Characterization and Process Improvement of Extrusion-Based Ceramic Additive Manufacturing Process

Advanced ceramics have been increasingly applied in the electrical industry, such as sensors, capacitors, resistors, aerospace areas (e.g. jet engine turbine) [1], automotive areas (e.g. brake discs and spark plug) [2], and biomedical areas (e.g. teeth, dentures, bone and joint) [3] due to their outstanding properties including lightweight, good electrical insulation, stability at high temperature, thermal insulation, and low erosion rate [4]. Moreover, additive manufacturing of advanced ceramics is advantageous in manufacturing flexibility and high degree of part complexity. The material extrusion of advanced ceramics, compared with other additive manufacturing techniques, could generate high-density ceramic parts with great mechanical properties at low cost.

In this study, binder-coated zirconia, as a rod-shaped raw material, was supplied to a piston extruder in a customized 3D printer to fabricate green structures, by considering rheological properties of the binder-coated zirconia. In addition, effects of process parameters such as material flow rate, extruder temperature on the dimensional accuracy and microstructure of a part were investigated. A polymer binder of green parts was removed through a solvent and thermal debinding process, and then densified by a sintering process to obtain a solid ceramic structure. In addition, mechanical properties of printed structures were evaluated by varying process parameters such as layer thickness and rater angle. Furthermore, in order to improve the dimension accuracy, warping was minimized using a heating bed as well as heating chamber. Using the customized 3D printer and material, several zirconia structures were successfully fabricated, ending up with improved mechanical properties comparable with other ceramic additive manufacturing methods.

With binder-coated zirconia as a raw material, through the material extrusion additive manufacturing method, a high-solid ceramic structure with great compressive strength, high-temperature strength, and fracture toughness properties which are hard to achieve through other additive manufacturing methods (such as stereolithography and selective laser sintering) could be manufactured. Process improvements have not only expanded the application range of ceramic additive manufacturing, but also exerted a significant industrial impact on the production of high-performance ceramic structures.

Reference

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