JPS61161442A - Method for measuring hydrogen and oxygen concentration in molten copper or copper alloy - Google Patents

Abstract

PURPOSE:To measure the hydrogen or oxygen concn. in molten copper or copper alloy without being affected by a disturbing gas by blowing nitrogen or helium as a carrier gas into the molten metal and maintaining the hydrogen and oxygen under the equil. partial pressure in the melt and vapor phase. CONSTITUTION:Nitrogen is first blown as the inert carrier gas into the molten metal and the gas blown from the molten metal is again returned into the molten metal to maintain the partial pressure of the hydrogen in the equil. state with the vapor phase in the molten metal in the case of measuring the hydrogen in the molten metal. The heat conductivity of the vapor phase is measured and the hydrogen concn. is determined. The measurement is made possible without disturbance by gaseous carbon dioxide, etc. Helium is used as the carrier gas and the oxygen is measured similarly without being disturbed by gaseous carbon dioxide, etc. in the case of measuring the oxygen in the molten metal. The equilibrium between partial pressure of the hydrogen or oxygen with the vapor phase in the molten metal is maintained by blowing the carrier gas into the molten metal in the above-mentioned manner and therefore the measurement of the hydrogen or oxygen concn. with high reliability without being affected by the disturbing gas is made possible.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is directed to the measurement of hydrogen and oxygen concentrations in copper or copper alloy molten metal by measuring the thermal conductivity of the gas phase side. The present invention relates to a method for measuring hydrogen and oxygen concentrations in copper or copper alloys, which improves the reliability of the measurement by eliminating the influence of.

[Prior Art] It is well known that gas components present in metals have a great influence on the physical and chemical properties of the metals.For example, for iron and copper, if the content of gas components becomes excessive, Distortion, solid solution hardening, delayed cracking during welding, etc. occur, significantly reducing product quality.

The same applies to copper and copper alloys, and depending on the content of hydrogen or oxygen, cracks in the ingot or pore defects may occur, and these effects also affect the product. Therefore, in order to improve product quality by controlling the above-mentioned excessive gas components to below the appropriate content, gas analysis should be performed using rI:.

Gas analysis must be performed reliably and quickly and the results must be reflected in manufacturing operations, and in this sense, gas analysis is also extremely important.

By the way, gas analysis of copper and copper alloys has traditionally been carried out mainly by solid extraction methods (Lev and Itak methods). Although this method gives fairly good results in terms of measurement reliability.

(1) It costs a lot of money. (2) It takes time to measure.
(3) If a satisfactory measurement result is not obtained, the ingot must be melted again and returned to the degassing process, resulting in seven points of waste. There are problems such as:

Therefore, a method of measuring thermal conductivity has been proposed, but this method does not cause the problems mentioned above, but it does not necessarily give satisfactory results in terms of reliability in measurement. In order to use this method, it was necessary to add some kind of ingenuity.

[Problems to be solved by the invention] The present invention has been made in view of the above-mentioned situation,
The purpose is to improve the reliability of the above measurement by removing the influence of interfering gases in the measurement of hydrogen and acid 111 degrees in copper or copper alloy molten metal by measuring thermal conductivity. It is.

[Means for Solving the Problems] The method for measuring hydrogen concentration in molten copper or copper alloy according to the present invention, which meets the above objectives, is a method for measuring hydrogen concentration in molten copper or copper alloy, in which a plurality of gas components containing hydrogen are present between the molten copper or copper alloy and the gas phase. When measuring the water am content in the molten metal by measuring the thermal conductivity of the gas phase while maintaining partial pressure equilibrium, nitrogen is used as a carrier gas to eliminate the influence of interfering gases. It has a gist.

In addition, when multiple gas components including both hydrogen and oxygen maintain partial pressure equilibrium between the molten copper or copper alloy and the gas phase, first use nitrogen as a carrier gas to eliminate the effects of interfering gases. Remove it and find the hydrogen concentration,
Next, the gist lies in measuring the oxygen concentration by using helium as a carrier gas and using the measurement results of the hydrogen concentration to remove the influence of the interfering gas.

[Function] The structure and effects of the present invention will be clarified below while tracing the process leading up to the completion of the present invention.4 At that time, the basic operations of the measuring method of the present invention will first be explained1.
Next, the characteristics of unexploded +51 will be explained separately for hydrogen and oxygen.

The basic operations for measurement are as follows. That is, (1) select an inert gas that does not react with the molten metal as a carrier gas, (2) blow a certain amount of it into the molten metal, and (
3) The scum components blowing out from the molten metal are blown into the molten metal again, and (4) the above operation (3) is repeated cyclically to maintain partial pressure equilibrium between the molten metal and the gas phase. (5) Measure the thermal conductivity of the gas phase, and (6) Calculate using the results to analyze the gas in the molten metal.

Next, the effect of the present invention will be explained separately for the case of hydrogen and the case of oxygen.

(1) Permanent The present inventors have found that the thermal conductivity is considerably different from that of N2 gas and is 0.
The idea was that a gas having a thermal conductivity similar to that of interfering gases such as 2 gas, CO2 gas, and CO gas should be selected as the carrier gas in the basic operation (1) above. Based on.

The present invention was completed as a result of extensive research on the selection of N2 gas. The ideation stage as described above will be further explained using Table 1.

Table 1 Table 1 shows the values of the heat transfer coefficient at room temperature for each of A constant gas, carrier gas, and interference gas, but the thermal conductivity of N2 gas, which is the gas to be measured. is 419
X 10-' al/ssc cm"c (For all gases, X I O-' Cal/see
C1l"0 (7) part is omitted), whereas the carrier gas N2 is 57, and the main interfering gas is 0.
2 is 58. When N2 gas is selected as the carrier gas in this way, since its thermal conductivity is similar to that of 02, which is the supporting interfering gas, 02 can also be treated as a gear carrier gas, and the measurement target gas H2 is a hindrance
The measurement will be performed without being affected by the gas o2. Note that CO2 gas and CO gas also exist as interfering gases, but the thermal conductivity of CO gas is 53, which is similar to that of N2 gas, which is a carrier gas, so they are not interfering gases as above, and CO2 gas Since the total content of N2 gas and CO gas in the molten metal is generally less than 1%, it can be said that CO2 and CO can be ignored when fixing with N2 gas.

(2) Similar to the case of oxygen and N2 gas, the present inventors found that the thermal conductivity of the N2 gas is considerably different from that of the 02 gas.

Based on the idea that a gas similar to interfering gases such as CO2 gas and CO gas should be selected as the carrier gas in the basic operation (1) mentioned above, we selected He gas and conducted intensive research. This led to the completion of the invention.

However, the similarity in thermal conductivity between the carrier gas He and the main interfering gas H2 in the case of 02 gas is weaker than the similarity in thermal conductivity between the carrier gas N2 and the main interfering gas 02 in the case of N2 gas measurement, and this is the cause. Therefore, some ingenuity is required in the calculation shown in basic operation (6), but the circumstances will be explained again with reference to Table 1. It can be seen that the thermal conductivity of the carrier gas He is 343, while that of the main interfering gas H2 is 419, and there is a considerable difference in these values. Therefore, when thermal conductivity is measured using He gas as a carrier gas, the thermal conductivity includes the influence of other elements other than He gas and O2 gas, that is, N2 gas. Therefore, in order to improve reliability in 02 gas measurement, it is necessary to eliminate the influence of N2 gas. However, since the N2 gas concentration in the molten metal was determined in the hydrogen gas measurement described above, it is a known value.On the other hand, a calibration curve was separately created to grasp the influence of N2 gas on He gas, and the above-mentioned known N2 By comparing the gas concentration with this calibration curve, the influence of N2 gas on the 02 concentration in the molten metal can be known, and the 02 gas concentration can be corrected based on this knowledge. Conceptually, the influence of the interfering gas is removed as described above, but specifically, it is performed as follows.

(1) First, carrier gas N2 is circulated through the molten metal to achieve partial pressure equilibrium.

(2) Measure the concentration of H2 in N2φ and find the partial pressure of H2 in the molten metal.

■Using the relationship between solubility and partial pressure (measured separately).

Convert the H2 partial pressure to the H2 concentration in the molten metal.

(2) Add carrier gas He to the molten metal by ff1l13 to balance the partial pressure by 11.

(Measure the concentration of 02 in He, and determine the partial pressure of 02 in the molten metal.

Using the correction value determined in advance in the He-H2 system, 02 partial pressure is converted to 026 degrees of molten metal φ using a relational expression between solubility and partial pressure (separately measured).

[Example] Table 2 shows a comparison between the measurement results by the method of the present invention and the I-determined results by the solid extraction method.
H2 gas was analyzed using the Reco and Itatsuk methods, respectively.

Table 2 (Pp,) Regarding the cost for 02 measurement, the conventional cost is about 171
It became 0. In the conventional method using thermoelectromotive force, the immersion part is used only once and becomes a consumable item, resulting in high measurement costs.

[Effects of the Invention] As explained above, according to the present invention, the influence of interfering gases when measuring the hydrogen and oxygen concentrations in copper or copper alloy molten metal can be removed, thereby improving the reliability in gas measurement. It has become a +il ability to improve.

Claims (2)

[Claims] (1) The hydrogen concentration in the molten metal can be determined by measuring the thermal conductivity of the gas phase in a state where multiple gas components including hydrogen maintain partial pressure equilibrium between the molten copper or copper alloy and the gas phase. A method for measuring hydrogen concentration in molten copper or copper alloy, characterized in that during measurement, the influence of interfering gases is removed by using nitrogen as a carrier gas. (2) When measuring the thermal conductivity of the gas phase in a state where multiple gas components including hydrogen and oxygen maintain partial pressure equilibrium between the molten copper or copper alloy and the gas phase, use nitrogen as a carrier gas. By using this method, the influence of interfering gases is removed and the hydrogen concentration is determined. On the other hand, when measuring oxygen, the influence of interfering gases is removed by using helium as a carrier gas and using the above hydrogen concentration measurement results. A method for measuring oxygen concentration in molten copper or copper alloy.