Mechanical properties of material jetted zirconia complex geometries with hot isostatic pressing

Additive manufacturing of ceramics stands to transform applications requiring wear resistance in severe environments (including high temperatures and pressures, harsh chemicals, and biomedical implants, among many other uses). However, applications in electromagnetics are gaining increased attention as newly-available materials like zirconia provide very low electromagnetic loss and also provide the highest permittivity possible in 3D printing with near full density. By 3D printing zirconia lattices, the density can be modulated spatially by varying strut and beam thicknesses at arbitrary positions (such as when following a spatial function). As the effective permittivity is related to the density, the speed of electromagnetic radiation (the speed of light, c) can be controlled in the 3D space. As a preliminary investigation to understand processing limits and mechanical performance, this effort has focused on evaluating the compression and flexural strength of both 3D printed solid and lattice structures with millimeter-scale unit cells post-processed with different conditions. Non-destructive computer tomography was included to identify and validate remediation of internal delamination with hot isostatic pressing. Although zirconia lattices fabricated with NanoParticle Jetting™ were relatively delicate, millimeter periodic features were possible and provided sufficient strength to maintain structural integrity for non-critical loading.