The preparation of fine TiC powders by carbothermal reduction of TiO2 in vacuum was investigated by XRD,SEM,XRF and laser particle sizer.Thermodynamic analysis indicates that it is easy to prepare TiC in vacuum and th...The preparation of fine TiC powders by carbothermal reduction of TiO2 in vacuum was investigated by XRD,SEM,XRF and laser particle sizer.Thermodynamic analysis indicates that it is easy to prepare TiC in vacuum and the formation sequence of products are Ti4O7（Magneli phase）,Ti3O5,Ti2O3,TiCxO1-x and TiC with the increase of reaction temperature.Experimental results demonstrate that TiC powders with single phase are obtained with molar ratio of TiO2 to C ranging from 1：3.2 to 1：6 at 1 550 ℃ for 4 h when the system pressure is 50 Pa,and TiC1.0 is gained when the molar ratio of TiO2 to C is 1：4 and 1：5.In addition,fine TiC1.0 powders（D50 equals 3.04 μm） with single phase and low impurities are obtained when the molar ratio of TiO2 to C is 1：4.SEM observation shows that uniform shape,low agglomeration,and loose structure are observed on the surface of block product.展开更多
To develop an effective process for titanium powders production, a calciothermic reduction process of pigment titanium dioxide （w（TiO2）〉98%）, based on the preform reduction process （PRP）, was investigated by me...To develop an effective process for titanium powders production, a calciothermic reduction process of pigment titanium dioxide （w（TiO2）〉98%）, based on the preform reduction process （PRP）, was investigated by means of XRD, SEM and EDS. In this process, the mixture of TiO2 powder and CaC12 was pressed into pieces as feed preform and was reduced by calcium vapor. Titanium powders was recovered after leaching from the reduced preform with hydrochloric acid and deionized water. The results indicate when the mass ratio of CaC12 to TiO2 is about 1：4 and at a constant temperature of 1 273 K for 6 h in vacuum furnace, titanium powders with 99.55% purity by EDS analysis and irregular shape （8-15 μm in particle size） are obtained.展开更多
承钢采用三氧化二钒为原料,天然鳞片石墨为还原剂、聚乙烯醇为黏结剂生产钒氮合金。研究了聚乙烯醇的浓度、压球压力、石墨种类对钒氮合金压球效果和成品成分的影响。实验结果表明,牌号为298-C的天然鳞片石墨,选用浓度2.5%的聚乙烯醇作...承钢采用三氧化二钒为原料,天然鳞片石墨为还原剂、聚乙烯醇为黏结剂生产钒氮合金。研究了聚乙烯醇的浓度、压球压力、石墨种类对钒氮合金压球效果和成品成分的影响。实验结果表明,牌号为298-C的天然鳞片石墨,选用浓度2.5%的聚乙烯醇作为黏结剂时,在14 M Pa压力下压制料球,成球率达到94.81%,得到的最终产品全部为VN16合金,合格率达到100%。展开更多
X-ray photoelectron spectroscopy(XPS)and Raman spectroscopy were used to analyze the complexes in LiCl−KCl eutectic salt containing VCl_(3) and KF.The additional fluoride ions would replace chloride ions and combine w...X-ray photoelectron spectroscopy(XPS)and Raman spectroscopy were used to analyze the complexes in LiCl−KCl eutectic salt containing VCl_(3) and KF.The additional fluoride ions would replace chloride ions and combine with V(Ⅲ)to form VF_(6)^(3-).The electrochemical behavior of V(Ⅲ)was evaluated under condition of the molar concentration ratio of F−to Vn+(α)equal to 0:1,1:1,2:1,5:1,20:1 and 50:1,respectively.The results showed that a new reduction step appeared:VF_(6)^(3-)→V^(2+),and the reduction mechanism of vanadium ions became more complicated.The metallic vanadium was deposited on the tungsten electrode at−2.90 V in the LiCl−KCl melts for 6 h,and the products were characterized by SEM−EDS.It was indicated that the particle size of the product decreased with adding fluoride ions for the forming of the coordination compound VF_(6)^(3-).展开更多
In this study,Al-65V alloy has been produced by electrode heating for 3−15 min.The impurities content,microstructure and the vanadium content of the alloy in the slag are investigated.The results indicate that differe...In this study,Al-65V alloy has been produced by electrode heating for 3−15 min.The impurities content,microstructure and the vanadium content of the alloy in the slag are investigated.The results indicate that different heating time shows obviously impacts not only on the impurities and microstructure of AlV alloy,but also on the vanadium recovery rate of slag.The impurities contents of C,O and N are 0.085%,0.022%and 0.036%,respectively,which meet the commercial standard when the electric heating time is controlled to 10 min,and the content of vanadium in slag is 0.18%.展开更多
基金Project(u0837604)supported by the Natural Science Foundation of Yunnan Province,ChinaProject(51004058)supported by the National Natural Science Foundation of ChinaProject(20095314110003)supported by Specialized Research Fund for the Doctoral Program of Higher Education
文摘The preparation of fine TiC powders by carbothermal reduction of TiO2 in vacuum was investigated by XRD,SEM,XRF and laser particle sizer.Thermodynamic analysis indicates that it is easy to prepare TiC in vacuum and the formation sequence of products are Ti4O7（Magneli phase）,Ti3O5,Ti2O3,TiCxO1-x and TiC with the increase of reaction temperature.Experimental results demonstrate that TiC powders with single phase are obtained with molar ratio of TiO2 to C ranging from 1：3.2 to 1：6 at 1 550 ℃ for 4 h when the system pressure is 50 Pa,and TiC1.0 is gained when the molar ratio of TiO2 to C is 1：4 and 1：5.In addition,fine TiC1.0 powders（D50 equals 3.04 μm） with single phase and low impurities are obtained when the molar ratio of TiO2 to C is 1：4.SEM observation shows that uniform shape,low agglomeration,and loose structure are observed on the surface of block product.
基金This work was financially supported by the National Natural Science Foundation of China(No.51734006)the Outstanding Youth Project of Yunnan Province,China(No.202001AV070002)the Fundamental Research Project of Yunnan Province,China(No.2019FD037).
基金Project(51004058) supported by the National Natural Science Foundation of ChinaProject(2011FB039) supported by the Natural Science Foundation of Yunnan Province,China
文摘To develop an effective process for titanium powders production, a calciothermic reduction process of pigment titanium dioxide （w（TiO2）〉98%）, based on the preform reduction process （PRP）, was investigated by means of XRD, SEM and EDS. In this process, the mixture of TiO2 powder and CaC12 was pressed into pieces as feed preform and was reduced by calcium vapor. Titanium powders was recovered after leaching from the reduced preform with hydrochloric acid and deionized water. The results indicate when the mass ratio of CaC12 to TiO2 is about 1：4 and at a constant temperature of 1 273 K for 6 h in vacuum furnace, titanium powders with 99.55% purity by EDS analysis and irregular shape （8-15 μm in particle size） are obtained.
文摘承钢采用三氧化二钒为原料,天然鳞片石墨为还原剂、聚乙烯醇为黏结剂生产钒氮合金。研究了聚乙烯醇的浓度、压球压力、石墨种类对钒氮合金压球效果和成品成分的影响。实验结果表明,牌号为298-C的天然鳞片石墨,选用浓度2.5%的聚乙烯醇作为黏结剂时,在14 M Pa压力下压制料球,成球率达到94.81%,得到的最终产品全部为VN16合金,合格率达到100%。
基金supports from the National Key Research and Development Program of China (No.2021YFC2901600)supported by the State Key Laboratory of Special Rare Metal Materials (No.SKL2020K004)。
文摘X-ray photoelectron spectroscopy(XPS)and Raman spectroscopy were used to analyze the complexes in LiCl−KCl eutectic salt containing VCl_(3) and KF.The additional fluoride ions would replace chloride ions and combine with V(Ⅲ)to form VF_(6)^(3-).The electrochemical behavior of V(Ⅲ)was evaluated under condition of the molar concentration ratio of F−to Vn+(α)equal to 0:1,1:1,2:1,5:1,20:1 and 50:1,respectively.The results showed that a new reduction step appeared:VF_(6)^(3-)→V^(2+),and the reduction mechanism of vanadium ions became more complicated.The metallic vanadium was deposited on the tungsten electrode at−2.90 V in the LiCl−KCl melts for 6 h,and the products were characterized by SEM−EDS.It was indicated that the particle size of the product decreased with adding fluoride ions for the forming of the coordination compound VF_(6)^(3-).
基金Project(51734006)supported by the National Natural Science Foundation of ChinaProject(2014HA003)supported by the Cultivating Plan Program for the Leader in Science and Technology of Yunnan Province of China+1 种基金Project(2017HB009)supported by the Science and Technological Talent Cultivation Plan of Yunnan Province,ChinaProject(2017HA006)supported by the Program for the Academician Free Exploration Fund of Yunnan Province,China
文摘In this study,Al-65V alloy has been produced by electrode heating for 3−15 min.The impurities content,microstructure and the vanadium content of the alloy in the slag are investigated.The results indicate that different heating time shows obviously impacts not only on the impurities and microstructure of AlV alloy,but also on the vanadium recovery rate of slag.The impurities contents of C,O and N are 0.085%,0.022%and 0.036%,respectively,which meet the commercial standard when the electric heating time is controlled to 10 min,and the content of vanadium in slag is 0.18%.
