Application of factorial model for an optimization of partial replacement of feldspar by talc on the sintering process

Abstract

This research used a factorial model containing two levels and three variables to evaluate the partial substitution of sodium feldspar (albite) by a talc ore found in abundance in the region of Itaiacoca-Brazil. The model can also be used to verify the influence of initial talc particle size, proportion, and sintering threshold temperature on the following physical properties, such as linear shrinkage, water absorption, bulk density, total porosity, and firing color. In this study, the mechanical strength of the compositions was evaluated by the flexural strength test. The factorial model indicated the sintering temperature as the variable that most affects the samples' densification and the proportion of talc as the variable that changes the firing color. The experiment that used a higher sintering temperature combined with a coarser talc granulometry presented the highest mechanical strength. When more refined granulometry was used, there was the beginning of an overfire process. Water absorption values in the range of .04% and modulus of rupture of 49 MPa were obtained, confirming the talc's effectiveness as a secondary flux agent suitable for the formulation of ceramic bodies.

Characterization of Talcose Rocks Derived from Serpentinite—Pilot Study in the Ultramafic Complex of Cabo Ortegal (Spain) for Potential Use and Commercialization

“…From the results for this pilot research, it seems that the talc from the area of study is not very appropriate for use in pharmaceuticals and the cosmetic industry [18], but talcose rocks may be used for carving and in ceramics (e.g., [5,29]). Furthermore, talc has been shown to be an excellent substitute for feldspar (albite) in porcelain manufacture [30] or in blocks for electric and thermal insulation [3]. It should be noted that talcose rocks in general have distinct and useful applications compared to serpentinites.…”