Low-toxic gelcasting of zircon ceramics

Abstract

Zircon (ZrSiO4) ceramics are highly valued in various industries due to their exceptional physical and chemical properties. In the present work, zircon ceramics with high-density and desirable mechanical properties were successfully prepared using an aqueous gelcasting method, involving the use of a low-toxic and water-soluble monomer, N,N-dimethylacrylamide (DMAA), as the binder. A high solid loading and low viscosity zircon slurry was achieved by optimizing the pH and the dosage of the ammonium polyacrylate (PAA-NH3) dispersant. Zircon green bodies fabricated through the gelcasting method exhibited uniform microstructures and relatively high mechanical strength exceeding 11.0 MPa. The impact of solid loading on the density, decomposition, flexural strength, micro-hardness, and microstructure of the final ceramics were carefully studied. Notably, the ceramics, prepared by solidifying the slurry with a 45 vol% solid loading and sintering the green body at 1550 °C for 2 h, exhibited a relative density of 96.3 %, high phase purity, a uniform microstructure, and the highest flexural strength of 407.9 MPa. The results demonstrate that mechanically robust dense zircon ceramics can be effectively prepared using the low-toxic gelcasting method.