Stereolithography of ceramics.

Abstract

Rapid prototyping or freeform fabrication has become one of the fastest growing new technologies since its introduction in 1986. These prototypes are fabricated freeform directly from computer aided design (CAD) files without the use of molds. 'Stereolithography' was one of the first rapid prototyping technologies. This technique involves the polymerization of liquid monomers from exposure to ultraviolet radiation from a laser. With a stereolithography machine (SLA), a three-dimensional part or prototype is fabricated in a layer by layer process. The stereolithography process fabricates highly accurate objects in a matter of hours, but only a few polymeric materials are available now. The menu of available materials must be expanded, where one such area is in ceramics. With ceramic stereolithography, this process would fabricate net shape ceramics without the need of molds. For ceramic stereolithography, ceramic powders are added to a UV-curable solution. After the ceramic suspension is cured by the laser, the result is a ceramic green body where the polymer is used as a binder to hold the ceramic particles together. This net shape green body is subsequently fired, to remove the binders and sinter the ceramic. This dissertation addresses the freeform fabrication of ceramic materials using the technique of stereolithography. The main issues include rheology of highly concentrated ceramic suspensions, ultraviolet curing of these highly concentrated ceramic suspensions (experimental and theory), and ceramic part fabrication on a stereolithography machine. We have considered a range of ceramic materials, including silica, alumina, and silicon nitride. These were dispersed as powders in a variety of ultraviolet-curable solutions to create stereolithography suspensions. Freeform fabrication of ceramic parts has been achieved using a stereolithography machine.