INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
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2025
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IF 4.6
Taotao Cai,Ying Zhang,Shili Zheng,Longkai Liu,Yi Zhang,Bin Yu
V Al master alloys are essential raw materials for producing high-quality titanium alloys, which are generally produced by aluminothermic reduction, metal-slag gravitational separation method. The conventional way faces the challenges of excessively high reaction temperatures, metallic inclusions in slag, and difficulties in fabricating higher-Al-content alloy in one step. To conquer these issues, this research has reported a new method to precisely fabricate V Al master alloy with a designated composition, which is an aluminum reduction coupled with an acid leaching process. The reduction byproduct of weak-acid-soluble calcium aluminate, the critical parameters for Al reduction, and the reaction routes are determined. This research has demonstrated that various V Al master alloys (expressed as AlV x ) are successfully prepared by heating the optimal mixture of V 2 O 3 + (2 + 2 x -)/ x Al + 2.0CaO + 1.35CaCl 2 (in molar ratio) at 1000 °C for 5 h in Ar and pickling the reduction material using HCl acid with pH controlled at 1.2. Oxygen in 6Al4V, 4Al6V, and 2Al8V alloy powders are 400 ppm, 500–700 ppm, and 1800–2000 ppm, respectively. The 4Al6V powder produced by this reported method is compared with the commercial one, with comparable phase and chemical compositions but with finer sizes preferred in powder metallurgy sintering. The main reactions or phase changes that happen during heating include stepwise removal of surface and crystalline water from CaCl 2 , melting of Al, reaction between V 2 O 3 and CaO, melting of CaO-CaCl 2 binary compound, and Al reduction reaction. The method developed in this study can also be used to prepare other alloys, such as Ti Al and Ti Fe alloy powders.
研究领域:
材料科学
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冶金工程
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产品关联
DOI
高影响因子
Journal of Materials Research and Technology-JMR&T
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2025
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IF 6.6
Zhenyun Tian,Weichao Zheng,Liu Yang,ChuanMing Wu,Jialong Kang,Jiawen Chen,Guibao Qiu
The recovery of valuable metals from spent SCR catalysts currently centers on chromium and tungsten oxides. However, this approach demands substantial consumption of acids and bases, and due to the low vanadium and tungsten content, its economic output is minimal. In contrast, titanium dioxide, which exists in significantly higher proportions within the catalyst, is largely overlooked, aggravating environmental issues and leading to considerable resource wastage. This research proposes utilizing spent SCR catalysts as raw materials to directly synthesize titanium alloys, thereby increasing the recovery value of these discarded materials. The findings reveal that aluminum, employed as a reducing agent, efficiently reduces the majority of valuable metals in the catalyst, resulting in the formation of titanium alloys. Furthermore, the addition of calcium oxide markedly enhances the reduction process and improves slag-metal separation. When the CaO content reaches 50 wt%, titanium recovery achieves an impressive rate of 93.34 wt%. The produced alloy comprises primarily a Ti–Al alloy matrix, with a Ti–Si alloy as a dispersed reinforcing phase uniformly distributed within the matrix, demonstrating significant potential for practical applications.
研究领域:
材料科学
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环境工程
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产品关联
DOI
高影响因子
JOURNAL OF SOLID STATE CHEMISTRY
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2024
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IF 3.2
Ya-Long Wang,Guo-Hua Zhang
Herein, we report a low-temperature method for synthesizing high-entropy rare earth hexaboride powders by reaction among rare earth oxides, B 4 C, and Al powders. Al was used as a reducing and decarburization agent in this process, which further reduced the Gibbs free energy change for the reaction of Re x O y with B 4 C to form REB 6 . By investigating the influence of reacting temperature and amount of Al added on preparation of LaB 6 , the optimum experimental conditions of this method were determined to be 1300 °C and 2 times the stoichiometric ratio of Al. Theoretical supports were proposed to verify the feasibility for formation of high-entropy borides. Then, multicomponent hexaborides La 0.5 Ce 0.5 B 6 , La 0.33 Ce 0.33 Nd 0.33 B 6 , and La 0.25 Ce 0.25 Nd 0.25 Sm 0.25 B 6 as well as high-entropy hexaboride La 0.2 Ce 0.2 Nd 0.2 Sm 0.2 Eu 0.2 B 6 powders were successfully prepared by doping with Ce, Nd, Sm, and Eu on LaB 6 . RE elements with different radius were uniformly distributed in the multicomponent boride powders without obvious segregation. More importantly, the lattice distortion and stress induced by the element substitution contribute to the reduction of the average powder particle size. Finally, the DTA-TG curves show that rare earth hexaborides have good oxidation resistances when the temperature is below about 1000 °C.
研究领域:
材料科学
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无机化学
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产品关联
DOI
高影响因子
Journal of Cleaner Production
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2024
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IF 9.7
Taotao Cai,Ying Zhang,Shili Zheng,Peiyi Yan,Yi Zhang
Titanium is a highly valued material. Developing a lower-cost titanium (Ti) metal powder production process, potentially substituting the conventional Kroll-HDH method, has challenged the titanium community for decades. The ease of aluminum forming alloys with titanium and the strong chemical affinity of titanium to oxygen rule out the possibility of fabricating pure Ti metal directly by aluminum reduction of TiO 2 . Based on the demonstrated enhanced deoxidation of Ti using Mg metal, this paper proposes an Al–Mg combined stepwise reduction of TiO 2 to fabricate Ti metal powder. Critical challenges overcome in this research include predicting reaction thermodynamics and preparing Ti 2 O intermediate by Al reduction of TiO 2 without significant Al alloying, which is made possible by forming mild-acid soluble Ca 12 Al 14 O 32 Cl 2 byproduct. Various Al reduction conditions were investigated and optimized. To the best of our knowledge, it is the first report to fabricate Ti 2 O powder by Al reduction of TiO 2 with a highly stable chemical composition. The difficulty of sintering the Ti 2 O intermediate before Mg deoxidation to reduce the surface oxygen contribution is mitigated by mixing a certain amount of low-oxygen titanium powder with the Ti 2 O powder. This allows the densification temperature to be lowered from 1400 °C for sintering pure Ti 2 O powder to 1100 °C. Even with as much as around 15 wt% oxygen, the sintered powder can be effectively deoxidized by Mg with the help of hydrogen. A titanium metal powder with an oxygen content of 0.134 wt%, an Al content of 0.123 wt%, and other impurities meeting the standard of pure titanium metal powder (GB/T 34486-2017 FTA1) is successfully prepared by the Al reduction-Mg deoxidation combined process. It is a promising alternative for producing titanium metal powder and its derivatives.
研究领域:
材料科学
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冶金学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
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