In this paper ,spodumene mineral was used as raw material for fabricating glass ceramic with the addition of MgO,ZnO and TiO2,ZrO2. The expansion coefficient of the materials is 5. 5×107/℃ . Also the effects of ...In this paper ,spodumene mineral was used as raw material for fabricating glass ceramic with the addition of MgO,ZnO and TiO2,ZrO2. The expansion coefficient of the materials is 5. 5×107/℃ . Also the effects of the heat treatment on the crystallzing behaviour has been discussed by XRD and DTA.展开更多
Thermal expansion is a common phenomenon in both metals and alloys, which is important for metallic material applications in modern industry, especially in nuclear and aerospace industries. A lower thermal expansion c...Thermal expansion is a common phenomenon in both metals and alloys, which is important for metallic material applications in modern industry, especially in nuclear and aerospace industries. A lower thermal expansion coefficient may cause lower thermal stress and higher accuracy. A new Zr-based alloy is developed and presented.The XRD diffraction results demonstrate that only a close-packed hexagonal phase（α or α＇ phase） exists in the microstructure. The thermal expansion and mechanical properties are studied. According to the experimental results, the new Zr-based alloy presents a low thermal expansion coefficient and good mechanical properties.Also,its thermal expansion coefficient is stable through solution treatment.展开更多
The self-stress trial of the fifteen high-strength, low-heat andmicro-expansion concrete-filled steel tube(CFST)is introduced, andthe generating and distributing features of pre-stress and itsrelation to add- ing quan...The self-stress trial of the fifteen high-strength, low-heat andmicro-expansion concrete-filled steel tube(CFST)is introduced, andthe generating and distributing features of pre-stress and itsrelation to add- ing quantity of expansive agent, which providespersuasive dependences for optimal design of high-strength, low- heatand micro-expansion CFST were investigated, especially for the designof added quantity of expansive agent.展开更多
Low thermal expansion materials are mostly ceramics with low conductive property, which limits their applications in electronic devices. The poor conductive property of ceramic ZrV_2 O_7 could be improved by bi-substi...Low thermal expansion materials are mostly ceramics with low conductive property, which limits their applications in electronic devices. The poor conductive property of ceramic ZrV_2 O_7 could be improved by bi-substitution of Fe and Mo for Zr and V, accompanied with low thermal expansion. Zr_(0.1) Fe_(0.9) V_(1.1 )Mo_(0.9 )O_7 has electrical conductivity of 8.2× 10^(-5) S/cm and 9.41× 10^(-4) S/cm at 291 K and 623 K, respectively. From 291 K to 413 K, thermal excitation leads to the increase of carrier concentration, which causes the rapid decrease of resistance. At 413–533 K, the conductivity is unchanged due to high scattering probability and a slowing increase of carrier concentration. The conductivity rapidly increases again from533 K to 623 K due to the intrinsic thermal excitation. The thermal expansion coefficient of Zr_(0.1) Fe_(0.9) V_(1.1 )Mo_(0.9 )O_7 is as low as 0.72× 10^(-6 )K^(-1) at 140–700 K from the dilatometer measurement. These properties suggest that Zr_(0.1) Fe_(0.9) V_(1.1 )Mo_(0.9 )O_7 has attractive application in electronic components.展开更多
Ceramics usually have irregular grains, cracking, or porosity, which result in their lightproof.Y2Mo3O12 ceramics have more porosity due to the heavy hygroscopicity.Introducing ZnLi to Y2Mo3O12 could form regular grai...Ceramics usually have irregular grains, cracking, or porosity, which result in their lightproof.Y2Mo3O12 ceramics have more porosity due to the heavy hygroscopicity.Introducing ZnLi to Y2Mo3O12 could form regular grains, reduce cracking and porosity.With increasing the content of ZnLi, the grain shapes self-assembly gradually and then the laser scattering and transmittance improve.The laser scattering property and transmittance of diverging rays become the best in ceramics Y2-x(ZnLi)xMo3O12(x = 1.0 and 1.2) with regular grains and low thermal expansion.The formation mechanism of regular grains is ascribed to the substitutions of Zn^2+ and Li+for Y^3+ in Y2Mo3O12 resulting in the preferential growth.The investigation in laser scattering, transmittance and low thermal expansion behaviors of Y2-x(ZnLi)xMo3O12 could pave a way to weaken the strong-laser attack from the high-power laser weapon and the other.展开更多
The effect of phosphorus on the oxidation resistance of low thermal expansion alloy IN909 was studied. The composition and structure of the oxidation layer were analyzed. It is found that the oxidation initiates at th...The effect of phosphorus on the oxidation resistance of low thermal expansion alloy IN909 was studied. The composition and structure of the oxidation layer were analyzed. It is found that the oxidation initiates at the grain boundaries. During the oxidation, Fe atoms diffuse toward the surface and form the outside oxidation layer as the oxide of iron. The transition oxidation layer lies between the oxidation layer and the matrix which is enriched with Nb, Ti and Si, forming FeTiO5, Nb2O5,Fe2SiO4 and TiO2. Phosphorus hardly influences the thermal expansion coefficient of IN909 alloy. However, it increases the formation ofεphase at the boundary of the transition oxidation layer and matrix. As a result, the oxidation rate is decreased efficiently because theεphase inhibits the diffusion of the element such as iron from the matrix to the oxidation layer.展开更多
A new material of Zr0.1Al1.9Mo2.9V0.1O12 is synthesized by the traditional solid state synthesis method.The phase transition,coefficient of thermal expansion,and luminescence properties of Zr0.1Al1.9Mo2.9V0.1O12 are e...A new material of Zr0.1Al1.9Mo2.9V0.1O12 is synthesized by the traditional solid state synthesis method.The phase transition,coefficient of thermal expansion,and luminescence properties of Zr0.1Al1.9Mo2.9V0.1O12 are explored with Raman spectrometer,dilatometer,and x-ray diffraction(XRD)diffractometer.The results show that the Zr0.1Al1.9Mo2.9V0.1O12 possesses the strong broad-band luminescence characteristics almost in the whole visible region.The sample is crystallized in a monoclinic structure group of P21/a(No.14)crystallized at room temperature(RT).The crystal is changed from monoclinic to orthorhombic structure when the temperature increases to 463 K.The material has very low thermal expansion performance in a wide temperature range.Its excellent low thermal expansion and strong pale green light properties in a wide temperature range suggest its potential applications in light-emitting diode(LED)and other optoelectronic devices.展开更多
The preparation technics of glass-ceramics with super low coefficient of thermal expansion containing β-quartz solid solution as a main crystal phase based on the glass in the system Li2O-Al2O3-SiO2 was introduced. T...The preparation technics of glass-ceramics with super low coefficient of thermal expansion containing β-quartz solid solution as a main crystal phase based on the glass in the system Li2O-Al2O3-SiO2 was introduced. The composition of base glass, technics of melting and heat treatment effecting on characteristic of glass-ceramics was described. Specimens were prepared by melting, anneal and controlled two steps heat treatment. Crystal phase, microstructure and elementary distributing were studied by using XRD, SEM and EDS respectively. Prepared specimens show excellent transparency and super low thermal expansion coefficient of 2×10-8 ·K-1, which reaches international advanced level.展开更多
The electrolysis expansion of semigraphitic cathode in [K3AlF6/Na3AlF6]-AlF3-Al2O3 bath system was tested by self-made modified Rapoport apparatus. A mathematical model was introduced to discuss the effects of acR （c...The electrolysis expansion of semigraphitic cathode in [K3AlF6/Na3AlF6]-AlF3-Al2O3 bath system was tested by self-made modified Rapoport apparatus. A mathematical model was introduced to discuss the effects of acR （cryolite ratio） and βKR （elpasolite content divided by the total amount of elpasolite and sodium cryolite） on performance of cathode electrolysis expansion. The results show that K and Na （potassium and sodium） penetrate into the cathode together and have an obvious influence on the performance of cathode electrolysis expansion. The electrolysis expansion and K/Na penetration rate increase with the increase of αCR. When αCR=1.9 and βKR=0.5, the electrolysis expansion is the highest, which is 3.95%; and when αCR=I.4 and βKR=0.1, the electrolysis expansion is the lowest, which is 1.28%. But the effect offlKR is correlative with αCR. When αCR=1.6 and 1.9, with the increase of titan, the electrolysis expansion and K/Na penetration rate increase. However, when αCR=l.4, the electrolysis expansion and K/Na penetration rate firstly increase and then decrease with the increase of βKR.展开更多
Low thermal expansion composites are difficult to obtain by using Al with larger positive thermal expansion coefficient（TEC） and the materials with smaller negative TECs. In this investigation, Y2Mo3O12 with larger ...Low thermal expansion composites are difficult to obtain by using Al with larger positive thermal expansion coefficient（TEC） and the materials with smaller negative TECs. In this investigation, Y2Mo3O12 with larger negative TEC is used to combine with Al to obtain a low thermal expansion composite with high conductivity. The TEC of Al is reduced by 19%for a ratio Al：Y2Mo3O12 of 0.3118. When the mass ratio of Al：Y2Mo3O12 increases to 2.0000, the conductivity of the composite increases so much that a transformation from capacitance to pure resistance appears. The results suggest that Y2Mo3O12 plays a dominant role in the composite for low content of Al（presenting isolate particles）, while the content of Al increases enough to contact each other, the composite presents mainly the property of Al. For the effect of high content Al, it is considered that Al is squeezed out of the cermets during the uniaxial pressure process to form a thin layer on the surface.展开更多
In this paper, we give necessary and sufficient conditions for two families of Gabor functions of a certain type to yield a reproducing identity on L^2（R^n）. As applications, we characterize when such families yield...In this paper, we give necessary and sufficient conditions for two families of Gabor functions of a certain type to yield a reproducing identity on L^2（R^n）. As applications, we characterize when such families yield orthonormal or bi-orthogonal expansions. We also obtain a generalization of the Balian-Low theorem for general reprodueing identities （not necessary coming from a frame）.展开更多
In order to meet the needs of hot repairing technology of coke oven, the zero expansion, silica brick with super properties has been developed, and the problem of poor thermal stability of common silica brick has been...In order to meet the needs of hot repairing technology of coke oven, the zero expansion, silica brick with super properties has been developed, and the problem of poor thermal stability of common silica brick has been over-comed . This product can be directly used after being rapidly heated after construction. At present, it has been applied in coke ovens in Italy and Baosteel.展开更多
To improve the performance of the Turbofan engine,several measures should be considered during design process.Such measures,relating to aerodynamic characteristic design,include the maximum enthalpy per stage,the shor...To improve the performance of the Turbofan engine,several measures should be considered during design process.Such measures,relating to aerodynamic characteristic design,include the maximum enthalpy per stage,the shortest axial length,the minimum blade rows and the highest efficient in design and off design condition.To satisfy theses design characters,the meridian geometry of the engine will be excurvature at a high degree transition part between HP and LP turbines.The study is to investigate the effect of blade bowing on flow loss at blade tip and root of the type of turbine.Such turbine,tending towards separation,with severe secondary flow at the tip and strong radial flow at exit,was simulated by the 3D N-S solver Numerca,and there were several different stacking line bowing schemes in all.The results show that tip negative bowing and root positive bowing is able to weaken radial flow,consequently reduce the flow loss at the tip and root.展开更多
文摘In this paper ,spodumene mineral was used as raw material for fabricating glass ceramic with the addition of MgO,ZnO and TiO2,ZrO2. The expansion coefficient of the materials is 5. 5×107/℃ . Also the effects of the heat treatment on the crystallzing behaviour has been discussed by XRD and DTA.
基金Supported by the Postdoctoral Science Foundation of Hebei Province under Grant No B2017003008the National Natural Science Foundation of China under Grant Nos 51531005,51671166,51571174 and 51604241the Natural Science Foundation of Hebei Province under Grant No E2016203395
文摘Thermal expansion is a common phenomenon in both metals and alloys, which is important for metallic material applications in modern industry, especially in nuclear and aerospace industries. A lower thermal expansion coefficient may cause lower thermal stress and higher accuracy. A new Zr-based alloy is developed and presented.The XRD diffraction results demonstrate that only a close-packed hexagonal phase（α or α＇ phase） exists in the microstructure. The thermal expansion and mechanical properties are studied. According to the experimental results, the new Zr-based alloy presents a low thermal expansion coefficient and good mechanical properties.Also,its thermal expansion coefficient is stable through solution treatment.
文摘The self-stress trial of the fifteen high-strength, low-heat andmicro-expansion concrete-filled steel tube(CFST)is introduced, andthe generating and distributing features of pre-stress and itsrelation to add- ing quantity of expansive agent, which providespersuasive dependences for optimal design of high-strength, low- heatand micro-expansion CFST were investigated, especially for the designof added quantity of expansive agent.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574276,51702097,and 11574083)the Program for Innovative Research Team(in Science and Technology)in University of Henan Province,China(Grant No.16IRTSTHN017)Henan Science and Technology Development Project,China(Grant No.182102210241)
文摘Low thermal expansion materials are mostly ceramics with low conductive property, which limits their applications in electronic devices. The poor conductive property of ceramic ZrV_2 O_7 could be improved by bi-substitution of Fe and Mo for Zr and V, accompanied with low thermal expansion. Zr_(0.1) Fe_(0.9) V_(1.1 )Mo_(0.9 )O_7 has electrical conductivity of 8.2× 10^(-5) S/cm and 9.41× 10^(-4) S/cm at 291 K and 623 K, respectively. From 291 K to 413 K, thermal excitation leads to the increase of carrier concentration, which causes the rapid decrease of resistance. At 413–533 K, the conductivity is unchanged due to high scattering probability and a slowing increase of carrier concentration. The conductivity rapidly increases again from533 K to 623 K due to the intrinsic thermal excitation. The thermal expansion coefficient of Zr_(0.1) Fe_(0.9) V_(1.1 )Mo_(0.9 )O_7 is as low as 0.72× 10^(-6 )K^(-1) at 140–700 K from the dilatometer measurement. These properties suggest that Zr_(0.1) Fe_(0.9) V_(1.1 )Mo_(0.9 )O_7 has attractive application in electronic components.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.60976016,61350012,and 11574276)the Key Scientific Research Projects of Henan Province,China(Grant No.15B140004)+2 种基金Henan Science and Technology Development Project,China(Grant No.182102210241)Key Projects of Science and Technology Research of Henan Provincial Department of Education,China(Grant No.18A140014)Industrial Science and Technology Research Projects of Kaifeng,Henan Province,China(Grant No.1501049)
文摘Ceramics usually have irregular grains, cracking, or porosity, which result in their lightproof.Y2Mo3O12 ceramics have more porosity due to the heavy hygroscopicity.Introducing ZnLi to Y2Mo3O12 could form regular grains, reduce cracking and porosity.With increasing the content of ZnLi, the grain shapes self-assembly gradually and then the laser scattering and transmittance improve.The laser scattering property and transmittance of diverging rays become the best in ceramics Y2-x(ZnLi)xMo3O12(x = 1.0 and 1.2) with regular grains and low thermal expansion.The formation mechanism of regular grains is ascribed to the substitutions of Zn^2+ and Li+for Y^3+ in Y2Mo3O12 resulting in the preferential growth.The investigation in laser scattering, transmittance and low thermal expansion behaviors of Y2-x(ZnLi)xMo3O12 could pave a way to weaken the strong-laser attack from the high-power laser weapon and the other.
基金Projects(50271072, 504710831) supponed by the National Natural Science Foundation of China
文摘The effect of phosphorus on the oxidation resistance of low thermal expansion alloy IN909 was studied. The composition and structure of the oxidation layer were analyzed. It is found that the oxidation initiates at the grain boundaries. During the oxidation, Fe atoms diffuse toward the surface and form the outside oxidation layer as the oxide of iron. The transition oxidation layer lies between the oxidation layer and the matrix which is enriched with Nb, Ti and Si, forming FeTiO5, Nb2O5,Fe2SiO4 and TiO2. Phosphorus hardly influences the thermal expansion coefficient of IN909 alloy. However, it increases the formation ofεphase at the boundary of the transition oxidation layer and matrix. As a result, the oxidation rate is decreased efficiently because theεphase inhibits the diffusion of the element such as iron from the matrix to the oxidation layer.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11874328,U1731121,and 41401384)the Shandong Province Higher Educational Science and Technology Program,China(Grant No.J17KB127).
文摘A new material of Zr0.1Al1.9Mo2.9V0.1O12 is synthesized by the traditional solid state synthesis method.The phase transition,coefficient of thermal expansion,and luminescence properties of Zr0.1Al1.9Mo2.9V0.1O12 are explored with Raman spectrometer,dilatometer,and x-ray diffraction(XRD)diffractometer.The results show that the Zr0.1Al1.9Mo2.9V0.1O12 possesses the strong broad-band luminescence characteristics almost in the whole visible region.The sample is crystallized in a monoclinic structure group of P21/a(No.14)crystallized at room temperature(RT).The crystal is changed from monoclinic to orthorhombic structure when the temperature increases to 463 K.The material has very low thermal expansion performance in a wide temperature range.Its excellent low thermal expansion and strong pale green light properties in a wide temperature range suggest its potential applications in light-emitting diode(LED)and other optoelectronic devices.
文摘The preparation technics of glass-ceramics with super low coefficient of thermal expansion containing β-quartz solid solution as a main crystal phase based on the glass in the system Li2O-Al2O3-SiO2 was introduced. The composition of base glass, technics of melting and heat treatment effecting on characteristic of glass-ceramics was described. Specimens were prepared by melting, anneal and controlled two steps heat treatment. Crystal phase, microstructure and elementary distributing were studied by using XRD, SEM and EDS respectively. Prepared specimens show excellent transparency and super low thermal expansion coefficient of 2×10-8 ·K-1, which reaches international advanced level.
基金Project (2005CB623703) supported by the Major State Basic Research and Development Program of ChinaProject (2008AA030502) supported by the National High-Tech Research and Development Program of China
文摘The electrolysis expansion of semigraphitic cathode in [K3AlF6/Na3AlF6]-AlF3-Al2O3 bath system was tested by self-made modified Rapoport apparatus. A mathematical model was introduced to discuss the effects of acR （cryolite ratio） and βKR （elpasolite content divided by the total amount of elpasolite and sodium cryolite） on performance of cathode electrolysis expansion. The results show that K and Na （potassium and sodium） penetrate into the cathode together and have an obvious influence on the performance of cathode electrolysis expansion. The electrolysis expansion and K/Na penetration rate increase with the increase of αCR. When αCR=1.9 and βKR=0.5, the electrolysis expansion is the highest, which is 3.95%; and when αCR=I.4 and βKR=0.1, the electrolysis expansion is the lowest, which is 1.28%. But the effect offlKR is correlative with αCR. When αCR=1.6 and 1.9, with the increase of titan, the electrolysis expansion and K/Na penetration rate increase. However, when αCR=l.4, the electrolysis expansion and K/Na penetration rate firstly increase and then decrease with the increase of βKR.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10974183 and 11104252)the Doctoral Fund of the Ministry of Education of China(Grant No.20114101110003)+2 种基金the Fund for Science&Technology Innovation Team of Zhengzhou,China(Grant No.112PCXTD337)the Industrial Science and Technology Research Projects of Kaifeng,Henan Province,China(Grant No.1501049)the Key Research Projects of Henan Higher Education Institutions,China(Grant No.18A140014)
文摘Low thermal expansion composites are difficult to obtain by using Al with larger positive thermal expansion coefficient（TEC） and the materials with smaller negative TECs. In this investigation, Y2Mo3O12 with larger negative TEC is used to combine with Al to obtain a low thermal expansion composite with high conductivity. The TEC of Al is reduced by 19%for a ratio Al：Y2Mo3O12 of 0.3118. When the mass ratio of Al：Y2Mo3O12 increases to 2.0000, the conductivity of the composite increases so much that a transformation from capacitance to pure resistance appears. The results suggest that Y2Mo3O12 plays a dominant role in the composite for low content of Al（presenting isolate particles）, while the content of Al increases enough to contact each other, the composite presents mainly the property of Al. For the effect of high content Al, it is considered that Al is squeezed out of the cermets during the uniaxial pressure process to form a thin layer on the surface.
基金This work is partially financed by NSC under 87-2115-M277-001.
文摘In this paper, we give necessary and sufficient conditions for two families of Gabor functions of a certain type to yield a reproducing identity on L^2（R^n）. As applications, we characterize when such families yield orthonormal or bi-orthogonal expansions. We also obtain a generalization of the Balian-Low theorem for general reprodueing identities （not necessary coming from a frame）.
文摘In order to meet the needs of hot repairing technology of coke oven, the zero expansion, silica brick with super properties has been developed, and the problem of poor thermal stability of common silica brick has been over-comed . This product can be directly used after being rapidly heated after construction. At present, it has been applied in coke ovens in Italy and Baosteel.
基金Sponsored by the National Natural Science Foundation of China(Grant No.50576017)
文摘To improve the performance of the Turbofan engine,several measures should be considered during design process.Such measures,relating to aerodynamic characteristic design,include the maximum enthalpy per stage,the shortest axial length,the minimum blade rows and the highest efficient in design and off design condition.To satisfy theses design characters,the meridian geometry of the engine will be excurvature at a high degree transition part between HP and LP turbines.The study is to investigate the effect of blade bowing on flow loss at blade tip and root of the type of turbine.Such turbine,tending towards separation,with severe secondary flow at the tip and strong radial flow at exit,was simulated by the 3D N-S solver Numerca,and there were several different stacking line bowing schemes in all.The results show that tip negative bowing and root positive bowing is able to weaken radial flow,consequently reduce the flow loss at the tip and root.
