Enhanced oxidation resistance of SiC/SiC minicomposites via slurry infiltration of oxide layers

Abstract

SiC based composite materials commonly have protective silica surface in air. Under humid environments at high temperatures, like occur in jet engines, the silica surface layer reacts with water molecules to form volatile silicon hydroxide (Si(OH) 4) and the protection is reduced which cause jet engine degradation. An alternative approach to protect SiC based composites would be to infiltrate the SiC matrix via slurry with an oxide material that is resistant to the hightemperature and humid environment. As proof of concept, aqueous based mullite particle slurries were infiltrated by pressurized flow and by capillarity of the wetting slurry on the external surface of the porous SiC matrix of single-fiber-tow SiC/SiC minicomposites. Minicomposites were precracked at room temperature during tensile tests then tested in tensile creep in air at 1200 °C to study the degree of protection that the infiltrated mullite provided at high temperatures. Next, fracture surfaces were examined using SEM.

Morphological Control of Silicon Carbide Deposited on Hi-Nicalon Type S Fiber Using Atmospheric Pressure Chemical Vapor Infiltration

“…The cumulative AE energy at each sequential event number and time was then calculated as a function of time and applied tensile stress as shown previously . The evolution of the normalized cumulative AE energy during fast fracture tensile testing is directly propositional and representative of the evolution of damage in ceramic matrix minicomposites. , Scanning electron microscopy (SEM) at UCONN was conducted using a Thermo Fisher Scientific Teneo LVSEM with an accelerating voltage of 5 kV. SEM of fractured surfaces was done at NASA with a Tescan MIRA3 with an accelerating voltage of 7 kV.…”

“…This allows toughening mechanisms such as fiber debonding and pullout, crack deflection, and crack splitting to take place . A variety of materials are available for fiber, interphase, and matrix composition. − Silicon carbide (SiC) is an attractive matrix material due to high mechanical strength, creep resistance, melting point, hardness, and chemical inertness …”

A Review on Si-Based Ceramic Matrix Composites and their Infiltration Based Techniques

“…These C/C-SiC and SiC/SiC composites are extensively used as functional materials in the aeronautical and aviation industrial sectors due to their higher thermal prevention, enhanced propulsive systems, and other properties such as higher fracture toughness, strength at higher temperatures, reduced density, superior thermal conduction, and oxidative resistance [171,172].Various ceramics are used to fabricate or manufacture different parts especially ceramics such as Si 3 N 4 , Al 2 O 3 , and SiC parts such as ballistic-resistant exterior tiling for planes, helicopters, and drones, supplanted metal-based armor plates for body armor are fabricated. Among the ceramics mentioned Al 2 O 3 is used in most parts because of its hardness, modulus of elasticity, refractoriness, and low cost [173].…”