Perspective Methods for Producing Composite Materials Based on Carbon, Silicon and Silicon Carbide: Progress and Challenges

Abstract

The patent review is devoted to consideration and analysis of several methods of producing materials and arti- cles based on carbon, silicon and silicon carbide. Common to these methods are: (i) the use of carbon as initial material for growth of Si or SiC, (ii) the use of single crystal Si as substrate for synthesis of nanocrystalline carbon, (iii) execution of the processes at low pressure of the reagents and their strong chemical interaction. The methods considered do not im- ply preliminary grinding of initial components, their sintering, hot pressing, etc. In fact, this group of methods and rele- vant materials hold a peculiar position between crystal growth and techniques of producing composite materials. The analysis made allows formulating the following debatable conclusions: (a) non-porous SiC-Si composites forming upon direct contact of molten silicon with fibrous carbons can be used as resistive material in diverse technical applications; (b) in spite of the wide variety of methods of growing solar grade silicon sheets, only self-supported methods can be regarded as viable; the optimal silicon sheet structure includes parallel twin boundaries, the average dislocation density should not exceed 10 5 cm -2 ; (c) deep purification of bulk graphite is possible under the conditions of cycling inlet/outlet of halogen agents; the process realized can be environmentally safe even when using Freon; (d) carbon nanoclusters produced by chemical vapor deposition can be considered as components for creation of drug delivery preparations.