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Thread: Liquid Nitrogen

  1. #21
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    Default Re: Liquid Nitrogen

    Tell that to the people who I burn skin lesions off of with it. I feels like a hot coal on your skin, and the spot dies and falls out in a couple of weeks. Please don't play with it at home.
    How is it being applied?

  2. #22
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    Default Re: Liquid Nitrogen

    > You can actually immerse your hand into liquid nitrogen BRIEFLY with no ill effects.

    I cringe just reading this. PLEASE, no one attempt this!!!
    Michael Bush bushfarms.com/bees.htm "Everything works if you let it." ThePracticalBeekeeper.com 40y 200h 37yTF

  3. #23
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    Default Re: Liquid Nitrogen

    Quote Originally Posted by gmcharlie View Post
    Never used it on hot steel?? (oil or sodioum only) how does it react?
    Well, it reacts a lot like you'd expect when putting someting thats arounf 1500deg into something at negative 300 deg. a fair bit of isntant boiling going on. this must be done in a well ventilated area becasue it quickly puts out a lot of nitrogen gas. The end result was a very nice knife, but i don;t think it was worth the effort. i havent had a knife break yet, but i wanted to try it as i had read a fair bit on the subject.

  4. #24
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    Default Re: Liquid Nitrogen

    Quote Originally Posted by dnichols View Post
    I teach this concept to my physics students. Would I recommend the practice. NO! But it is a cool physics principal. Key words here guys! Briefly and momentarily. There will be a quiz on this tomorrow.
    Will the appropriate use of the word principle also be on this quiz? Your principal may take a dim view of being dipped in liquid nitrogen, regardless of the principle you are attempting to illustrate. Key words, indeed!
    Graham
    USDA Zone 7A Elevation 1400 ft

  5. #25
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    Default Re: Liquid Nitrogen

    Quote Originally Posted by KPeacock View Post
    Well, it reacts a lot like you'd expect when putting someting thats arounf 1500deg into something at negative 300 deg. a fair bit of isntant boiling going on. this must be done in a well ventilated area becasue it quickly puts out a lot of nitrogen gas. The end result was a very nice knife, but i don;t think it was worth the effort. i havent had a knife break yet, but i wanted to try it as i had read a fair bit on the subject.
    Thanks.. Familiar with cryo treatment on finished steel never heard of useing it as a quench. Brain tells me it would still be hard as glass and teh temper needs to be softened, but I suppose it could also effect grain size. wondered if the gas would have been so violent it would be dangerous...

  6. #26
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    Default Re: Liquid Nitrogen

    Quote Originally Posted by Rader Sidetrack View Post
    Will the appropriate use of the word principle also be on this quiz? Your principal may take a dim view of being dipped in liquid nitrogen, regardless of the principle you are attempting to illustrate. Key words, indeed!
    HaHa! I knew someone would catch that! Oh boy...You should meet our principal.

    I didn't bother changing it because I figured the reply would fire people up anyways. Grammer and spelling aside.
    "Someday we will look back and realize someone was right...and conveniently forget we were the ones that were wrong."

  7. #27
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    Default Re: Liquid Nitrogen

    ****DISCLAIMER****

    DO NOT DIP YOUR HAND IN LIQUID NITROGEN

    Everybody hear that?
    "Someday we will look back and realize someone was right...and conveniently forget we were the ones that were wrong."

  8. #28
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    Default Re: Liquid Nitrogen

    Caution for stiches! (not what you think). We used to pour it into our IR camera when doing inspections. One of our tech’s did not have a dewar and put it in a thermos bottle. He was fighting to get the top off of it and when it finally came off it hit right in the forehead and knocked him back in his boots. Tell you what, thermos bottle stopper to the forehead really bleeds.
    “Why do we fall, sir? So that we might learn to pick ourselves up” Alfred Pennyworth Batman Begins (2005)

  9. #29
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    Default Re: Liquid Nitrogen

    Yes, LN2 (liquid nitrogen) is dangerous and I know it for sure since I am working with this substance for 30+ years. No jokes around LN2, it is literally, deadly serious. It is dangerous when it gets:
    - on your clothes - more dangerous than direct skin contact;
    - in your eyes
    - evaporated in small, non-ventilated area
    - inside your boots...
    - it may splash violently

    LN2 burns heal very slow and painful, there are huge scars after that.

    If got it - treat it as a severe burn from boiling water.

    Beekeepers need to know that the best remedy against burns is a propolis tincture (1-5% propolis in alcohol) - apply every few hours,works great on my 3rd degree burn from 50 sparkles...
    Серёжа, Sergey

  10. #30
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    Default Re: Liquid Nitrogen

    Yes, the idea was to have a VERY fine grain after the quench and then temper to reduce the brittleness. I am a pretty small time knife maker and sadly, i didn;t ahev teh time to appropriately test my results. it would ahev been nice to destry the knife to see the grain structure, and also test the rockwell hardness. i did neitehr and had to settle for simply flexing it in a vice and giving it a thumbs up, or thumbs down.

    The birth of my son has shelved my knife making for the forseeable future. I just don't have the solid blocks of time required to make the damascus steel anymore. I dealt mostly in damascus because it plain old looks cool when done. Even monosteel blades take me a relatively long time to make as i choose to avoid the use of power tools. I know it's all in my head, but i like the feel of a blade that hasn't been abused my power tols, but rather has been coaxed into existence with simple tools used by a simple human. Clealrly, I have no hope of making acareer with this mentallity. Once the boy gets biger and can "help" me, I'll pick it back up again.

  11. #31
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    Default Re: Liquid Nitrogen

    Quote Originally Posted by KPeacock View Post
    ...Yes, the idea was to have a VERY fine grain after the quench and then temper to reduce the brittleness. ...
    I am sorry to interfere, but it seems to me that the idea of using LN2 (liquid nitrogen) is not really great. Since LN2 evaporates very quickly, it creates a gas "cushion", which works as an insulation. So, LN2 cold temperature actually did not reach the metal in timely manner. It is my understanding that in quenching what is important is a speed of cooling, not absolute temperature. In case of LN2 because of the gas "cushion" the speed is slow. In research Lab, we used to use a liquidized freon to eliminate the gas "cushion", but I am not sure that freon could survive a direct contact of very hot metal... another Lab option - is super-cooled ethane, but it is extremely flammable... oil has a very good heat-conducting property. Water - the same as LN2 - vapor's "cushion".
    Серёжа, Sergey

  12. #32
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    Default Re: Liquid Nitrogen

    I also a knife maker (well, swords mostly but you have to start somewhere) I've used acetone cooled to sub zero temps with dry ice, it also works very well and is easier to get than nitrogen.

  13. #33
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    Default Re: Liquid Nitrogen

    Making knives I've always been quite satisfied with quenching in oil... after getting it hot enough it does not attract a magnet...
    Michael Bush bushfarms.com/bees.htm "Everything works if you let it." ThePracticalBeekeeper.com 40y 200h 37yTF

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