Stereolithography using compositions containing ceramic powders

Stereolithography can now be used to build three-dimensional plastic parts based on the layer-by-layer ultraviolet (UV)-curing of photo-monomers under laser irradiation controlled by Computer Aided Design (CAD) data from a computer. This thesis is an investigation of the extension of stereolithography to allow the fabrication of ceramic components. The issues that are addressed are the dispersion of high volume-fraction ceramic powder in liquid monomer while maintaining a low viscosity, UV-curing of these ceramic suspensions under laser exposure, and fabrication of ceramic parts including the debinding and sintering steps.; Photosensitive suspensions have been developed by dispersing selected ceramic powders in non-aqueous acrylate- or epoxy-based monomer solutions. The highly-loaded ceramic suspensions produced include alumina. mullite and silica dispersions which have shown viscosities and cure depths that are compatible with the stereolithography process. Examples of alumina and silica parts fabricated using a stereolithography apparatus (SLA-250) with a 30 mW He-Cd laser are presented. The alumina parts are fully densified after debinding and sintering at 1600{dollar}spcirc{dollar}C. The light scattering that occurs at the interface of the particles and a surrounding medium of a different refractive index reduces the cure depth of the suspensions by limiting the depth of light transmission. The penetration depths for these ceramic suspensions are described by UV diffuse reflectance and transmittance measurements and subsequent Kubelka-Munk analysis. Finally, a two-stream multiple scattering model is applied to the ceramic suspensions to study the fundamental parameters that control the curing behavior. The calculated results are compared with experimental data. The insight gained about the principles of the UV-curing of a concentrated suspension provides guidelines for designing suspensions with controlled curing behavior.