• Dusserre, Gilles
• Farrugia, Anaïs
• Cutard, Thierry

Abstract

International audience ; Aqueous suspensions of geopolymeric precursors are promising ways to produce glass-ceramic matrix composites by conventional liquid composite moulding processes (slurry infiltration). However, the rheological behaviour is complex and not necessarily suitable for such processes because of high viscosity values. A long “maturation” step of the suspension is therefore necessary to obtain a Newtonian behaviour, and the amount of water must be optimized to reach the desired viscosity without reducing drastically the solid fraction. This work investigates the changes in rheological behaviour of an aqueous suspension of geopolymeric precursors during maturation at -18°C. A phenomenological model is proposed to describe the effect of the “maturation” step on the rheological behaviour in the processing temperature range, before the onset of polymerization, and accounts for dilution with water. The model assumes a population of large particles (up to 1 μm) suspended in an aqueous suspension of fine particles. A full-scale separation between both particle populations allows expressing the viscosity of the suspension as the product of two Krieger-Dougherty models. “Maturation” is schematized as the dissolution of large particles into the suspension of fine particles, which is assumed to be Newtonian. A thixotropic model, acting on the effective solid fraction of large particles, is identified and results in a proper description of the viscosity of the suspension at equilibrium between 10-2 s-1 and 200 s-1, as well as during destructuration experiments at 70 s-1.

Topics

• impedance spectroscopy
• experiment
• glass
• reactive
• glass
• composite
• viscosity
• aging
• ceramic