polymer film that is resistant to fluorine etching? 1

[chrissieb]

I am looking for a solution to our etched glass problem. Currently the flourine gas being given off in our plant is causing the glass (particularly that of mobile machinery) to become etched, making it near impossible to see through.
Does anyone now of a particular kind of film we could use to coat the glass with so we are not constantly replacing it?

 

[btrueblood]

Geez, do you drive around in a fluorine fog all day? How do you breathe? Fluorine will etch or attack darn near everything (even teflon). You might try wiping a light film of Krytox grease on the glass to restore some transparency, also it may form a protective barrier that will add some life to the glass. I think standard automobile "safety glass" is a soda-lime glass (i.e. nothing special). You might try replacing it with sheet borosilicate (i.e. Pyrex) glass, or even straight fused silica/quartz, ideally flame-treated.

 

[moltenmetal]

Sounds like the glass is the least of your problems. Sounds like you have a very major health and safety issue there...

Fluorine is going to be tough on transparent materials of any sort, if there's enough around to etch glass. You may get more transparent life out of a polymeric material than out of glass in this case.

Correct me if I'm wrong, but fluorine isn't really the issue here, it's fluoride ion. Perhaps a polymeric coating on the glass would do the job. Most of the coatings will be permeable to fluorine gas, but as long as they're not permeable to water there won't be anything to solvate the glass and carry it away. A wax may be sufficient for this purpose.

 

[unclesyd]

As stated by moltenmetal wax will help stop the attack on glass. Hydrofluoric Acid used to be transported and stored in wax coated containers prior to the advent of polyethylene and polypropylene.

My biggest concern is the personnel exposure to the fumes that are etching the glass as posted by btureblood. The damage done by fluorine and it's products is insidious in that the body has hard time repairing the damage even if one is removed from the source. We had to abandon a very efficient process because of the problem with HF fumes.

 

[btrueblood]

Straight hydrocarbon waxes will provide a temporary protection from HF, but almost no protection to pure F2 gas; the raw fluorine will attach to the C & H atoms in the polymers to create HF. Fluorinated hydrocarbons (like Krytox) might last a bit longer, since some of the side chains are already fluorinated, thus the F2 gas is a little more likely to just do an "exchange" with the existing F atoms. Pure fluorine gas will "rot" through even pure quartz. About the only way to hold onto it is to use very thick steel. Again, if the gas concentration is high enough to etch window glass, like unclesyd points out, the toxic effects on personnel are nasty. HF, even in low concentrations, will attack the calcium in bones, and causes a nasty condition similar to leprosy in persons who handle the liquid without good gloves.

 

[westcoastr]

ditto on the dangers of F gas floating around. i've worked with HF and we had to carry around antidote syringes with us. we were forbidden by code to use any glass in our process but I would check with one of the semiconductor equipment manufacturers (applied materials, novellus..) as they use NF3 to generate F ions in their machines to clean them. many of these have glass windows so you should be able to get the glass specs from their websites. let me know if no luck and i could ask around.

westcoastr

 

[ribrin]

Chrisseib:

I am not sure you still looking for the film material that will help in a fluorine environement but an excellent material that can be manufactured into a film pyrolytic graphite. This material is impervious to corrosion of F2.

 

[MikeHalloran]

Try Rain-X.

I honestly don't know if it's resistant to HF or F, but it's resistant to everything else, and you can still see through it.



Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA