Mullite whisker-mullite/yttrium aluminosilicate oxidation protective coatings for SiC coated C/C composites

Microstructure and properties of porous anorthite/mullite whiskers ceramics with high porosity

“…Overall, samples with mullite whiskers showed high specific strength (0.45‐0.69 MPa with bulk density 0.24‐0.27 g/cm 3 ) than pure anorthite materials (0.19 MPa with bulk density 0.23 g/cm 3 ). Small pore size, small grains, and the stable three‐dimension network formed by mullite whiskers also were benefit to high strength, except for the reinforcement and excellent resistance to crack propagation of mullite whiskers 29,30 . As well as, there was the coupling effect and similar lattice structure enables the better bonding strength at the grain boundaries between mullite whiskers and anorthite.…”

“…In addition, the maximum stress and the maximum strain of the sample at high temperature (800°C ~ 1100°C) were greater than that at room temperature. Except for the enhancement mechanisms of the whisker breakage, bridging and unplugging of the mullite whisker enhancement appeared, and the crack tip was passivated by the interface softened glass phase 29 …”

“…Small pore size, small grains, and the stable three-dimension network formed by mullite whiskers also were benefit to high strength, except for the reinforcement and excellent resistance to crack propagation of mullite whiskers. 29,30 As well as, there was the coupling effect and similar lattice structure enables the better bonding strength at the grain boundaries between mullite whiskers and anorthite. Meanwhile, Mullite whiskers arrest and deflection cracks by causing grain boundary diffusion and cavitation.…”

“…Except for the enhancement mechanisms of the whisker breakage, bridging and unplugging of the mullite whisker enhancement appeared, and the crack tip was passivated by the interface softened glass phase. 29 Using foam gel-casting method, porous anorthite/mullite w ceramics with high porosity and high strength at both room temperature and high temperature have been successfully fabricated. Through adjusting mullite whiskers content from 20 to 60 mo.%, the porosity of all the composite materials was about 91.1%, the thermal conductivity was between 0.03 and 0.065 W/m•K, and the compressive strength above 1000°C exceeded 0.45 MPa much higher than that of pure anorthite samples.…”

Effect of Mullite Film Layers on the High-Temperature Oxidation Resistance of AISI 304 Stainless Steel

“…Mullite is a ceramic material composed of Al 2 O 3 and SiO 2 , which has the characteristics of low expansion coefficient, high melting point, strong corrosion resistance and excellent thermal shock resistance [21][22][23][24][25]. It is a potential high-temperature engineering material [26][27][28][29][30] due to its excellent high-temperature performance, which makes it widely used in kiln linings, pipelines, and steam turbines. Different kinds of mullite materials are prepared 2 of 12 and used for the water vapor corrosion at elevated temperature [29], hot gas and oily water cleaning and antibacterial biofilm.…”