Manufacturing of lithium disilicate glass-ceramics by Vat-photopolymerization of water-based photocurable suspensions

Abstract

In this work an eco-friendly methodology to manufacture lithium disilicate complex parts using a water-based photocurable suspension is proposed. The particles surface was modified with polyethyleneimine to improve it rheological and chemical stability in water media. The surface functionalization of powders allows the formulation of high solid content slurries with relatively small (17–20 vol%) amounts of poly(ethylene glycol)diacrylate (PEGDA) as reactive monomer and Lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) as photoinitiator. The printing parameters for Vat-photopolymerization were determined based on photo-rheological measurements. Simple geometrical shapes were successfully printed with suspensions containing 42–45 vol% of solids for structural and mechanical characterization. Due to the aqueous-based media, a fast debinding cycle was employed (≈ 10 h), resulting in sintered samples with ≈ 98 % of relative density and a flexural strength of ≈280 MPa. The optimized photocurable suspension and printing parameters were then selected to print different kind of dental prostheses as a proof-of concept.