SU434299A1 - METHOD FOR DETERMINING GASES IN METALS OF ALLOYS1 - Google Patents

Description

This invention relates to the field of analyzing materials for the content of gas impurities, such as oxygen and nitrogen.

In the prior art of vacuum deposition, a sample is melted under vacuum in a graphite crucible or in a carbon-saturated crucible metal melt (bath), the gases released from the sample are pumped to a gas analyzer, where the quantitative composition of the gas mixture is determined.

High temperatures (1800–2000 ° C) are required for the complete reduction of oxides and decomposition of nitrides of a number of metals, for example, refractory metals, and at such temperatures the melt into which the analyzed sample is introduced is strongly carbonized by the crucible material, which slows down the extraction of the gas to be determined especially nitrogen, from the melt and leads to a deterioration in the sensitivity and accuracy of the analysis. In addition, the degassing of a graphite crucible takes a long time (1.5-3.0 hours), a limited number of samples can be analyzed in one crucible, which significantly reduces the productivity of the analytical setup.

The proposed method provides higher sensitivity and accuracy of the analysis due to the fact that the extraction of gases from the sample is carried out in water-cooled copper

the mold with a skull, formed from the original liquid metal (material "bath"). In this case, the bath material can be dosed with carbon to a concentration that

ensuring the optimal course of the extraction process.

The proposed method allows to increase productivity by 1.5-2 times, since there is no need to degass the graphite crucible. Due to the fact that as a "bath, you can use a material with a precisely metered carbon concentration (with the usual method this concentration is too high due to the dissolution of carbon in the bath

crucible), it is possible to increase the sensitivity and accuracy of the analysis. The possibility of heating the melt to high temperatures without increasing the carburization makes it possible to determine nitrogen in many metals and alloys, for the analysis of which in the usual case the method of vacuum melting is not applicable.

Subject invention

A method for determining gases in metals and alloys by vacuum melting a sample in a liquid metal with a given carbon concentration, followed by analysis of the evolved gases, characterized in that, in order to increase the sensitivity and accuracy of the analysis, the extraction of gases from the sample is performed in a copper water-cooled mold with a skull forming from the original liquid metal.