Polymer-derived yttrium silicate coatings on 2D C/SiC composites

Yttrium silicate environmental barrier coatings (EBCs) on C/SiC composites were fabricated by using polysiloxanes-derived ceramic process. In order to reduce the free silica in the resultant ceramic coatings, Y2O3 was added as an active filler. The materials with different weight ratios of polysiloxanes to Y2O3 were synthesized. Their coefficient of thermal expansion (CTE) and water-vapor resistance were tested. The results indicated that the composition of 50% Y2O3-50% polysiloxanes (Y50) was suitable to be the EBCs for C/SiC composites. The C/SiC composites coated with Y50 were tested in the water-vapor environments at 1400 degrees C for 200 h. The results revealed that such a coating could effectively protect the C/SiC composites. (C) 2012 Elsevier Ltd. All rights reserved.