Fabrication of Complex-Shaped Ceramic Components by Room-Temperature Injection Molding of Ceramic Suspension Gels

Novel forming of ceramics into complex shapes of silicon nitride Si3N4 and boron carbide B4C has been investigated. Common to our approach was to use a polymer in the ceramic-loaded suspensions. The polymer employed was flowable at room-temperature, water soluble, imparted green strength to the formed body, and in some cases, acted as a dispersing agent. Lisa Rueschhoff developed suspensions of silicon nitride powders. She was able to show that that water reducing admixtures used in concrete are effective for dispersing Si3N4 in water. These suspensions have been injection molded. Andres Diaz Cano has investigated preparation of aqueous suspensions of boron carbide powders, achieving up to 56 vol. percent B4C powder loadings. He has also studied the best sintering aids to density B4C without external pressure at low temperatures 2000 deg C. We were fortunate enough to win both a URAP and HRAP awards for the summer of 2015. In this work, we developed suspensions of alumina Al2O3 and boron carbide, and used a syringe-style additive manufacturing approach to print complex shapes. William Costakis was the undergraduate awardee, while Alycia McEachen was the high student student awardee. As a team they were very successful using a 3D printing process to make B4C parts.