High-temperature melt-infiltration preparation and erosion behavior of γ-Y 2 Si 2 O 7 /Y2O3-SiO2-Al2O3 glass coating on porous Si3N4 ceramics

Dense gamma-Y2Si2O7/Y2O3-SiO2-Al2O3 2 Si 2 O 7 /Y 2 O 3 -SiO 2 -Al 2 O 3 glass coatings were prepared on porous Si3N4 3 N 4 ceramics using high- temperature melt-infiltration preparation method to improve their stability in service environments, specifically including water resistance and erosion wear resistance. Evolution of structure and mechanical properties during coating preparation was studied. Damage mechanism in erosion wear process was illustrated by putting the coated samples into a high-speed water flow with quartz particles. Dense double-layer microstructure could be formed when sintering at 1350-1450 degrees C for 1 h. The proportion of each phase inside the coating material prepared by various sintering temperatures was different, resulting in different elastic modulus and hardness, and ultimately affected the erosion resistance of the coatings. The "plasticity index" ( E/H value) of gamma-Y2Si2O7/ 2 Si 2 O 7 / Y2O3-SiO2-Al2O3 2 O 3 -SiO 2 -Al 2 O 3 glass coating prepared at lower temperature (1350 and 1400 degrees C) was low, and the erosion failure of the coating was brittleness mode, leading to an obvious decrease on waterproof performance after erosion test. While coating prepared at higher temperature (1450 degrees C) showed a better erosion resistance. After erosion for 2 h, water absorption of coating surface was changed by only 1.34 %. Micro-morphology of the coating was almost unchanged before and after erosion, maintaining excellent waterproof performance.