Effects of humidity and composition on enamels

Abstract

This paper reports possibilities for use of nonconventional natural and synthetic raw materials in ceramic bodies and glazes.Reactivity during the process of heating can be considered as a modern criterion for ceramic raw materials. A review of several types of alkali-containing rocks is made, which are more fusible than the common fluxes. The greater fluxing power of these raw materials compared to the traditional types provides for a higher rate of body sintering. As a result of this intensified process, a higher structural density and better mechanical strength of the bodies are achieved with shortened firing cycles. The introduction of more active fluxes reduces firing costs and allows economy of high quality traditional fluxing raw materials in the production of some tablewares, sanitary wares and faience tiles.In combination with more reactive silicon-containing raw materials, the influence of the fluxes on sintering increases. This combined beneficial effect is experimentally confirmed in glaze frit melting and in the firing of glaze coatings. Investigations on these processes are discussed.As a nonconventional raw material in the modern ceramic production, wollastonite can be considered. Since natural deposits of this valuable material are rarely found the use of synthetic wollastine is discussed. Obtaining an anorthite reaction phase in the ceramic bodies provides the formation of a compact and stable structure that permits firing in short and single cycle.