lahthffire
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nichrome in vacuum
I've been told that nichrome should not be used in a vacuum. The person that told me this couldn't remember where they heard it. I've done some
research and all i can come up with is that K-type thermocouples (which use Chromel, a brand name for a nichrome alloy) are not recommended for vacuum
use. I could not find any reason for this, however.
Does anybody know why nichrome might not be suitable for use in a vacuum? The guy I talked to at Omega seemed to thing it was some sort of chemical
degredation, but he didn't know what.
I need to design a heating element for a vacuum furnace, and I would like to use nichrome because it is cheap and readily available. I'm hoping the
only issue will be that it is necessary to multiply the maximum power density by some correction factor to account for the loss of convective heat
transfer.
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AllanD
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Have you considered using "glow rod" heating elements?
They are form of Silicon Carbide commonly used in industrial heat treating kilns in atmosphere of hydrogen gas, inert gas as well as in vacuum.
AllanD
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12AX7
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It might be the alloy needs oxygen to remain corrosion-resistant, and one or both of the metals may be prone to evaporation at maximum temperature.
Tim
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