Effect of Particle Size, Binder Selection and Sintering Aid on the Properties of µ-featured Silicon Carbide Parts
V.P. Onbattuvelli, S.V. Atre
Oregon State University, US
Keywords: pre-ceramic polymer, binder, sintering aid, torque rheometry
Abstract:Influence of particle size and sintering aids over the mechanical properties of the fabricated silicon carbide parts was investigated. Commercially available pre-ceramic polymer like polysilazane is used as the binder with its concentration ranging from 30-40 vol.%. Both micro and nanosized SiC particles are used as powders. The powder/binder is first crosslinked (vinyl polymerized) at 150 °C in the presence of peroxide initiator. The “Green” thus synthesized is then sintered under inert atmospheres at different temperature cycles. TGA along with mass spectroscopy is performed on the sintering parts at different temperature zones. Mass loss due to the evolution of ammonia and hydrocarbons is noticed. Possible mechanisms involved in these evolutions are discussed. Ceramic yield, composition and porosity are determined along with the mechanical properties. SiC parts are also prepared by using conventional thermoplastics (combination of polypropylene, wax and stearic acid in our case) as the binder. Torque rheometry is used to determine the optimal solids loading. The µ-featured parts thus prepared with 2 different binders are compared for their properties. Comparative studies are also conducted on the influence of the particle size over the microstructure and mechanical properties. Alumina (Al¬2O3) is included to the mixture as the sintering aid. Addition of Al2O3 is found to reduce the sintering temperature, % porosity thus enhancing the mechanical properties.