Mg alloys have the defects of low stiffness,low strength,and high coefficient of thermal expansion(CTE).The composites strategy and its architecture design are effective approaches to improve the comprehensive perform...Mg alloys have the defects of low stiffness,low strength,and high coefficient of thermal expansion(CTE).The composites strategy and its architecture design are effective approaches to improve the comprehensive performance of materials,but the processing difficulty,especially in ceramics forming,limits the control and innovation of material architecture.Here,combined with 3D printing and squeeze infiltration technology,two precisely controllable architectures of AZ91/Al_(2)O_(3)interpenetrating phase composites(IPC)with ceramic scaffold were prepared.The interface,properties and impact of different architecture on IPC performance were studied by experiments and finite element simulation.The metallurgical bonding of the interface was realized with the formation of MgAl_(2)O_(4)reaction layer.The IPC with 1 mm circular hole scaffold(1C-IPC)exhibited significantly improved elastic modulus of 164 GPa,high compressive strength of 680 MPa,and good CTE of 12.91×10^(-6)K^(−1),which were 3.64 times,1.98 times and 55%of the Mg matrix,respectively.Their elastic modulus,compressive strength,and CTE were superior to the vast majority of Mg alloys and Mg based composites.The reinforcement and matrix were bicontinuous and interpenetrating each other,which played a critical role in ensuring the potent strengthening effect of the Al_(2)O_(3)reinforcement by efficient load transfer.Under the same volume fraction of reinforcements,compared to IPC with 1 mm hexagonal hole scaffold(1H-IPC),the elastic modulus and compressive strength of 1C-IPC increased by 15%and 28%,respectively,which was due to the reduced stress concentration and more uniform stress distribution of 1C-IPC.It shows great potential of architecture design in improving the performance of composites.This study provides architectural design strategy and feasible preparation method for the development of high performance materials.展开更多
As a novel lightweight metallic material with excellent heat and corrosion resistance,elastic disordered microporous metal rubber(EDMMR)functions as an effective damping and support element in high-temperature environ...As a novel lightweight metallic material with excellent heat and corrosion resistance,elastic disordered microporous metal rubber(EDMMR)functions as an effective damping and support element in high-temperature environments where traditional polymer rubber fails.In this paper,a multi-scale finite element model for EDMMR is constructed using virtual manufacturing technology(VMT).Thermo-mechanical coupling analysis reveals a distinct inward expansion and dissipation phenomenon in EDMMR under high-temperature conditions,distinguishing it from porous materials.This phenomenon has the potential to impact the overall dimensions of EDMMR through transmission and accumulation processes.The experimental results demonstrate a random distribution of internal micro springs in EDMMR,considering the contact composition of spring microelements and the pore structure.By incorporating material elasticity,a predictive method for the thermal expansion coefficient of EDMMR based on the Schapery model is proposed.Additionally,standardized processes are employed to manufacture multiple sets of cylindrical EDMMR samples with similar dimensions but varying porosities.Thermal expansion tests are conducted on these samples,and the accuracy of the predicted thermal expansion coefficient is quantitatively validated through residual analysis.This research indicates that EDMMR maintains good structural stability in high-temperature environments.The thermal expansion rate of the material exhibits an opposite trend to the variation of elastic modulus with temperature,as the porosity rate changes.展开更多
Blends of inorganic nano zirconium dioxide(ZrO-2) and poly(ether-sulfone)(PES) were prepared by mechanical blending. Their mechanical, thermal and electrical properties were investigated. Compared with pure PES, this ...Blends of inorganic nano zirconium dioxide(ZrO-2) and poly(ether-sulfone)(PES) were prepared by mechanical blending. Their mechanical, thermal and electrical properties were investigated. Compared with pure PES, this kind of organic/inorganic nano-composite exhibit a better electrical property, lower coefficients of thermal expansion, as well as a similar thermal properties. The mechanical properties are composition-dependent.展开更多
对毫米波TR(transmitter and receiver)组件焊接过程中线膨胀系数(CTE)失配机理和由于CTE失配导致的热机械应力对组件可靠性的影响进行了分析。根据阶梯焊接温度精确控制和无铅焊料可靠浸润的要求,从实践中总结出了一种真空预镀涂焊接...对毫米波TR(transmitter and receiver)组件焊接过程中线膨胀系数(CTE)失配机理和由于CTE失配导致的热机械应力对组件可靠性的影响进行了分析。根据阶梯焊接温度精确控制和无铅焊料可靠浸润的要求,从实践中总结出了一种真空预镀涂焊接新工艺。实践表明,该新工艺可以精确地进行阶梯焊接温度控制,使无铅焊料有很好的浸润效果,焊透率由70%以下提高到98.3%,延长了CTE不匹配造成的疲劳失效发生时间,提高了TR组件使用可靠性。展开更多
This work investigates the transient behaviour of a phase change material based cool thermal energy storage (CTES) system comprised of a cylindrical storage tank filled with encapsulated phase change materials (PCMs) ...This work investigates the transient behaviour of a phase change material based cool thermal energy storage (CTES) system comprised of a cylindrical storage tank filled with encapsulated phase change materials (PCMs) in spherical container integrated with an ethylene glycol chiller plant. A simulation program was developed to evaluate the temperature histories of the heat transfer fluid (HTF) and the phase change material at any axial location during the charging period. The results of the model were validated by comparison with experimental results of temperature profiles of HTF and PCM. The model was also used to investigate the effect of porosity, Stanton number, Stefan number and Peclet number on CTES system performance. The results showed that increase in porosity contributes to a higher rate of energy storage. However, for a given geometry and heat transfer coefficient, the mass of PCM charged in the unit decreases as the increase in porosity. The St number as well as the Ste number is also influential in the performance of the unit. The model is a convenient and more suitable method to determine the heat transfer characteristics of CTES system. The results reported are much useful for designing CTES system.展开更多
基金supported by the National Key Research and Development Program of China(No.2022YFB3708400)the National Natural Science Foundation of China(No.52305158)+1 种基金the Young Elite Scientists Sponsorship Program by CAST(No.2022QNRC001)the Science Innovation Foundation of Shanghai Academy of Spaceflight Technology(No.USCAST2021-18).
文摘Mg alloys have the defects of low stiffness,low strength,and high coefficient of thermal expansion(CTE).The composites strategy and its architecture design are effective approaches to improve the comprehensive performance of materials,but the processing difficulty,especially in ceramics forming,limits the control and innovation of material architecture.Here,combined with 3D printing and squeeze infiltration technology,two precisely controllable architectures of AZ91/Al_(2)O_(3)interpenetrating phase composites(IPC)with ceramic scaffold were prepared.The interface,properties and impact of different architecture on IPC performance were studied by experiments and finite element simulation.The metallurgical bonding of the interface was realized with the formation of MgAl_(2)O_(4)reaction layer.The IPC with 1 mm circular hole scaffold(1C-IPC)exhibited significantly improved elastic modulus of 164 GPa,high compressive strength of 680 MPa,and good CTE of 12.91×10^(-6)K^(−1),which were 3.64 times,1.98 times and 55%of the Mg matrix,respectively.Their elastic modulus,compressive strength,and CTE were superior to the vast majority of Mg alloys and Mg based composites.The reinforcement and matrix were bicontinuous and interpenetrating each other,which played a critical role in ensuring the potent strengthening effect of the Al_(2)O_(3)reinforcement by efficient load transfer.Under the same volume fraction of reinforcements,compared to IPC with 1 mm hexagonal hole scaffold(1H-IPC),the elastic modulus and compressive strength of 1C-IPC increased by 15%and 28%,respectively,which was due to the reduced stress concentration and more uniform stress distribution of 1C-IPC.It shows great potential of architecture design in improving the performance of composites.This study provides architectural design strategy and feasible preparation method for the development of high performance materials.
基金Supported by National Natural Science Foundation of China(Grant Nos.U2330202,52175162,51805086,51975123)Fujian Provincial Technological Innovation Key Research and Industrialization Projects(Grant Nos.2023XQ005,2024XQ010)Project of Guangdong Provincial Science and Technology Bureau of Jiangmen City(Grant No.2023780200030009506)。
文摘As a novel lightweight metallic material with excellent heat and corrosion resistance,elastic disordered microporous metal rubber(EDMMR)functions as an effective damping and support element in high-temperature environments where traditional polymer rubber fails.In this paper,a multi-scale finite element model for EDMMR is constructed using virtual manufacturing technology(VMT).Thermo-mechanical coupling analysis reveals a distinct inward expansion and dissipation phenomenon in EDMMR under high-temperature conditions,distinguishing it from porous materials.This phenomenon has the potential to impact the overall dimensions of EDMMR through transmission and accumulation processes.The experimental results demonstrate a random distribution of internal micro springs in EDMMR,considering the contact composition of spring microelements and the pore structure.By incorporating material elasticity,a predictive method for the thermal expansion coefficient of EDMMR based on the Schapery model is proposed.Additionally,standardized processes are employed to manufacture multiple sets of cylindrical EDMMR samples with similar dimensions but varying porosities.Thermal expansion tests are conducted on these samples,and the accuracy of the predicted thermal expansion coefficient is quantitatively validated through residual analysis.This research indicates that EDMMR maintains good structural stability in high-temperature environments.The thermal expansion rate of the material exhibits an opposite trend to the variation of elastic modulus with temperature,as the porosity rate changes.
文摘Blends of inorganic nano zirconium dioxide(ZrO-2) and poly(ether-sulfone)(PES) were prepared by mechanical blending. Their mechanical, thermal and electrical properties were investigated. Compared with pure PES, this kind of organic/inorganic nano-composite exhibit a better electrical property, lower coefficients of thermal expansion, as well as a similar thermal properties. The mechanical properties are composition-dependent.
文摘对毫米波TR(transmitter and receiver)组件焊接过程中线膨胀系数(CTE)失配机理和由于CTE失配导致的热机械应力对组件可靠性的影响进行了分析。根据阶梯焊接温度精确控制和无铅焊料可靠浸润的要求,从实践中总结出了一种真空预镀涂焊接新工艺。实践表明,该新工艺可以精确地进行阶梯焊接温度控制,使无铅焊料有很好的浸润效果,焊透率由70%以下提高到98.3%,延长了CTE不匹配造成的疲劳失效发生时间,提高了TR组件使用可靠性。
文摘This work investigates the transient behaviour of a phase change material based cool thermal energy storage (CTES) system comprised of a cylindrical storage tank filled with encapsulated phase change materials (PCMs) in spherical container integrated with an ethylene glycol chiller plant. A simulation program was developed to evaluate the temperature histories of the heat transfer fluid (HTF) and the phase change material at any axial location during the charging period. The results of the model were validated by comparison with experimental results of temperature profiles of HTF and PCM. The model was also used to investigate the effect of porosity, Stanton number, Stefan number and Peclet number on CTES system performance. The results showed that increase in porosity contributes to a higher rate of energy storage. However, for a given geometry and heat transfer coefficient, the mass of PCM charged in the unit decreases as the increase in porosity. The St number as well as the Ste number is also influential in the performance of the unit. The model is a convenient and more suitable method to determine the heat transfer characteristics of CTES system. The results reported are much useful for designing CTES system.
