Direct observation of pore growth in unidirectionally solidified water-carbon dioxide solution

Water-carbon dioxide solutions with different concentrations of carbon dioxide are unidirectionally solidified upwards in a glass cell at varying growth rates, and the formation of the gas pores is directly observed. Long columnar pores of carbon dioxide are formed in low concentration solutions at low growth rates. The length of the columnar pores becomes short 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 appearance of the periodic formation of the pores are explained in terms of the supply of carbon dioxide to the growing pores.