The Use of Petalite to Limit Thermal Expansion in Ceramic Bodies

摘要

The effect of petalite additions on the thermal expansion behavior of ceramic bodies is investigated. The behavior of bodies which are most easily formed by adding petalite to clays or kaolin is illustrated. Clays with a low quartz content are used for producing bodies with low thermal expansions. Depending on requirements, the petalite content must be at least 40 percent while the optimum amount is about 60 percent. These percentages of petalite correspond to Li2O contents of 1,6 percent to 2,4 percent. The extent to which the thermal expansion is reduced depends on the firing temperatures used and, also, on the nature of the plastic components in the body. A reduction in the thermal expansion of ceramic bodies is achieved by using a lithium compound such as petalite together with other materials. the alkaline earths are particular suitable for this purpose, whereas feldspar has no noticeable effect. The amount of petalite in a body is reduced effectively by replacing some of it with talc to achieve similar results. Relatively good stability during firing is expected from bodies containing petalite and talc because their vitrification ranges appear to be adequate for practical purposes.