[Jewelry making - Article 00419] - Re: [Orchid] Broken drill bits remover

[marlin]

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    I too, was surprised at the idea of dissolving tungsten carbide,
    until I looked at the actual chemistry. These drills are not pure
    tungsten carbide, but a fine powder of tungsten carbide cemented or
    welded together in a sintered mixture with cobalt. Even if the
    tungsten carbide were insoluble, there is literature and patents
    which suggest that the cobalt can be dissolved leaving behind a slush
    of tungsten carbide particles. I have not tried this myself, but my
    texts say cobalt is soluble in acids. There are two different
    compounds of tungsten carbide, WC and W2C. I believe that most tools
    use the insoluble WC form. W2C is slightly soluble in H2SO4 and
    soluble in hot nitric acid - although I for one am not quite crazy
    enough to do that without a fume hood. 

Marlin
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