Thermal cycling resistance of ZrB2‒SiC coatings with MgO additive on SiC coated graphite

Abstract

To improve the thermal cycling resistance of ZrB2–SiC/SiC dual layer coating, MgO was added into the pack powders used to prepare ZrB2–SiC outer coating by pack cementation. The composition, microstructure and thermal cycling resistance of these coatings were studied. The results show that as-received coatings were mainly composed of SiC, ZrB2 and Si. ZrB2–SiC outer coating contained 5wt%, 7wt%, 9wt% MgO additive showed better thermal cycling resistance with 97.6%, 98.8% and 96.5% weight retention after 15 thermal shock cycles between 1500°C and room temperature.