Silicon-based ceramics

There are two further processes. Silicon-based ceramics can be fabricated by sintering or by hot-pressing. But a new route, reaetion bonding (Fig. 19.6), is cheaper and gives good precision. If pure silicon powder is heated in nitrogen gas, or a mixture of silicon and carbon powders is sintered together, then the reactions... 

XI. APPLICATION OF CYCLOSILAZANES AS PRECURSORS FOR SILICON-BASED CERAMICS... 

MoSi SiC Composites An obvious approach to the problem of thermal oxidation of composites during creep is to select a matrix and reinforcement that are both oxidation-resistant phases such as oxides or silicon-based ceramics. Because oxide reinforcements are not widely available, and those that are available are prohibitively expensive, the latter approach has proven... 

The polymeric precursor route to silicon-based ceramics was developed by Yajima et al. using polycarbosilane (-[MeHSiCH2] -) as precursor to One of the drawbacks of this method was the initial Si C ratio of 1 2,... 

R. Riedel, G. Passing, H. Schonfelder, and R. J. Brook, Synthesis of Dense Silicon-Based Ceramics at Low Temperatures, Nature, 355, 714-7 (1992). 

K.N. Lee, D.S. Fox, R.C. Robinson, and N.P. Bansal, Environmental Barrier Coatings for Silicon-Based Ceramics, in High Temperature Ceramic Matrix Composites, W. Krenkel, R. Naslain, and H. Schneider, Eds, Wiley-VCH, Weinheim, Germany, (2001), pp. 224-229. 

But CMCs will be commercially successful only when they are produced cost-effectively. Polymer-derived ceramic (PDC) technology is one of the most promising low cost fabrication methods for ceramic matrix composites, particularly for large, complex shapes. In PDC technology, a silicon-based polymer (siloxane, carbosilane, silazane, etc) with fiber or particle reinforcement is shaped and cured in the polymer condition and then pyrolyzed in a controlled atmosphere to form a stable silicon-based ceramic, such as silicon carbide, sihcon nitride, silicon oxycarbide, or silicon oxynitride. 

Boettger, J.M., Ker, M.K., Shore, P., and Stephenson, D.J., Influence of ductile mode grinding on the strength of silicon based ceramics. Proceedings of the International Conference on Machining of Advanced Materials, NIST Special Publication 847,1993, pp. 353-358. 

Riedel R., Passing G.. Schonfelder H., Brook R. J.. Synthesis of dense silicon-based ceramics at low temperatures, Nature 1992, 355(6362), 714-717. 

Isomeric Cyclosilazanes and their Application as Precursors for Silicon-Based Ceramics... 

Isomeric Cyclosilazanes and their Application as Precursors for Silicon-Based Ceramics 267 Dilithiated OMCTS reacts with F2BN(CHMe2)2 to 4 (Si B N = 4 2 6 Scheme 2). 

Matsumoto K, Matsuoka H (2005) Synthesis of core-crosslinked carbosilane block copolymer micelles and their thermal transformation to silicon-based ceramics nanoparticles. J Polym Sci A Polym Chem 43(17) 3778-3787... 

SILICON-BASED CERAMICS AS HIGH-TEMPERATURE HIGH-STRENGTH MATERIALS... 

Improvements in the properties and reliability of silicon-based ceramic components as well as those in the technologies of designing and assembling of them have enabled the extremely high engine efficiency of 35% or more with the 300 kW-class gas turbine systems installed with ceramic components, which usually show efficiencies of around 20% with metallic components. 

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