Evaluating the Feasibility of Processing Ceramic-Based Materials in Powder Bed Additive Manufacturing

Ceramic materials, commonly defined as metallic oxides, nitrides or carbides, exhibit outstanding mechanical, chemical, and thermal stability. Their favorable properties have resulted in a global market of more than $400 Billion and are commonly used in the electronics, automotive, tooling, defense, and refractory industries. Despite their advantages and popularity, ceramic materials are lagging in additive manufacturing (AM) technologies and comprise only 1% of the global market for additively manufactured materials. Therefore, ceramic materials have not realized the numerous advantageous associated with additive manufacturing: cheaper/faster rapid prototyping, unprecedent design freedoms, cheaper small-batch fabrication, shorter supply chains, and less material waste. This thesis evaluates the feasibility of additively manufacturing oxide and carbide-based ceramics using the binder jetting and laser powder bed fusion AM processes. This involves developing print parameters, evaluating post processing methods, understanding the effects of process parameters on part quality, and comparing printed parts to those manufactured using conventional methods. 

This thesis presents a body of knowledge, methodologies, and results that can be used as the basis to fabricate ceramic-based materials in powder bed processes. First, a comprehensive design of experiments coupled with statistical analyses determined which binder jet parameters influence the printed densities of oxide preforms. Regression models accurately predict printed densities and can assist in selecting process parameters that will print a desired density. Then, a study investigated the densification behavior of postprocessed binder jet preforms composed of three distinct oxide powders: (1) large grained, highly faceted alumina powder, (2) large grained, spherical silica powder, and (3) small grained, polycrystalline zirconia powder. The heating profiles were parametrized to understand the effect of sintering parameters on densification behavior, microstructure, and phase composition. In another study, carbides were binder jetted with a metallic binder introduced by spherical, sintered-agglomerated composite powder and post processed via sintering and hot isostatic pressing (HIP) steps. The effects of sinterHIP parameters on porosity, microstructure, hardness and oxidation behavior of these cemented carbides were evaluated. In a final study, the laser powder bed fusion process was used to additively manufacture dense carbides with a metallic binder phase. A range of processing parameters yielding highly dense (99%) specimens were discovered using a sequential series of experiments comprised of single bead, multi-layer, and cylindrical builds. The methodologies and results presented in this thesis suggest numerous exciting avenues for future research topics, many of which have the potential to significantly impact ceramic manufacturing for years to come by realizing the advantageous of additive manufacturing.