METHOD OF MAKING THIN-WALLED ARTICLES FROM COMPOSITE MATERIAL WITH GRADIENT PROPERTIES ON THICKNESS THEREOF

摘要

FIELD: chemistry.;SUBSTANCE: invention relates to composite materials with carbon-silicon-carbide matrix, intended for operation in conditions of high thermal load and one-side impact of oxidising medium with high oxidative potential. Method involves formation of frame, made of heat-resistant carbon and/or silicon-carbide fibres with coating of pyrocarbon, or silicon pyrocarbide, or boron nitride, then filling it with carbon matrix material to obtain workpiece of material with open porosity, decreasing from protective layers to bearing layers of future item, and complete filling of workpiece material with carbon-silicon-carbide matrix material using siliconisation process. Filling frame with carbon matrix material is made as follows: plastic workpiece is moulded based on a coke-forming binder, carbonised, and saturated with pyrocarbon via vacuum isothermal method to open porosity of material bearing layers 6-12 %, with exclusion of carbon-containing gas access from side of protective layers of material. Then, intermediate siliconisation is conducted by vapour and liquid method with introduction into pores of workpiece material at temperature of 1,300-1,550 °C a limited amount of silicon, not exceeding stoichiometric amount of carbon contents in protective layers of material, heated and cured workpiece at 1,700-1,800 °C, and cooled in silicon vapour at workpiece temperature equal to or 10-15 degrees higher than silicon vapour temperature. Complete filling of workpiece material with carbon-silicon-carbide matrix material is performed by growing nanocarbon in workpiece material pores and final siliconisation by vapour and liquid method with silicon introduction into pores of workpiece material via capillary condensation of its vapours at temperature of 1,300-1,550 °C, followed by further heating and cure at temperature of 1,750-1,800 °C.;EFFECT: technical result is production of thin-walled articles with significantly differing across their thickness properties while preserving high level, without need to apply mechanical processing operation.;3 cl, 17 ex, 1 tbl