Effect of SiC whiskers on the anti‐oxidation properties of Yb2Si2O7/mullite/SiC tri‐layer environmental barrier coating for CMCs. Issue 3 (20th January 2023)

• Record Type: Journal Article
• Authors: Pan, Ling; Chen, Pengju; Xiao, Peng; He, Ling; Zhou, Wei; Li, Yang
• Is Part Of: International journal of applied ceramic technology. Volume 20:Issue 3(2023)
• Page Start: 1740
• Page End: 1752
• Publication Date: 2023-01-20
• Subjects: anti‐oxidation -- β‐Yb2Si2O7 -- coating -- mullite -- SiC whisker; Ceramics -- Periodicals; Ceramics -- Technological innovations -- Periodicals; 620.1405
• DOI: 10.1111/ijac.14325
• Languages: English
• ISSNs: 1546-542X

Abstract

Abstract: The mullite and ytterbium disilicate (β‐Yb2 Si2 O7 ) powders as starting materials for the Yb2 Si2 O7 /mullite/SiC tri‐layer coating are synthesized by a sol–gel method. The effect of SiC whiskers on the anti‐oxidation properties of Yb2 Si2 O7 /mullite/SiC tri‐layer coating for C/SiC composites in the air environment is deeply studied. Results show that the formation temperature and complete transition temperature of mullite were 800–1000 and 1300°C, respectively. Yb2 SiO5, α‐Yb2 Si2 O7, and β‐Yb2 Si2 O7 were gradually formed between 800 and 1000°C, and Yb2 SiO5 and α‐Yb2 Si2 O7 were completely transformed into β‐Yb2 Si2 O7 at a temperature above 1200°C. The weight loss of Yb2 Si2 O7 /(SiCw –mullite)/SiC tri‐layer coating coated specimens was 0.15 × 10 −3 g cm −2 after 200 h oxidation at 1400°C, which is lower than that of Yb2 Si2 O7 /mullite/SiC tri‐layer coating (2.84 × 10 −3 g cm −2 ). The SiC whiskers in mullite middle coating can not only alleviate the coefficient of thermal expansion difference between mullite middle coating and β‐Yb2 Si2 O7 outer coating, but also improve the self‐healing performance of the mullite middle coating owing to the self‐healing aluminosilicate glass phase formed by the reaction between SiO2 (oxidation of SiC whiskers) and mullite particles.