2018 年 69 巻 12 号 p. 641-642
When Kalcolor membranes were calcined at 300 ℃, the color changed from black-brown to brown. At temperatures higher than 750 ℃, the color became white. To ascertain the cause of the color change, the membranes were analyzed using EDX. Decreasing concentrations of carbon and sulfur in the membranes were observed during calcination. Carbon was not detected when calcined at temperatures higher than 750 ℃. Therefore, the cause of the membrane coloring is inferred as carbon.