A new process, flame spray synthesis (FSS), has been developed for producing ceramic containing composite coatings. By combining self propagation high temperature synthesis (SHS) and flame spraying, the cermet based m...A new process, flame spray synthesis (FSS), has been developed for producing ceramic containing composite coatings. By combining self propagation high temperature synthesis (SHS) and flame spraying, the cermet based material was synthesized and deposited simultaneously. TiC Fe coatings were deposited from commercial ferrotitanium, iron and graphite powders by the flame spraying synthesis process. Microstructure analyses revealed that TiC was synthesized during spraying, and that submicron and round TiC particles were dispersed within an iron matrix. Flame spray synthesized coatings were composed of alternate soft and hard layers, whose hardness were 3.0～6.0 GPa and 11～13 GPa, respectively.展开更多
Li/Sb-doped (Na,K)NbO3 with a nominal composition of [Li0.05(Na0.535K0.48)0.95](Nb0.94Sb0.06)O3 ceramic was synthesized by normal sintering. The phase structure, microstructure, and electrical properties were investig...Li/Sb-doped (Na,K)NbO3 with a nominal composition of [Li0.05(Na0.535K0.48)0.95](Nb0.94Sb0.06)O3 ceramic was synthesized by normal sintering. The phase structure, microstructure, and electrical properties were investigated with a special emphasis on the influence of the sintering temperature. A polymorphic phase transition (PPT) from orthorhombic to tetragonal symmetry was observed when the sintering temperature was raised from 1040 to 1050 ℃, whereby the piezoelectric coefficient d33 and the electromechanical coupling coefficient kp reached the peak values of 245 pC·N-1 and 41.2%, respectively. The PPT induced by varying the sintering temperature is due to the different volatilization extents of alkali metals and appears to a lower sintering temperature with increasing Li content. The trace modifying of alkali metal content is more effective than doping B site element to enhance the d33 value.展开更多
Niobium nanoparticles with high purity were prepared by a sodiothermic reduction process using Nb2O5 as the raw material, LiCl, NaCl, KCl and CaCl2 as the diluents and sodium as the reducing reagent. The effects of th...Niobium nanoparticles with high purity were prepared by a sodiothermic reduction process using Nb2O5 as the raw material, LiCl, NaCl, KCl and CaCl2 as the diluents and sodium as the reducing reagent. The effects of the different molten salt systems, CaCl2 content, reaction time, excessive sodium and reaction temperature on the characteristics of the obtained niobium powder were discussed. The as-prepared niobium nanoparticles under the optimum experimental conditions were obtained by sodiothermic reduction with 20% excessive sodium in the NaCl-52mol%CaCl2- 2mol%Nb2O5 molten salts at 650 ℃for 6 h, and the molar ratio of the oxygen element in Nb2O5 and the CaCl2 of the molten salts is less than 19.23% at 750 ℃. Moreover, the particle size of niobium nanoparticles is ranged about 40~240 nm with increasing of reaction temperature from 650 to 800 ℃.展开更多
A(polymer network/liquid crystal/chiral dopants) composite exhibiting a temperature-sensing switch of infrared spectrum has been developed.Because of the different change of the chiral dopant in the helical twisting p...A(polymer network/liquid crystal/chiral dopants) composite exhibiting a temperature-sensing switch of infrared spectrum has been developed.Because of the different change of the chiral dopant in the helical twisting power and the anchoring effect of the polymer network,the polymer stabilized liquid crystal(PSLC) films,of which the bandwidth of the selective reflection spectra increased with changing temperature,were obtained.展开更多
The effects of Mg on the inclusion characteristics of 35CrNi3MoV steel have been studied. The results show that Mg treatment reduces obviously the amount of inclusion in the steel. Magnesium and oxygen in liquid steel...The effects of Mg on the inclusion characteristics of 35CrNi3MoV steel have been studied. The results show that Mg treatment reduces obviously the amount of inclusion in the steel. Magnesium and oxygen in liquid steel form dispersed fine particles of MgO, to which other oxides or sulphides nucleated at heterogeneity and grown during solidification. In this way the inclusions are modified. The small spherical inclusions containing MgO have been observed in the Mg treated steel in contrast to the large angular inclusions with Al2O3 in the conventional steel. Especially the elongated MnS inclusion is replaced by small MgS . MgO or MgS. MnS . MgO complex inclusion. The formation of inclusions have been discussed.展开更多
With a newly modified algorithm, the attained time exponent of grain growth n equals 0.49 plus or minus 0.01, very close to the theoretical value 0.5. By simulating the complete process of normal grain growth, the gr...With a newly modified algorithm, the attained time exponent of grain growth n equals 0.49 plus or minus 0.01, very close to the theoretical value 0.5. By simulating the complete process of normal grain growth, the grain size distribution was found to be initially a gamma distribution, then varies continuously and slowly with time, finally approaches the function proposed by Hillert in 1965 at the quasi-steady grain growth stage. The so-called self-similarity of the grain size distribution was discussed according to the new simulation results. (Edited author abstract) 12 Refs.展开更多
Based on the review of latest papers related to the application of barium alloy, the deoxidization effects of barium and barium alloy, and the dynamic characteristics of molten bath have been systematically studied by...Based on the review of latest papers related to the application of barium alloy, the deoxidization effects of barium and barium alloy, and the dynamic characteristics of molten bath have been systematically studied by means of the convection free bath, natural convection bath, air and vacuum induction melting experiments. It was found that both the total oxygen content and soluble oxygen content in molten bath decreased rapidly. The results obtained provided practical and theoretical basis for further synthetic applications of barium alloy in metallurgical industry.展开更多
Using a special constant deflection device, the in situ TEM observations of dislocation emission, motion and the initiation of nanocrack in 310 stainless steel in water were carried out. The results show that SCC in t...Using a special constant deflection device, the in situ TEM observations of dislocation emission, motion and the initiation of nanocrack in 310 stainless steel in water were carried out. The results show that SCC in thin foil specimen of 310 stainless steel can occur in water. A nanocrack initiated in the DFZ or at the blunt crack tip in corrosion solution after dislocation emission, multiplication and motion, which were induced by the localized anodic dissolution, reached a critical condition. The nanocrack propagated by a cleavage mode because of the influence of the corrosion solution.展开更多
In situ tensile test of brass foil specimens in TEM showed that many dislocations were emitted from a loaded crack tip, and a dislocation free zone (DFZ) was formed under the condition of constant displacement. The D...In situ tensile test of brass foil specimens in TEM showed that many dislocations were emitted from a loaded crack tip, and a dislocation free zone (DFZ) was formed under the condition of constant displacement. The DFZ is an elastic zone, where the stress may equal to the cohesive strength sigma //t//h when the applied stress is high enough. As a result, nano-cracks would initiate discontinuously in the DFZ or, sometimes, at a blunted-crack tip. As soon as the nano-crack nucleated, it quickly blunts into a void, which results in ductile fracture. (Edited author abstract) 10 Refs.展开更多
By defining the yield stress in a latent hardening test as the first deviation from the elastic straight line, the yielding and hardening behavior on a latent system in the positive and negative slip direction was stu...By defining the yield stress in a latent hardening test as the first deviation from the elastic straight line, the yielding and hardening behavior on a latent system in the positive and negative slip direction was studied in aluminium single crystals. It is shown that the yield stresses on both the positive and negative latent systems are about equal to or a little lower than the maximum resolved shear stress in the primary test, but much higher than that of the active system. The Influence of relative orientation and prestrain on latent hardening and initial work-hardening in the secondary test was also investigated, and it was found that there is a considerable effect on initial work-hardening, but none on latent hardening. With reasonable approximation, a hardening rule for single crystal could be proposed from the experimental results, that is, except for the yield stress on the system negative to the active system that is very low, hardening on the other systems is nearly the same as self-hardening.展开更多
The results show that Mg has less effect on the tensile properties and hardness of the steel at room temperature, but a right amount of Mg improves impact and fracture toughness and decreases the fracture-transition t...The results show that Mg has less effect on the tensile properties and hardness of the steel at room temperature, but a right amount of Mg improves impact and fracture toughness and decreases the fracture-transition temperature considerably due to inclusions modification, as well as prolongs the notch stress rupture life dramatically through strengthening grain boundary and modifying boundary carbides. There is an optimum Mg content, which is about 0.0030% in the experimental 35CrNi3MoV steel. (Edited author abstract) 8 Refs.展开更多
Two calculation models of mass action concentrations for CaO-MgO-SiO_2-Al_2O_3-Cr_2O_3 penta-slag was presented whether 3CaO·Cr_2O_3·3SiO_2 was existence or not.Equilibrium mass action concentration of each ...Two calculation models of mass action concentrations for CaO-MgO-SiO_2-Al_2O_3-Cr_2O_3 penta-slag was presented whether 3CaO·Cr_2O_3·3SiO_2 was existence or not.Equilibrium mass action concentration of each element structure was gained.And the models results were compared with experimental activity.The final results illustrated the model without 3CaO·Cr_2O_33SiO_2 was suit for reality.The model could response the element structure of slag as well.展开更多
This paper studied the fractal characteristic of the interfacial shear surface of steel-Al solid to liquid bonding plate, and determined the relationship between fractal dimension and interfacial shear strength. The r...This paper studied the fractal characteristic of the interfacial shear surface of steel-Al solid to liquid bonding plate, and determined the relationship between fractal dimension and interfacial shear strength. The research results showed that the relationship between fractal dimension and interfacial shear strength could be described as y=26.2x+4.2 (where y was interfacial shear strength, x was fractal dimension) and when 08Al steel plate was coarsened by steel wire wheel which was made up with steel wires whose diameter were 1.4 similar to 1.6 mm, the optimum coarsening pattern of the steel plate surface could be got, the corresponding maximum interfacial shear surface fractal dimension of the bonding plate was 2.33, and the maximum interfacial shear strength of the bonding plate was 65.3 MPa.展开更多
A novel series of chiral dopants synthesized from(S)-1,2-propanediol and mesogenic carboxylic acids were characterized by FT-IR,~1H NMR,elemental analysis and their helical twisting properties were investigated by dop...A novel series of chiral dopants synthesized from(S)-1,2-propanediol and mesogenic carboxylic acids were characterized by FT-IR,~1H NMR,elemental analysis and their helical twisting properties were investigated by doping the chiral dopants into a nematic liquid crystal host(SLC-1717).The results show that,the helical pitch of N~*-LC mixture exhibited a terminal alkyl chain length dependence and the molecular twisting power β also exhibited a temperature dependence(increasing β with increasing temperature).展开更多
The liquid steel will be leaked from the slit between the bottom of solidification mold and mother sheet during inversion casting process. By substitution of the actual liquid steel, the Ph-Sn alloy and the numerical ...The liquid steel will be leaked from the slit between the bottom of solidification mold and mother sheet during inversion casting process. By substitution of the actual liquid steel, the Ph-Sn alloy and the numerical simulation can be used to study the fluid flow in the inversion solidification mold, the mother sheet critical speed is determined for preventing the leakage from the slit of bottom. When the mother sheet speed is more than 0.06 m/s, Pb-Sn liquid alloy will not leak from the slit of the mold. Otherwise, the Ph-Sn liquid alloy can leak from the slit of the mold.展开更多
The effect of austenite ageing on martensite transformation in an iron and nickel alloy was studied. Attention was paid to the variation of dislocation configurations in austenite before martensite transformation, The...The effect of austenite ageing on martensite transformation in an iron and nickel alloy was studied. Attention was paid to the variation of dislocation configurations in austenite before martensite transformation, The clusters or precipitates produced during austenite ageing and the alteration of dislocation configurations affect together the consequent martensite transformation. Dispersed fine clusters and precipitates cripple nucleus role of special dislocation configurations and drop M-s. Coarse precipitates make M-g rise again. Densely piled up dislocations in nuclei lead to rise of M-s. All the changes in austenite are of benefit to small martensite plates.展开更多
The tensile behaviors of two bolt steels 20Cr12NiMoWV and 25Cr2MoV, and rotor steel 30Cr2Ni4MoV used in a nuclear power plant were studied at different temperatures up to 280℃ in air and aqueous solution. The result...The tensile behaviors of two bolt steels 20Cr12NiMoWV and 25Cr2MoV, and rotor steel 30Cr2Ni4MoV used in a nuclear power plant were studied at different temperatures up to 280℃ in air and aqueous solution. The results showed that blue brittleness occurred near 230℃ and 180℃ for steels 30Cr2Ni4MoV and 25Cr2MoV, respectively. No blue brittleness was found for the steel containing higher Cr content. Susceptibility to stress corrosion cracking (SCC) for the steels in aqueous solution at the test temperatures was very low except at the blue brittleness temperature. At the blue brittleness temperatures, however, the susceptibility to SCC was very high.展开更多
Ag-sheathed Bi-2223 superconducting tapes with rectangular cross section were fabricated by hydrostatic extrusion. Microstructural analysis, microhardness measurement and X-ray diffraction have been carried out. The...Ag-sheathed Bi-2223 superconducting tapes with rectangular cross section were fabricated by hydrostatic extrusion. Microstructural analysis, microhardness measurement and X-ray diffraction have been carried out. The field dependence of the critical current density was investigated at 77 K. The rectangular shaped specimens show a higher density of oxide core, better grain alignment and less weak-linked microstructure compared with the traditional specimens. (Edited author abstract) 10 Refs.展开更多
文摘A new process, flame spray synthesis (FSS), has been developed for producing ceramic containing composite coatings. By combining self propagation high temperature synthesis (SHS) and flame spraying, the cermet based material was synthesized and deposited simultaneously. TiC Fe coatings were deposited from commercial ferrotitanium, iron and graphite powders by the flame spraying synthesis process. Microstructure analyses revealed that TiC was synthesized during spraying, and that submicron and round TiC particles were dispersed within an iron matrix. Flame spray synthesized coatings were composed of alternate soft and hard layers, whose hardness were 3.0～6.0 GPa and 11～13 GPa, respectively.
基金financially supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20090006110010)Beijing Natural Science Foundation(No.2112028)
文摘Li/Sb-doped (Na,K)NbO3 with a nominal composition of [Li0.05(Na0.535K0.48)0.95](Nb0.94Sb0.06)O3 ceramic was synthesized by normal sintering. The phase structure, microstructure, and electrical properties were investigated with a special emphasis on the influence of the sintering temperature. A polymorphic phase transition (PPT) from orthorhombic to tetragonal symmetry was observed when the sintering temperature was raised from 1040 to 1050 ℃, whereby the piezoelectric coefficient d33 and the electromechanical coupling coefficient kp reached the peak values of 245 pC·N-1 and 41.2%, respectively. The PPT induced by varying the sintering temperature is due to the different volatilization extents of alkali metals and appears to a lower sintering temperature with increasing Li content. The trace modifying of alkali metal content is more effective than doping B site element to enhance the d33 value.
基金financially supported by the National Science Foundation of China(Nos.51102015and21071014)China Postdoctoral Science Foundation(No.20110490009)+2 种基金Research Fund for the Doctoral Program of Higher Education of China(No.20110006120027)the Program for New Century Excellent Talents in University(No.NCET-11-0577)the Program for Changjiang Scholars and Innovative Research Team in University(No.IRT0708)
文摘Niobium nanoparticles with high purity were prepared by a sodiothermic reduction process using Nb2O5 as the raw material, LiCl, NaCl, KCl and CaCl2 as the diluents and sodium as the reducing reagent. The effects of the different molten salt systems, CaCl2 content, reaction time, excessive sodium and reaction temperature on the characteristics of the obtained niobium powder were discussed. The as-prepared niobium nanoparticles under the optimum experimental conditions were obtained by sodiothermic reduction with 20% excessive sodium in the NaCl-52mol%CaCl2- 2mol%Nb2O5 molten salts at 650 ℃for 6 h, and the molar ratio of the oxygen element in Nb2O5 and the CaCl2 of the molten salts is less than 19.23% at 750 ℃. Moreover, the particle size of niobium nanoparticles is ranged about 40~240 nm with increasing of reaction temperature from 650 to 800 ℃.
基金support from National Natural Science foundation (No.20674005)Major project of Ministry Education of the People's Republic of China(No.104187)Doctoral Fund of Ministry of Education of the People's Republic of China(No.20050425850)
文摘A(polymer network/liquid crystal/chiral dopants) composite exhibiting a temperature-sensing switch of infrared spectrum has been developed.Because of the different change of the chiral dopant in the helical twisting power and the anchoring effect of the polymer network,the polymer stabilized liquid crystal(PSLC) films,of which the bandwidth of the selective reflection spectra increased with changing temperature,were obtained.
文摘The effects of Mg on the inclusion characteristics of 35CrNi3MoV steel have been studied. The results show that Mg treatment reduces obviously the amount of inclusion in the steel. Magnesium and oxygen in liquid steel form dispersed fine particles of MgO, to which other oxides or sulphides nucleated at heterogeneity and grown during solidification. In this way the inclusions are modified. The small spherical inclusions containing MgO have been observed in the Mg treated steel in contrast to the large angular inclusions with Al2O3 in the conventional steel. Especially the elongated MnS inclusion is replaced by small MgS . MgO or MgS. MnS . MgO complex inclusion. The formation of inclusions have been discussed.
文摘With a newly modified algorithm, the attained time exponent of grain growth n equals 0.49 plus or minus 0.01, very close to the theoretical value 0.5. By simulating the complete process of normal grain growth, the grain size distribution was found to be initially a gamma distribution, then varies continuously and slowly with time, finally approaches the function proposed by Hillert in 1965 at the quasi-steady grain growth stage. The so-called self-similarity of the grain size distribution was discussed according to the new simulation results. (Edited author abstract) 12 Refs.
文摘Based on the review of latest papers related to the application of barium alloy, the deoxidization effects of barium and barium alloy, and the dynamic characteristics of molten bath have been systematically studied by means of the convection free bath, natural convection bath, air and vacuum induction melting experiments. It was found that both the total oxygen content and soluble oxygen content in molten bath decreased rapidly. The results obtained provided practical and theoretical basis for further synthetic applications of barium alloy in metallurgical industry.
文摘Using a special constant deflection device, the in situ TEM observations of dislocation emission, motion and the initiation of nanocrack in 310 stainless steel in water were carried out. The results show that SCC in thin foil specimen of 310 stainless steel can occur in water. A nanocrack initiated in the DFZ or at the blunt crack tip in corrosion solution after dislocation emission, multiplication and motion, which were induced by the localized anodic dissolution, reached a critical condition. The nanocrack propagated by a cleavage mode because of the influence of the corrosion solution.
文摘In situ tensile test of brass foil specimens in TEM showed that many dislocations were emitted from a loaded crack tip, and a dislocation free zone (DFZ) was formed under the condition of constant displacement. The DFZ is an elastic zone, where the stress may equal to the cohesive strength sigma //t//h when the applied stress is high enough. As a result, nano-cracks would initiate discontinuously in the DFZ or, sometimes, at a blunted-crack tip. As soon as the nano-crack nucleated, it quickly blunts into a void, which results in ductile fracture. (Edited author abstract) 10 Refs.
文摘By defining the yield stress in a latent hardening test as the first deviation from the elastic straight line, the yielding and hardening behavior on a latent system in the positive and negative slip direction was studied in aluminium single crystals. It is shown that the yield stresses on both the positive and negative latent systems are about equal to or a little lower than the maximum resolved shear stress in the primary test, but much higher than that of the active system. The Influence of relative orientation and prestrain on latent hardening and initial work-hardening in the secondary test was also investigated, and it was found that there is a considerable effect on initial work-hardening, but none on latent hardening. With reasonable approximation, a hardening rule for single crystal could be proposed from the experimental results, that is, except for the yield stress on the system negative to the active system that is very low, hardening on the other systems is nearly the same as self-hardening.
文摘The results show that Mg has less effect on the tensile properties and hardness of the steel at room temperature, but a right amount of Mg improves impact and fracture toughness and decreases the fracture-transition temperature considerably due to inclusions modification, as well as prolongs the notch stress rupture life dramatically through strengthening grain boundary and modifying boundary carbides. There is an optimum Mg content, which is about 0.0030% in the experimental 35CrNi3MoV steel. (Edited author abstract) 8 Refs.
文摘Two calculation models of mass action concentrations for CaO-MgO-SiO_2-Al_2O_3-Cr_2O_3 penta-slag was presented whether 3CaO·Cr_2O_3·3SiO_2 was existence or not.Equilibrium mass action concentration of each element structure was gained.And the models results were compared with experimental activity.The final results illustrated the model without 3CaO·Cr_2O_33SiO_2 was suit for reality.The model could response the element structure of slag as well.
文摘This paper studied the fractal characteristic of the interfacial shear surface of steel-Al solid to liquid bonding plate, and determined the relationship between fractal dimension and interfacial shear strength. The research results showed that the relationship between fractal dimension and interfacial shear strength could be described as y=26.2x+4.2 (where y was interfacial shear strength, x was fractal dimension) and when 08Al steel plate was coarsened by steel wire wheel which was made up with steel wires whose diameter were 1.4 similar to 1.6 mm, the optimum coarsening pattern of the steel plate surface could be got, the corresponding maximum interfacial shear surface fractal dimension of the bonding plate was 2.33, and the maximum interfacial shear strength of the bonding plate was 65.3 MPa.
基金the National Science Foundation(No.20674005)the Flat-Panel Display Special Project of China 863 Plan(No.2008AA03A318)Projects of Chinese National Science and Technology Tackling Key Problems(No.2007BAE31B02)
文摘A novel series of chiral dopants synthesized from(S)-1,2-propanediol and mesogenic carboxylic acids were characterized by FT-IR,~1H NMR,elemental analysis and their helical twisting properties were investigated by doping the chiral dopants into a nematic liquid crystal host(SLC-1717).The results show that,the helical pitch of N~*-LC mixture exhibited a terminal alkyl chain length dependence and the molecular twisting power β also exhibited a temperature dependence(increasing β with increasing temperature).
基金supported by the National Nature Foundation of China.
文摘The liquid steel will be leaked from the slit between the bottom of solidification mold and mother sheet during inversion casting process. By substitution of the actual liquid steel, the Ph-Sn alloy and the numerical simulation can be used to study the fluid flow in the inversion solidification mold, the mother sheet critical speed is determined for preventing the leakage from the slit of bottom. When the mother sheet speed is more than 0.06 m/s, Pb-Sn liquid alloy will not leak from the slit of the mold. Otherwise, the Ph-Sn liquid alloy can leak from the slit of the mold.
文摘The effect of austenite ageing on martensite transformation in an iron and nickel alloy was studied. Attention was paid to the variation of dislocation configurations in austenite before martensite transformation, The clusters or precipitates produced during austenite ageing and the alteration of dislocation configurations affect together the consequent martensite transformation. Dispersed fine clusters and precipitates cripple nucleus role of special dislocation configurations and drop M-s. Coarse precipitates make M-g rise again. Densely piled up dislocations in nuclei lead to rise of M-s. All the changes in austenite are of benefit to small martensite plates.
基金the Special Funds forthe Major State Basic Research Projects G19990650, andby the National Natural Science Foundation of Chi
文摘The tensile behaviors of two bolt steels 20Cr12NiMoWV and 25Cr2MoV, and rotor steel 30Cr2Ni4MoV used in a nuclear power plant were studied at different temperatures up to 280℃ in air and aqueous solution. The results showed that blue brittleness occurred near 230℃ and 180℃ for steels 30Cr2Ni4MoV and 25Cr2MoV, respectively. No blue brittleness was found for the steel containing higher Cr content. Susceptibility to stress corrosion cracking (SCC) for the steels in aqueous solution at the test temperatures was very low except at the blue brittleness temperature. At the blue brittleness temperatures, however, the susceptibility to SCC was very high.
文摘Ag-sheathed Bi-2223 superconducting tapes with rectangular cross section were fabricated by hydrostatic extrusion. Microstructural analysis, microhardness measurement and X-ray diffraction have been carried out. The field dependence of the critical current density was investigated at 77 K. The rectangular shaped specimens show a higher density of oxide core, better grain alignment and less weak-linked microstructure compared with the traditional specimens. (Edited author abstract) 10 Refs.
