| 摘要 |
A shaped wollastonite (CaO. SiO2) structure is prepared by mixing quick or slaked lime and silica, e.g. quartz, in a molar ratio of about 1 : 1 with about 7.5-.75 times their combined weight of water, shaping the mixture, if necessary after the addition of an agent preventing settling out of the solids, such as spiculated asbestos, highly pulped and beaten paper and starch, indurating at above 173 DEG C. and 125 p.s.i. to form an integrated, porous, crystalline structure of 5CaO. 5SiO2. H2O and subjecting this structure, before or after the removal of uncombined water, to a temperature gradually increasing to 760 DEG C. until wollastonite in a similar form is produced. One form of wollastonite is formed at 760 DEG C., but if heating is continued up to 1150 DEG C. a second form is produced. Since a contraction is involved in passing from 5CaO. 5SiO2. H2O to CaO. SiO2, it is necessary to allow for this when shaping the initial mixture. The product is suitable for use e.g. as a refractory, for thermal insulation and for sound deadening, the properties being varied by suitable control of the water content of the initial mixture. Specification 702,057 is referred to. |
