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To improve the thermal cycling resistance of ZrB 2 –SiC/SiC dual layer coating, MgO was added into the pack powders used to prepare ZrB 2 –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, ZrB 2 and Si. ZrB 2 –SiC outer coating contained 5 wt%, 7 wt%, 9 wt% 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.

In order to further improve the oxidation protective ability of (ZrB 2 –SiC)/SiC coated graphite, ferrocene was introduced into the outer ZrB 2 –SiC coatings during pack cementation process. The ferrocene addition increased the porosity of the outer ZrB 2 –SiC coatings, which was favorable to thermal shock resistance of (ZrB 2 –SiC)/SiC coated specimens. The ZrB 2 –SiC coating with 3 wt% ferrocene (ZS50-3f) has optimum oxidation protective ability. Its weight retention after 15 thermal shock cycles between 1500 °C and room temperature was 96. 2%. The weight loss of ZS50-3f was only 0.2% after 19 h oxidation at 1500 °C.