Flux forming additives have played an important role of energy reduction in the ceramic industry for centuries. Though there are available fluxing materials in the market, attempts of searching for new flux systems have still been extensively done. This paper presents the use of a combined flux system and its roles on phase transformation and physical properties of a triaxial porcelain body. Illite was used as the primary flux in the main recipe while talc, the supplementary flux, was added at 0, 3, 5 weight %. In pure form, talc dissociated into enstatite around 900 ^oC but when mixed in the recipe, phase changes of talc differed. Talc and illite disappeared around 1,000 ^oC. Around 1,200-1,300 ^oC, indialite and pyrophillite appeared only on the body with talc addition. Early densification could be observed when talc was present, suggesting that talc also played an important role in vitrification. The body with 3% talc showed the greatest firing shrinkage and flexural strength but lowest water absorption after firing at 1,200 ^oC, which was ~50 ^oC lower than the body without talc. Further increasing of talc content to 5% resulted in an adverse effect of these properties.

Keywords: Triaxial porcelain, Illite, Talc, Phase transformation, Vitrification