Effects of initial contact angle on pore shape in solid

The pore shape affected by initial contact angle of a bubble entrapped by a solidification front is predicted. Initial contact angle affects bubble nucleation, surface area and solute transport across the bubble cap, solid gas pressure in the pore and shape of pores in solid. Porosity influences microstructure and functional properties of materials, etc. This work accounts for solute transport across the coupled shape of cap in balance of pressures and physico-chemical equilibrium. Similar to previous work, it shows that pore shape depends on directions and magnitudes of solute across the cap. In contrast to Case 2, solute transport in Case 1 is from the pore into surrounding liquid in the early stage. The results find that a decrease in initial contact angle expedites bubble entrapment in Case 1. Solute gas pressure in the pore further exhibits three stages for initial contact angle greater than 90°. Significant drops occur in the early and late stages. In the middle stage, where contact angle is near 90°, solute concentration at the cap is about initial solute concentration in liquid, and responsible for length of the pore. Except for initial contact angle less than 90°, an isolated pore cannot be formed in Case 2. The predicted pore shape agrees with experimental data.