Hot extraction process

Process to determine the gas content in a solid sample or to determine dissolved or bound gases in metals, alloys and inorganic substances (see Hot extraction).

This process is applied as reference process for hydrogen determination of all operational test units. A solidified sample - or also a casting section - is heated to solidus temperature in an evacuated vessel. The emitted hydrogen is collected and the hydrogen content is determined with a mass spectrometer by means of a hydrogen-absorbing palladium probe.

The process is suitable for all gases like hydrogen, oxygen, nitrogen or methane that are principally of interest in technical applications. The samples are molten and overheated in a graphite crucible in a high vacuum. Quick melting in an electrode furnace (up to 2800 °C) guarantees quick dissociation of nitrides and reduction of oxides. The gases that are emitted during melting and overheating are extracted and analyzed by gas chromatography, which has proven to be a reliable process with high sensitivity of detection.

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