3D printing in silicon nitride

With the advancement of technologies, more industries are considering new manufacturing methods to reduce cost and time while ensuring quality and consistency. One such manufacturing method is Three-Dimensional (3D) printing. This project’s focus is to study the characteristics of various sintering additives in Silicon Nitride (Si3N4) as a 3D printable feedstock. The study will be conducted with Si3N4 powder, polyacrylic acid, polyethylenimine solution and methyl cellulose powder. For all experiments, Si3N4 liquid suspensions are kept at a fixed volume of 10ml. Experiments are broken down into 3 major components (a) varying concentration of solid loading, (b) varying concentration of dispersant and (c) varying concentration of rheology modifier. Observations on the characteristics of Si3N4 liquid suspensions are determined by Rotational Rheometer (Discovery Hybrid Rheometer-2, TA Instruments, UK), Archimedes Principle and Scanning Electron Microscopy (SEM) (JSM-5600 LV, Jeol, Japan). As observed in the viscosity graphs produced by rheometer, shear thinning phenomenon was demonstrated in Si3N4 liquid suspensions. Increasing concentration of solid loading and rheology modifier results in increase in initial viscosity whereas increasing concentration of dispersants decreases initial viscosity but illustrates better shear thinning properties. From the Archimedes principle and SEM results, we analysed that higher concentrations of solid loading causes Si3N4 liquid suspensions to increase in density, showing a lower rate of agglomeration. While higher concentrations of dispersants and rheology modifier shows a decrease in density and higher rate of agglomeration. The results of this initial study would be useful for further investigations to achieve the best Si3N4 composition for 3D printing of Direct Ink Writing.Bachelor of Engineering (Mechanical Engineering