Editors: | F. Kongoli, K. Aifantis, C. Capiglia, A. Fox, R. Yazami, A. U. H. Qurashi |
Publisher: | Flogen Star OUTREACH |
Publication Year: | 2023 |
Pages: | 90 pages |
ISBN: | 978-1-989820-82-7 (CD) |
ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
The unique physicochemical properties of tungsten, its alloys and compounds (infusibility, chemical, abrasive and erosion resistance, high mechanical strength, emissive ability, catalytic activity, etc.) determined their widespread use in modern science and technology. This is evidenced by the high growth rates of the tungsten industry throughout the world. An important area of tungsten application is the use of tungsten carbides in the production of cutting and wear-resistant materials. These materials are used in metalworking, the oil, gas, mining, energy, construction, and automotive industries, etc. A promising direction to improve the performance properties of tungsten-based materials is the reduction of the grain size in the material to the nanometer. Analysis of experts on the development of the world market for tungsten carbide indicates the importance of this direction and predicts an increase in carbide production from 2018 to 2028 on average by 4.07% per year in value equivalent [1, 2].
The high-temperature electrochemical synthesis method allows one to obtain both single-phase powders of tungsten, tungsten bronzes, tungsten carbides, and composite materials based on them with carbon and metals (Pt, Co, Ni) in one stage at relatively low temperatures (700 °C) and energy consumption for electrolysis with an average grain size of up to 10 nm and a specific surface area of up to 30 m2/g. The carbon source for the synthesis of carbides is carbon dioxide, which is introduced into the melt under pressure. At the same time, this method is an electrochemical utilizing of carbon dioxide, the content of this greenhouse gas in the Earth’s atmosphere rises catastrophically every year [3]. The method allows one to capture and convert carbon dioxide into new value-added chemical products. Therefore, in addition to technological and applied tasks, this study solves an important environmental problem.
Two variants of electrochemical synthesis were realized:
1. Joint electro-reduction of oxygen-containing compounds of tungsten and carbon with doping agents Pt, carbon in chloride-oxide melts.
2. Electro-reduction of oxygen-containing tungsten compounds that are found in chloride melts in the solid phase.
Physico-chemical properties of the synthesized materials (phase and chemical composition, morphological and structural features, thermal stability, electro-catalytically activity) were studied and the correlation of properties with electrolysis conditions was established. Evaluation of the catalytic activity of the materials obtained was done in the reaction of hydrogen evolution in acidic solutions.