Deflocculation and stabilization of Ti₃SiC₂ ceramic powder in gelcasting process

抄録

This paper presents results on the deflocculation and stabilization of Ti₃SiC₂ that are crucial for determining the quality of the ceramics after sintering in colloidal processing. Five different dispersants diammonium hydrogen citrate, citric acid, polyethyleneimine, polycarboxylic acid and ammonium polyacrylate were examined by measuring the zeta potential and performing stabilization tests and rheological measurements. The dispersant, found to exhibit the most desirable properties, was then used in the gelcasting process as a novel and attractive means of obtaining high-quality Ti₃SiC₂ materials with a complex-shape without the addition of pressure. Furthermore, the utility of a glycerol derivative as a low-toxicity, water-soluble monomer in the fabrication of Ti₃SiC₂ by gelcasting was examined. Our measurements showed that polyelectrolytes such as polyethyleneimine, polycarboxylic acid and ammonium polyacrylate have a positive effect on the deflocculation and stabilization of Ti₃SiC₂ ceramic suspensions. Nevertheless, only ammonium polyacrylate effectively stabilizes the Ti₃SiC₂ slurry in the gelcasting process. Using ammonium polyacrylate, it was possible to obtain both high solid loading of approximately 60 vol % and a low-viscosity suspension. Using a suitable monomer and dispersant, the green bodies with a high density (62% of the theoretical density) were obtained, which resulted in ceramic part with high mechanical strength. The tensile strength of the green bodies was approximately 1.5 MPa.