Fabrication and thermal shock resistance of multilayer gamma-Y2Si2O7 environmental barrier coating on porous Si3N4 ceramic

摘要

A dense multilayer gamma-Y2Si2O7 environmental barrier coating was in-situ fabricated by the liquid infiltration and filling method on porous Si3N4 ceramic for water resistance. When the sintering temperature was 1350 degrees C, as-prepared coating consisted of the top glass layer, the gamma-Y2Si2O7 interlayer and the bottom bond layer. With increasing sintering temperature from 1350 to 1450 degrees C, the microstructure of the coating transformed from three layers into two layers including the gamma-Y2Si2O7 layer and the bond layer. The gamma-Y2Si2O7 layer in the coating consisted of gamma-Y2Si2O7 and Y-Si-Al-O glass, and the gamma-Y2Si2O7 content increased with the increase of sintering temperature. Thermal shock resistance of the coatings was tested. The results showed that the coating prepared at 1450 degrees C displayed the better thermal shock resistance. After thermal shock for 15 times from 1000 degrees C to room temperature, the microstructure of the coating showed little change, and water absorption increased slightly from 4.8% to 5.3%. (C) 2015 Elsevier Ltd. All rights reserved.