Thermodynamic and Kinetic Studies on the Thermal Stability of Amorphous Si–(B–)C–N Ceramics
نویسنده
چکیده
Amorphous Si–(B–)C–N polymer-derived ceramics (PDCs) with a boron contentranging from 0 to 8.3 at.% were synthesized by thermolysis of the boron-modifiedpoly(methylvinylsilazane). Correlation of the boron content and the thermal stability ofthese materials in the course of annealing were investigated using high temperaturethermal gravimetric analysis (HT-TGA). Furthermore, the initial crystallization of theas-thermolyzed amorphous ceramics was studied by X-ray diffraction (XRD)measurements. The increase of boron content promotes the crystallization of SiC, andinhibits the crystallization ofSi3N4. Moreover, the ratio of α-Si3N4 / β-Si3N4 incrystalline ceramic decreases with increasing boron content. Thermodynamic modelingproves the influence of boron content on driving force for crystallization. The availablethermodynamic model of amorphous Si–C–N domains, nanocrystalline silicon nitride,and nanocrystalline silicon carbide treated as the separated phases has been used tointerpret the obtained results.
منابع مشابه
Fundamentals of Self-Diffusion in Amorphous Si-(B-)C-N
1. Introduction Using solid state thermolysis of pre-ceramic polymers, it is possible to produce amorphous Si-(B-)C-N ceramics which are a new form of a glassy-like state with an enormous stability range up to 1700 °C (see e. g. [1,2]). Si-(B-)C-N ceramics are promising candidates for the design of ultra-high temperature stable structure materials. The thermal stability and the crystallization ...
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