METHOD OF PROTECTING CARBON-CONTAINING COMPOSITE MATERIALS OF LARGE-SIZE ARTICLES FROM OXIDATION Russian patent published in 2020 - IPC C04B41/87 C04B35/577 C04B35/83 

FIELD: technological processes.

SUBSTANCE: invention relates to methods of protecting carbon-containing materials from oxidation and to protection against oxidation of large-size articles. According to the method, workpiece from porous carbon-containing composite material is subjected to preliminary silicification by liquid-phase method at heating to 1,650–1,750 °C at pressure in reactor 600–760 mm Hg in argon using silicon nitride as precursor of liquid silicon. Remaining non-carbidized silicon is distilled in vacuum at 1,800–1,850 °C. Silicisation and distillation of free silicon from the pores of the material are carried out in a single process. Then high-porous carbon is formed in pores of billet material using one of known methods, preferably, by growing nanocarbon in form of particles, fibers or tubes. Thereafter, on billet surface formed a slurry coating based on diborides of refractory metals and chemically active to silicon component(s): nanodispersed carbon, molybdenum carbides (MoC and Mo₂C) or Mo₅Si₃, or a mixture of carbon with molybdenum with particle size of up to 5 mcm. Final siliconisation is carried out using vapor-liquid-phase method. Coating based on oxides of refractory metals is formed over obtained coating.

EFFECT: high reliability of protecting carbon-containing materials of large-size articles from oxidation at temperatures of 2,000 °C and higher while simultaneously increasing reproducibility of the obtained results.

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