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When obtaining unfired quartz ceramics according to the method of strengthening by impregnating the products in pure nonhydrolyzed ethyl silicates or in tetraethoxysilane [1][2][3] with subsequent treatment in an aqueous ammonia solution [i] or in hot water [2,3], the required binder materials are relatively costly and scarce. In view of this, experimental studies have been proposed for producing unfired ceramic products by impregnating them with the solutions of sodium silicate (liquid glass) that forms a cheap and easily available binder material.Dilute liquid glass solutions having adensity of 1.02-1.06 g/cm 3 have been used as chemically active liquid media for obtaining unfired quartz ceramics according to a number of methods [4].Liquid glass imparts high strength to the impregnated unfired ceramics after natural air cooling. However, when the products are heated up to a temperature exceeding 600~ their strength decreases abruptly since sodium silicates acting as the bonding base (binder) of liquid glass undergo polymorphic transformations during the heating process [5, pp. 10-16] and their bond-forming films are destroyed (Fig. i, curve 2). In order to remove sodium, it is necessary to carry out chemical decomposition of sodium silicate into silicon dioxide and soluble or volatile compounds of sodium. This is achieved by treating liquid glass with acids (HNO 3, HCI, HgSO~, etc.). During this treatment, silicon dioxide and a water-soluble sodium salt of the acid used for the treatment form as a result of the exchange reaction. In view of the hazards associated with the use of these acids, watersoluble salts are employed [6]. Ammonium salts, viz., ammonium chloride NH4CI and ammonium nitrate (ammonium saltpeter) NH4NO 3, are most widely used [7][8][9]. In this study, we used an aqueous solution of ammonium nitrate since it interacts with liquid glass to form sodium nitrate that is highly soluble in water (its solubility is three times higher than that of sodium chloride) and can be removed easily from the ceramic owing to this.Slip cast quartz ceramic products and specimens (measuring 8 mm in diameter) were impregnated in a solution of liquid glass (the modulus was equal to 4) having a density of 1.112 g/cm 3 for a period of 24 h after drying in air for 2 days. Thereafter, the specimens were taken out. They were held for 1-2 min above the bath in order to ensure removal (runoff) of the excess quantity of the adhered liquid glass and were immediately immersed in a bath containing an aqueous solution of ammonium nitrate. They were held in this solution for 20-24 h to ensure complete occurrence of the following chemical reaction between liquid glass and ammonium nitrate: Na20. nSiO2+2NH4NOa=n SiO2+2Na NOa +2NHa-{-H20.The amorphous silicon dioxide formed during the reaction precipitates along the grain boundaries of the ceramic and increases the area of contact and the forces of interaction between the grains owing to which the ceramic attains high strength characteristics. SodiumScientific-Research and Producti...