JPS5917148A - Oxygen probe - Google Patents

Abstract

PURPOSE:To prevent breakdown of a solid electrolyte during immersion into molten steel in an easy way, by covering the lower part of the protruded solid electrolyte with a metallic cylinder. CONSTITUTION:The solid electrolyte 3 made mainly of zirconia is protruded on the end face of the housing 2 of a main support, and in its inside, the end part is filled with a standard substance 5 and the bottom part is filled with a heat resistant power 6. The bottom part of the solid electrode 3 is surrounded with the metallic cylinder 10. Abrupt temperature grade occurring on the border face of the housing 2 and the solid electrolyte 3 is alleviated by said constitution, and breakdown of the solid electrolyte 3 is prevented during its immersion into molten steel.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oxygen glove that prevents a zirconia-based solid electrolyte, which is a detection element, from being destroyed by sudden thermal shock when immersed in molten metal.

Generally, in the smelting and refining of metals, controlling the amount of dissolved oxygen has a significant effect on the quality of the material.
The oxygen activity value in the molten metal is measured using a smelting piece. We have achieved considerable results2 in measuring oxygen activity values in molten steel.

This oxygen globe uses the principle of an oxygen concentration cell to measure the electromotive force that is the difference between the oxygen potential in the molten metal and the oxygen potential shown by the reference electrode material, and a typical one is shown in Figure 1. , as shown in FIG.
A zirconia-based solid electrolyte 3 containing zirconia as a main component such as r02-MgO, and molten metal side electrodes 4 and 2 are embedded and protruding, and a reference electrode material 5 is placed at the hollow tip of the former, and a stable electrode is placed at the base side. The oxygen activity value in the molten metal is measured by recording the lead wire 7 connected to the reference electrode material 5 and the lead wire 7a connected to the molten metal 11111 electrode 4. It is designed to be guided by a meter. A thermocouple 8 is installed in the housing 2 so that the temperature of the molten metal can be measured simultaneously, and a metal cap 9 is installed at the end of the glove body to protect part of the sensor from slag during immersion measurement. Usually provided.

Generally, when measuring the acid accumulation value using this type of oxygen glove, there is a problem that the solid electrolyte is destroyed at the same time as the oxygen glove is immersed in molten metal, making measurement impossible. Was.

This destruction is thought to be due to the following causes.

When the solid electrolyte 3 comes into contact with the molten metal, the surface of the solid electrolyte is rapidly heated to the temperature of the molten metal.

However, the part that is heated rapidly cannot be heated rapidly because it is only the protruding part from the housing 2 and is embedded in the housing 2, and the root part is embedded in the heat-resistant material. Therefore, a large temperature IJI gradient occurs at the boundary between the protrusion and the root of the solid electrolyte.

In other words, since the temperature in the isoelectrolyte is different between the inner root part and the protrusion part of the housing, the degree of volumetric expansion is different.The difference is significant at the boundary part where the temperature gradient is large. occurs, and the isoelectrolyte is destroyed at the boundary.

To prevent such destruction, the entire OL solid electrolyte 3 is covered with a closed tube at one end, or a heat-resistant coating material is applied to the entire surface except for the tip, to prevent thermal shock when immersed in molten steel. However, if most of the surface is covered in this way, it will take time for the reference electrode to reach the same temperature as the molten metal, and it will take time for the electromotive force to stabilize. The so-called response time is long (and a stable waveform cannot be obtained within the allowable immersion time of the oxygen glove).
(・5)

In addition, the application of the coating material requires strict control of drying temperature and drying time during the manufacturing process, and furthermore, careful handling during assembly is required to avoid damaging the coating film, making the process complicated. I can't get enough of it. Furthermore, in molten metal at high temperature and low oxygen activity, oxides that form a coating film may dissociate into the molten metal and contaminate the vicinity of the measurement end, causing the measured oxygen activity value to decrease. There is a risk that it may cause problems itself.

Unlike these methods, the present invention provides an oxygen glove in which the destruction of the solid electrolyte during immersion in molten steel is eliminated by a simple method. Ding 1. By covering the protruding base of the solid electrolyte 3 on the side of the housing 2 from the reference electrode material 5 with a metal tube, the sharp S degree gradient that occurs at the boundary between the root and the protruding part when immersed in molten steel is alleviated and damage is prevented. This is what I am trying to do.

FIG. 3 shows the most preferred embodiment of the present invention.
A metal cylinder 1 with an inner diameter that almost matches the outer diameter of the solid electrolyte 3
0 and covers the protruding base on the side of the housing 2 from the reference electrode material 5. Figures 4 to 6 show other embodiments. In Figure 4, the cylinder 11 has a rectangular outer shape, in Figure 5, the cylinder 12 has a polygonal outer shape, and in Figure 6, the cylinder 12 has a polygonal outer shape. 1 shows the case where the open tube 13 is covered with the open tube 13. (・Even in the case of misalignment, the tube should be made of metal.)

In the case of the present invention, is the material of the covering cylinder the same as the molten metal used for oxygen activity measurement? Although it is preferable to use gold, it is also possible to use gold, which has a lower melting point.

As described above, since the present invention covers only the protruding base of the solid electrolyte with metal, it does not delay the reference electrode reaching thermal equilibrium (and the response time does not increase).
. Furthermore, since the molten metal near the measurement end is not contaminated, the amount of dissolved oxygen can be measured accurately. Furthermore, manufacturing is extremely simple, as all you have to do is fit a cylindrical body that matches the outer diameter of the solid electrolyte (・σ).

[Brief explanation of drawings]

FIG. 1 is a sectional view of a general oxygen glove, and FIG. 2 is a bottom view of FIG. 1 with the bottom surface of the cap removed. Figures 3-6
The figure shows part 9 of the embodiment of the present invention, and 1 and □ indicate the bottom view and tb> indicates the center sectional view. 1. Heat-resistant exterior material, 2... Support main body housing, 3...
Zirconia solid electrolyte, 5... Reference electrode material, 10.
...Metal cylinder, 11...Cylinder with square outer shape, 12...
・Cylinder with polygonal outer shape, 13...open [J cylinder patent applicant Nissin Steel Co., Ltd. Yamazato Electronite Co., Ltd. Mitsuru Shindo Tanukito

Claims (1)

[Claims] Is the zirconia solid Yoi 1 solution protruding from the end surface of the support body and the oxygen globe? Then, the solid 8. The protruding base on the support side of the M-quality reference electrode material is covered with metal and has a 16 oxygen globe.