Stereolithography 3D-Printing of Ceramics, Master Thesis work, Teemu Vastamäki
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Additive manufacturing has been found to be suitable processing method for ceramic materials in recent years. For other material groups, like plastics and metals, the 3D-printing is widely studied and the industrial markets are growing. For ceramics, there is still a lot to study before its potential in ceramic manufacturing can be acquired. Stereolithography (SLA) is one method to 3D-print ceramics. Stereolithography uses photons to initiate polymerization reaction at monomer, oligomer or prepolymer solution. In stereolithography, the ceramic powder is dispersed in monomer medium and polymer network is printed around the particles. These monomer solutions can be the same as used in the plastic stereolithography 3D-printing. Usually the main components of the monomer solution are acrylates, methacrylates or epoxies. To polymerize the monomers, proper photoinitiators is added. Photoinitiator should be chosen according the photon wavelength that the SLA printer is using and the reaction type that it should initiate, radical initiators for acrylates and methacrylates and cationic initiators for epoxies. During this Master thesis work new slurry is tailored and commercial Lithoz GmbH manufactures slurries are studied. Only small components can be made so far. One limiting factor is the layered structure that are prone to the delamination. Delamination leaves cracks and flaws at the surface, reducing the mechanical properties of the ceramic component and bigger components than few cubic centimeters could not be printed with sufficient mechanical properties. The overall processing time of the ceramic 3D-printing is long, even small component takes over a week to process. This is because of the heat treatments that are necessary for the process takes long time. The post thermal curing and polymer degradation at 3D-printed ceramic parts is studied in this Master thesis work. With the newly tailored slurry, consisting from the acrylate-monomer body and aluminium oxide particles, the heat treatment’s total time was reduced significantly compared to the commercial Lithoz GmbH’s slurries. Ceramic components are successfully made and printing properties are studied widely with all slurries. This study also highlights the aspects in stereolithography ceramic 3D-printing that requires further studies.