 SiOH2 + H2O = SiO(OH)2

SiOH2 + 2H2O = Si(OH)4

2SiOH2 + 3H2O = Si2O(OH)6

The thermodynamic data for these reactions has been experimentally determined over many years to determine that Si(OH)4 is generally the dominant vapor species.Even more advanced environmental barrier coatings are required to protect these CMCs from water vapor as well as other environmental degradants.For instance, as the gas temperatures increase towards 1400 K-1500 K, sand particles begin to melt and react with coatings.