JPH06122929A - Production of extremely low-oxygen copper - Google Patents

Abstract

PURPOSE:To obtain an extremely low-oxygen copper having a lower content of oxygen than before by transiently blowing gaseous oxygen into the molten copper which is agitated to deoxidize the molten copper. CONSTITUTION:Electrolytic copper as the raw material is melted in the atmosphere of gaseous Ar, etc. In this case, a reducing gas is introduced into the molten copper for a specified time, then a specified amt. of pure gaseous oxygen or a gaseous mixture of Ar and oxygen is blown into the molten copper from another blowing port, and further gaseous CO is introduced to deoxidize the molten copper. The amt. of gaseous oxygen is preferably controlled so that the oxygen concn. in the molten copper is adjusted to 100-300ppm. When the molten copper is reduced by gaseous CO, the oxygen and hydrogen in the molten copper and H2O in the atmosphere approach equilibrium. Since the bonding strength between H and O is stronger than that between CO and O, the molten copper is not further oxidized. Accordingly, gaseous oxygen is blown into the molten copper to remove the dissolved hydrogen from the molten copper as H2O, hence CO reacts with O more easily, and deoxidation further proceeds. An extremely low-oxygen copper contg. <= about 0.05ppm is obtained in this way.

Description

Detailed Description of the Invention

[0001]

This invention has an oxygen concentration of 0.5 pp.
The present invention relates to a method for producing extremely low oxygen copper of m or less.

[0002]

2. Description of the Related Art As one of the methods for producing oxygen-free copper,
A method is known in which commercially available electrolytic copper is melted in an atmosphere of an inert gas or a reducing gas to prepare molten copper, and the reducing gas is blown into the molten copper and stirred to degas.

The oxygen concentration of oxygen-free copper produced by this method can be lowered to only 1 ppm, and it was extremely difficult to reduce it to less than 1 ppm.

Particularly, in recent years, oxygen-free copper has been used as a member of a particle accelerator used under high vacuum, and if gas is contained in this oxygen-free copper, the degree of vacuum decreases during operation of the particle accelerator. It will be.

Therefore, there is a demand for oxygen-free copper having a very small amount of residual gas as a particle accelerator member, and a baking process has been performed to obtain such oxygen-free copper having a small amount of residual gas.

[0006]

However, most of the gas remaining in oxygen-free copper is hydrogen, and when oxygen remains in oxygen-free copper, hydrogen is trapped in the remaining oxygen and baking is performed. Is not removed enough. for that reason,
There has been a demand for ultra-low oxygen copper having a lower oxygen content than ever before.

[0007]

Therefore, the present inventors have
As a result of research to obtain ultra-low oxygen copper having a lower oxygen concentration than before, (a) In the step of deoxidizing a molten copper obtained by dissolving electrolytic copper by blowing a reducing gas, the above reduction is performed. If oxygen gas is temporarily blown during the blowing of the volatile gas, the oxygen concentration of the obtained ingot decreases to 0.5 ppm or less. (B) The amount of oxygen gas blown temporarily is It was found that it is more preferable that the oxygen concentration with respect to copper is equivalent to 100 to 300 ppm.

The present invention has been made on the basis of the above findings, and is an extremely low oxygen copper alloy in which oxygen gas is temporarily blown during the process of stirring and deoxidizing molten copper while blowing a reducing gas. It is characterized by the manufacturing method.

The amount of oxygen gas to be blown temporarily is preferably such that the oxygen concentration with respect to the molten copper is 100 to 300 ppm. If it is less than 100 ppm, the subsequent deoxidizing effect is not sufficient, while if it exceeds 300 ppm. It is not preferable because excess oxygen remains in the molten copper. Therefore, the amount of oxygen gas blown into the molten copper is 100 to 300 pp relative to the molten copper.
I decided to m.

The molten copper preferably dissolves electrolytic copper in an Ar gas atmosphere, and the reducing gas blown in in the deoxidizing step is C.
O 2 gas is preferred.

In the deoxidizing step, CO gas is blown for a predetermined time, and then a predetermined amount of pure O ₂ gas or a mixed gas of Ar gas and O ₂ gas is blown from a blowing port different from the CO gas, and further, Blow in CO gas.

The reason why the oxygen concentration can be made extremely low by temporarily blowing O ₂ gas during the deoxidation by blowing CO gas to the molten copper is considered to be as follows.

That is, when molten copper is reduced with CO gas and deoxidation proceeds, oxygen and hydrogen in the molten copper and H _{2 in the} atmosphere
O approaches equilibrium. Here, since the binding force of H and O is stronger than that of CO and O, further deoxidation becomes difficult with CO gas. Therefore, if O ₂ gas is blown into the molten copper to remove the solid solution hydrogen in the form of H ₂ O from the molten copper, the reaction between CO and O is facilitated, and the deoxidation proceeds further.

[0014]

[Example] As a raw material, electrolytic copper containing oxygen: 20 ppm was prepared, and 15 kg of this electrolytic copper was charged into a graphite crucible heated in an Ar gas atmosphere.

When the raw material electrolytic copper was dissolved, CO gas was blown into the molten copper at a flow rate of 5 l / min for 10 minutes, and then O _{2 was} added.
Gas was blown in under the conditions shown in Table 1, and further 5 l / min of CO gas was blown in for 10 minutes to deoxidize by the methods 1 to 5 of the present invention and the comparative methods 1 to 4.

The deoxidized molten copper was cast in a mold having a diameter of 30 mm to produce ingots, and the oxygen concentration of these ingots was measured. The measured values are shown in Table 1.

For comparison, deoxidation was carried out by the conventional method by blowing CO gas for 20 minutes without blowing O ₂ gas on the way, and the same method was followed by casting into a mold. The ingot was manufactured, the oxygen concentration of the obtained ingot was measured, and the measurement results are shown in Table 1.

[0018]

[Table 1]

From the results shown in Table 1, the O ₂ gas was temporarily added to the molten copper in the range of 100 to 30 during the blowing of the CO gas.
Molten copper ingots deoxidized by the present invention methods 1 to 5 in which 0 ppm is blown,
It can be seen that the oxygen concentration is extremely low as compared with the ingot obtained by the conventional method of deoxidizing only with CO gas.

However, as seen in Comparative Methods 1-4,
It can be seen that when the blowing amount of O ₂ gas is out of the range of the present invention, the oxygen concentration of the obtained ingot is increased and the oxygen is not sufficiently deoxidized.

As described above, according to the method of the present invention, it is possible to produce an extremely low oxygen copper having a much lower oxygen concentration than the conventional oxygen-free copper, and the hydrogen present in the material due to the low oxygen concentration. A gas can be easily removed by baking or the like, and a vacuum container material that does not reduce the degree of vacuum of a vacuum container used under high vacuum can be provided, which has an excellent industrial effect.

Claims (2)

[Claims] 1. A method for producing ultra-low oxygen copper, characterized in that oxygen gas is temporarily blown in the middle of the step of stirring and deoxidizing molten copper while blowing a reducing gas. 2. The method for producing ultra-low oxygen copper according to claim 1, wherein the amount of oxygen gas blown in temporarily is an amount corresponding to an oxygen concentration with respect to molten copper of 100 to 300 ppm.