Controlling gas content using the measurement on solid by hot gas extraction under inert gas

• Used in addition to the "in situ" methods based on direct control of hydrogen in liquid metal (Telegas, Alscan, first bubble test) already installed at MERCUS , which may not ensure a low level of hydrogen in the cast solidified product.
• There is a risk for re-gasing between the liquid metal sampling on the solidification equipement.

• PHP laboratory has now bought a piece of equipment called H-MAT 2020 (designed by Stroehlein-Germany) for gas analysis in solids. The device is a perfected ITHAC and similar the LECO..
• The principle is the destructive melting of the sample and gas extraction ; two flows of nitrogen are measured by thermal conductivity (one for a reference, the second for the sample). The difference of thermal conductivity is related to the hydrogen content.
• Results are given in ppb (mass of hydrogen on mass of initial sample). Detection limit is around 20 ppb, and precision is around +/-10 ppb for a 100 ppb level.
• Capability of the equipement is regularly checked through the use of internal (not commercial) reference samples having known levels of internal hydrogen. This equipment is a much improved version of the famous ITHAC (no more produced nowadays) with a lot of improvements especially in terms of sensitivity and measurement range. With the H-MAT 2020, the ease of operation has been greatly improved in order to be able to use the equipment on a routine basis.
• But hydrogen content within the finished target may be different from the initial as cast product.

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