# Ceramic Matrix Composites for Aero Engine Applications--A Review
## 4 Oxide CMCs
### Aluminosilicate Matrix CMCs  
Literature review indicates that aluminosilicate (Al\({}_{2}\)O\({}_{3}\)/SiO\({}_{2}\)) ceramics improve the bonding strength of oxide CMCs and are mainly composed of alumina, silica, and mullite [55]. SiO\({}_{2}\) matrix is a potential material for high-temperature ceramic applications due to the advantage of low and stable dielectric constant, high chemical and good mechanical stability, and excellent thermal shock resistance. The literature also shows that aluminosilicate CMCs are applied in antenna housing and aerospace engineering applications [65]. Mullite ceramics are known to have high creep and thermal shock resistance but less strength resistance at high temperatures [66]. Furthermore, mullite ceramics have lower mechanical properties in comparison with other ceramics at room temperature applications [67,68]. For their creep and oxidation resistance properties to be exploited, researchers introduced second-phase enhancers in the form of particles, fibers, and whiskers, allowing for better overall property results [69]. Some of the most popular composite material filler reinforcements are zirconia and alumina, and they are composed of a mullite base matrix with electrophoretic deposition or sintering [70]. This way, the mechanical properties of the mullite-based matrix increased more than double the use of pure mullite. * Aluminosilicate matrix and alumina/mullite fiber CMCs  
Research studies show that the Aluminosilicate and Mullite composites have been used for complex-shaped components, such as the heat insulation tile of the combustion chamber, which was verified by simulation tests [71,72]. Literature studies showcased the thermal shock resistance of Al\({}_{2}\)O\({}_{3}\)/SiO\({}_{2}\) being able to withstand very hard conditions, similar to those nickel and metal alloys withstand in aero engine applications, by using the residual stress field theory of periclase-hercynite refractories [65,73]. Aluminosilicate CMCs' residual strength is higher than the majority of other oxide CMC materials [74,75]. It was also found that Al\({}_{2}\)O\({}_{3}\)/SiO\({}_{2}\) composites exhibit high strength,excellent oxidation resistance, and environmental stability at high temperatures [68]. In aluminosilicate CMCs, the most common composition of alumina base matrix ranges between 50 and 90% Volume of fraction (Vf), while the filler reinforcement materials compositional summary depends on the synthesis procedure used to create the aluminosilicate composite [76]. Studies also investigated the porous Oxide CMCs in greater depth, which allowed the synthesis of Nextel 720 fiber-reinforced porous mullite-Al\({}_{2}\)O\({}_{3}\) composites with the use of the infiltration-wound (SI-W) process. This resulted in aluminosilicate composites having high tensile strength (up to 149 MPa). These results allowed this type of oxide CMCs to be applied in the inner and outer linings of the aero-engine combustion chamber and the hot parts of a spacecraft nose cone [19]. Literature suggests the use of aluminosilicate matrix CMCs in aerospace applications [77,78]. Until now, aluminosilicate CMCs have been used as environmental barrier coatings (EBCs) and thermal barrier coatings (TBCs) in the hot section of gas turbine engines [78]. Research has proved that aluminosilicate CMCs can replace nickel superalloys as they provide better temperature and corrosion resistance in oxidating environments [79]. NASA has also been implementing these types of CMCs in ultra-efficient engine technology by implementing aluminosilicate CMCs as a three-layer barrier coating system to avoid crack formation [80]. A very common manufacturing method for porous Oxide/Oxide CMCs, that also allows the preparation of Nextel 720 fiber-reinforced porous mullite-Al\({}_{2}\)O\({}_{3}\) composites is the slurry infiltration-wound (SI-W) process [81].