A Novel Process to Synthesize High-Quality Ferrovanadium Nitride
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CENTLY, the high-strength low-alloy (HSLA) steel has been used widely in industry on account of its economic benefits and superior performance. The HSLA steel is strong, plastic, and weldable and retains its operational characteristics at extremely low temperatures, which result from microalloying with carbideand nitride-forming metals (Al, Ti, V, Nb, etc.).[1–6] HSLA steel microalloyed with vanadium and nitrogen is of particular economic importance. Vanadium nitrides and carbonitrides formed in the steel on cooling and thermomechanical treatment processes can harden and refine grains effectively, so as to improve the overall mechanical characteristics of the steel.[7,8] In order to improve the contents of vanadium and nitrogen in the HSLA steel, ferrovanadium nitride and vanadium nitride are used. Compared with vanadium nitride, ferrovanadium nitride has more economic advantages and stable properties, including higher refined grains, strength promotion, malleability promotion, and toughness promotion. In the meantime, ferrovanadium nitride also has a higher yield than vanadium nitride when added to the liquid steel because of its high density, about 5.0 vs 3.5 g/cm3, respectively. Synthesis of ferrovanadium nitride has been studied for a long time. Solid nitration, liquid nitration, and sintering processes are the traditional methods to the
microintroduction of nitrogen.[1,9–12] Grishchenko[10] utilized the powder of ferrovanadium to produce ferrovanadium nitride in vacuum furnaces at around 1327 K (1050 C) for about 17 hours. Pomarin[11] used ferrovanadium alloys to prepare ferrovanadium nitride under nitrogen atmosphere by plasma smelting. In addition, Ziatdinov[1] synthesized the ferrovanadium nitride using the method of high-temperature self-propagation, which used ferrovanadium as the raw material. During the liquid nitration of ferrovanadium melts,[1,12] the high viscosity of ferrovanadium nitride is also a big problem. Furthermore, at high temperatures, the nitrogen solubility is low which results in a low nitrogen content. In summary, most of these methods are time consuming when taking the production of ferrovanadium into consideration, and energy consumptions are also high. In this study, a new and facile approach, based on the carbothermic reduction of V2O5 and Fe2O3 under nitrogen atmosphere at 1673 K to 1873 K (1400 C to 1600 C), has been researched in detail to prepare high-quality ferrovanadium nitride. Compared with traditional methods, this method is a short process, which avoids the production of ferrovanadium and decrease the production cost and energy consumption. In the meantime, the product has a relatively high nitrogen content and a low residual carbon content.
II. YUE-DONG WU, Master Student, GUO-HUA ZHANG, Associated Professor, and KUO-CHIH CHOU, Professor, are with the State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing 100083, China. Contact e-mail: ghzhang_ [email protected] Manuscript submitted April 5, 2016. Article published online August 23, 2016. ME
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