Compositional effect on humidity self-regulation functionality in gibbsite-based ceramic tiles

Abstract

This paper analyses the effect of the starting composition on the humidity regulating capacity of a gibbsite-based composition successfully tested for the manufacture of ceramic tiles. For this purpose, the proportion of gibbsite and quartz has been varied and the effect of these two ingredients of the composition on the moisture regulating capacity and on the kinetics of adsorption-desorption of sintered tiles has been studied. To explain the effect, the microstructure of the sintered bodies has been also characterised. It has been found that increasing the proportion of gibbsite in the starting composition produces a significant increase in the moisture regulating capacity as a consequence of the higher proportion of transition alumina in the sintered bodies that provide a larger mesopore reservoir. In contrast, the addition of quartz does not affect the moisture regulating capacity but does affect the rate at which moisture adsorption and desorption phenomena take place by increasing the fraction of larger pores in the structure. In both cases, the kinetic model tested corroborates the observed relationship between microstructure and moisture regulating capacity.