Ceramic matrix composite systems

TABLE 1. Examples of dispersion-reinforced glass and glass-ceramic matrix composite systems... 

As high performance ceramic matrix composite systems, such as Melt Infiltrated (MI) SiC/SiC, are being considered for advanced gas turbine engine applications, the characterization of the material becomes more important. A series of tests were conducted where Pt and Ni sheathed Pt thermocouples were used to monitor temperature for short and long duration fast fracture, fatigue and creep tests. While it is known that Si forms eutectics with Pt and Ni, this was initially not considered an issue. But since Ml SiC/SiC composite achieves much of its performance from the infiltrated phase of Silicon (for high conductivity and low porosity), it was felt that further study of possible interactions of the Si phase has to be considered. 

Ojard. G., Rugg, K., Riester, L., Gowayed, Y. and Colby, M., Constituent Properties Determination and Model Verification for a Ceramic Matrix Composite Systems , Ceramic Engineering and Science Proceedings. Vol. 26, no. 2, pp. 343-350. 2005. 

Although few applications have so far been found for ceramic matrix composites, they have shown considerable promise for certain military applications, especially in the manufacture of armor for personnel protection and military vehicles. Historically, monolithic ("pure") ceramics such as aluminum oxide (Al203), boron carbide (B4C), silicon carbide (SiC), tungsten carbide (WC), and titanium diboride (TiB2) have been used as basic components of armor systems. Research has now shown that embedding some type of reinforcement, such as silicon boride (SiBg) or silicon carbide (SiC), can improve the mechanical properties of any of these ceramics. 

Silicon carbide has attracted considerable interest because of its good mechanical and physical properties and chemical inertness. One of the most important applications of SiC is to produce a matrix reinforced by fibres, forming ceramic-matrix composites. These composite materials exhibit much better fracture toughness than monolithic ceramics. Compared with carbon/carbon composites, fibre-reinforced SiC matrix composites possess superior oxidation resistance and mechanical properties. The Si-C-H-Cl system (e.g. methyltrichlorosilane, CH3SiCl3) has been used for SiC deposition because it is easy to produce stoichiometric SiC deposits. 

Up to now, polymer pyrolysis has been investigated especially to develop ceramic fibers [46,47] and ceramic matrix for ceramic matrix composites [48-50]. More recently studies have been undertaken to exploit this method to develop ceramic thin films [51-53], foams [54], joints [55], and bulk materials [56]. Moreover, noncon-ventional heating systems such as laser [57], microwave heating [53], or even athermal conversion processes such as ion bombardment are just now starting to be applied to the polymer route and the preliminary results are very promising [58-60]. In this chapter we focus on the polymer processing of bulk ceramics obtained by pyrolysis of partially cross-linked preceramic bodies and of thin ceramic films (obtained either by traditional pyrolysis or by the innovative ion irradiation process). 

Originally, requirements in aerospace applications played a decisive role in developing ceramic matrix composites. Selection criteria for materials in power plants, heat shield systems for space shuttles and rockets, were a desperate temperature resistance and good characteristics considering its mass. In practice, one of the first... 

R. Kochenddrfer and W. Krenkel, CMC Intake Ramp for Hypersonic Propulsion Systems, High-Temperature Ceramic-Matrix Composites I Design, Durability atuiPerformance (Eds. A. G. Evans, R. Naslain), Ceramic Transactions, Vol. 57 (1995), p. 13-22. 

One approach for fabricating fiber reinforced ceramic matrix composites is the directed oxidation of metals, a process first introduced by Lanxide Corporation [1, 2] and later used successfully to produce turbine engine and aerospace components. Rights to the DIMOX technology, as it was identified, were ultimately acquired by Power Systems Composites, L.L.C., a subsidiary of the Power Systems business of the General Electric Company. 

D.J. Landini, A.S. Fareed, H. Wang, P.A. Craig Jr andS. Hemstad, Ceramic Matrix Composites Development at GE Power Systems Composites, LLC, submitted for publication in Ceramic Gas Turbine Design and Test Experience - Progress in Ceramic Gas Turbine Development Vol. 2, ed D. Richerson, M. Ferber and M. Van Roode, ASME Press. 

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