Technological aspects of heat resistance in carbon-ceramic composite refractories

Abstract

A technology has been developed for making carbon-ceramic composite refractories by combining carbon fibers as reinforcing component with a mixture matrix, which allows one to make refractory components of various sizes and geometry, including thin-walled large constructions. The heat resistance of these composite refractories increases with the bulk silicization during ceramic production on a carbon-carbon substrate. The degree of silicization is determined by the volume of the open microporosity of transport type, which is formed by pyrolysis of a polymer coke-forming matrix in the initial carbon plastic. The transport micropores are produced by a modification of the phenol-formaldehyde resin additive treatment, which does not give rise to coke on pyrolysis. As a result, the content of open pores in the carbon framework attains 55%, which enables one to make a silicized composite refractory of density up to 2.7 g/cm3 with a compressive strength of 250 – 300 MPa, bending strength 120 – 140, and tensile strength 60 – 80 MPa, elastic modulus 120 – 140 GPa, linear expansion coefficient 3.5 × 10–6 – 4.5 × 10–6 K–1, and thermal conductivity 6 – 8 W/(m ∙ K). These refractories are widely used in various branches of industry