| 摘要 |
FIELD: chemistry.SUBSTANCE: composite material contains thermostable carbon and/or silicon carbide fibre framework, carbon-silicon carbide matrix and impermeability-imparting free silicon. Content of silicon carbide in carbon-silicon carbide matrix and nanosize particles present in it changes depending on product material thickness. The largest content is protective layers, and the lowest - in bearing layer of product material. Size of embedment of free silicon in silicon carbide in volume and in surface layers does not exceed respectively 8-10 mcm and 2-3 mcm. First made is porous blank from carbon-containing material based on thermostable carbon and/or silicon carbide fibres with coefficients of linear thermal expansion (CLTE), close to CLTE of carbon-carbidosilicon matrix components, which has open porosity, decreasing from protective layers to bearing layers from 20-60 to 6-12%. Then, open pores are filled with nanodispersive carbon or its mixture with finely-dispersive carbon with particle size not larger than 5 mcm. Obtained blank is siliconised by steam-liquid phase method by heating, exposure at temperature of silicon carbidisation termination and cooling in its vapours. Initial mass transfer of silicon into pores is carried out by capillary condensation of its vapours in temperature interval on blank 1300-1600°C, pressure in reactor not higher than 27 mm Hg and at temperature of silicon vapours, which is100-10°C higher than blank temperature.EFFECT: increase of exploitation characteristics of produced products under conditions of high temperature influence of oxidative medium and presence of pressure difference from the side of their internal and external surface.4 cl, 1 tbl, 3 ex |
