Cleaning PEEK to UHV Standards

I think there are some substitutes for tri-chlor (trichloroethane) that may be suitable. It really depends on how much you use and what regulations exist.

Other than that, a hydrogen furnace does an amazing job.

Is the part injection molded? Machined?

Be careful of stresses when using solvents. I'd think a vacuum bake would be as good as anything.

What are you trying to clean off the PEEK?

The contaminant will determine which solvent(s) to use.

Just general handling & machining contaminants. The parts look pretty clean but we need to ensure that any oils or solvents are removed as any trace will show up on a mass spectrometer & confuse experiments.

If you use a cleaning solvent that is totally foreign to the monitored process (experiment) then any traces of it could be disregarded or filtered from the data. Same same for the other known contaminants.

peek is pretty impervious to solvents so I figure thorough rinsing with a solvent that cuts the contaminants and then vacuum drying would work. Holding at temp and vacuum and monitoring till traces of solvent contaminant are no longer detectable. Don't run the experiment till you get the all clean signal....?

Have you tried contact cleaner yet? Claims to leave NO residue and is plastic safe.

Alchohol perhaps? Soapy water then flush with DMW.

You might need two or more stage cleaning. Stage one cuts the contaminant, stage two cuts the first solvent and so on.

You appear to have the kit so start experimenting.

PEEK is not the best choice from an outgassing point of view.

PEEK

(PolyEtherEtherKetone)

PEEK is pure, easily machinable, chemically resistant, stable, and also has relatively low outgassing values ( 0.31% TML, 0.00% CVCM, 0.06 % WVR). PEEK has good mechanical properties, but will not take temperatures over 350°F, so it may not have the mechanical or thermal performance needed.
Check out www.boedeker.com/outgas.htm

Thanks for all the suggestions. I think we've pretty much decided on a wash in alcohol, several stages of demin water ultrasonic & a vacuum bake at below the glass temperature for PEEK, around 100°C.

I'm guessing you are aware that if you experience an out-gassing problem under UHV conditions, it won't matter how well you have cleaned the outside surface of the PEEK. For that reason, I suggest you take a closer look at materials such as PCTFE which exhibit better out gassing properties. Of course, you may have additional requirements (strength, machinability, etc.), but haven't specified them.

Outgassing is not really the problem as the system will be continuously pumped, I was more concerned with avoiding adding soluble material to the PEEK. There are additional requirements as you say, machinability, stiffness, dielectric strength so PEEK seemed the best option.

How did you cleaning process workout out? My Peek parts are currently baking at 100C, at atmospheric pressure. I'm thinking of leaving it over night.

Regarding running the baking process under vacuum I wonder if this will only speed up the outgassing process?

Hi,

I have been seeing, what I thought to be carryover, but if what you say about acetone is correct, it might be that the acetone is being absorbed into my peek?

I place the unit at about 150C in 0.1 torr for 10min.

Our system worked great, it was part of a Velocity Map Imaging system. We built 2 systems at the same time for 2 customers & they both got delivered and have produced really good results. We are hoping to build 2 or 3 systems a year. The PEEK parts did not give any problems.

Glad to hear the project went well.

Hi Nigh,what kind of vacuum were you able to achieve with the PEEK parts in the system? Just wondering if they are really UHV compatible without a long bake out.I'm working at research lab, and a current concept is to use a great deal of PEEK in a HV/UHV (10^-8 Torr) beamline, but we have no good data on outgassing rates for PEEK.

Our systems are working at 10^-9 or 10^-10 Torr & have been in use for over a year with out any problems. As mentioned before, these systems are continuously pumped so any outgassing might not be noticed.

That's great to hear, that's the region we're aiming for. Would you be able to give an estimate of the area of the PEEK and the pump size or pumping speed? We're looking at a substantial amount of PEEK in the beamline, and our pumping is usually sized to deal with the outgassing of the stainless and aluminum that is part of the beamline.Many thanks,

In these systems the area of PEEK was quite low, around 20cm² & the system was pumped by 2x Edwards Maglev pumps. We have used bigger areas of PEEK since then but these would all have been supplied to customers to attach to their own systems so I have no information about pumping.

Stop searching the term vacuum and posting your website Doris.