In the context of carbon geo-sequestration projects, brine-CO(2) interfacial tension γ and brine-CO(2)-rock surface water contact angles θ directly impact structural and residual trapping capacities. While γ is fairly well understood there is still large uncertainty associated with θ. We present here an investigation of γ and θ using a molecular approach based on molecular dynamics computer simulations. We consider a system consisting of CO(2)/water/NaCl and an α-quartz surface, covering a brine salinity range between 0 and 4 molal. The simulation models accurately reproduce the dependence of γ on pressure below the CO(2) saturation pressure at 300 K, and over predict γ by ~20% at higher pressures. In addition, in agreement with experimental observations, the simulations predict that γ increases slightly with temperature or salinity. We also demonstrate that for non-hydroxylated quartz surfaces, θ strongly increases with pressure at subcritical and supercritical conditions. An increase in temperature significantly reduces the contact angle, especially at low-intermediate pressures (1-10 MPa), this effect is mitigated at higher pressures, 20 MPa. We also found that θ only weakly depends on salinity for the systems investigated in this work.

Creep deformation characteristics of pure tin, and Sn-3.5Ag and Sn-5Sb electronic solder alloys, have been studied at various temperatures between ambient and 473 K (homologous temperature 0.58 to 0.85). Power-law relationships between strain rate and stress were observed at most of the temperatures. The stress exponent (n ϭ 7.6, 5.0, and 5.0) and activation energy (Q c ϭ 60.3, 60.7, and 44.7 kJ/mol) values were obtained in the case of tin, Sn-3.5Ag, and Sn-5Sb respectively. Based on n and Q c values, it is suggested that the rate controlling creep-deformation mechanism is dislocation climb controlled by lattice diffusion in pure tin and Sn-3.5Ag alloy, and viscous glide controlled by pipe diffusion in Sn-5Sb alloy. The results on Sn-3.5Ag bulk material are compared with the initial results on solder bump arrays.

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