Coatings ceramic matrix composites

E. P. Butler, and E. R. EuUer, Jr., Ductile Coating for High Toughness Ceramic Matrix Composites," unpublished work, 1992. 

Composite interfaces, ceramic—matrix composites, 5 558-561 Composite liner, in landfills, 25 877 Composite material coatings, 14 105 Composite materials, 13 533 26 750-785. See also Composites advanced materials in, 1 693 classification by geometry, 26 752-755 classification by matrix material,... 

Brun, M.K. and Singh, R.N. (1988). Effeet of thermal expansion mismatch and fiber coating on the fiber/ matrix interfacial shear stress in ceramic matrix composites. Adv. Ceram. Mater. 3, 506-509. 

Sun, E.Y., Nutt, S.R. and Brennan, J.J. (1994). Interfacial microstructure and chemistry of SiC/BN dual-coated Nicalon-fiber reinforced glass-ceramic matrix composites. J. Am. Ceram. Soc. 77, 1329-1239. 

Chemical vapour deposition (CVD) is employed to prepare adherent films of controlled composition and thickness. Protective coatings, micro- and opto-electronics, ceramic fibres and ceramic-matrix composites production represent the usual applications of this technique, which allows surfaces of complex geometry to be uniformly coated. 

BN coating on SiC fibers or Al203 fibers reduces the thermal mismatch between fiber and matrix and also reduces fiber-matrix interfacial shear strength in ceramic matrix composites leading to higher overall strength and toughness. 

E. Y. Sun, S. R. Nutt, and J. J. Brennan, Interfacial Microstructure and Chemistry of SiC/BN Dual-Coated Nicalon Fiber Reinforced Glass-Ceramic Matrix Composites, J. Am. Ceram. Soc., 77[5], 1329-1339 (1994). 

H. S. Starrett, A Test Method for Tensile Testing Coated Carbon-Carbon and Ceramic Matrix Composites at Elevated Temperatures in Air, Cer. Eng. Sci. Proc., 11[9—10], 1281-1294 (1990). 

Protective Coatings for Ceramic Matrix Composites and Corrosion Resistance - ... 

Wider use of fiber-reinforced ceramic matrix composites for high temperature structural applications is hindered by several factors including (1) absence of a low cost, thermally stable fiber, (2) decrease in toughness caused by oxidation of the commonly used carbon and boron nitride fiber-matrix interface coatings, and (3) composite fabrication (consolidation) processes that are expensive or degrade the fiber. This chapter addresses how these shortcomings may be overcome by CVD and chemical vapor infiltration (CVI). Much of this chapter is based on recent experimental research at Georgia Tech. 

Segadaes et al. [79] Cooper and Hall [80] and Morgan and Marshall [81] have proposed the use of j3-aluminas, the related magnetoplumbite oxides, micaceous materials, and monazites as interface coatings for ceramic matrix composites. The principle... 

D. Lewis, R.W. Rice, Further Assessment of Ceramic Fiber Coating Effects on Ceramic Fiber Composites, NASA Conf. on Metal Matrix, Carbon, and Ceramic Matrix Composites, (Ed. J. D. Buckley), Cocoa Beach, FL, 1985. 

A.M. Segadaes, P.D. Warren, A.G. Evans, Interface Studies of an Alternative Coating Materials for SiC Fibers in Class-Ceramic Matrix Composites Mica, Symp. on Composites, 2nd Int. Ceram. Sci. Techn. Cong. Orlando, FL, November 13, 1990 (Paper No. 36-SI-90C). 

Zirconium dioxide, Zr02, displays a variety of desirable properties including hardness, chemical durability and corrosion resistance. It is employed in numerous applications such as coatings for cutting tools, optical filters, thermal barrier coating, interfacial coatings in fiber reinforced ceramic matrix composites, dielectric films in microelectronics [24] and other applications such as mirrors [25] and sensors [26]. 

The fibres are not resistant to the temperatures encountered in metal and ceramic matrix composite melt processing, and protective coatings or low-temperature manufacturing routes are needed. 

Mullite has many important high-tech applications. We use mullite for coatings and for fibers. One use of mullite is in ceramic-matrix composites or CMCs it has useful mechanical strength and has promise as the matrix for oxide-reinforcing fibers. Above all, when we heat a clay containing AI2O3 and Si02 we form mullite. Hence the claim that mullite is the most important ceramic and certainly the most important silicate for the ceramist. 

Chemical vapor deposition is one of the most important deposition techniques for forming ceramic films and coatings. We described two examples in Chapter 20 in which CVD is used in composites. It is used to form SiC fibers by the reaction between CHsSiCls and H2 on a tungsten wire. It is also used to form the matrix phase in a ceramic matrix composite (CMC) by a process known as chemical-vapor infiltration. In later chapters we describe the CVD technique again, e.g., it is used in the formation of optical fibers. 

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