Polymer-derived ceramic technology

The remaining discussion will focus on four key issues that must be addressed and understood to advance the technology of polymer-derived ceramic fibers. 

Fiber reinforced ceramic matrix composites (CMCs) are under active consideration for large, complex high temperature structural components in aerospace and automotive applications. The Blackglas resin system (a low cost polymer-derived ceramic [PDC] technology) was combined with the Nextel 312 ceramic fiber (with a boron nitride interface layer) to produce a sihcon oxycarbide CMC system that was extensively characterized for mechanical, thermal, and electronic properties and oxidation, creep mpture, and fatigue. A gas turbine tailcone was fabricated and showed excellent performance in a 1500-hour engine test. 

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. 

FIGURE 3-14 One-hour bend stress relaxation ratio of polymer-derived SiC fibers and other polycrystalline SiC and AI2O3 fibers. Source Reprinted from Composites Science and Technology, Volume number 51(2), J.A. DiCarlo, Creep limitations of current polycrystalline ceramic fibers, Pp. 213-222. Copyright 1994, with permission from Elsevier Science. 

Lipowitz, J., J.A. Rabe, and R.M. Salinger. 1993. Ceramic fibers derived from organosilicon polymers. Pp. 207-273 in Handbook of Fiber Science and Technology. Vol. 3, High Technology Fibers, Part C, M. Lewin and J. Preston, eds. New York Marcel Dekker, Inc. 

Natural rubber (NR) currently presents a set of consolidated scientific, technological and industrial applications, being of fundamental significance for several sectors of the global economy. Such applications derive from its distinguished mechanical and thermal properties, obtained through thermal and chemical processes e.g. the vulcanization process). In contrast, new fields of application are pursued mainly in sectors traditionally occupied by materials with a nature distinct from polymers, such as ceramic and metallic materials. 

In 19 6 the principle means of measuring mechanical properties of polymers were the test methods derived from older technologies such as metals and ceramics. They had to be revised for these relatively new materials but little atttention had been payed to the question of whether or not these materials were so different that a new approach should be taken. We asked ourselves what does one really need to know about polymers to apply them properly. 

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