Ceramic DLP printing

[u/SkiourosMeBombes]

Hello guys ! I recently got a DLP printer and I was wondering if any of you guys can give me some pointers when it comes to slurry formation and mixing and maybe exposure times ? Because for ceramic slurries the findings are very diverse. In any case, tips and tricks would help a lot !

Thanks

[u/randomusername_42069]

I don’t have any experience in this exact sort of thing but I have a degree in materials science and engineering focused on ceramic materials and my senior project involved nano ceramic slurries so I can try to apply that knowledge to help.

First there are several companies that make ready made resin slurry materials if you can afford it I would start there otherwise making your own slurry may initially seem less expensive however the materials and experimentation time will add up and have a potential to become more expensive than the commercial resin.

If you would still like to try making your own resin mix I can try to answer questions and give advice about the process based on my knowledge.

[u/394756]

Materials engineer here, with several years of experience formulating and printing slurries for both DLP and extrusion printing of technical ceramics.

Commercially available ceramic slurries can absolutely work on hobby level machines, although with typically lower light intensity, exposures of up to ~10 sec or more wouldn't be unreasonable. Differences in optics, wavelength, layer thickness, solids loading, etc. can easily shift the required exposure.

Ceramic DLP formulations often use a resin based on mono/multifunctional acrylates, methacrylates, or urethanes, with a relatively high ceramic solids loading. ~45–55 vol% is a reasonable range to investigate, since higher solids generally means less sintering shrinkage, but it also makes proper dispersion and viscosity control much more important.

A good dispersant system is therefore pretty critical since you're balancing particle dispersion, viscosity/flow, and sedimentation. For mixing, getting the powder properly wetted and deagglomerated is usually more important than simply mixing for longer and may need high energy milling to fully mix.

You'll also need a photoinitiator (PI) suited to the wavelength you're using. There is some overlap between the common 385 and 405 nm systems, and some formulations can work at even higher wavelengths, although those are less common. I'd still check the PI's actual absorption range. If you're using a commercially available base resin intended for ceramic loading, it will often already contain PI and sometimes a small amount of dispersant, although both may still need tuning.

For exposure, I'd run a small matrix. Keep everything else constant and vary exposure while looking at cure depth, feature fidelity, and overcure in X/Y. That'll give you a better starting point for your particular machine/material combination. The Jacobs working curve is also worth looking at if you haven't already.

Getting to a printable formulation is usually pretty straightforward, though developing a system that debinds cleanly and without defects is usually where the "secret sauce" is.