Oxidation/corrosion of BN-based coatings as prospective interphases for SiC/SiC composites

Abstract

The ceramic matrix composites envisaged as structural parts in the hot section of aircraft engines consist of SiC-based fibres and matrices with a BN interphase coating between them. To control their service life, the oxidation/corrosion behaviour of these materials must be determined. For this purpose, samples of different geometries were prepared by chemical vapour deposition and thermally subjected to wet air. The behaviour of BN alone depends on its crystallization degree, structural homogeneity and the considered direction in the coating. In the case of a thin layer of pure BN of interphase type, recession is significantly reduced at 800°C by the formation of a sealing borosilicate phase in the confined space surrounded by SiC. At 1000°C, the protection is no longer sufficient and a steady recession remains. The presence of aluminium added to BN improves protection at 1000°C due to the formation of alumina combined with borosilicate.

Synthesis of coatings on SiC fibers and their effects on microstructure and mechanical properties of SiCf/SiBCN composites

“…No references were found on modeling for CMCs, though experimental studies o ing process have been reported. Studies o derived SiC ceramic 25 and SiC/SiC c shown that porosity decreases and mecha prove with the increasing number of PIP show that increasing pyrolysis temperatu tration of SiC fillers in polycarbosilane improved mechanical properties in two-d SiC (C/SiC) composites fabricated using Starting with pyrolysis of a "cured prepreg-based composite, each processin process involves infiltration of a precera porous ceramic preform followed by a py which the polymer is converted into ceram cess modeling is focused on these two ste Modeling of infiltration of liquids in well-studied subject, especially in the where it is used to model seepage of wa soils and rocks. 29,30 The physics of resin under pressure is similar to the seepage pr lar approaches have been used also to mod into a mold containing fiber mats.…”

“…21 BN coatings are another choice for SiC f because the liquid B 2 O 3 resulting from BN oxidation can heal pores and cracks at high temperatures, making it wider potential applications than those of PyC at oxygen-sensitive environments. [23][24][25] The toughening effects of BN coatings depend on their crystallization degree and structural homogeneity when coated with SiC f . 25 The single-/double-layer BN-coated SiC f by chemical vapor infiltration method has confirmed to effectively increase the strength of the SiC/ SiC composites.…”

“…[23][24][25] The toughening effects of BN coatings depend on their crystallization degree and structural homogeneity when coated with SiC f . 25 The single-/double-layer BN-coated SiC f by chemical vapor infiltration method has confirmed to effectively increase the strength of the SiC/ SiC composites. 23 ZrB 2 is one of the refractory transition metal borides within the family of ultrahigh-temperature ceramics.…”

“…No references were found on modeling of the PIP process for CMCs, though experimental studies on this manufacturing process have been reported. Studies on polycarbosilanederived SiC ceramic 25 and SiC/SiC composite 26,27 have shown that porosity decreases and mechanical properties improve with the increasing number of PIP cycles. Zhu et al 28 show that increasing pyrolysis temperature and the concentration of SiC fillers in polycarbosilane polymer result in improved mechanical properties in two-dimensional Carbon/ SiC (C/SiC) composites fabricated using the PIP process.…”

Microstructural Regulation, Oxidation Resistance and Mechanical Properties of Cf/SiC/SiHfBOC Composites Prepared By Chemical Vapor Infiltration With Precursor Infiltration Pyrolysis

“…The coating will reduce the area of carbon fiber exposed to oxygen atmosphere, thus improving the oxidation resistance of the composites Therefore, Chemical vapor deposition (CVD), chemical vapor infiltration (CVI), and hydrothermal methods can be used to prepare coatings on carbon fiber surface [1,17,20]. The types of coatings can include C coating [21], BN coating [22], SiC coating [23], etc. These coatings can not only change the surface roughness of carbon fiber but also improve the interface bonding performance between ceramic matrix and carbon fiber reinforcement.…”