outgassing and vaccuum ovens...

[Gibson486]

Not really electronic related, but I have a question about out gassing. Do vacuum ovens make out gassing worse? i was under the assumption that people use vacuum ovens to limit the amount of out gassing. is this wrong? Also, when I put a material in google and put out gassing next to it, it gives me mixed results. For example, searching for silicon, the first link says it out gasses alot, but other links say Nasa used it because it does not out gas as much. Which is it?

[Kleinstein]

Heat up the material will increase the rate of out-gassing while the material is hot. If done long enough the gas content can be reduced so far the after cooling back to normal there will be less gas coming out.
The high temperature treatment may also change the material - some may show more out-gassing later, especially if heated to much.

With silicone there are many different types. Especially silicone based plastics that can be quite different from the silicone sealant that only hardens later. The usual silicone sealant in know to out-gaz a lot and for serious vacuum it is not considered gas tight at all, more like fine filter that easily lets water vapor pass through.

[wizard69]

Not really electronic related, but I have a question about out gassing. Do vacuum ovens make out gassing worse? i was under the assumption that people use vacuum ovens to limit the amount of out gassing. is this wrong?

It depends upon what he oven is used for.    For example heat treatment of metal under vacuum is done often to reduce oxidation.    If you get a bit hotter the oven can melt the metal and under vacuum degas it.    Using vacuum to degas in an oven or not is very common in industry.   So yeah a vacuum can accelerate a degassing operation.   I'm not sure how putting something under vacuum could ever limit out gassing as it would rather accelerate it.

Also, when I put a material in google and put out gassing next to it, it gives me mixed results. \

That statement makes no sense to me.

For example, searching for silicon, the first link says it out gasses alot, but other links say Nasa used it because it does not out gas as much. Which is it?

I guess the first question is why are you asking.   Because I suspect that the details matter.

[ConKbot]

I think some of the confusion here is a bit of difference in the meaning of outgassing. For NASA they are looking for <1% mass loss, and for <0.1% to condense on a 25C surface.

For general vacuum systems you're talking about anything that can spoil your pumping efforts.  So if a particular silicone picks up 0.85% moisture, it can be low outstanding per NASA standards, but still frustrating you in a vacuum system as it ourgasses water for days.