CERAMIC WALL ARTICLE AND A METHOD OF ITS MAKING Russian patent published in 1996 - IPC

FIELD: ceramics, building industry. SUBSTANCE: ceramic wall article is made of raw mixture containing, wt.-%: quartz sand 70-85; calcium oxide 5-10; sodium hydroxide (measured for Na₂O) 5-10; water glass at specific gravity 1.3-1.35 g/cm³ 5-10. Pigment can be added to mixture at amount 1-2% (above 100%). Quartz sand is ground up to specific surface 2000-7000 cm²/g, mixed with calcium-containing component, then mixture is wetted with sodium hydroxide solution and water glass at specific gravity 1.3-1.35 g/cm³. Half-finished products were pressed, dried at 200-300 C for 1-3 hr and calcined at 850-1000 C at isothermal exposition for 2-4 hr. Physico-chemical indices: water absorption is 5-10%, hardiness is 70-100 cycles and more, bending strength limit is 25-70 MPa, compression strength limit is 50-120 MPa. Articles are moisture-resistant and their strength after drying is 30-45 MPa. EFFECT: enhanced quality and properties of article. 5 cl, 2 tbl