Fabrication of Sialon ceramic via non-aqueous gelcasting based on the HEMA gelling agent

Abstract In the traditional raw materials used for preparing Sialon ceramics, hydrolytic AlN, cannot easily be used for aqueous gelcasting. To overcome this problem, a new type of gelcasting technique was developed. By introducing 1-methyl-2-pyrrolidinone (NMP) as a solvent, Sialon ceramics were formed using a low-viscosity non-aqueous gel system based on the 2-hydroxyethyl methacrylate (HEMA) gelling agent in this work. Based on this gel system, the rheological properties of the slurry and the solidification and sintering properties of Sialon ceramics were studied. The results show that the best rheological properties of slurry can be obtained with the dispersant dosage of 6 vol%. As the HEMA content increases, the flexural strength of the green bodies increase. When the ratio of HEMA to TMPTA (trimethylolpropane triacrylate) is 10:1 and the HEMA content is 15 wt%, the flexural strength of the green body reaches a maximum of 13.07 MPa. β′-Sialon ceramic has the best comprehensive mechanical properties at the sintering temperature of 1700 °C. Its bulk density, Vickers hardness, fracture toughness and flexural strength were 3.207 g/cm3, 1484 HV, 7.11 MPa m1/2 and 351 MPa, respectively.