METHOD OF PREPARING HEAT-INSULATING SHEET WOLLASTONITI- BASED MATERIAL Russian patent published in 1999 - IPC

FIELD: manufacture of heat-insulating sheet materials based on natural stock such as wollastonite, quartz, and lime. SUBSTANCE: method comprises combined grinding of highly pure burned lime, quartz sand and moistening of mixture in order to slave lime, intensive stirring of mixture of burned lime, quartz sand and highly needle-shaped wollastonite as pore-forming agent or aqueous suspension of aluminium powder or aqueous surfactant solution as foaming agent, molding mixture in moist heat-insulating sheet material, autoclave treatment, drying, calibration and roasting. Preparation of finely porous structure and highly strong material involves using highly needle-shaped wollastonite in amount of 50-70 % based on weight of dry components containing at least 50% elementary needles at needle length to diameter ratio of 5-20 including needle content of at least 15% at needle length to diameter ratio of 10- 20, molding of moist mixture to form sheet material is carried out by nibromethod. Drying is carried at 250-300 C to maintain mixture for 1.5-3 hours, and roasting is carried out at 850-900 C for 4-6 hours. Finally porous asbestos-free heat-insulating material is used at temperature not higher than 1000 C for contact with liquid aluminium. EFFECT: more efficient preparation method. 5 ex