Binder removal from ceramic stereolithography green bodies: A neutron imaging and thermal analysis study

Abstract

AbstractStereolithography of ceramics remains one of the most powerful additive manufacturing routes for the creation of intricate ceramic parts. Despite its utility as a forming tool, ceramic stereolithography requires a challenging debinding stage due to the requisite high polymeric loading. Earlier research has identified both the polymeric resin composition and debinding atmosphere to be crucial factors in improving debinding performance. Here, we use a combination of thermogravimetric analysis and neutron imaging to examine samples of different compositions printed using the same processing and exposure parameters. We quantify the influence of both polyethylene glycol addition and the use of different debinding atmospheres (argon and vacuum) on the debinding behavior of ceramic pellets. Specifically, we demonstrate a method for examining the concentration gradients that develop during thermal debinding with the aid of neutron tomography. We find that at a constant heating rate of 1°C/min up to 500°C, vacuum atmosphere appears to result in a greater number of cracks as compared to the use of argon. The vacuum atmosphere led to the development of lower concentration gradients in the samples on average. The greatest improvement resulted with the addition of polyethylene glycol to the samples. This addition led to significantly less cracking and much lower concentration gradients in samples during debinding. These results prompt us to conclude that while keeping printing and exposure parameters constant, composition modification has a more significant effect on the debinding improvement than heating atmosphere.