It is practically difficult to find titanium sponges with low and stable aluminum impurities on the market even though it is the precondition to prepare high-purity titanium. Analysis indicates that almost all the alu...It is practically difficult to find titanium sponges with low and stable aluminum impurities on the market even though it is the precondition to prepare high-purity titanium. Analysis indicates that almost all the aluminum impurities in the titanium sponge are inherited from the magnesium used to reduce titanium tetrachloride. However, it remains elusive for decades why magnesium produced through the silicothermic reduction method contains a high content of aluminum impurities with large fluctuations. By recourse to thermodynamic calculations and comparative experiments, we demonstrate that fluorite, a material used as a catalyst in the silicothermic reduction method to produce magnesium, is the chief culprit for the pest aluminum and propose a mechanism to rationalize the observed phenomena. Our findings indicate that one practical way to produce qualified magnesium for the production of high-purity titanium is to abandon fluorite during the production of magnesium with the silicothermic reduction method.展开更多
High-purity titanium powder was prepared by molten salt electrorefining from sponge titanium in NaCl-KCl-TiClx salts. The titanium valence, purity and electrocrystallization during electrolysis process were studied. T...High-purity titanium powder was prepared by molten salt electrorefining from sponge titanium in NaCl-KCl-TiClx salts. The titanium valence, purity and electrocrystallization during electrolysis process were studied. The XPS analysis showed that the titanium valences are mainly ＋4, ＋3 and ＋2 at the earlier, medium and later stages of electrolysis, respectively. During the electrolysis process, the contents of impurities Si, Cr, Mn, Al vary little, and the contents of impurities Fe, Cu, Ni decrease markedly, while the contents of impurities O, N, H increase obviously. The residual impurities are usually distributed in small tunnel of dendritic crystals. Enhancing the electrolysis temperature and prolonging the electrolysis time can increase the titanium particle size. The TEM analysis showed that the electrodeposited titanium is not a single crystal, but contains many nanostructured grains and subgrains, with grain size of 100-500 nm. The electrolysis mechanisms were also discussed.展开更多
The‘plainification of materials’has been conceptualized to promote the sustainable development of materials.This perspective,for the first time in the field of biomaterials,proposes and defines‘plain metallic bioma...The‘plainification of materials’has been conceptualized to promote the sustainable development of materials.This perspective,for the first time in the field of biomaterials,proposes and defines‘plain metallic biomaterials(PMBs)’with demonstrated research and application case studies of pure titanium with high strength and toughness,and biodegradable,fine-grained and high-purity magnesium.Then,after discussing the features,benefits and opportunities of PMBs,the challenges are analyzed from both technical and regulatory aspects.Regulatory perspectives on PMB-based medical devices are also provided for the benefit of future research,development and commercialization.展开更多
基金the support from the National Natural Science Foundation of China (No.52031011)funding from the Science and Technology Departments of Shaanxi and Xi’an,China (Nos.2021GXLH-Z-015,2016KTZDGY-04-04 and 201805064ZD15CG48)。
文摘It is practically difficult to find titanium sponges with low and stable aluminum impurities on the market even though it is the precondition to prepare high-purity titanium. Analysis indicates that almost all the aluminum impurities in the titanium sponge are inherited from the magnesium used to reduce titanium tetrachloride. However, it remains elusive for decades why magnesium produced through the silicothermic reduction method contains a high content of aluminum impurities with large fluctuations. By recourse to thermodynamic calculations and comparative experiments, we demonstrate that fluorite, a material used as a catalyst in the silicothermic reduction method to produce magnesium, is the chief culprit for the pest aluminum and propose a mechanism to rationalize the observed phenomena. Our findings indicate that one practical way to produce qualified magnesium for the production of high-purity titanium is to abandon fluorite during the production of magnesium with the silicothermic reduction method.
基金Project(20110942K)supported by Open Fund of State Key Laboratory of Powder Metallurgy,ChinaProject(51021063)supported by the National Natural Science Foundation of China
文摘High-purity titanium powder was prepared by molten salt electrorefining from sponge titanium in NaCl-KCl-TiClx salts. The titanium valence, purity and electrocrystallization during electrolysis process were studied. The XPS analysis showed that the titanium valences are mainly ＋4, ＋3 and ＋2 at the earlier, medium and later stages of electrolysis, respectively. During the electrolysis process, the contents of impurities Si, Cr, Mn, Al vary little, and the contents of impurities Fe, Cu, Ni decrease markedly, while the contents of impurities O, N, H increase obviously. The residual impurities are usually distributed in small tunnel of dendritic crystals. Enhancing the electrolysis temperature and prolonging the electrolysis time can increase the titanium particle size. The TEM analysis showed that the electrodeposited titanium is not a single crystal, but contains many nanostructured grains and subgrains, with grain size of 100-500 nm. The electrolysis mechanisms were also discussed.
基金supported by the first batch of Chinese Drug Regulatory Science Action Plan(Regulatory science research on new materi-als for medical device)This work was also supported by the sec-ond batch(“5.5 Research on technical evaluation of recombinant collagens,cartilage repair materials and antimicrobial orthope-dic/dental materials”)of Chinese Drug Regulatory Science Action Plan of NMPA.
文摘The‘plainification of materials’has been conceptualized to promote the sustainable development of materials.This perspective,for the first time in the field of biomaterials,proposes and defines‘plain metallic biomaterials(PMBs)’with demonstrated research and application case studies of pure titanium with high strength and toughness,and biodegradable,fine-grained and high-purity magnesium.Then,after discussing the features,benefits and opportunities of PMBs,the challenges are analyzed from both technical and regulatory aspects.Regulatory perspectives on PMB-based medical devices are also provided for the benefit of future research,development and commercialization.
