Creation of three-dimensional structures by direct ink writing with kaolin suspensions

Abstract

The fabrication of micro-sized three-dimensional (3D) patterns with kaolin-based materials has significant potential in structural, functional, and industrial applications. In this study, kaolin suspensions with varying silicate moduli of water glass (WG) were used in direct ink writing (DIW) for assembly of 3D structures. To investigate the influence of suspension stability and writability with various silicate moduli of WG, a series of zeta potential and rheological tests were implemented. The kaolin suspension with a WG silicate modulus of 2.4 has the maximum zeta potential absolute value of 75.93 mV, which reflected the highly stabilized suspension. These rheological results demonstrated that a kaolin suspension with a WG silicate modulus of 2.4 was the optimal DIW suspension because of its good shear thinning and viscoelastic properties at a lower shear stress. The filaments in this kaolin suspension maintained their initial shape without spreading. Excellent 3D written structures with a geometrical dimension of 700 μm were successfully prepared.