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Protective Atmosphere or Inert Gas Oven

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  • Protective Atmosphere or Inert Gas Oven

    Doing a little home baking. Apparently, the recipe calls for some relatively hi-temp (1000*C) baking in a protective atmosphere. Argon maybe, or Nitrogen.

    Question is, where would I find someone who has one of these within reach? Like I know NASA has one, but I don't think I can come over and play.

    My gas oven doesn't get that hot. My friend the pottery guy has a decent kiln, but I don't think I can change the atmosphere.

    How about hardening places for tools and stuff...Would they have one? Or maybe metal casting places. Is that a good place to look?

    Thing is, it's a small, experimental job- I can't very well take it to like, General Electric R & D, or NASA. (never mind; it's a long story) Question is where might I find a friendly furnace? How about dental tech labs? Would they have one maybe, for all their weird castings?

    Any ideas?

  • #2
    The temperature fits into the range of a burn out oven used by jewelry people. The burnout ovens have a vent in the top to let the fumes out when melting wax. You might be able to use one of them and pipe the inert gas in through the vent. I would use nitrogen as a cover gas.

    We used nitrogen in our anneling furnaces in the aluminum industry but didn't got as hot as you are talking about.

    Hope this helps.



    • #3
      The heat treaters I use all have inert atmosphere furnaces. They seem to be gas fired. Most have a little flame coming out a vent on the top.


      • #4
        You can do it in a pottery kiln that is electrically heated. A simple way to do it for a one time use would be to get some polyethylene sheeting from Home Depot and make a big enough bag by folding it over and sealing it with an iron. Make the bag large enough to put the kiln inside. Get a bottle of Argon from the local welding supply with a pressure regulator and set the pressure low enough to just inflate the bag with a flow of gas going out a tube on the opposite side or top of the bag. The Argon is heavier than air so put it in at the bottom and let it exit at the top. If you put a small vacuum pump or even a vacuum cleaner on the bag before letting in the Argon you can clear the oxygen pretty quickly. You can check it by seeing when a match is extinquished by the gas flow. About 2 psi in the bag will keep it inflated tightly. Of course you can have an oxygen analyzer on the bag but I assume you don't want to spend a lot of money. When the gas has been flowing a while turn on the kiln. It might be a good idea to have a flow into the kiln with an extra hose and a piece of metal pipe to some point on the outside but when the furnace starts to get hot the atmosphere will change from convection. If you think about it you can come up with a way to close the lid from outside the bag so that you can leave the kiln open while you are purging the oxygen. This bag idea is fairly common when TIG welding large titanium fabrications since Ti oxidizes badly when it is at welding temperature and needs more shielding than the TIG torch gas flow can provide.


        • #5
          Wow, great answer! All of them. Now I at least have a clue on where to begin.


          • #6
            What yah making Rob? You're not trying to anneal Thrud's meatloaf are you?

            Just curious.



            • #7
              Depending on part size and material another idea is to use a product called StayBrite (sp). Heat the part to a few hundred degrees, sprinkle the StayBrite powder onto part and continue heating. StayBrite forms a crust on the part to prevent oxidation.

              StayBrite is made for heat treating, which I've used it for. It works well, several parts I've used it on came out bright and shiny after heating and quenching. The only downside I know of is if you have small tapped holes it can be a pain to chip it out (still better than having a scale on the part, though).


              • #8
                Helped a man who made those pins used in multipin connectors (boy, there is a lot more to those pins than you would think). Hehadto heat treat in a inert atmoshpere. He started with a pottery kiln, gas from a bottle. Too much gas lost. final configuration was to wrap in heat treating foil shove a pipe through the kiln wall, into the foil wrapper. Itworked well, pressure was just a fraction of inch of water. We discussed making a sealed container, but the gas costs drop so much that we played with other things in the operation and never did the box business. it was very much like cass's way except the "bag" was in the box (kiln). The foil was reusable, just a few thousand pins on the foil roll it gently and pipe through the end of the roll.