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Polyethylene coating at elevated temperature

 

We are interested in coating aluminum parts with polyethylene to maximum thicknesses of 0.005". The coating will be immersed in aqueous LiCl at 300 F for extended periods. Such an environment would be extremely corrosive to aluminum. If there are no pinholes and no mechanical loads on the substrate, would the polyethylene protect the aluminum. I suspect the film would soften because of the high temperature, but would there be more serious consequences, such as embrittlement and cracking?

Tom Tonon
- Princeton, New Jersey

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Tom,

I really feel the Pe will fail @ 300 degr. C ... also, never having 'handled' LiCl, I'd be very, very wary of using it.

So what can you use? PP would be better but I feel that the temperature is still far too high. PVDF might be OK but it's nbg in high pH, especially that hot. It's normal max. reommended temperature is l40 versus 80 or so for PP and 70 or so for h.d.Pe.

What about one of the fluorocarbons (tefzel, halar or FEP?) I'm afraid that that will be your only answer but I'd be very pessimistic that you would be able to coat it to such a thin veneer as low as 0.005".

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).