Effects of heating and aluminum content on the dissolution of magnesium-rich amorphous silicate fibers in a simple amino acid solution

This study suggests that heat treatment around 700 °C increases the dissolution rate of Mg-rich and Al-free amorphous alkaline earth silicate (AES) fibers, which are designed to be biosoluble, in a simple amino acid solution. The dissolution experiments of Mg-rich AES fibers in the Al-free and Al-bearing systems heat-treated in the temperature range from 110 to 1260 °C were carried out in a glycine, a simple amino acid, solution. These experiments show that the dissolution rate of the Al-free AES fibers in the glycine solution is rising sharply with increasing heat treatment temperature and reaches its maximum around 700°C. The sharp rise in the dissolution rate is assumed to be due to the formation of chemically less durable phases caused by phase separation resulting from the heat treatment. These chemically less durable phases may be preferentially attacked by glycine ions. In contrast, the heat treatment around 700 °C brought no increase in the dissolution rate for the Al-bearing AES fibers. This is due to the fact that small amounts of Al 2 O 3 can change the internal glass structure and lead to retardation of the dissolution process.