Flexural Properties of 3D- SiO₂/ SiO₂ Composites

Abstract

Silica fiber preform reinforced fused silica composites were fabricated with the variation of silica fiber content by repeated vacuum-assisted liquid-phase infiltrations. Flexural test was conducted to investigate the effect of silica fiber content and treatment temperature on the flexural strength of the 3D-SiO 2 /SiO 2 composite. Fracture behavior of the composites was investigated to study the relationship with the flexural property data. The flexural strength improved with the increment of silica fiber content and decreased with the increment of treatment temperature. The flexural strength of the composite showed the maximum value at 50vol% silica fiber content and treatment temperature at 700 o C. Fractography revealed that the composite was damaged by microdebonding at the fiber/matrix interface and the fracture of fiber.

Mechanical properties and microstructure of 2.5D (shallow bend-joint) quartzf/silica composites by silicasol-infiltration-sintering

“…As the treatment temperature increased, the fl exural strength of the Q f /S composite showed a linear decrease for the fi ber degradation [21] . Under the sintering temperature of 450 ° C, after 10 cycles, no fi ber degradation could be observed (see Figure 6C and D); so, the 2.5D Q f /S composites exhibited a good fl exural strength.…”

Continuous silica fiber reinforced silica composites densified by polymer-derived silicon nitride: Mechanical properties and microstructures

“…1) with the fiber volume fraction about 48%. The 2.5D silica fiber fabric reinforced silica composites (2.5D SiO 2f /SiO 2 ) were prepared by repeated vacuumassisted liquid-phase infiltration of silica sol suspensions [3,4], followed by heat-treatment at 873-923 K in air. The starting preceramic oligomer, synthesized by the ammonolysis of dichlorosilane (CH 3 SiHCl 2 ), was a low viscosity transparent liquid that could be cured into gum-like polyhydridomethylsilazane (PHMS) [11].…”

“…'AS-3DX' material was made by densifying a three-dimensional (3D) glass fiber preform by repetitive cycles of infiltration with Ludox aqueous silica colloidal suspensions, and drying and sintering at relatively low temperatures to a rigidized body, leading to a low density of 1.50-1.60 g/cm 3 [2]. Chen et al developed a vacuum-assisted liquid phase infiltration process with suspension of silica and the addition of a non-ionic surfactant to enhance the densification of 3D SiO 2f /SiO 2 materials, resulting in a density of 1.65 g/cm 3 with a flexural strength of about 75 MPa [3,4]. Additionally, an electrophoretic infiltration process of colloidal silica sol was applied to fabricate SiO 2f /SiO 2 composites, which showed a low density of 1.50-1.65 g/cm 3 strength just about 25-60 MPa due to the sensitive surface of glass fibers [5,6].…”

High-temperature properties and associated structure evolution of continuous SiNO fiber-reinforced BN composites for wave transparency

“…Since quartz fiber-reinforced silica (SiO 2f /SiO 2 ) composites [1] were first fabricated by sol-gel techniques [2], they have been the materials of choice for wave transparency [3], with low dielectric constant, low loss tangent, good ablation resistance, good thermal shock damage resistance [4], and chemical stability [5]. However, the disadvantages of SiO 2f /SiO 2 composites [6], such as tensile strength reduction due to crystallization at high temperatures [7], an unacceptably low softening temperature of 1730°C, poor rain erosion resistance, as well as poor moisture-proof properties, limit their applications in aggressive environments [8].…”