Publication Date:
2019
Description:
Abstract
Mullite coating, SiC whiskers toughened mullite coating (SiCw‐mullite), and cristobalite aluminum phosphate (c‐AlPO4) particle modified SiCw‐mullite coating (c‐AlPO4‐SiCw‐mullite) were prepared on SiC coated C/SiC composites by a novel sol–gel method combined with air spraying. Results show that molten SiO2 formed by the oxidation of SiC whiskers and molten c‐AlPO4 improved the bonding strength between mullite outer coating and SiC–C/SiC composites due to their high‐temperature bonding properties. The bonding strength between mullite, SiCw‐mullite, c‐AlPO4‐SiCw‐mullite outer coatings and SiC–C/SiC composites were 2.41, 4.31, and 7.38 MPa, respectively. After 48 thermal cycles between 1773 K and room temperature, the weight loss of mullite/SiC coating coated substrate was up to 11.61%, while the weight losses of SiCw‐mullite/SiC and c‐AlPO4‐SiCw‐mullite/SiC coatings coated substrate were reduced to 7.40 and 5.12%, respectively. Appropriate SiC whiskers as addition can considerably improve the thermal shock resistance of mullite coating owing to their excellent mechanical properties at high‐temperature. In addition, c‐AlPO4 particles can further improve the thermal shock resistance of SiCw‐mullite coating due to their high‐temperature bonding and sealing properties. No obvious micro‐pores and cracks were observed on the surface of c‐AlPO4‐SiCw‐mullite coating after 48 thermal due to timely healing effect by formation of secondary mullite.
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Print ISSN:
0002-7820
Electronic ISSN:
1551-2916
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
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