3D printing of porous glass products using the robokasting technique

Abstract

3D printing of porous SiO₂–Al₂O₃–Fe₂O₃–MgO–CaO–Na₂O glass products with the use of the robocasting technique was comprehensively studied. Features in the preparation of glass-based pastes with gelatin or agar for 3D printing were established and recommendations on the printing of porous glass products employing a ZMORPH 3D printer equipped with a ceramic paste extrusion module were developed. The method of preparing glass/gelatin and glass/agar pastes for 3D printing was tested experimentally. Mixtures with different contents of gelatin or agar, glass, and water were studied, and conditions for their storage from the time the paste components were mixed to the time they were loaded into the 3D printer were determined. The optimal 3D printing parameters were chosen with the Voxelizer Software for the ZMORPH 3D printer with a ceramic paste extruder. A modification to the ceramic module for printing with pastes was proposed. The heat treatment process at 160 and 260 °C and sintering at 600–650 °C for the printed samples were studied. The temperature threshold at which a powdered glass material sintered without transiting to the molten state was found by experimental selection of the optimal temperature regime and holding time. Heat treatment resulted in glass samples of complex shape. The samples reached 49% porosity. The mechanical properties and microstructure of the sintered porous glass samples were studied. The wear resistance and fracture of the samples were examined by repeated scratching with a conical diamond indenter.