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A W-Mo-Si/SiC double-layer oxidation protective coating for carbon/carbon (C/C) composites was prepared by a two-step pack cementation technique.XRD (X-ray diffraction) and SEM (scanning electron microscopy) results show that the coating obtained by the first step pack cementation was a thin inner buffer layer of SiC with some cracks and pores,and a new phase of (W_xMo_(1-x))Si_2 appeared after the second step pack cementation.Oxidation test shows that,after oxidation in air at 1773 K for 175 h and thermal cycling between 1773 K and room temperature for 18 times,the weight loss of the W-Mo-Si/SiC coated C/C composites was only 2.06%.The oxidation protective failure of the W-Mo-Si/SiC coating was attributed to the formation of some penetrable cracks in the coating.
A W-Mo-Si / SiC double-layer oxidation protective coating for carbon / carbon (C / C) composites was prepared by a two-step pack cementation technique. XRD (X-ray diffraction) and SEM (scanning electron microscopy) results show that the coating obtained by the first step pack cementation was a thin inner buffer layer of SiC with some cracks and pores, and a new phase of (W_xMo_ (1-x)) Si_2 after the second step pack cementation. Oxidation test shows that after after oxidation in air at 1773 K for 175 h and thermal cycling between 1773 K and room temperature for 18 times, the weight loss of the W-Mo-Si / SiC coated C / C composites was only 2.06%. failure of the W-Mo-Si / SiC coating was attributed to the formation of some penetrable cracks in the coating.