An FeMo-alloy-doped β-SiA1ON （FeMo/β-SiA1ON） composite was fabricated via a reaction-bonding method using raw materials of Si, Al2O3, A1N, FeMo, and Sm2O3. The effects of FeMo on the microstructure and mechanical ...An FeMo-alloy-doped β-SiA1ON （FeMo/β-SiA1ON） composite was fabricated via a reaction-bonding method using raw materials of Si, Al2O3, A1N, FeMo, and Sm2O3. The effects of FeMo on the microstructure and mechanical properties of the composite were investi- gated. Some properties of the composite, including its bending strength at 700℃ and after oxidization at 700℃ for 24 h in air, thermal shock resistance and corrosion resistance to molten aluminum, were also evaluated. The results show that the density, toughness, bending strength, and thermal shock resistance of the composite are obviously improved with the addition of an FeMo alloy. In addition, other properties of the composite such as its high-temperature strength and oxidized strength are also improved by the addition of FeMo alloy, and its corrosion re- sistance to molten aluminum is maintained. These findings indicate that the developed FeMo/β-SiA1ON composite exhibits strong potential for application to molten aluminum environments.展开更多
The iron molybdenum cofactor(FeMoco) of nitrogenase MoFe protein from Azotobacter vinelandii OP was extracted by N methylformamide(NMF). The effects of FeMoco(in NMF) on electronic spectrum and fluorescence...The iron molybdenum cofactor(FeMoco) of nitrogenase MoFe protein from Azotobacter vinelandii OP was extracted by N methylformamide(NMF). The effects of FeMoco(in NMF) on electronic spectrum and fluorescence intensity of fluorescein dimercury acetate(FDMA)(in 1 mol/L NaOH) were investigated by fluorophotometric titrations and compared with those of (NH 4) 2MoS 4 and complexes of (NH 4) 2MoS 4 with Na 2S or Na 2S 2 or (NH 4) 2S x on the relative properties of FDMA. It was found that the electronic spectrum of FDMA displayed hypsochromic shift(17 nm) in the presence of FeMoco just like that in the presence of other inorganic sulfides and that the titration curve for the quench of FDMA with FeMoco is very similar to that for the quench of FDMA with complex of (NH 4) 2MoS 4 with Na 2S 2(mole ratio is 1∶3). The results showed that FeMoco(N) probably contained S—S bonds and its structure was found to be changed compared with Kim Rees structural model. This change should profit the formation of the polymer.展开更多
Raising the efficiency of production, for the most part depends on the use of secondary material resources, particularly such wastes as metallurgical slags of the operating plants. Huge quantity of such slags generate...Raising the efficiency of production, for the most part depends on the use of secondary material resources, particularly such wastes as metallurgical slags of the operating plants. Huge quantity of such slags generates an urgent problem of their reasonable utilization with maximum extraction of valuable metals. The objective of the thesis is the development of an efficient technology for obtaining powder iron-monosilicon alloy by means of processing of iron and silicon containing dump slags on the basis of out-of-furnace aluminothermic reduction. Thus, structure of the obtained alloy strоngly depends on the state of the initial slags, on their correlation and on the amount of components contained in the complement of the burden. The structurization processes of the iron powder-like silicide obtained by the method of self-propagating high-temperature synthesis of the preliminarily mechano activated burden are investigated. The combination of these two methods allows to form unique materials and alloys, significantly reducing the power expenditure by applying the exothermal effect of the reactions, and to obtain a product with special physico-chemical properties. The results of the investigation are to obtain monophase iron silicide by preliminary mechano-chemical activation of the burden, containing a mixture of wastes of a certain composition obtained from metallurgical production—the Alaverdi copper-smelting and the Yerevan molybdenum factories, as well as KNO<sub>3</sub> and CaO by combined aluminothermal reduction in the SHS regime. By the X-ray fluorescent method of analysis, the structurization process of the obtained alloy is studied. It is shown that, at the expense of preliminary mechano-chemical activation of the burden, a finer and homogeneous structure of powder-like iron silicide is formed.展开更多
基金financially supported by the National Natural Science Foundation of China (No. 51272208)the Program for New Century Excellent Talents in University (NCET–12–0454)the Program for Young Excellent Talents in Shaanxi Province, China (2013KJXX–50)
文摘An FeMo-alloy-doped β-SiA1ON （FeMo/β-SiA1ON） composite was fabricated via a reaction-bonding method using raw materials of Si, Al2O3, A1N, FeMo, and Sm2O3. The effects of FeMo on the microstructure and mechanical properties of the composite were investi- gated. Some properties of the composite, including its bending strength at 700℃ and after oxidization at 700℃ for 24 h in air, thermal shock resistance and corrosion resistance to molten aluminum, were also evaluated. The results show that the density, toughness, bending strength, and thermal shock resistance of the composite are obviously improved with the addition of an FeMo alloy. In addition, other properties of the composite such as its high-temperature strength and oxidized strength are also improved by the addition of FeMo alloy, and its corrosion re- sistance to molten aluminum is maintained. These findings indicate that the developed FeMo/β-SiA1ON composite exhibits strong potential for application to molten aluminum environments.
文摘The iron molybdenum cofactor(FeMoco) of nitrogenase MoFe protein from Azotobacter vinelandii OP was extracted by N methylformamide(NMF). The effects of FeMoco(in NMF) on electronic spectrum and fluorescence intensity of fluorescein dimercury acetate(FDMA)(in 1 mol/L NaOH) were investigated by fluorophotometric titrations and compared with those of (NH 4) 2MoS 4 and complexes of (NH 4) 2MoS 4 with Na 2S or Na 2S 2 or (NH 4) 2S x on the relative properties of FDMA. It was found that the electronic spectrum of FDMA displayed hypsochromic shift(17 nm) in the presence of FeMoco just like that in the presence of other inorganic sulfides and that the titration curve for the quench of FDMA with FeMoco is very similar to that for the quench of FDMA with complex of (NH 4) 2MoS 4 with Na 2S 2(mole ratio is 1∶3). The results showed that FeMoco(N) probably contained S—S bonds and its structure was found to be changed compared with Kim Rees structural model. This change should profit the formation of the polymer.
文摘Raising the efficiency of production, for the most part depends on the use of secondary material resources, particularly such wastes as metallurgical slags of the operating plants. Huge quantity of such slags generates an urgent problem of their reasonable utilization with maximum extraction of valuable metals. The objective of the thesis is the development of an efficient technology for obtaining powder iron-monosilicon alloy by means of processing of iron and silicon containing dump slags on the basis of out-of-furnace aluminothermic reduction. Thus, structure of the obtained alloy strоngly depends on the state of the initial slags, on their correlation and on the amount of components contained in the complement of the burden. The structurization processes of the iron powder-like silicide obtained by the method of self-propagating high-temperature synthesis of the preliminarily mechano activated burden are investigated. The combination of these two methods allows to form unique materials and alloys, significantly reducing the power expenditure by applying the exothermal effect of the reactions, and to obtain a product with special physico-chemical properties. The results of the investigation are to obtain monophase iron silicide by preliminary mechano-chemical activation of the burden, containing a mixture of wastes of a certain composition obtained from metallurgical production—the Alaverdi copper-smelting and the Yerevan molybdenum factories, as well as KNO<sub>3</sub> and CaO by combined aluminothermal reduction in the SHS regime. By the X-ray fluorescent method of analysis, the structurization process of the obtained alloy is studied. It is shown that, at the expense of preliminary mechano-chemical activation of the burden, a finer and homogeneous structure of powder-like iron silicide is formed.
