# Ceramic Matrix Composites for Aero Engine Applications--A Review
## 5 Non-Oxide CMCs
### Carbon Matrix CMCs
Such CMCs have high stiffness and strength. Such properties are, to some extent, achieved because of the control of microcracks in the interphase of the carbon matrix and fiber matrix and the fact that these are practically closed when exposed to high temperatures. They can be used in environments where temperature can approach 3000 \({}^{\circ}\)C [105]. In addition to their good strength and stiffness, they have low thermal expansion and good thermal shock resistance, as well as good creep and corrosion attributes. Their mechanical strength is increased with temperature [106]. Research indicates that the strength of advanced Carbon/Carbon CMCs can increase with temperatures close to 2000 \({}^{\circ}\)C. Furthermore, their properties vary depending on the fiber fraction, the type and structure of the carbon fiber, and the processing cycle used to fabricate the composite [107]. Therefore, they have higher stiffness, strength, and thermal conductivity across the fiber axis, while their mechanical and thermal properties are lower along the fiber direction. Most C/C composites are manufactured using the preformed yarn method (PY), which consists of a bundle of carbon fibers in a matrix of coke and pitch binder powders [108]. This method allows faster production than other conventional methods (impregnation of the chemical vapor deposition method). The standard composition manufactured by this type of method is between 40-50% volume fracture of carbon fiber content by volume, which after graphitization at 2000 \({}^{\circ}\)C becomes 100% of carbon [109]. Other researchers have created Carbon/Carbon CMCs using different base carbon fibers weaved together and densified by chemical vapor infiltration (CVI), which is recognized as one of the most used manufacturing processes to fabricate this type of composite [110]. The mechanical properties of Carbon/Carbon composites show that this type of composites have lower densities than other ceramic components with also thermal properties higher than copper and silver, making them suitable for usage in aero vehicles [93; 106; 111; 112]. An example of aeronautical applications of Carbon/Carbon CMC is the wings and the fuselage nose, created for the American Space shuttle, which was able to withstand 100 missions under extreme re-entry conditions [113]. The aerospace industry requires reliability and reduced system costs; hence carbon fibers are replacing previously used multiple components with a one-piece assembly, having in most cases one-tenth of the density of previous steel components but offering similar strength and heat resistance [113]. Other commercial applications that use Carbon/Carbon composites include furnace fixtures, heathshields, heating elements, and load plates [114]. * Carbon/Resin matrix CMCs  
Resin is a structural material that has been introduced for aerospace applications due to high-temperature resistance in engine environments. This type of fiber reinforcement is used in a ceramic composite matrix to bridge cracks and toughen the matrix by crack blunting and debonding at the matrix interface [115; 116; 117]. When the resin filler/reinforcement is combined with carbon, the composite which occurs benefits from a high strength to low weight ratio increase. In addition, research has shown that the heat resistance, strength, and stiffness of the resin filler/reinforcement has been improved when carbon is added [118; 119]. The resin, on the other hand, allows the composite to conduct force to the fibers and secure them when exposed to high-pressure [118; 119]. The mechanical properties of carbon/resin composites have been improved drastically. More specifically, the maximum shear strength has been increased between 10-75% depending on the type of manufacturing process and the added interface of the composite. Surface roughness has also increased [120; 121; 122]. Such CMCs present improved flexural modulus. The thermal conductivity of the carbon/resin composite is improved at room temperature and can withstand higher temperatures without failing [123].