Objective:This study investigated the effect of proximal contact strength on the three-dimensional displacements of cantilever fixed partial denture(CFPD) under vertically concentrated loading with digital laser speck...Objective:This study investigated the effect of proximal contact strength on the three-dimensional displacements of cantilever fixed partial denture(CFPD) under vertically concentrated loading with digital laser speckle(DLS) technique.Methods:Fresh mandible of beagle dog was used to establish the implant-supported CFPD for specimen.DLS technique was employed for measuring the three-dimensional displacement of the prosthesis under vertically concentrated loading ranging from 200 to 3 000 g.The effect of the contact tightness on the displacement of CFPD was investigated by means of changing the contact tightness.Results:When an axial concentrated loading was exerted on the pontic of the implant-supported CFPD,the displacement of the CFPD was the greatest.The displacement of the prosthesis decreased with the increase of contact strength.When the contact strength was 0,0.95,and 3.25 N,the displacement of the buccolingual direction was smaller than that of the mesiodistal direction but greater than that of the occlusogingival direction.When the force on the contact area was 6.50 N,the mesiodistal displacement of the prosthesis was the biggest while the buccolingual displacement was the smallest.Conclusions:The implant supported CFPD is an effective therapy for fully or partially edentulous patients.The restoration of the contact area and the selection of the appropriate contact strength can reduce the displacement of the CFPD,and get a better stress distribution.The most appropriate force value is 3.25 N in this study.展开更多
The model for computing frictional coefficient between two teeth faces at the state of mixed elastohydrodynamic lubrication is established.And then more than 80 sets of numerical calculations and six sets of disc fati...The model for computing frictional coefficient between two teeth faces at the state of mixed elastohydrodynamic lubrication is established.And then more than 80 sets of numerical calculations and six sets of disc fatigue tests are completed.The results show that when the film thickness ratioλ〈1.6,frictional coefficientμis drastically decreased asλ.rises;Thereafter it decreases smoothly untilλ=4.5.Whenλ〉4.5,however,it goes up again withλ,which indicates that the excessive film thickness ratio will deteriorate gearing contact fatigue strength.At the end,the formulae for determining the frictional coefficients are formed.展开更多
With the method of group test, fourty pairs of carburization-quenching gears made from 16NCD13 steel for aerocraft were tested to research the contacting fatigue strength on tooth flank. As a result, the samples of fa...With the method of group test, fourty pairs of carburization-quenching gears made from 16NCD13 steel for aerocraft were tested to research the contacting fatigue strength on tooth flank. As a result, the samples of fatigue life at the moments when the pitting appears and reaches failure criterion were obtained at four stressing levels respectively. The distribution rule of fatigue life were distinguished, and the distribution parameters were estimated by statistical analysis. Based on that, the R-S-N curves with confidence 95% of contacting fatigue on gear tooth flank were evaluated. Therefore, the basic data were provided for the reliability design of the gears and prediction of their life.展开更多
本文搭建快速暂态过电压(very fast transient overvoltage,VFTO)放电模拟平台,以大量雷电冲击波模拟VFTO对电力设备的影响,研究放电幅值对三元乙丙橡胶(EPDM)电气绝缘性能的影响规律。结果表明:经200次脉冲放电后,EPDM表面生成羧酸盐基...本文搭建快速暂态过电压(very fast transient overvoltage,VFTO)放电模拟平台,以大量雷电冲击波模拟VFTO对电力设备的影响,研究放电幅值对三元乙丙橡胶(EPDM)电气绝缘性能的影响规律。结果表明:经200次脉冲放电后,EPDM表面生成羧酸盐基团,介电常数与介质损耗因数上升,而交流电气强度与表面水接触角明显下降。上述性能劣化程度随放电场强增大而加剧。当场强达到40 kV/mm时,经200次脉冲放电后EPDM试样的交流电气强度由42.28 kV/mm下降至37.16 kV/mm,降幅为12.11%,水接触角由100.53°下降至88.63°。展开更多
To downsize and lighten automatic transmission components, the gears installed must be strengthened in terms of pitting endurance and/or wear resistance. The most important metallurgical factor affecting fractures is ...To downsize and lighten automatic transmission components, the gears installed must be strengthened in terms of pitting endurance and/or wear resistance. The most important metallurgical factor affecting fractures is well known to be resistance to softening when steel is tempered at approximately 573 K. Carbonitriding with a high amount of nitrogen is a very effective production technique because nitrogen increases the resistance during tempering. However, structural anomalies begin to appear in the surface layer when the nitrogen content exceeds 0.6 mass% in the chromium steel generally used. To address this, we have developed new high-strength chromium steel with an optimized chemical composition that effectively inhibits anomalies even when Carbonitriding with a nitrogen content of more than 0.6 mass%. We performed a drivetrain durability test on an automatic transmission component designed to have excellent contact fatigue strength and a tooth root bending impact and fatigue strength. We found that the developed steel that was carbonitrided with a content of about 0.9 mass%, and then shot peened hard, has a pitting life of roughly 4.5 times that of conventionally manufactured steel.展开更多
CuCr25W1Ni2 alloy was prepared by means of vacuum induction melting (VIM). A series of Cu/Cr alloys with different compositions (mass fraction, 25%～75%) and Cr grain sizes (up to 150 μm) were investigated for their ...CuCr25W1Ni2 alloy was prepared by means of vacuum induction melting (VIM). A series of Cu/Cr alloys with different compositions (mass fraction, 25%～75%) and Cr grain sizes (up to 150 μm) were investigated for their differences in physical properties and breakdown voltage. The influence of alloy elements and microstructure on the performance of CuCr25W1Ni2 alloy was also discussed. Experimental results show that the chromium phase is strengthened and its size is minimized by the addition of tungsten powder. After electrical breakdown, very fine tungsten particles in the melt layer form the external nuclei in the solidification process. The microstructure of surface melt layer of CuCr25W1Ni2 alloy is much flatter. It can notably improve the dielectric strength. On the other hand, the nickel can enhance the mutual solubility of copper and chromium, and the whole alloy is strengthened. [展开更多
In this study, the interaction between cylindrical specimen made ofhomogeneous, isotropic, and linearlyelastic material and loading jaws of any curvature is considered in the Brazilian test. It is assumed thatthe spec...In this study, the interaction between cylindrical specimen made ofhomogeneous, isotropic, and linearlyelastic material and loading jaws of any curvature is considered in the Brazilian test. It is assumed thatthe specimen is diametrically compressed by elliptic normal contact stresses. The frictional contactstresses between the specimen and platens are neglected. The analytical solution starts from the contactproblem of the loading jaws of any curvature and cylindrical specimen. The contact width, correspondingloading angle （2 ^0）, and elliptical stresses obtained through solution of the contact problems are used asboundary conditions for a cylindrical specimen. The problem of the theory of elasticity for a cylinder issolved using Muskhelishvili＇s method. In this method, the displacements and stresses are represented interms of two analytical functions of a complex variable. In the main approaches, the nonlinear interactionbetween the loading bearing blocks and the specimen as well as the curvature of their surfacesand the elastic parameters of their materials are taken into account. Numerical examples are solved usingMATLAB to demonstrate the influence of deformability, curvature of the specimen and platens on thedistribution of the normal contact stresses as well as on the tensile and compressive stresses actingacross the loaded diameter. Derived equations also allow calculating the modulus of elasticity, totaldeformation modulus and creep parameters of the specimen material based on the experimental data ofradial contraction of the specimen.展开更多
Low drug loading efficiency is one of the main obstacles hindering the application of contact lenses(CLs) as the carrier for extended ocular drug delivery. Here in this study, a simple and effective drug loading metho...Low drug loading efficiency is one of the main obstacles hindering the application of contact lenses(CLs) as the carrier for extended ocular drug delivery. Here in this study, a simple and effective drug loading method based on salt induced modulation was proposed and demonstrated with mechanism elucidation. First of all, using poly(2-hydroxyethyl methacrylate)(p-HEMA) as the contact lens material, betaxolol hydrochloride, Diclofenac Sodium and Betaxolol Base as the model drugs with different solubility, influence of salt concentration,salt type(sodium salts of sulfate, chloride, and sulfocyanate) and drug properties in the loading solution on drug loading efficiency was investigated. Mechanism of enhanced drug loading in contact lens was further explored via studying the influence of salt on the absorption isotherm, drug solubility and water content of CLs. Applicability of this method to other CLs materials was also investigated. It was demonstrated that adjusting the ionic strength of loading solutions resulted in significant increase of drug loading in CLs. Type and concentration of the salts and solubility of the drug were the main factors influencing enhancement ratio of drug loading. The mechanism for improved drug loading was related to the reduced drug solubility in loading solutions and the reduced bound water content in contact lenses. Modulation of drug loading by adjusting ionic strength was also applicable to other CLs and the light transmittance was not affected. This method was more suitable for salt-form drugs with high solubility. In summary, adjusting ionic strength of loading solution is an economical and effective way to improve drug loading in CLs, and this simple method may also find application in other hydrogel based drug delivery systems.展开更多
Shear strength and shear-induced Hertzian contact damage in Ti_3SiC_2 were investigated using double-notched-beam specimen and steel spherical indenter, respectively. The shear strength of 40 MPa that was only about 1...Shear strength and shear-induced Hertzian contact damage in Ti_3SiC_2 were investigated using double-notched-beam specimen and steel spherical indenter, respectively. The shear strength of 40 MPa that was only about 10% of bending strength was obtained for this novel ceramic. The SEM fractograph of specimens failed in shear test indicated a combination of intergranular and transgranular fracture. Under a contact load, plastic indent without cone crack could be formed on the surface of Ti3SiC2 sample. Optical observation on side view showed half-circle cracks around the damage zone below the indent, and the crack shape was consistent with the contrail of the principal shearing stress. The low shear strength and the shearing-activated intergranular sliding were confirmed being the key factors for failure in Ti3SiC2.展开更多
Mechanical behavior such as stress-strain response, shear strength, resistance to liquefaction, modulus, and shear wave velocity of granular mixes containing coarse and fine grains is dependent on intergrain contact d...Mechanical behavior such as stress-strain response, shear strength, resistance to liquefaction, modulus, and shear wave velocity of granular mixes containing coarse and fine grains is dependent on intergrain contact density of the soil. The global void ratio e is a poor index of contact density for such soils. The contact density depends on void ratio, fine grain content （Cv）, size disparity between particles, and gradation among other factors. A simple analysis of a two-sized particle system with large size disparity is used to develop an understanding of the effects of Cv, e, and gradation of coarse and fine grained soils in the soil mix on intergrain contact density. An equivalent intergranular void ratio （ec）oq is introduced as a useful intergrain contact density for soils at fines content of less than a threshold value Crth. Beyond this value, an equivalent interfine void ratio （ef）eq is introduced as a primary intergrain contact density index. At higher values of Cv beyond a limiting value of fine grains content CVL, an interfine void ratio ef is introduced as the primary contact density index. Relevant equivalent relative density indices （Drc）eq and （Drf）eq are also presented. Experimental data show that these new indices correlate well with steady state strength, liquefaction resistance, and shear wave velocities of sands, silty sands, sandy silts, and gravelly sand mixes.展开更多
As the thickness of silicon solar wafer and solar cells becomes thinner, the cells are subjected to high stress due to the thermal coefficient mismatch induced by metallization process. Handling and bowing problems as...As the thickness of silicon solar wafer and solar cells becomes thinner, the cells are subjected to high stress due to the thermal coefficient mismatch induced by metallization process. Handling and bowing problems associated with thinner wafers become increasingly important, as these can lead to cells cracking and thus to high yield losses. The goal of this work to provide experimental understanding of Al rear side microstructure development and mechanical properties as well as correlate the obtained results with fracture behaviour of the cell. It is shown that the aluminium back contact has a complex microstructure, consisting of five main components: 1) the back surface field layer;2) a eutectic layer;3) spherical (3 - 5 μm) hypereutectic Al-Si particles surrounded by a thin aluminium oxide layer (200 nm);4) a bis- muth-silicate glass matrix;and 5) pores (14 vol%). It was concluded that the eutectic layer thickness and waviness depends on Al particle size, amount of Al paste and textured surface roughness of silicon wafers. The Young’s modulus of the Al-Si particles is estimated by nano-indentation and the overall Young’s modulus is estimated on the basis of bowing measurements and found to be ~43 GPa. It was found, that there is a relation between aluminium paste composition, eutectic layer thickness, mechanical strength and bowing of solar cells. Three main parameters were found to affect the mechanical strength of mc-silicon solar cells with an aluminium contact layer, namely the eutectic layer thickness and uniformity, the Al layer thickness (which results from the Al particle size and its distribution), and the amount of porosity and the bismuth glass fraction.展开更多
The atom (Ag,Cu) diffusion behavior and the effect of technology on the interface of rolled Ag/Cu composite contact were investigated. The concentration of Ag and Cu atoms near the interface was determined with electr...The atom (Ag,Cu) diffusion behavior and the effect of technology on the interface of rolled Ag/Cu composite contact were investigated. The concentration of Ag and Cu atoms near the interface was determined with electron probe. The bonding strength of composite interface was tested and the fracture in tensile sample was observed by SEM. The results show that there was inter diffusion of Ag and Cu atoms on the interface, which formed compact layer with high bonding strength of 98 MPa. The practical application proved that the Ag/Cu composite interface is reliable.展开更多
Bimetallic lined steel pipe （LSP） is a new anti-corrosion technology. It is widely used to transport oil, gas, water and corrosive liquid chemicals. At present, the hydroforming pressure for LSP has been investigate...Bimetallic lined steel pipe （LSP） is a new anti-corrosion technology. It is widely used to transport oil, gas, water and corrosive liquid chemicals. At present, the hydroforming pressure for LSP has been investigated theoretically and experimentally by most researchers. However, there are a few reports on the thermal strength of bimetallic LSP. Actually, the bimetallic LSP will be subjected to remarkable thermal load in the process of three layer polyethylene （3PE） external coating. Reverse yielding failure may occur on the inner pipe of the bimetallic LSP when it suffers from remarkable thermal load and residual contact pressure simultaneously. The aim of this paper is to study the thermal load and strength of the bimetallic LSP. A mechanical model, which can estimate the thermal strength of the bimetallic LSP, was established based on the elastic theory and the manufacture of the bimetallic LSP. Based on the model, the correlation between the thermal strength of the bimetallic LSP and residual contact pressure and wall thickness of the inner pipe was obtained. Reverse yielding experiments were performed on the LSP （NT80SS-316L） under different thermal loads. Experiment results are consistent with calculated results from the theoretical model. The experimental and simulation results may provide powerful guidance for the bimetallic LSP production and use.展开更多
The English and Chinese languages are languages developing in the constant contact with other languages. Both countries experienced foreign or exotic invasion and conquest. In Britain, the language of the conquerors w...The English and Chinese languages are languages developing in the constant contact with other languages. Both countries experienced foreign or exotic invasion and conquest. In Britain, the language of the conquerors was adopted, while in China, the language of the conquered was honored. One reason is the preference of the particular ruler, the other reason is the level of culture or civilization. From the histories of the English language and the Chinese language, it can be seen that no language acquires importance because of what is assumed to be purely internal advantage. The choice is made by people imitating those with prestige or power in their society.展开更多
文摘Objective:This study investigated the effect of proximal contact strength on the three-dimensional displacements of cantilever fixed partial denture(CFPD) under vertically concentrated loading with digital laser speckle(DLS) technique.Methods:Fresh mandible of beagle dog was used to establish the implant-supported CFPD for specimen.DLS technique was employed for measuring the three-dimensional displacement of the prosthesis under vertically concentrated loading ranging from 200 to 3 000 g.The effect of the contact tightness on the displacement of CFPD was investigated by means of changing the contact tightness.Results:When an axial concentrated loading was exerted on the pontic of the implant-supported CFPD,the displacement of the CFPD was the greatest.The displacement of the prosthesis decreased with the increase of contact strength.When the contact strength was 0,0.95,and 3.25 N,the displacement of the buccolingual direction was smaller than that of the mesiodistal direction but greater than that of the occlusogingival direction.When the force on the contact area was 6.50 N,the mesiodistal displacement of the prosthesis was the biggest while the buccolingual displacement was the smallest.Conclusions:The implant supported CFPD is an effective therapy for fully or partially edentulous patients.The restoration of the contact area and the selection of the appropriate contact strength can reduce the displacement of the CFPD,and get a better stress distribution.The most appropriate force value is 3.25 N in this study.
基金supported by Provincial Natural Science Foundation of Shanxi,China(No.20041057)Scholarship Council of Shanxi,China(No.2005-22)
文摘The model for computing frictional coefficient between two teeth faces at the state of mixed elastohydrodynamic lubrication is established.And then more than 80 sets of numerical calculations and six sets of disc fatigue tests are completed.The results show that when the film thickness ratioλ〈1.6,frictional coefficientμis drastically decreased asλ.rises;Thereafter it decreases smoothly untilλ=4.5.Whenλ〉4.5,however,it goes up again withλ,which indicates that the excessive film thickness ratio will deteriorate gearing contact fatigue strength.At the end,the formulae for determining the frictional coefficients are formed.
文摘With the method of group test, fourty pairs of carburization-quenching gears made from 16NCD13 steel for aerocraft were tested to research the contacting fatigue strength on tooth flank. As a result, the samples of fatigue life at the moments when the pitting appears and reaches failure criterion were obtained at four stressing levels respectively. The distribution rule of fatigue life were distinguished, and the distribution parameters were estimated by statistical analysis. Based on that, the R-S-N curves with confidence 95% of contacting fatigue on gear tooth flank were evaluated. Therefore, the basic data were provided for the reliability design of the gears and prediction of their life.
文摘To downsize and lighten automatic transmission components, the gears installed must be strengthened in terms of pitting endurance and/or wear resistance. The most important metallurgical factor affecting fractures is well known to be resistance to softening when steel is tempered at approximately 573 K. Carbonitriding with a high amount of nitrogen is a very effective production technique because nitrogen increases the resistance during tempering. However, structural anomalies begin to appear in the surface layer when the nitrogen content exceeds 0.6 mass% in the chromium steel generally used. To address this, we have developed new high-strength chromium steel with an optimized chemical composition that effectively inhibits anomalies even when Carbonitriding with a nitrogen content of more than 0.6 mass%. We performed a drivetrain durability test on an automatic transmission component designed to have excellent contact fatigue strength and a tooth root bending impact and fatigue strength. We found that the developed steel that was carbonitrided with a content of about 0.9 mass%, and then shot peened hard, has a pitting life of roughly 4.5 times that of conventionally manufactured steel.
文摘CuCr25W1Ni2 alloy was prepared by means of vacuum induction melting (VIM). A series of Cu/Cr alloys with different compositions (mass fraction, 25%～75%) and Cr grain sizes (up to 150 μm) were investigated for their differences in physical properties and breakdown voltage. The influence of alloy elements and microstructure on the performance of CuCr25W1Ni2 alloy was also discussed. Experimental results show that the chromium phase is strengthened and its size is minimized by the addition of tungsten powder. After electrical breakdown, very fine tungsten particles in the melt layer form the external nuclei in the solidification process. The microstructure of surface melt layer of CuCr25W1Ni2 alloy is much flatter. It can notably improve the dielectric strength. On the other hand, the nickel can enhance the mutual solubility of copper and chromium, and the whole alloy is strengthened. [
文摘In this study, the interaction between cylindrical specimen made ofhomogeneous, isotropic, and linearlyelastic material and loading jaws of any curvature is considered in the Brazilian test. It is assumed thatthe specimen is diametrically compressed by elliptic normal contact stresses. The frictional contactstresses between the specimen and platens are neglected. The analytical solution starts from the contactproblem of the loading jaws of any curvature and cylindrical specimen. The contact width, correspondingloading angle （2 ^0）, and elliptical stresses obtained through solution of the contact problems are used asboundary conditions for a cylindrical specimen. The problem of the theory of elasticity for a cylinder issolved using Muskhelishvili＇s method. In this method, the displacements and stresses are represented interms of two analytical functions of a complex variable. In the main approaches, the nonlinear interactionbetween the loading bearing blocks and the specimen as well as the curvature of their surfacesand the elastic parameters of their materials are taken into account. Numerical examples are solved usingMATLAB to demonstrate the influence of deformability, curvature of the specimen and platens on thedistribution of the normal contact stresses as well as on the tensile and compressive stresses actingacross the loaded diameter. Derived equations also allow calculating the modulus of elasticity, totaldeformation modulus and creep parameters of the specimen material based on the experimental data ofradial contraction of the specimen.
基金supported by the Distinguished Professor Project of Liaoning Province(2015)
文摘Low drug loading efficiency is one of the main obstacles hindering the application of contact lenses(CLs) as the carrier for extended ocular drug delivery. Here in this study, a simple and effective drug loading method based on salt induced modulation was proposed and demonstrated with mechanism elucidation. First of all, using poly(2-hydroxyethyl methacrylate)(p-HEMA) as the contact lens material, betaxolol hydrochloride, Diclofenac Sodium and Betaxolol Base as the model drugs with different solubility, influence of salt concentration,salt type(sodium salts of sulfate, chloride, and sulfocyanate) and drug properties in the loading solution on drug loading efficiency was investigated. Mechanism of enhanced drug loading in contact lens was further explored via studying the influence of salt on the absorption isotherm, drug solubility and water content of CLs. Applicability of this method to other CLs materials was also investigated. It was demonstrated that adjusting the ionic strength of loading solutions resulted in significant increase of drug loading in CLs. Type and concentration of the salts and solubility of the drug were the main factors influencing enhancement ratio of drug loading. The mechanism for improved drug loading was related to the reduced drug solubility in loading solutions and the reduced bound water content in contact lenses. Modulation of drug loading by adjusting ionic strength was also applicable to other CLs and the light transmittance was not affected. This method was more suitable for salt-form drugs with high solubility. In summary, adjusting ionic strength of loading solution is an economical and effective way to improve drug loading in CLs, and this simple method may also find application in other hydrogel based drug delivery systems.
基金This work was supported by the National Outstanding Young Scientist Foundation(No.50125204 for Y.Bao and No.59925208 for Y.Zhou)“The Hundred-Talent Program”of Chinese Academy of Sciences and“863”program in China.
文摘Shear strength and shear-induced Hertzian contact damage in Ti_3SiC_2 were investigated using double-notched-beam specimen and steel spherical indenter, respectively. The shear strength of 40 MPa that was only about 10% of bending strength was obtained for this novel ceramic. The SEM fractograph of specimens failed in shear test indicated a combination of intergranular and transgranular fracture. Under a contact load, plastic indent without cone crack could be formed on the surface of Ti3SiC2 sample. Optical observation on side view showed half-circle cracks around the damage zone below the indent, and the crack shape was consistent with the contrail of the principal shearing stress. The low shear strength and the shearing-activated intergranular sliding were confirmed being the key factors for failure in Ti3SiC2.
文摘Mechanical behavior such as stress-strain response, shear strength, resistance to liquefaction, modulus, and shear wave velocity of granular mixes containing coarse and fine grains is dependent on intergrain contact density of the soil. The global void ratio e is a poor index of contact density for such soils. The contact density depends on void ratio, fine grain content （Cv）, size disparity between particles, and gradation among other factors. A simple analysis of a two-sized particle system with large size disparity is used to develop an understanding of the effects of Cv, e, and gradation of coarse and fine grained soils in the soil mix on intergrain contact density. An equivalent intergranular void ratio （ec）oq is introduced as a useful intergrain contact density for soils at fines content of less than a threshold value Crth. Beyond this value, an equivalent interfine void ratio （ef）eq is introduced as a primary intergrain contact density index. At higher values of Cv beyond a limiting value of fine grains content CVL, an interfine void ratio ef is introduced as the primary contact density index. Relevant equivalent relative density indices （Drc）eq and （Drf）eq are also presented. Experimental data show that these new indices correlate well with steady state strength, liquefaction resistance, and shear wave velocities of sands, silty sands, sandy silts, and gravelly sand mixes.
文摘As the thickness of silicon solar wafer and solar cells becomes thinner, the cells are subjected to high stress due to the thermal coefficient mismatch induced by metallization process. Handling and bowing problems associated with thinner wafers become increasingly important, as these can lead to cells cracking and thus to high yield losses. The goal of this work to provide experimental understanding of Al rear side microstructure development and mechanical properties as well as correlate the obtained results with fracture behaviour of the cell. It is shown that the aluminium back contact has a complex microstructure, consisting of five main components: 1) the back surface field layer;2) a eutectic layer;3) spherical (3 - 5 μm) hypereutectic Al-Si particles surrounded by a thin aluminium oxide layer (200 nm);4) a bis- muth-silicate glass matrix;and 5) pores (14 vol%). It was concluded that the eutectic layer thickness and waviness depends on Al particle size, amount of Al paste and textured surface roughness of silicon wafers. The Young’s modulus of the Al-Si particles is estimated by nano-indentation and the overall Young’s modulus is estimated on the basis of bowing measurements and found to be ~43 GPa. It was found, that there is a relation between aluminium paste composition, eutectic layer thickness, mechanical strength and bowing of solar cells. Three main parameters were found to affect the mechanical strength of mc-silicon solar cells with an aluminium contact layer, namely the eutectic layer thickness and uniformity, the Al layer thickness (which results from the Al particle size and its distribution), and the amount of porosity and the bismuth glass fraction.
文摘The atom (Ag,Cu) diffusion behavior and the effect of technology on the interface of rolled Ag/Cu composite contact were investigated. The concentration of Ag and Cu atoms near the interface was determined with electron probe. The bonding strength of composite interface was tested and the fracture in tensile sample was observed by SEM. The results show that there was inter diffusion of Ag and Cu atoms on the interface, which formed compact layer with high bonding strength of 98 MPa. The practical application proved that the Ag/Cu composite interface is reliable.
基金financial support from the National Natural Science Foundation of China (Nos. 51004084, 51274170)the Doctoral Fund of Ministry of Education of China (No. 20105121120002)
文摘Bimetallic lined steel pipe （LSP） is a new anti-corrosion technology. It is widely used to transport oil, gas, water and corrosive liquid chemicals. At present, the hydroforming pressure for LSP has been investigated theoretically and experimentally by most researchers. However, there are a few reports on the thermal strength of bimetallic LSP. Actually, the bimetallic LSP will be subjected to remarkable thermal load in the process of three layer polyethylene （3PE） external coating. Reverse yielding failure may occur on the inner pipe of the bimetallic LSP when it suffers from remarkable thermal load and residual contact pressure simultaneously. The aim of this paper is to study the thermal load and strength of the bimetallic LSP. A mechanical model, which can estimate the thermal strength of the bimetallic LSP, was established based on the elastic theory and the manufacture of the bimetallic LSP. Based on the model, the correlation between the thermal strength of the bimetallic LSP and residual contact pressure and wall thickness of the inner pipe was obtained. Reverse yielding experiments were performed on the LSP （NT80SS-316L） under different thermal loads. Experiment results are consistent with calculated results from the theoretical model. The experimental and simulation results may provide powerful guidance for the bimetallic LSP production and use.
文摘The English and Chinese languages are languages developing in the constant contact with other languages. Both countries experienced foreign or exotic invasion and conquest. In Britain, the language of the conquerors was adopted, while in China, the language of the conquered was honored. One reason is the preference of the particular ruler, the other reason is the level of culture or civilization. From the histories of the English language and the Chinese language, it can be seen that no language acquires importance because of what is assumed to be purely internal advantage. The choice is made by people imitating those with prestige or power in their society.
