Interpretation of the optimization course of Silicon Nitride nano-powder content in biomedical resins for vat photopolymerization additive manufacturing

As the use of Additive Manufacturing (AM) expands, the need for materials capable of satisfying the demanding specifications is increasing. This is more intense in the medical field, where specifications are more sophisticated, restricting the choice of compatible materials. Herein, the performance of a medical specification resin (Biomed clear) was improved by introducing silicon nitride (Si3N4) nanoparticles as a filler. Silicon nitride is a commonly used ceramic in implants, scaffolds, etc. Composites were developed with filler loadings up to 2 wt %, for the Stereolithography (SLA) 3D printing process. Specimens were fabricated, to be assessed following international standards for their mechanical performance (tensile, flexural, Charpy impact, and Vickers microhardness). The thermal, structural, electrical, and rheological properties of the composites were investigated. Morphological examination was conducted using a field emission Scanning Electron Microscope. A sophisticated micro-computed scanner was utilized to investigate the dimensional accuracy of the 3D-printed samples and their porosity. Overall, fifteen different tests were conducted to fully characterize the nanocomposites and locate possible correlations between their different qualities. The composites with 1 wt % filler concentration presented the highest strength values (23.6 % and 44.8 % improvement in the tensile and flexural strength, respectively) and lowest dimensional deviation and porosity. Such composites have merit for use in demanding medical applications.