NANOSTRUCTURED FUNCTIONAL-GRADIENT COMPOSITE MATERIAL AND METHOD OF PRODUCING SAID MATERIAL Russian patent published in 2011 - IPC C04B35/573 C04B35/80 B82B3/00 

FIELD: chemistry.

SUBSTANCE: invention relates to engineering ceramics and particularly to ceramic-matrix composite material based on silicon carbide reinforced with carbon fibres. Disclosed is composite material which contains a matrix made from reaction bonded silicon carbide reinforced with bundles of carbon fibres and a working layer made from reaction bonded silicon carbide on at least one of its surfaces. The matrix and the working layer consist of 75-92 vol. % silicon carbide which is in form of primary grains and nanosized secondary grains, and 8-25 vol. % free silicon. The ratio of volume content of the matrix and reinforcing bundles of fibre increases from 25/75 to 60/40 in the direction towards the working layer. The method of producing the composite material involves steps for moulding a workpiece, hardening, carbonisation and silicon impregnation. Before moulding, reinforcing bundles of carbon fibre are treated with a suspension containing silicon carbide particles in amount of not more than 50 wt % and binder, and the carbon fibres for the working layer is treated with a suspension containing silicon carbide particles in amount of not more than 30 wt % and polymer binder in amount of not more than 20 wt %. When forming at least a set of thickness, reinforcing bundles of carbon fibre treated with a suspension with increasing content of silicon carbide particles in an interval from 30 to 50 wt % and/or with increasing average size of silicon carbide particles from 5 to 30 mcm are laid in the direction towards the working layer. The silicon impregnation step is carried out at temperature 1400-1450°C.

EFFECT: obtaining composite ceramic-matrix material with improved tribological properties and high strength and impact viscosity.

8 cl, 6 tbl, 3 dwg