Interfacial reaction, tensile strength and creep resistance of Sn-58Bi-x Zn(x=0, 0.7, mass fraction, %) solder samples during liquid-state aging were investigated. The coarsening of Bi and the growth of Cu-Sn intermet...Interfacial reaction, tensile strength and creep resistance of Sn-58Bi-x Zn(x=0, 0.7, mass fraction, %) solder samples during liquid-state aging were investigated. The coarsening of Bi and the growth of Cu-Sn intermetallic compounds(IMCs) in Sn-58Bi-0.7Zn solder sample were both effectively suppressed. With the addition of 0.7% Zn, ultimate tensile strengths(UTSs) of the Sn-58 Bi solder slabs were respectively increased by 6.05% and 5.50% after reflow soldering and liquid-state aging, and those of the Cu/Sn-58Bi/Cu solder joints were also increased by 21.51% and 29.27%, respectively. The increase in strengthening effect of Cu/Sn-58Bi-x Zn/Cu solder joints could be attributed to the fracture surface which was changed from the Cu/IMC interface to the IMC/solder interface due to the finer Bi grain. Nanoindentation results revealed that the creep behavior of Sn-58Bi-0.7Zn solder was significantly improved compared with that of the eutectic Sn-58 Bi solder after reflow soldering and liquid-state aging.展开更多
In order to study the in?uence of the physical state of solder on the interfacial reaction of dip-soldered Sn-3.0 Ag-0.5 Cu/Cu system, two kinds of experiments were designed, including:(1) solid-state aging between th...In order to study the in?uence of the physical state of solder on the interfacial reaction of dip-soldered Sn-3.0 Ag-0.5 Cu/Cu system, two kinds of experiments were designed, including:(1) solid-state aging between the solder and Cu substrate;(2)liquid-state aging between the metastable supercooled liquid-state solder and Cu substrate. The aging times were 30, 60,120 and 180 min, respectively, and the aging temperature was 8 ℃ lower than the melting point of the Sn-3.0 Ag-0.5 Cu(SAC305) alloy(217 ℃). The experimental data revealed that the physical state of the solder obviously affected the formation of the intermetallic compound(IMC), and resulted in the difference in the diffusion of atoms on the interface between the SAC305 solder and Cu substrate. The IMC interface after aging for 30 min presents unique characteristics compared with that of the sample after dip soldering. The IMC interface of solid-state aged SAC305/Cu couple is relatively planar, while the IMC interface under metastable supercooled liquid-state aging conditions presents scallop-like shape.展开更多
We report progress towards a modern scientific description of thermodynamic properties of fluids following the discovery (in 2012) of a coexisting critical density hiatus and a supercritical mesophase defined by perco...We report progress towards a modern scientific description of thermodynamic properties of fluids following the discovery (in 2012) of a coexisting critical density hiatus and a supercritical mesophase defined by percolation transitions. The state functions density ρ(p,T), and Gibbs energy G(p,T), of fluids, e.g. CO<sub>2</sub>, H<sub>2</sub>O and argon exhibit a symmetry characterised by the rigidity, ω = (dp/dρ)<sub>T</sub>, between gaseous and liquid states along any isotherm from critical (T<sub>c</sub>) to Boyle (T<sub>B</sub>) temperatures, on either side of the supercritical mesophase. Here, using experimental data for fluid argon, we investigate the low-density cluster physics description of an ideal dilute gas that obeys Dalton’s partial pressure law. Cluster expansions in powers of density relate to a supercritical liquid-phase rigidity symmetry (RS) line (ω = ρ<sub>rs</sub>(T) = RT) to gas phase virial coefficients. We show that it is continuous in all derivatives, linear within stable fluid phase, and relates analytically to the Boyle-work line (BW) (w = (p/ρ)<sub>T</sub> = RT), and to percolation lines of gas (PB) and liquid (PA) phases by: ρ<sub>BW</sub>(T) = 2ρ<sub>PA</sub>(T) = 3ρ<sub>PB</sub>(T) = 3ρ<sub>RS</sub>(T)/2 for T T<sub>B</sub>. These simple relationships arise, because the higher virial coefficients (b<sub>n</sub>, n ≥ 4) cancel due to clustering equilibria, or become negligible at all temperatures (0 T T<sub>B</sub>)<sub> </sub>within the gas phase. The Boyle-work line (p/ρ<sub>BW</sub>)<sub>T</sub> is related exactly at lower densities as T → T<sub>B</sub>, and accurately for liquid densities, by ρ<sub>BW</sub>(T) = −(b<sub>2</sub>/b<sub>3</sub>)<sub>T</sub>. The RS line, ω(T) = RT, defines a new liquid-density ground-state physical constant (ρ<sub>RS</sub>(0) = (2/3)ρ<sub>BW</sub>(0) for argon). Given the gas-liquid rigidity symmetry, the entire thermodynamic state functions below T<sub>B</sub> are obtainable from b<sub>2</sub>(T). A BW-line ground-state crystal density ρ<sub>BW</sub>(0) can be defined by the pair potential minimum. The Ar<sub>2</sub> pair potential, ∅ij</sub>(r<sub>ij</sub>) determines b<sub>2</sub>(T) analytically for all T. This report, therefore, advances the salient objective of liquid-state theory: an argon p(ρ,T) Equation-of-state is obtained from ∅<sub>ij</sub>(r<sub>ij</sub>) for all fluid states, without any adjustable parameters.展开更多
储能电池具有能够平滑可再生能源输出,提高电力系统灵活性和应对电力需求峰谷等优势,有助于推动可再生能源发展,从而应对环境污染和能源紧缺的双重压力。目前市场主流的储能电池为锂离子电池,具有高比能特性,同时新型储能电池也在蓬勃发...储能电池具有能够平滑可再生能源输出,提高电力系统灵活性和应对电力需求峰谷等优势,有助于推动可再生能源发展,从而应对环境污染和能源紧缺的双重压力。目前市场主流的储能电池为锂离子电池,具有高比能特性,同时新型储能电池也在蓬勃发展,其中全钒液流电池具有高安全性的优势,液态金属电池具有超长循环寿命,在电力储能领域具有重要应用前景。储能电池的建模和状态估计对提高储能电池系统性能,确保其安全性以及优化维护效率至关重要,因此文中对锂离子电池、全钒液流电池和液态金属电池的建模和状态估计进行综述。首先,介绍了储能电池状态估计的整体框架,对基于实验的方法、基于模型的方法和基于数据驱动的方法进行整体介绍,并对荷电状态(state of charge,SOC)、健康状态(state of health,SOH)和剩余使用寿命(remaining useful life,RUL)进行概括;然后,从原理出发,分别总结了不同储能电池体系的内部工作过程、模型构建、状态估计与电池管理过程;最后,对不同储能电池体系的主要工作特性进行横向对比和总结,旨在为储能电池选择和发展提供启示。展开更多
基金Project(51074112)supported by the National Natural Science Foundation of China
文摘Interfacial reaction, tensile strength and creep resistance of Sn-58Bi-x Zn(x=0, 0.7, mass fraction, %) solder samples during liquid-state aging were investigated. The coarsening of Bi and the growth of Cu-Sn intermetallic compounds(IMCs) in Sn-58Bi-0.7Zn solder sample were both effectively suppressed. With the addition of 0.7% Zn, ultimate tensile strengths(UTSs) of the Sn-58 Bi solder slabs were respectively increased by 6.05% and 5.50% after reflow soldering and liquid-state aging, and those of the Cu/Sn-58Bi/Cu solder joints were also increased by 21.51% and 29.27%, respectively. The increase in strengthening effect of Cu/Sn-58Bi-x Zn/Cu solder joints could be attributed to the fracture surface which was changed from the Cu/IMC interface to the IMC/solder interface due to the finer Bi grain. Nanoindentation results revealed that the creep behavior of Sn-58Bi-0.7Zn solder was significantly improved compared with that of the eutectic Sn-58 Bi solder after reflow soldering and liquid-state aging.
基金supported financially by the National Natural Science Foundation of China (Nos. 51465039, 51665038 and 51765040)the Natural Science Foundation of Jiangxi Province (No. 20161BAB206122)the Nature Science Basic Research Plan in Shaanxi Province of China (No. 2016JM5085)
文摘In order to study the in?uence of the physical state of solder on the interfacial reaction of dip-soldered Sn-3.0 Ag-0.5 Cu/Cu system, two kinds of experiments were designed, including:(1) solid-state aging between the solder and Cu substrate;(2)liquid-state aging between the metastable supercooled liquid-state solder and Cu substrate. The aging times were 30, 60,120 and 180 min, respectively, and the aging temperature was 8 ℃ lower than the melting point of the Sn-3.0 Ag-0.5 Cu(SAC305) alloy(217 ℃). The experimental data revealed that the physical state of the solder obviously affected the formation of the intermetallic compound(IMC), and resulted in the difference in the diffusion of atoms on the interface between the SAC305 solder and Cu substrate. The IMC interface after aging for 30 min presents unique characteristics compared with that of the sample after dip soldering. The IMC interface of solid-state aged SAC305/Cu couple is relatively planar, while the IMC interface under metastable supercooled liquid-state aging conditions presents scallop-like shape.
文摘We report progress towards a modern scientific description of thermodynamic properties of fluids following the discovery (in 2012) of a coexisting critical density hiatus and a supercritical mesophase defined by percolation transitions. The state functions density ρ(p,T), and Gibbs energy G(p,T), of fluids, e.g. CO<sub>2</sub>, H<sub>2</sub>O and argon exhibit a symmetry characterised by the rigidity, ω = (dp/dρ)<sub>T</sub>, between gaseous and liquid states along any isotherm from critical (T<sub>c</sub>) to Boyle (T<sub>B</sub>) temperatures, on either side of the supercritical mesophase. Here, using experimental data for fluid argon, we investigate the low-density cluster physics description of an ideal dilute gas that obeys Dalton’s partial pressure law. Cluster expansions in powers of density relate to a supercritical liquid-phase rigidity symmetry (RS) line (ω = ρ<sub>rs</sub>(T) = RT) to gas phase virial coefficients. We show that it is continuous in all derivatives, linear within stable fluid phase, and relates analytically to the Boyle-work line (BW) (w = (p/ρ)<sub>T</sub> = RT), and to percolation lines of gas (PB) and liquid (PA) phases by: ρ<sub>BW</sub>(T) = 2ρ<sub>PA</sub>(T) = 3ρ<sub>PB</sub>(T) = 3ρ<sub>RS</sub>(T)/2 for T T<sub>B</sub>. These simple relationships arise, because the higher virial coefficients (b<sub>n</sub>, n ≥ 4) cancel due to clustering equilibria, or become negligible at all temperatures (0 T T<sub>B</sub>)<sub> </sub>within the gas phase. The Boyle-work line (p/ρ<sub>BW</sub>)<sub>T</sub> is related exactly at lower densities as T → T<sub>B</sub>, and accurately for liquid densities, by ρ<sub>BW</sub>(T) = −(b<sub>2</sub>/b<sub>3</sub>)<sub>T</sub>. The RS line, ω(T) = RT, defines a new liquid-density ground-state physical constant (ρ<sub>RS</sub>(0) = (2/3)ρ<sub>BW</sub>(0) for argon). Given the gas-liquid rigidity symmetry, the entire thermodynamic state functions below T<sub>B</sub> are obtainable from b<sub>2</sub>(T). A BW-line ground-state crystal density ρ<sub>BW</sub>(0) can be defined by the pair potential minimum. The Ar<sub>2</sub> pair potential, ∅ij</sub>(r<sub>ij</sub>) determines b<sub>2</sub>(T) analytically for all T. This report, therefore, advances the salient objective of liquid-state theory: an argon p(ρ,T) Equation-of-state is obtained from ∅<sub>ij</sub>(r<sub>ij</sub>) for all fluid states, without any adjustable parameters.
文摘储能电池具有能够平滑可再生能源输出,提高电力系统灵活性和应对电力需求峰谷等优势,有助于推动可再生能源发展,从而应对环境污染和能源紧缺的双重压力。目前市场主流的储能电池为锂离子电池,具有高比能特性,同时新型储能电池也在蓬勃发展,其中全钒液流电池具有高安全性的优势,液态金属电池具有超长循环寿命,在电力储能领域具有重要应用前景。储能电池的建模和状态估计对提高储能电池系统性能,确保其安全性以及优化维护效率至关重要,因此文中对锂离子电池、全钒液流电池和液态金属电池的建模和状态估计进行综述。首先,介绍了储能电池状态估计的整体框架,对基于实验的方法、基于模型的方法和基于数据驱动的方法进行整体介绍,并对荷电状态(state of charge,SOC)、健康状态(state of health,SOH)和剩余使用寿命(remaining useful life,RUL)进行概括;然后,从原理出发,分别总结了不同储能电池体系的内部工作过程、模型构建、状态估计与电池管理过程;最后,对不同储能电池体系的主要工作特性进行横向对比和总结,旨在为储能电池选择和发展提供启示。
