Polymer‐Derived SiOC–barium–strontium aluminosilicate Coatings as an Environmental Barrier for C/SiC Composites

Abstract

Polysiloxanes polymer coatings were formed on carbon fiber‐reinforced silicon carbide (C/SiC) composites at 100°C in air with barium–strontium aluminosilicate (BSAS) as fillers. After the polymeric coatings were pyrolyzed at 1350°C under argon, a dense SiOC–BSAS‐coated C/SiC composite was obtained. The oxidation test in dry air and the corrosion test in water vapor were carried out on the coated composites at 1250°C, respectively. The results indicated that the polymer‐derived SiOC–BSAS coatings could protect the C/SiC composites well both in dry air and water vapor. Even after corroded for 200 h in water vapor, the coated C/SiC composites showed little weight loss and high residual flexural strength.

Failure Mechanism Associated with the Thermally Grown Silica Scale in Environmental Barrier Coated C/SiC Composites

“…(b)]. It is believed that the formation of these pores is due to the pyrolysis of the polysilazane during the fabrication process . Figure (c) shows the XRD patterns of the BSAS coating.…”

“…7,8 In the past decades, several EBCs systems have been developed, including yttria-stabilized zirconium, 7,9 barium strontium aluminosilicate (BSAS), 7,10-14 and rare-earth silicates. [15][16][17][18][19] Previously, most research has focused on the EBCs themselves only: studying their water vapor resistance, [9][10][11][12][15][16][17] fabrication process, 14,18,19 and hot corrosion behavior. 13,20,21 Very few works considered the failure behaviors of the entire system contained both the substrate and the EBCs.…”

Polymer-derived yttrium silicate coatings on 2D C/SiC composites

“…The thickness of the SiO 2 scale is about 500 nm, which is much thinner than that of our previous study. 22 It is indicated that the yttrium silicate coatings are pretty dense. For the composites without yttrium silicate coatings, the carbon fibers are almost burnt out, leaving a lot of holes inside (Fig.…”

“…19 Compared with other technologies, polymer-derived ceramic coating process is a potential method due to its relative low cost, ability to coat complex structures, and low process temperatures. [20][21][22] With adding the active or inert fillers in the polymer precursors, the shrinkage during pyrolysis and resultant cracks of the coatings can be avoided. 23 In our previous study, 24 dense SiOC-BSAS was coated on C/SiC composites using polysiloxanes as polymer precursors and BSAS as inert fillers.…”

Fabrication and oxidation resistance of mullite/yttrium silicate multilayer coatings on C/SiC composites

“…Recently, a new route to synthesize yttrium silicate from the pyrolysis of Y 2 O 3 powder filled silicone resin has been reported [14,15]. This route is a promising method because of good adhesive and covering ability of silicone resin, low process temperature, and relatively low cost [16,17]. Dense Y 2 Si 2 O 7 coating was fabricated on SiC foam by pyrolysis in air of silicone resin containing Y 2 O 3 powders [14], but the oxidation protection for C/SiC composites was not investigated.…”