I want to fabricate a sample holder and shadow masks to use in vacuum chambers. The type of printing material is not important to me PLA/ABS/PC-ABS/nylon).
I'm worried that 3d printed objects (FDM) would degas under high vacuum. Is that an actual concern?
I found much the same question at Does PLA outgas? An answer there pointed to a NASA outgassing database, Outgassing Data for Selecting Spacecraft Materials, and says that:
ABS (unknown supplier), MakerGeeks PET and Makerbot PLA have been measured and are listed in the NASA database.
Poster there recommended PLA for lower outgassing, and clear PLA because there would be fewer additives to complicate the problem.
Almost all of the FDM materials outgas even at normal atmospheric pressure, and, in fact, most plastics outgas. Further, FDM and many other printing processes do not guarantee no internal voids - meaning that putting a 3D printed object into a vacuum may result in breakage, cracking, and possible explosion hazards.
For this reason I would focus only on SLA, as the model is printed within the liquid resin pool and should have a reduced possibility of internal voids.
Finding a resin that has a low out-gas rate after curing, though, is still going to be difficult.
For this to be answered more completely, you need to specify your tolerable outgassing rate, and the processes used inside the vacuum chamber. For instance the answer would be completely different if you are discussing an electron microscope vs a sputtering chamber. As a start you might consider companies that specialize in engineered materials intended for vacuum use. They may be able to provide guidance as to which of their materials might be 3D printed and usable in your setup.
This naturally depends on the ultimate pressure you require. I have made a few tests with LEGO pieces (ABS) in vacuum and reached 10-5 mbar without problems. I did not try to go any lower.
Otherwise, have a look here: A 3D printed beam splitter for polar neutral molecules.
A Formlabs Stereolithography machine was used there, producing a material that basically is PMMA. Pressures in the 10-8 mbar range are possible with that. Recently, Formlabs has presented a resin that produces heatable plastic up to 280°C, and that can be baked to get into the 10-10 mbar range (tested here).
At work, I put a 3d ABS part printed via 3d hubs (5*20*30), in the chamber at 1 mbar. No signs of breakage what so ever. No signs of sudden leaks.
Going anywhere below 1mbar, i.e., to 10^-infinity mbar, I think should theoretically still not cause any breakage or sudden leaks, as the expected mechanism of failure depends on the pressure difference; i.e., [1atm-1mbar] ~=[1atm-10^-infinity mbar].
Based on the above I have made some more parts to be put in a chamber at 1E-5 mbar.
