FIELD: chemical industry. SUBSTANCE: material is impregnated with aqueous solution containing precursors of formation of phosphate glass substrate modified by zinc oxide, dried and heat treated to form internal coating. Molar ratio between modifying oxides containing zinc oxide and glass-forming oxides containing predominantly or only phosphoric anhydride is at least 0.6, preferably 0.9 so as to render glass (phosphate) substrate resistant to corrosion caused by moisture. Solution is prepared when polyphosphate such as metaphosphate or trimetaphosphate dissolves in water. Sodium trimethylphosphate is capable of subsequently dissolving, due to complexation without formation of precipitate, desired number of salts of modifying oxides containing at least one zinc salt such as zinc nitrate or sulfate. Method makes it possible to afford internal antioxidative protection of carbon materials which are slightly sensitive to moisture. EFFECT: more efficient protection method. 33 cl, 6 ex, 2 tbl
