Microstructure and isothermal oxidation of 3Al₂O₃·2SiO₂/SiC coating on high and low density carbon-carbon composites

Abstract

Carbon-carbon composite (C/C) materials are prone to severe oxidation and volatilization problems. To address these issues, mullite (3Al₂O₃·2SiO₂)/silicon carbide (SiC) coatings were deposited on C/C composite substrates characterized into high and low densities. The coatings were applied by a two-step approach: pack cementation and silica sol based slurry coating processes. The relationship between the microstructure of 3Al₂O₃·2SiO₂/SiC coatings and C/C substrates during isothermal oxidation cycle at 1 500 °C was investigated using X-ray diffractometer (XRD) and scanning electron microscope (SEM) mounted with energy dispersive spectrometer (EDS). The results indicate that the density of the substrates has a marked effect on the coatings. Dense, thick and well-bonded coatings are obtained in the high density substrate. After 106 h of isothermal oxidation, the high density substrate with 3Al₂O₃·2SiO₂/SiC coating offers effective protection as compared to low density substrate suffering recession.

Keywords

mullite / carbon-carbon composite / slurry coating / isothermal oxidation

References

[1] WhiteJ. D. E., AllenS. H., ShteinbergA. S., MaA. S.. Combustion joining of refractory materials: Carbon-Carbon composites [J]. J Mater Res, 2008, 23(1): 160-169

[2] PaccaudO., DerrA.. Silicon carbide coating for carbon materials produced by a pack-cementation process [J]. Le Journal de Physique IV, 1995, 5(C5): 135-142

[3] Barry BinesE.ThomasC. R.. The protection of carbon-carbon against oxidation at elevated temperatures. [M]. Essentials of Carbon-Carbon Composites, 1993LondonThe Royal Society of Chemistry204-227

[4] SchneiderH., KomarneniS.SchneiderH., KomarneniS.. Mullite coatings. Mullite, 2005WeinheimWilley-VCH Verlag GmbH, Co. KGaA349-376

[5] LeeK.. Current status of environmental barrier coatings for Si-based ceramics [J]. Surface and Coatings Technology, 2000, 133: 1-7

[6] KrishnamurthyR., SheldonB. W.. Stability of mullite protective coatings for silicon-based ceramics [J]. J Am Ceram Soc, 2005, 88(5): 1099-1107

[7] SarkisovP. D., PopovichN. V., OrlovaL. A., Anan’evaY. E.. Barrier coatings for type C/SiC ceramic-matrix composites (Review) [J]. Glass and Ceramics, 2008, 65: 9-10

[8] HouP., BasuS., SarinV.. Structure and high-temperature stability of compositionally graded CVD mullite coatings [J]. International Journal of Refractory Metals and Hard Materials, 2001, 19(4/5/6): 467-477

[9] LeeK. N., FoxD. S., BansalN. P.. Rare earth silicate environmental barrier coatings for SiC/SiC composites and Si₃N₄ ceramics [J]. Journal of the European Ceramic Society, 2005, 25(10): 1705-1715

[10] LatzelS., VabenR., StoverD.. New environmental barrier coating system on carbon-fiber reinforced silicon carbide composites [J]. Journal of Thermal Spray Technology, 2005, 14(2): 268-272

[11] CairoC. A. A., GracaM. L. A., SilvaC. R. M., BressianiJ. C.. Unctionally gradient ceramic coatings for carbon-carbon anti oxidation protection [J]. Journal of European Ceramic Society, 2001, 21: 325-329

[12] ZhaoJ., WangG., GuoQ.-g., LiuLang.. Microstructure and property of SiC coating for carbon materials [J]. Fusion Engineering and Design, 2007, 82: 363-368

[13] HuangJ.-f., LiH.-j., ZengX.-rong.. Review of the recent research improvement of the oxidation protective coating for C/C composites [J]. Journal of Shanxi University of Science & Technology, 2004, 22: 60-67

[14] LEE K N, ROBERT A. Development and environmental durability of mullite and mullite/YSZ dual layer coatings for SiC and Si₃N₄ ceramics [J]. Surface and Coating Technology, 1996(Part 1): 86–87.

[15] FritzeH., JojicJ., WitkeT., RuscherC., WeberS., ScherrerS., WeibR., ChultrichB., BorchardtG.. Mullite base oxidation protection for SiC-C/C composites in air at temperatures up to 1900K [J]. Journal of European Ceramic Society, 1998, 18: 2351-2364