Kilnkilnkiln2017 Posted July 18, 2017 Report Share Posted July 18, 2017 Good Afternoon, I'm using a Paragon HT22 kiln with the Dwyer gas inlet flow meter. I'm producing small wire springs (stainless steel) that need to be heat treated in order to secure their final form. In my regular smaller kiln, the oxygen in the atmosphere is reacting with the heated stainless steel and results in pretty intense discoloration (brown/dark purple/etc). Using my new kiln with a tank of Nitrogen gas hooked up, I am able to produce springs that have only a slight blue discoloration. This drastic reduction in discoloration/oxidation means that the nitrogen gas is working it's magic, and pushing the vast majority of oxygen out of the kiln, creating an ALMOST perfect inert atmosphere. The question is: IS IT PHYSICALLY POSSIBLE to create a perfectly inert atmosphere in the kiln? Is there something I'm not seeing here? I'm investigating trying to get a higher flow dwyer meter to allow me to pump nitrogen in at a higher rate, but in my gut, I feel like it's not possible. The removal of this blue oxidation requires a chemical bath, which is certainly within my ability to perform, but I'd really rather not. Does anyone have any experience with these gas injected paragon kilns? Any words of wisdom/tips/tricks? Appreciate the help. Kiln on. Link to comment Share on other sites More sharing options...
Magnolia Mud Research Posted July 18, 2017 Report Share Posted July 18, 2017 I suggest you check out the writings by Dan Herring, aka The Heat-Treat-Doctor http://www.industrialheating.com/topics/2666-the-heat-treat-doctor He also has published a book on heat treating. LT Link to comment Share on other sites More sharing options...
jrgpots Posted July 22, 2017 Report Share Posted July 22, 2017 You may want to pump in Argon instead of nitrogen. I would suggest making a saggar that has a small inlet for the gas. Jed Link to comment Share on other sites More sharing options...
cabako Posted July 24, 2017 Report Share Posted July 24, 2017 have you checked the purity of your gas? You could try using lab grade ultra high purity "UHP" nitrogen or argon. Maybe if the kiln was under vacuum it would be perfectly inert....can you put a kiln that high temp under vacuum? Link to comment Share on other sites More sharing options...
No Longer Member Posted July 31, 2017 Report Share Posted July 31, 2017 have you checked the purity of your gas? You could try using lab grade ultra high purity "UHP" nitrogen or argon. Maybe if the kiln was under vacuum it would be perfectly inert....can you put a kiln that high temp under vacuum? Most "nitrogen" that is commonly available is just regular compressed air that it's "purity" is a measure of moisture content, not the amount of nitrogen. That "green" stuff they put in you tires now is exactly that; they just finally figured out a way to charge you $29.99 to put air in your tires; it's still only about 60-70% nitrogen. The problem of putting a kiln under a vacuum lies in the material it's made of and the shape thereof. I've considered flooding with argon before but never had a good enough reason to do so. I'd rather run a bead with my gas that fire a pot. Link to comment Share on other sites More sharing options...
cabako Posted July 31, 2017 Report Share Posted July 31, 2017 To follow up: you could also try an oxygen trap found here: http://www.sigmaaldrich.com/catalog/product/aldrich/z290238?lang=en®ion=US I would use UHP grade nitrogen ( trace amounts 100ppm or less usually of hydrocarbon, oxygen, and water) and then place an oxygen trap in line to get the last traces of oxygen out of your gas. Link to comment Share on other sites More sharing options...
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