Silicon Carbide Particle Size Range Able to be Utilized for Digital Light Processing

Silicon Carbide is a hard refractory ceramic known for its uses in many applications, such as aerospace, chemical processing, and electronics, due to its properties such as exceptionally high hardness and high thermal conductivity. Digital Light Processing is a type of additive manufacturing that cures photocurable ceramic resins using UV-Vis wavelengths, with typical layer thicknesses between 15–200 µm, where a thinner layer can lead to a more detailed design but also adhesion issues. The purpose of this work is to find a range of particle sizes for SiC that can achieve, at a minimum, a 15 µm cure depth to be considered for digital light processing additive manufacturing.

These results will help confirm how particle size affects cure depth and attenuation, providing further insight into the minimum particle size a dark powder such as SiC can be and still achieve a sufficient cure depth. Particle size can greatly affect the cure depth of a suspension, as having smaller particle sizes or a greater particle size range can lead to attenuation and a smaller cure depth. SiC is a darker powder, which also affects the cure depth as darker powders absorb more light, leading to increased attenuation and a smaller cure depth.

This study continues prior work on developing sufficiently curable suspensions for the dark powder ZrC for use in additive manufacturing. The suspension system consists of an oligomer, monomer, and photoinitiator with dispersed Silicon Carbide powder, with a solid loading of 20%, and is initially processed at a 385 nm wavelength with a Dymax BlueWave MX-250 set up for down-up digital light processing. The powder is milled to different sizes using a Sturtevant open manifold micronizer jetmill at varying feeding and grinding pressures and then sieved to minimize the amount of fines in the powders.

Three powders with a d50 of 6.5, 15.088, and 16.778 µm were found to have a sufficient cure depth for additive manufacturing, which could be due to the larger particles and smaller particle size distribution.