reasons for tig electrode degredation

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Hi guys,I was just wondering if anyone knows if, besides evaporation of elemental tungsten, if there is any chemical reactions present that cause degradation of the electrode. IE, do tungsten electrodes degrade quicker in an oxygenated environment due to formation of tungsten oxides with lower melting/boiling points? or any other reasons?Also on that note, for a completely theoretical situation, (ignoring flammability), would pure hydrogen thus act as a shielding gas due to a reducing nature, preventing tungsten oxides from being produced?Sorry, im not really a welder, just a curious chemist. Couldn't really find any literature on the net about it, figured maybe someone in the scene would know.Cheers
Reply:A tig torch creates a plasma arc. Also It has a magnetic component.Hydrogen would be no good because the whole purpose of the shielding gas is to keep away any oxygen. IT has been studied extensivily already. Look up plasma arc.Also hydrogen enbrittlement.AWS certified welding inspectorAWS certified welder
Reply:Thanks for the reply. Am reading about plasma arc at the moment. Could you please clarify what you mean by that? Apart from hydrogen gas igniting, causing possible recombination with oxygen, I don't see how using hydrogen would keep away the oxygen. Are you suggesting it cannot be used as a theoretical shielding gas due to the fact that it would ionise, thus becoming a "working gas" instead?
Reply:Hydrogen was/is? used in "atomic hydrogen" welding but is not suitable for use with iron alloys due to adsorption of the hydrogen. I don't know what kind of electrode such a a torch uses but do know that Hydrogen won't react with Tungsten, and it would definitely keep the oxygen away.  Degradation of Tungsten is mostly caused by other metal droplets contacting the Tungsten and the alloy which formed then has a lower melting temperature and 'sloughing off', I believe. There may also be some 'evaporation' due to both the high temperature and electrical potential present.That is, of course, assuming the shielding gas supply is adequate. Otherwise, Tungsten reacts with Oxygen, Nitrogen, CO2, Carbon.......
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Reply:FWIW hydrogen can be/is used, albeit as a mix with argon- the reducing atmosphere is useful for stainless and nickel alloys. The addition of H also increases the arc voltage- faster welding speeds, better depth to width ratios for the weld and cleaner, brighter welds. 2 - 5% hydrogen in argon is typical for manual welding but 10 or 15% H is available tooSmall amounts of nitrogen (around 2% ?) can be beneficial for duplex stainless (improved corrosion resistence, alters austenite - ferrite balance?).
Reply:I should clarify that comment about reactivity I made; Tungsten will react with Nitrogen, but under much more severe conditions than with the others. I understand N2 is used as a shielding gas for copper welding in Europe instead of Ar/He mixes. FWIW, Helium is recovered from Natural Gas wells in America, mainly in the Texas/Midwest area I think, and Europe has relatively little. Little is found in the atmosphere, partly 'cause it floats away from the Earth.