JPH0426708B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an oxygen analysis method in an oxygen analyzer using an electrochemical oxygen pump.

[Conventional technology]

Recently, a new type of oxygen analyzer has been developed that can measure the amount of oxygen contained in metals, alloys, their compounds, and metalloids such as selenium and tellurium with high precision and absolute values (Otsuka Written by Shinya and Zensaku Kozuka, Transaction of the Japan
Institute of Metals, Vol-25, No.9639-648
Page, published September 1984).

This oxygen analyzer has an electrochemical oxygen pump using a solid electrolyte interposed in a closed gas flow path that circulates carrier gas, and by applying a constant DC voltage to the oxygen pump, By discharging oxygen, the oxygen partial pressure within the closed gas flow path can be maintained at a sufficiently low constant value. Before measurement, the oxygen in the carrier gas is exhausted, the inside of the closed gas flow path is maintained at a sufficiently low constant oxygen partial pressure, and the sample is introduced into the closed gas flow path in this state. The introduced sample is heated and melted in a sample melting furnace, and oxygen is released from the sample. The oxygen released from the sample is carried by the carrier gas to the oxygen pump, and is discharged from the closed gas flow path by the oxygen pump, so that the inside of the closed gas flow path is again maintained at a constant low oxygen partial pressure. By measuring the amount of electricity required by the oxygen pump to discharge this oxygen, the amount of oxygen in the sample can be measured as an absolute value quickly and with high precision.

[Problem that the invention seeks to solve]

However, using the oxygen analyzer configured as above, high melting point metals (e.g. Fe, Ni,
In order to measure the amount of oxygen in materials (Co, Au, etc.), it is necessary to maintain the sample melting furnace at a high temperature of, for example, 1500°C or higher. In order to configure a sample melting furnace to be able to control such a high temperature, there are problems in that the cost of materials such as the heater and sample melting tube becomes considerably high, and the furnace body becomes large and complex.

The present invention focuses on these problems and makes it possible to release oxygen in a sample such as high melting point metal into a closed gas flow path at a temperature lower than the melting point of the sample, and uses special heat-resistant material in the sample melting furnace. The purpose is to eliminate the need to use a sample melting furnace and to simplify the configuration of the sample melting furnace.

[Means for solving problems]

The oxygen analyzer of the present invention that meets this objective includes an electrochemical oxygen pump that uses a solid electrolyte in a closed gas flow path that circulates a carrier gas, and that discharges oxygen in the closed gas flow path to the outside of the closed gas flow path. a sample introducing means for introducing a solid sample into the closed gas flow path; and a sample melting furnace for melting the solid sample introduced from the sample introduction means and releasing oxygen in the sample into the closed gas flow path. In the oxygen analysis method using an oxygen analyzer in which the The method consists of introducing a solid sample.

[Effect]

Generally, by forming a eutectic alloy or the like, the melting point of a metal is much lower than that of a single metal. Therefore, if the sample is introduced into the metal melted in the sample melting furnace in advance and a eutectic alloy etc. is formed between the molten metal and the sample, the introduced sample is compared to the case where it is melted alone. The oxygen in the sample is released into the closed gas flow path.
Since a particularly high temperature is no longer required for the sample melting furnace, inexpensive heaters and materials can be used.

〔Example〕

Preferred embodiments of the present invention will be described below with reference to the drawings.

The figure shows the overall configuration of an oxygen analyzer for carrying out a method according to an embodiment of the present invention, and each directional control valve shows the state at the time of oxygen content analysis of a sample.

In the figure, the path indicated by the thick line indicates a closed gas flow path 1 through which a carrier gas such as argon gas containing 0.01 to 10% hydrogen is circulated during oxygen content analysis of a sample. Each direction switching valve 2, 3, 4
consists of a four-way valve in this example, and when analyzing the oxygen content of the sample, the closed gas flow path 1 is closed as shown in the figure.
Flow the carrier gas inside in the direction of arrow A.

The closed gas flow path 1 includes a circulation pump 5 for circulating carrier gas along the carrier gas circulation direction A during measurement, and a sample 6 made of a metal, an alloy, a compound thereof, or a semimetal such as selenium or tellurium. a sample introduction means 7 for introducing into the closed gas flow path 1; a sample melting furnace 8 for heating and melting the sample 6 from the sample introduction means 7 to release oxygen in the sample;
The oxygen discharged from the sample 6 and carried by the carrier gas is discharged outside the closed gas flow path 1, using a solid electrolyte made of, for example, zirconia with a stabilizing agent such as ittria, calcia, or magnesia dissolved therein. A chemical oxygen pump 9, is interposed in series.

A flow meter 10 that can measure the flow rate (flow velocity) of the carrier gas circulated by the circulation pump 5 is provided upstream of the circulation pump 5 . Further, a carrier gas inlet 11 for introducing carrier gas into the closed gas flow path 1 is connected between the oxygen pump 9 and the circulation pump 5, and the carrier gas is introduced through the film 12 and the directional control valve 2. It is becoming more and more like this.

Note that when replacing this closed gas flow path 1 with carrier gas, the directional control valves 2, 3, and 4 are switched as shown by arrow B, but the reduced pressure suction port 13 is connected to the end of the path. The gas in the closed gas flow path 1 that has been expelled by the carrier gas supply is discharged to the outside of the system via the filter 14 and the suction pump 15.

The sample introducing means 7 and the sample melting furnace 8 are constructed as follows.

The sample introducing means 7 is configured in the shape of a sealable container, and includes a sample receiver 16 that temporarily holds the sample 6 and drops the sample 6 into the sample melting furnace 8 side.
is provided.

A sample melting furnace 8 provided on the downstream side of the sample introduction means 7 includes a sample melting tube 18 having a sample melting section 17 at the bottom, a heating device 19 for heating and melting the sample 6 introduced into the sample melting section 17, It consists of

In addition, 20 indicates a cooling means such as a cooling fan that cools the upper part of the sample melting tube 18, which condenses metal vapor etc. from the sample melting section 17 by cooling and prevents it from flowing out to the downstream side. Heat transfer from the heating device 19 side to the sample introduction means 7 side is prevented.

Using the apparatus configured as described above, the method of the present invention is carried out as follows.

When the sample 6 is dissolved in the sample dissolving section 17, the oxygen in the sample 6 is released into the closed gas flow path 1, and the released oxygen is carried to the oxygen pump 9 by the carrier gas. The amount of oxygen in the sample 6 is analyzed from the amount of electricity required to discharge the gas to the outside of the closed gas flow path 1. A metal 21 capable of forming an alloy with the sample 6 in the metal 21, e.g.
Sn, Pb, etc. are dissolved. Then, the sample 6 is dropped into the molten metal 21 from the sample introduction means 7.

When sample 6 is dropped, sample 6 and molten metal 21
forms an alloy with. When it becomes an alloy, the melting point is significantly lower than that of Sample 6 alone. Therefore, the sample 6 is melted at a temperature lower than its own melting point, and oxygen in the sample 6 is released into the closed gas flow path 1 by the melting. The amount of released oxygen is measured by the oxygen pump 9 in the same manner as described above.

Note that the oxygen contained in the metal 21 that forms the alloy is released into the closed gas flow path 1 before the measurement, and the inside of the closed gas flow path 1 is cleared by the oxygen discharge by the oxygen pump 9. The partial pressure of oxygen is maintained at a constant, sufficiently low level necessary for measuring the amount of oxygen in step 6. Therefore, by melting the metal 21 in advance, no error occurs in the measurement of the amount of oxygen in the sample 6.

〔Effect of the invention〕

As explained above, when using the oxygen analyzer method of the present invention, a substance that forms an alloy with the sample is melted in advance in a sample melting furnace, and the sample is introduced into the melting furnace to alloy the sample. By melting the sample above and releasing oxygen, the sample melting temperature can be significantly lowered than when using a single sample, without using special heat-resistant materials in the sample melting furnace, and with a simple structure. This has the effect of making it possible to analyze the amount of oxygen in samples such as high melting point metals. Therefore, it is possible to reduce the equipment cost and downsize the sample melting furnace.

[Brief explanation of drawings]

The figure is an overall configuration diagram of an oxygen analyzer for carrying out a method according to an embodiment of the present invention. 1... Closed gas flow path, 2, 3, 4... Directional switching valve, 5... Circulation pump, 6... Sample, 7... Sample introducing means, 8... Sample melting furnace, 9... Oxygen pump, 16... Sample receiver, 17... Sample dissolving section, 1
8... Sample dissolution tube, 19... Heating device, 21...
molten metal.

Claims (1)

[Claims] 1. In a closed gas flow path in which the carrier gas is circulated, oxygen in the closed gas flow path is discharged to the outside of the closed gas flow path.
An electrochemical oxygen pump using a solid electrolyte, a sample introduction means for introducing a solid sample into the closed gas flow path, and a method for dissolving the solid sample introduced from the sample introduction means and closing the oxygen in the sample. In an oxygen analysis method using an oxygen analyzer in which a sample melting furnace for discharging gas into a gas flow path and an oxygen analyzer are arranged in series, a substance forming an alloy with the sample is melted in advance in the sample melting furnace. an oxygen analysis method, characterized in that the solid sample from the sample introducing means is introduced into the solid sample.