ELECTROCATALYTIC COBALT-VANADIUM COATINGS FOR THE HYDROGEN EVOLUTION REACTION

The study of existing energy-saving materials and obtaining the new ones for reducing the cost of the hydrogen production, is relevant for modern hydrogen energy industry. Such properties can be predicted for materials containing vanadium, molybdenum, tungsten and exhibiting catalytic activity for the hydrogen evolution reaction Aforementioned metals can be co-deposited from aqueous solutions with iron subgroup metal-catalysts through the formation of cluster intermetallic compounds with Me-V bond adsorbed on the cathode surface. The induced co-deposition of cobalt with vanadium from the complex citrate electrolyte was investigated in the current work. As a result of the research, it was found that the uniform microcrystalline light-gray high-quality cobalt-vanadium alloy coating is possible to precipitate from a citrate electrolyte with content of 20 g/dm3 vanadium (in terms of metal) as a citrate complex The process was carried out at a current density of 5–10 A/dm2, at a temperature of 30–40°С, pH = 2,8–3,2. The content of vanadium in the coating is 0,37–0,53 % by weight. The maximum vanadium content in the coating is observed at current densities 8–9 А/dm2. The catalytic activity study of the coating that was obtained using cobalt-vanadium alloy in the reaction of hydrogen reduction at the cathode was performed in solution of 2,5М NaOH + 0,02 M NaCl. By increasing the vanadium content in the coating from 0,37 to 0,53% the hydrogen evolution overvoltage is reduced by 0,5 V. It was found that the overvoltage of the hydrogen ion evolution reaction on cathodes from steel 20 with cobalt-vanadium coating is 0.08–0,1 V lower, and the exchange current is higher than on electrodes made of steel 20, which are used in industrial water-alkali electrolysis. This indicates the electrocatalytic activity of the investigated materials for the hydrogen evolution reaction. Electrodes with coating, obtained by cobalt-vanadium alloy can be recommended as a cathode material for the hydrogen electrochemical production. Hydrogen evolution overvoltage reduction also decrease the energy consumption for this process by 15–20 %.

DEUTSCHE EDELSTAHLWERKE CRYODUR 2243

Deutsche Edelstahlwerke Cryodur 2243 is a high-carbon, chromium-silicon-vanadium alloy cold-work tool steel that is suitable for applications requiring a combination of high strength, high toughness, and good wear resistance. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on casting and heat treating. Filing Code: TS-821. Producer or source: Deutsche Edelstahlwerke Specialty Steel GmbH & Co.

DEUTSCHE EDELSTAHLWERKE CRYODUR 2249

Deutsche Edelstahlwerke Cryodur 2249 is a medium-carbon, silicon-chromium-vanadium alloy cold-work tool steel that provides an attractive combination of high strength, high hardness, and high toughness. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on heat treating. Filing Code: TS-817. Producer or source: Deutsche Edelstahlwerke Specialty Steel GmbH.

Preparation and wear properties of high-vanadium alloy composite layer

A high-vanadium alloy composite layer was prepared on the surface of a carbon steel using cast composite technology, and the wear properties of the composite layer were investigated. The results showed that the microstructure of the composite layer was composed of primary vanadium carbides (VC), flake martensite, residual austenite, and fine VC. The hardness of the cast alloy layer was 63 HRC. The abrasive wear resistance and impact wear resistance were increased by 60% and 26%, respectively, compared with those of high-chromium cast iron. The excellent wear resistance of the cast alloy layer is attributed to the high-hardness primary vanadium carbide and the large number of fine secondary vanadium carbides precipitated out of the cast alloy layer.

DEUTSCHE EDELSTAHLWERKE CRYODUR 2242

Deutsche Edelstahlwerke Cryodur 2242 is a medium-carbon, chromium-vanadium alloy cold-work tool steel that has medium hardenability and is suitable for applications requiring a combination of high strength, high toughness, and good wear resistance. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on forming, heat treating, and machining. Filing Code: TS-816. Producer or source: Deutsche Edelstahlwerke Specialty Steel.

Study of Controlled Aluminum-Vanadium Alloy Prepared by Vacuum Resistance Furnace

In this paper, V2O3 is used as the raw material, and an Al-V alloy is synthesized by vacuum resistance furnace heating. The results show that with the extension of the heating time, the separation effect of the alloy and the slag and the uniformity of the alloy are significantly improved. The slag is fully separated from the alloy, and the composition of the alloy is more uniformly distributed when the heating time is controlled at 1 hour. In addition, the composition of the alloy is affected by increasing content of Al. In particular, the obtained alloy composition meets commercial standards when the mass ratio of Al is 31-36 wt%. The effect of different mass ratios of CaO on the quality of slag series and alloys was also investigated. The results show that the composition distribution of the slag system can be effectively changed with increasing the mass ratio of CaO, and the uniformity of the alloy composition is also optimized. When the mass ratio of CaO is 27 wt%, the alloy and slag are well separated, and the composition distribution in the obtained alloy is more uniform. In addition, the content of impurities in the alloy can be effectively improved under vacuum. Therefore, it is suggested that a vacuum resistance furnace should be applied in the industrial production of high-quality Al-V alloy.

The Effect of Yttrium Addition on the Microstructure and Irradiation Hardening in V-4Cr-4Ti Alloy under Self-Ion Irradiation

Microstructure and irradiation hardening of V-4Cr-4Ti alloys with different yttrium (Y) contents were studied by self-ion irradiation at 550 °C via TEM and nano-indentation test technology. The peak damage of the V-4Cr-4Ti-xY alloy (x = 0, 0.1, 0.5, and 1, wt.%) irradiated by 2.5 MeV self-ion (V2+) is 8 dpa. Dense dislocation loops were observed in all vanadium alloy samples after irradiation. With the increase of Y content, both average size and number density of dislocation loops using g = <110> near the pole [001] decreased, while the irradiation hardness increment first decreased and then increased. In order to better reduce the irradiation hardening, it is considered that the addition of 0.1 wt.% Y in V-4Cr-4Ti alloy is reasonable.