Formation of Pores during Unidirectional Solidification of Water Containing Carbon Dioxide.

Water-carbon dioxide solutions of various concentrations of carbon dioxide are unidirectionally solidified upwards in a glass cell at various growth rates, and the formation of the pores of carbon dioxide is in-situ observed. Columnar pores are formed at low growth rates. The length of the columnar pores becomes shorter as the growth rate increases or as the carbon dioxide concentration increases. The distribution of the pores is not uniform but periodic along the solidification direction, except under the conditions of high growth rate and high concentration. The change in the length of the columnar pores and the periodic formation of the pores are explained in terms of the rate of supply of carbon dioxide to the growing pores from the surrounding liquid.