Thermodynamic modeling and phase diagram prediction of salt lake brine systems.Ⅰ. Aqueous Mg^2+–Ca^2+–Cl^- binary and ternary systems

Salt lake brine is a complex salt-water system under natural environment.Although many models can express the thermodynamic properties and phase equilibrium of electrolyte aqueous solution,the multi-temperature characteristics and predictability are still the goals of model development.In this study,a comprehensive thermodynamic model system is re-established based on the eNRTL model and some improvements:(1) new expression of long-range electrostatic term with symmetrical reference state is proposed to handle the electrolyte solution covering entire concentration range;(2) the temperature dependence of the binary interaction parameters is formulated with a Gibbs Helmholtz expression containing three temperature coefficients,the liquid parameters,which associated with Gibbs energy,enthalpy,and heat capacity contribution;and(3) liquid parameters and solid species data are regressed from properties and solubility data at full temperature range.Together the activity coefficient model,property models and parameters of liquid and solid offer a comprehensive thermodynamic model system for the typical bittern of MgCl2-CaCl2-H2 O binary and ternary systems,and it shows excellent agreement with the literature data for the ternary and binary systems.The successful prediction of complete phase diagram of ternary system shows that the model has the ability to deal with high concentration and high non-idealitv system,and the ability to extrapolate the temperature.

Reputation repair and corporate donations:An investigation of responses to regulatory penalties

According to the risk management and reputation insurance theory of corporate social responsibility, corporate donations can help a company to repair its reputation after a crisis.This study uses a propensity score matching–difference in difference(PSM + DID) methodology to investigate the charitable donation activities of companies that have been subject to regulatory penalties.The analysis of a sample of A-share listed companies in the 2004–2016 period shows that companies significantly increase their charitable donations after regulatory penalties, but this effect weakens over time.Further analysis reveals that non-state-owned companies, companies with higher ownership concentrations, and companies receiving severer penalties are more motivated to make donations after regulatory penalties.By studying the reputation repair behavior of companies that have been subject to regulatory penalties, this study offers further support for the risk management and reputation insurance theory of corporate social responsibility.It also enriches our understanding of companies’ active responses to regulatory penalties and provides insights into companies’ motives for making charitable donations.

Wetting Behaviors and Interfacial Reaction between Sn-10Sb-5Cu High Temperature Lead-free Solder and Cu Substrate

Sn-10Sb-5Cu lead-free solder was fabricated for high temperature application in electronic package. Wetting behaviors and interfacial reaction between such a high temperature lead-free solder and Cu substrate were investigated and compared with those of 95Pb-Sn solder. The results showed that the wetting properties of Sn-10Sb-SCu solder are superior to those of 95Pb-Sn solder in maximum wetting force, wetting time and wetting angle in the temperature range of 340-400℃. However, the surface of the Sn-10Sb-5Cu solder sample after wetting balance tests was rougher than that of 95Pb-Sn solder at the temperature lower than 360℃. In static liquid-state interracial reaction, the types and thickness of the intermetallic compounds （IMCs） of both solders were different from each other. The wetting kinetics in the Sn-10Sb-5Cu/Cu system was more rapid than that in 95Pb-Sn/Cu system, and the higher formation rate of IMCs in the former system was considered as the reason.

Shear strength of LED solder joints using SAC-nano Cu solder pastes

The addition of Cu nanoparticles into the solder pastes by mechanical mixing method creates a positive effect on the microstructure refinement of the LED solder joints. The grain size of β-Sn and Cu6Sn5 decrease obviously due to the increasing concentration of the nanoparticles in the solder pastes. However, the addition of nanoparticles facilitates the formation of voids in the solder joints, especially when the concentration of nanopar- ticles is higher than 0.5 wt% in the solder pastes. Both the microstructure refinement and void percentage affect the shear strength of the solder joints. Since the increase of the void percentage is limited when the concentration of nanoparticles increases from 0 to 0.5 wt%, the microstructure refinement shows a dominant effect on the shear performance and thus improves the shear strength of the solder joints from 49.8 to 55 MPa. Further addition of nanoparticles in the solder pastes leads to a sharp increase of the void percentage. Consequently, the shear strength of the solder joints decreases from 55 to 48.8 MPa when the concentration of doped particles increases from 0.5 to 1 wt% in the solder pastes.