention in recent years [1][2][3]. During high-energy ball milling, the shear stress and impact will activate the material, which is called mechanical activation [4].…”