PROCEDURE FOR STRENGTHENING NON-ROASTED SILICATE CERAMICS Russian patent published in 1996 - IPC

FIELD: silicate chemistry; manufacture of building materials. SUBSTANCE: in a procedure of hydrothermal strengthening non-roasted building ceramic pieces containing mainly calcium-manganese silicates, as a strengthening activator and inhibitor, sodium carbonate and carbon dioxide are respectively used. The process is conducted in steam autoclave under 0.3 MPa pressure for 2-3 h in the following way. Pressure rise is achieved by means of steam bubbling through sodium carbonate solution and maximum pressure is maintained in presence of carbon dioxide, the rate of rise and fall of pressure in the range of 0.01-0.05 MPa having not to exceed 910^-4 MPa/min for bulky pieces and 1310^-4 MPa/min for thin-walled ones. To improve external appearance of pieces, the latter are loaded into autoclave before strengthening at 100-110 C temperature in its working chamber. EFFECT: increased strength of pieces, shortened process of hydrothermal treatment and thereby reduced usage of fuel. 2 cl, 4 tbl