Innovations in the formulation of zirconia ceramics for additive manufacturing by digital light projection: development, mechanical analysis and case study

Abstract

The development of zirconia ceramic formulations for additive manufacturing has been assuming increasing relevance given the importance of these materials for different industrial and biotechnology applications. The super-loading of powders in the ceramic suspension is the key to densification of the parts during sintering, where resins aided by solvents, dispersants and organic vehicles exert a particular influence not only on the reduction of suspension viscosity, but also on the interaction between deposition layers and, above all, in the final mechanical properties of the sintered part. In this project, new advances will be tested in the formulations of yttrium-stabilized zirconia ceramic suspensions for additive manufacturing (AM) by digital light projection (DLP) and vat photopolymerization (VP) that will be prepared using a minimum amount of solvent and vegetable oils as dispersants. These formulations will be characterized by analyzing the rheological behavior (through the viscosity test), stability (through the sedimentation test) and modification of the surface of the powder particles (through the "Fourier transform infrared spectrum"). After defining the appropriate proportions of each element of formula composition, ceramic parts will be manufactured in a machine designed and built for this purpose. After sintering, samples of appropriate dimensions will be evaluated for shrinkage and density and will be subjected to mechanical tests for flexural strength, compression and wear; other parts will be analyzed by scanning electron microscopy (SEM) for the presence of porosities and cracks and for surface roughness. A case study will be carried out on orthodontic brackets produced with the studied formulations, which will be submitted to tribological tests, aiming at the application of the results in orthodontic practice and for possible future industrial production. (AU)