Fabrication and Properties of Three-dimensional Braided Carbon Fiber Reinforced SiO_a-rich Mullite Composites

Abstract

In order to enhance the fracture toughness of mullite, three-dimensional braided carbon fiber reinforced mullite (C/mullite) composites were prepared using the Al₂O₃-SiO₂ sol with a high solid content as raw material. Mullitization behavior of the sol was characterized. Then, the microstructure, mechanical properties and oxidation resistance of C/mullite composites were investigated. It is found that the SiO₂-rich mullite with desirable sintering shrinkage can be synthesized at 1 300 °C from the sol with an Al₂0₃/SiO₂ mass ratio of 1:1. The C/mullite composites with a total porosity of 21.5% were fabricated by repeating 18 cycles of vacuum impregnation-drying-heat treatment, showing a flexural strength of 234.5 MPa and a fracture toughness of 13.1 MPa·m^1/2. Since carbon fibers were protected by compact matrix, the C/mullite composites show favorable oxidation resistance during 1 200 °C-1 600 °C even if an open porosity of 10.3% was detected.

Keywords

mullite / carbon fiber reinforcement / sol / mechanical properties / oxidation resistance

References

[1] Schneider H, Schreuer J, Hildmann B. Structure and Properties of Mul-lite-A Review [J]. J. Eur. Ceram. Soc, 2008, 28: 329-344.

[2] Zhang JH, Wu HD, Zhang SX, et al. Preparation of Mullite Whiskers and Their Enhancement Effect on Ceramic Matrix Composites[J]. J. Wuhan Univ. Technol.-Mater. Sci. Ed., 2013, 28(3): 471-475.

[3] Ma QS, Cai LH. Preparation and Anti-oxidation Mechanism of Mul- lite/Yttrium Silicate Coatings on C/SiC Composites[J]. J. Wuhan Univ. Technol.-Mater. Sci. Ed., 2016, 31(6): 1284-1288.

[4] Kumar P, Nath M, Ghosh A, et al. Thermo-Mechanical Properties of Mullite-Zirconia Composites Derived from Reaction Sintering of Zircon and Sillimanite Beach Sand: Effect of CaO[J]. Trans. Nonferrous Met. Soc. China, 2016, 26: 2397-2403.

[5] Wu J, Jones FR, James PF. Continuous Fibre Reinforced Mullite Matrix Composites by Sol-Gel Processing Part I Fabrication and Micro-structures[J]. J. Mater. Sci., 1997, 32(13): 3361-3368.

[6] Wu J, Jones FR, James PF. Continuous Fibre Reinforced Mullite Matrix Composites by Sol-Gel Processing Part II Properties and Fracture Behavior[J]. J. Mater. Sci., 1997, 32(14): 3629-3635.

[7] Dong R, Hirata Y, Sueyoshi H, et al. Polymer Impregnation and Py-rolysis (PIP) Method for the Preparation of Laminated Woven Fabric/ Mullite Matrix Composites with Pseudoductility[J]. J. Eur. Ceram. Soc, 2004, 24: 53-64.

[8] Wang Y, Liu HT, Cheng HF, et al. Effective Fugitive Carbon Coatings for the Strength Improvement of 3D Nextel 440/Aluminosilicate Composites[J]. Master: Lett., 2014, 126: 236-239.

[9] Wang Y, Cheng HF, Wang J. Effects of the Single Layer CVD SiC Interphases on Mechanical Properties of Mullite Fiber-Reinforced Mullite Matrix Composites Fabricated via a Sol-Gel Process[J]. Ceram. Int., 2014, 40(3): 4707-4715.

[10] Wang Y, Liu HT, Cheng HF, et al. Effects of Sintering Temperature on Mechanical Properties of 3D Mullite Fiber (ALF FB3) Reinforced Mullite Composites[J]. Ceram. Int., 2013, 39(8): 9229-9235.

[11] Xiang Y, Wang Q, Cao F, et al. Sol-Gel Process and High-temperature Property of SiO₂/Zr0₂-SiO₂ Composites[J]. Ceram. Int., 2017, 43(1): 854-859.

[12] Wang Q, Cao F, Xiang Y, et al. Effects of Zr0₂ Coating on the Strength Improvement of 2.5D SiCf/SiO₂ Composites[J]. Ceram. Int., 2017, 43(1): 884-889.

[13] Fan CY, Ma QS, Zeng KH. Thermal Stability and Oxidation Resistance of C/A1₂0₃ Composites Fabricated from a Sol with High Solid Content[J]. Ceram. Int., 2017, 43(14): 10983-10990.

[14] Beran A, Voll D, Schneider H. Dehydration and Structural Development of Mullite Precursors: an FTIR Spectroscopic Study[J]. J. Eur. Ceram. Soc, 2001, 21: 2479-2485.

[15] Cividanes LS, Campos TMB, Rodrigues LA, et al. Review of Mullite Synthesis Routes by Sol-gel Method[J]. J. Sol-Gel Sci. Technol, 2010, 55: 111-125.