Eutectic ceramics

Harada, Y., Suzuki, T., Hirano, K., Nakagawa, N., Waku, Y. (2005). Environmental effects on ultra-high temperature creep behavior of directionally solidified oxide eutectic ceramics. Journal of the European Ceramic Society, 25(8 SPEC. ISS.), 1275-1283. 

Llorca, J., Orera, V. M. (2006). Directionally solidified eutectic ceramic oxides. Progress in Materials Science, 51,711-809. doi 10.1016/j.pmatsci.2005.10.002. 

Perriere, L., Valle, R., Mazerolles, L., Parlier, M. (2008). Crack propagation in directionally solidified eutectic ceramics. Journal of the European Ceramic Society, 28, 2337-2343. doi 10.1016/j.jeurceramsoc.2008.01.005. 

Chapter 10 The processing techniques, microstructures, and mechanical properties of directionally sohdified eutectic UHTCs are reviewed in this chapter. It is considered the main methods for preparing of eutectic ceramics and the relationships between thermal gradient, growth rate and microstructure parameters. Principles of coupled eutectic growth, main types of eutectic microstructure and the relationship between the eutectic microstructure and the mechanical properties of directionally sohdified eutectics at ambient and high temperatures are briefly... 

Slides Turbofan aero-engine super-alloy turbine blades, showing cooling ports [3] super-alloy microstructures [4] DS eutectic microstructures [3, 5] ceramic turbine blades. 

Sarver X V. and Hummel F. A. (1962). Solid solubility and eutectic temperature in the system Zn2Si04-Mg2Si04. J. Amer. Ceram. Soc., 45 304-314. 

Figure 2.19 Perspective drawing of a ternary system with a simple eutectic and no ternary compound. Reprinted, by permission, from Phase Diagrams for Ceramists, Vol. 1, p. 15. Copyright 1964, The American Ceramic Society.

This special class of brazes reacts chemically with the surfaces of ceramic components to produce wettable products with metallic characteristics, such as TiO, TiC x or TiN x as described in Sections 6.3 and 7.2. Thus the wetting is due to an in situ metallization . By definition, the brazes must contain chemically reactive elements such as Ti that are often added to eutectic brazes similar to those developed for joining metal components. Many sessile drop experiments have shown that active metal brazes can wet a wide range of ceramics when a suitable inert environment is used. Particularly high standards of environmental inertness... 

Ni brazes are attractive when components must endure high service temperatures and evaluation of the potential of Ni eutectic brazes containing additions of Cr, such as BNi-5 and BNi-7 (Ni-19Cr-1 OSi and Ni-14Cr-10P), as the active metal for joining Si3N4 and SiC ceramics has been vigorous, (McDermid et al. 1989,... 

Such excellent or at least adequate capillary behaviour is also typical of the process variant known as eutectic bonding in which the transient creation of a liquid phase is caused by the interdiffusion of two chemically different metal alloy component materials. In the laboratory variant process known as partial transient liquid phase bonding, (Shalz et al. 1992), a coated interlayer is used for ceramic-ceramic or ceramic-metal joints. In this process the interlayer is a ductile metal or alloy whose surface is coated with a thin layer of a lower melting temperature metal or alloy, for example Ni-20Cr coated with 2 microns of Au. The bonding temperature is chosen so that only the coating melts and the ductility of the interlayer helps to accommodate mismatches in the coefficient of thermal expansion of the component materials. 

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