Reduction of WO3 to WC nanoparticles by the reflux reaction

Abstract

WC is an important material mostly used for cutting tool application. Reduction of WO 3 to WC is being done by several techniques. The existing chemical processes involved in its reduction are long and energy consuming. In this work efforts have been made to reduce WO 3 to WC by reflux reaction technique. The composite obtained after reflux reaction has been analyzed to see the feasibility of the conversion of WO 3 to WC. The preliminary study exhibited the feasibility of conversion of WO 3 to WC. The technique seems to be promising one and cost effective for low temperature synthesis of ultrafine WC particles. The synthesized powders were characterized using X-ray diffraction, scanning electron microscope, energy dispersive X-rays, and transmission electron microscopy for phase identification and micro structural analysis. Keywords: tungsten carbide; transmission electron microscopy; nanoparticles.Cemented Tungsten carbide (WC) is an important material for cutting tool industry [1-3]. The particle size of WC has remarkable effect on the hardness and other mechanical properties of material. As the size is reduced, a large fraction of atoms may lie at the grain boundaries which may contribute to the enhancement in material toughness. Substances of small grain size are known to have a strong influence on the mechanical properties of materials [4][5][6]. Nanocrystalline cemented carbide with ultrafine grain has become one of the hottest research areas of the present time [7]. Spray conversion [8][9][10][11][12], mechanical ball milling [13][14][15][16][17][18][19][20][21], chemical vapor phase reaction synthesis [22][23][24][25][26][27][28][29][30] and plasma processing technique [31][32] are the basic techniques used to synthesize nano-WC/WC-Co composite [8]. The shortcomings of all these techniques are that they involve high temperature synthesis process. The present work is an effort to synthesize ultrafine WC particles by chemical vapor phase reflux reaction. The method is simple and efficient to obtain nanopowders of mixed oxides or metal composite. Basically this process consists of vaporizing and condensation of a carbon source through refluxing action which allows the reaction to proceed where carbon engulf the precursor WO 3 powder to convert it into the nanosized WC. The idea behind this work is to find the feasibility of WC nanopowder synthesis at lower temperature where synthesis can be made easy.Experimental. Chemicals. The powders of tungsten oxide (WO 3 ) and magnesium (Mg) were used as initial ingredients. The average particle size and purity of both ingredients were 20 µm, 99.9%, and 178 µm, 98% respectively. Magnesium powder was selected as a reducing agent. Apart from this, glycerol (99.9%) was used as a carbon source in the present study. All the chemicals were used in as received condition without further purification.Methodology. Experiments were performed in a round bottom flask (1000 ml) fitted with chilled water cooled condenser which allows the liquid to condense during

Environmental citizenship behavior (the effect of environmental sensitivity, knowledge of ecology, personal investment in environmental issue, locus of control towards students’ environmental citizenship behavior)

“…This implies that environmental sensitivity has a positive direct effect on students' environmental citizenship behavior. The results of this study are consistent with the opinion of [1,2] state that "ecological concerns are increasingly construed in a moralized fashion in the public arena, pressing companies to advance the environmental cause in a more responsive and holistic manner". Revealing about research on civic attitudes and citizenship behaviors of individuals in organizations is supported by [3,4].…”

“…SDGs embraced nested sustainability model, which means that the economy is part of the social, and the social is part of the environment. Conveying regard economic, social, and environmental pillars or thinking mode in triple bottom line surely is not right, and deny the basic logic where SDGs madeEcological concerns are increasingly construed in a moralized fashion in the public arena, pressing companies to advance the environmental cause in a more responsive and holistic manner [1,2]. Accompanying this trend, research on the civic attitudes and citizenship behaviors of individuals in organizations [3,4] has emphasized the need to consider the natural environment as a stakeholder in its own right.…”

Review on green carbon dot-based materials for the photocatalytic degradation of dyes: fundamentals and future perspective

“…On further increasing the intensity of the light from the optimum level, the reaction rate is independent of its intensity since there is competition between the formation and recombination of electron-holes. 127,155 This explanation was supported with the experimental setup in our work to degrade MG dye with namely four conditions;(i) dark + without CDs/ZnO (ii) dark + with CDs/ZnO (iii) MG + visible light + without CDs/ZnO (iv) MG + visible light + with CDs/ZnO. There was no significant progress in photocatalytic degradation under dark conditions.…”

“…Generally, by keeping the photocatalyst concentration constant and increasing dye concentration, one can observe a decline in degradation percentage. 154,155 The decline in degradation percentage is ascribed to the increase in adsorption of dye molecules on the surface of the photocatalyst when the concentration of the dye increases. The availability of photons to reach the catalyst's surface is less, which decreases the formation of OH radical.…”

Novel graphite-carbon encased tungsten carbide nanocomposites by solid-state reaction and their ORR electrocatalytic performance in alkaline medium

“…Two different efforts have been made to conduct the composition and structure modifications of WC by incorporating Ta, which results in an enhanced electrocatalytic activity and stability attributing to the formation of a W-Ta alloy phase [30,31]. On the other hand, various strategies have been developed to prepare WC nano or micro-structure such as nanoparticle [32][33][34][35][36][37], nanofiber [38,39], nonorod [40,41], and sphere [42][43][44]. In addition, many reports utilized WC and carbon-support WC as catalyst supports for highly dispersed Pt clusters to achieve an enhancement performance due to the synergistic effect, which will also be beneficial for the cost reduction of fuel cell system to a certain extent [45][46][47][48][49][50].…”