Session: 04-11-03: Advanced Materials Processing and Property Characterization

Paper Number: 150418

150418 - Evaluation of Heat Resistance of Sic/sic Composites Fabricated by Membrane Boiling Method 

Ceramic matrix composites (CMCs) are widely used in aircraft engines, space vehicles, incinerators, and nuclear reactors because of their light weight and high heat and oxidation resistance. CMCs are composed of a fiber, matrix, and interface layer, and the interface layer deflects cracks to enhance toughness. Conventional CMC matrix formation methods include chemical vapor infiltration (CVI), solid-phase impregnation (SIP), and liquid-phase impregnation (PIP), but these methods have low material yield and require long time for matrix formation. However, the film boiling (FB) method is a matrix formation method that improves raw material yield and filling speed by applying a temperature gradient to the raw material processing solution to induce a film boiling phenomenon. In this study, SiC/SiC composites, a type of CMC, were fabricated by a new matrix formation method (film boiling) and then applied with heat- and oxidation-resistant coatings, and their mechanical properties and microstructures were evaluated before and after exposure to an oxidizing high-temperature atmosphere.

First, Type-S SiC fibers were used, and the SiC matrix material liquid was poured into the 3D preform to form the matrix at high speed by film boiling. In order to prevent initial cracking due to volume shrinkage during the film boiling phenomenon, the matrix was densified by applying a cyclic treatment in which the heating temperature was repeatedly raised and lowered. To prevent SiC from being oxidized and damaged from the surface in a high-temperature oxidation atmosphere, a heat-resistant coating was applied to the surface of the material in an oxidation atmosphere at 1000°C to prevent the degradation of mechanical properties. The SiC/SiC composite was further exposed to a high-temperature oxidizing atmosphere. To evaluate the heat resistance and oxidation resistance of the material in terms of mechanical properties, we conducted four-point bending tests on uncoated specimens, specimens coated in a 1000°C oxidation atmosphere, and specimens coated and exposed to a high-temperature oxidation atmosphere. In the four-point bending tests, strains were obtained using strain gauges to compare the fracture behavior of the materials. In addition, to evaluate the heat and oxidation resistance of the material from the viewpoint of microstructure, we took SEM and TEM images of each specimen, and conducted elemental analysis by EDS and observation of diffraction by X-rays. Elemental analysis was used to evaluate the oxidation level of the SiC/SiC composite and the C/Si ratio of the matrix, while X-ray defraction was used to compare the crystallinity of the SiC matrix. The results of these tests show the denseness of the SiC matrix prepared by the film boiling method with temperature rise and fall cycles and the improvement of the oxidation resistance of the SiC/SiC composites by the coating treatment.

Presenting Author: Sho Inoue Waseda University

Presenting Author Biography: Sho Inoue completed his undergraduate studies in Mechanical Science and Aerospace Engineering at Waseda University, earning his Bachelor's degree in 2023. He is currently pursuing his Master's degree in the same field at Waseda University's Graduate School of Fundamental Science and Engineering.

Authors:

Sho Inoue Waseda University
Takumi Kondo Waseda University
Yuki Kubota IHI AEROSPACE Co., Ltd.
Keisuke Abe IHI AEROSPACE Co., Ltd.
Atsushi Hosoi Waseda University, Kagami Memorial Research Institute for Materials Science and Technology
Hiroyuki Kawada Waseda University, Kagami Memorial Research Institute for Materials Science and Technology