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
据科学新闻网站报道,目前,德国一支科学家小组最新研制一种化合物,能够将红外光线转变成为可见光线。德国马尔堡大学尼尔斯-威尔海姆-罗塞曼(Nils Wilhelm Rosemann)负责这项研究,他设计了锡和硫磺化合物,具有类似钻石的结构,然后喷涂...据科学新闻网站报道,目前,德国一支科学家小组最新研制一种化合物,能够将红外光线转变成为可见光线。德国马尔堡大学尼尔斯-威尔海姆-罗塞曼(Nils Wilhelm Rosemann)负责这项研究,他设计了锡和硫磺化合物,具有类似钻石的结构,然后喷涂有机配体。罗塞曼博士和同事指出,这种化合物是一种细小的非晶态粉末,它们不挥发,具有气体稳定性,在300°C高温下仍保持热稳定性。该化合物内核是无机纳米晶体结构,其表面是有机配体涂层。展开更多
Polycrystalline diamond compacts (PDC) were synthesized using diamond powder of average crystal size 3-20 μm by the Ni 70 Mn 25 Co 5 alloy infiltration technique at high temperature and high pressure (HPHT).The surfa...Polycrystalline diamond compacts (PDC) were synthesized using diamond powder of average crystal size 3-20 μm by the Ni 70 Mn 25 Co 5 alloy infiltration technique at high temperature and high pressure (HPHT).The surface residual stress of polycrystalline diamond (PCD) layer was measured using micro-Raman spectroscopy with hydrostatic stress model and X-ray diffraction (XRD).Measurements of the stress levels of PCDs show that the residual compressive stresses range from 0.12 to 0.22 GPa,which increase with the crystal size of diamond.Scanning electron microscopy (SEM) was used to observe the morphology of initial diamond grains and PCD cross-section.The results indicate that PCD has a dense and interlaced microstructure with diamond-diamond (D-D) direct bonding.And the smaller the crystal size of diamond,the better the growth of diamond direct bonding and the smaller the binder metal between diamond boundaries will be.展开更多
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.
文摘据科学新闻网站报道,目前,德国一支科学家小组最新研制一种化合物,能够将红外光线转变成为可见光线。德国马尔堡大学尼尔斯-威尔海姆-罗塞曼(Nils Wilhelm Rosemann)负责这项研究,他设计了锡和硫磺化合物,具有类似钻石的结构,然后喷涂有机配体。罗塞曼博士和同事指出,这种化合物是一种细小的非晶态粉末,它们不挥发,具有气体稳定性,在300°C高温下仍保持热稳定性。该化合物内核是无机纳米晶体结构,其表面是有机配体涂层。
基金supported by the National Natural Science Foundation of China (Grant Nos.50572032,50801030 and 50731006)
文摘Polycrystalline diamond compacts (PDC) were synthesized using diamond powder of average crystal size 3-20 μm by the Ni 70 Mn 25 Co 5 alloy infiltration technique at high temperature and high pressure (HPHT).The surface residual stress of polycrystalline diamond (PCD) layer was measured using micro-Raman spectroscopy with hydrostatic stress model and X-ray diffraction (XRD).Measurements of the stress levels of PCDs show that the residual compressive stresses range from 0.12 to 0.22 GPa,which increase with the crystal size of diamond.Scanning electron microscopy (SEM) was used to observe the morphology of initial diamond grains and PCD cross-section.The results indicate that PCD has a dense and interlaced microstructure with diamond-diamond (D-D) direct bonding.And the smaller the crystal size of diamond,the better the growth of diamond direct bonding and the smaller the binder metal between diamond boundaries will be.
