JPH11201963A - Method and apparatus for analysis of oxygen by kind of oxides or of oxides in sample to be analyzed - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure oxides by kind, by a method wherein a sample is reacted with a carbon source while a temperature rise speed is being controlled in a flow of an inert gas, and the flow rate of the inert gas is reduced whenever the peak of the reaction amount of oxygen detected from generated CO gas appears. SOLUTION: An analyzer which measures an amount of oxygen or an amount of oxides in a sample to be analyzed such as a metal or the like is constituted, e.g. of a direct electrification-type extraction furnace 1 provided with a graphite crucible 2, of flow controllers 8, 9 for an atmosphere gas as an inert gas such as Fe or the like, of an infrared CO absorption detecting device 10 and of the like. Then, a sample which contains, e.g. three kinds of oxides is housed in the crucible 2, and the temperature of the sample is raised while an atmosphere gas at a prescribed flow rate is being made to flow. After the appearance of the peak of a first waveform for the amount of oxygen measured by the detecting device 10 is finished, the flow rate of the atmosphere gas is reduced by a prescribed amount. After the appearance of the peak of a second waveform, the flow rate of the atmosphere gas is reduced further, and the peak of a third waveform is obtained. In this manner, when the flow rate of the atmosphere gas is reduced in the order of the appearance of the waveforms, the decomposition temperature of the oxides is changed sequentially to the side of a high temperature, and the reparability of the oxides is made good.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for analyzing an amount of oxygen or an oxide in a sample for analysis such as a metal, a refractory, and a slag. More specifically, the present invention relates to a method and an apparatus for extracting oxygen in an analysis sample by extracting oxygen as a CO gas and measuring the CO gas by an inert gas transport-infrared absorption method to analyze the amount of oxygen or the amount of oxide in the analysis sample.

[0002] In particular, the present invention relates to a method and an apparatus for analyzing the amount of oxygen or the amount of oxide for each type of oxide in an analysis sample.

[0003]

2. Description of the Related Art In recent years, there has been a demand for a technique for accurately and quickly analyzing the amount of oxygen or the amount of oxide in an analysis sample.

[0004] For example, in the steelmaking field, the development of ultra-low oxygen steel and high-purity iron in which the form of oxide is controlled has been advanced.
It is required to accurately quantify the concentration of trace amounts of oxygen at the ppm (parts per million) level. Among bearing steels used under severe conditions, among the trace inclusions, especially Al
₂ O ₃ , MgO.Al ₂ O ₃ , (Ca, Mg) O.Al
Inclusions such as ₂ O ₃ tend to form large grains, which cause fatigue failure. For this reason, it is important to reduce the amount of inclusions in the product and control the form of the inclusions, and there is a demand for an accurate and rapid technique for analyzing the types of inclusions in low oxygen steel.

[0005] In the method of analyzing inclusions in steel, conventionally, a test piece is collected from an analysis sample, and the surface to be inspected is observed under a microscope.
A method of classifying into a C system (JIS G0555) and a method of mirror-polishing a sample surface and performing instrumental analysis such as electron beam microanalysis have been performed.

[0006] However, since these methods are methods for measuring a cross section of a sample, it is impossible to detect true inclusions that cause material destruction, the measurement time is enormous, and sample adjustment such as polishing is required. There are problems such as complexity.

One solution to these problems is to:
Recently, an analysis method using an oxygen analyzer has been proposed (JP-A-6-148167). This method compares the oxygen content of easily reduced oxides (FeO, MnO, etc.) in which a decomposition reaction takes place at a relatively low temperature by continuously heating an analytical sample into a graphite crucible and heating it at a constant heating rate. Oxides (CaO, Al ₂
This is a method in which oxygen from O ₃ ) is separated using a CO gas extraction curve at the time of analysis.

However, the method disclosed in JP-A-6-148167 is intended for a high oxygen content of 10% or more in steelmaking slag, and is applied to a metal sample having a trace oxygen content on the order of several ppm. Since the peaks of the CO gas extraction curves are small and the waveforms of the respective CO gas extraction curves overlap, it is difficult to separate the respective waveforms.
It became clear that the method cannot be applied to a metal sample having a trace amount of oxygen on the order of m.

In addition, this method separates oxygen from easily reduced oxides and oxygen from hardly reduced oxides, and cannot be applied to the analysis of a small amount of oxides by type of oxide inclusions.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and provides a method and an apparatus for analyzing the amount of oxygen or the amount of oxide for each type of oxide in an analysis sample. The purpose is to do. In particular, it is an object of the present invention to provide a method and an apparatus capable of analyzing accurately and quickly even when the amount of oxygen or the amount of oxide in an analysis sample is very small.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its gist is as set forth in the appended claims. That is, the gist of the present invention is as follows: (1) An analysis sample is heated in an inert atmosphere and reacted with a carbon source while controlling a temperature rising rate, and oxygen in the analysis sample reacts with the carbon source. The sequentially generated CO gas is extracted into an inert gas stream, and the extracted CO gas is sequentially analyzed by an infrared absorption method to determine the amount of reactive oxygen, and the peak of the amount of reactive oxygen is obtained from the thus obtained reactive oxygen amount data. Detected and analyzed while decreasing the flow rate of the inert gas flow every time a peak of the detected reactive oxygen amount appears, accumulates the reactive oxygen amount data in time series, and performs the analysis from the accumulated reactive oxygen amount data. What is claimed is: 1. A method for analyzing the amount of oxygen in an analysis sample, the method comprising: determining the amount of oxygen by type of oxide in the sample.

(2) The analysis sample is heated in an inert atmosphere and reacted with the carbon source while controlling the temperature rising rate, and CO gas generated sequentially by the oxygen in the analysis sample reacting with the carbon source. Is extracted into an inert gas stream, the amount of the extracted CO gas is sequentially measured by an infrared absorption method, and the peak of the generated CO amount is detected from the generated CO amount data thus obtained. The generated CO amount data is accumulated in time series while decreasing the flow rate of the inert gas flow every time the peak appears, and the oxygen amount for each type of oxide in the analysis sample is obtained from the accumulated generated CO amount data. A method for analyzing oxygen by type of oxides in an analysis sample, characterized in that:

(3) The analysis sample is heated in an inert atmosphere and reacted with the carbon source while controlling the temperature rising rate, and the CO gas which is sequentially generated by the oxygen in the analysis sample reacting with the carbon source. Is extracted into an inert gas stream, the extracted CO gas is sequentially analyzed by an infrared absorption method to determine the amount of reactive oxygen, and the peak of the amount of reactive oxygen is detected from the thus obtained reactive oxygen amount data, and the detected amount of reactive oxygen is detected. Analyzed while decreasing the flow rate of the inert gas flow each time the peak of the generated reactive oxygen amount appeared, the reactive oxygen amount data was accumulated in time series, and the oxides in the analysis sample were calculated from the accumulated reactive oxygen amount data. A method for analyzing oxides in an analysis sample, wherein the amount of oxygen for each type is determined, and the amount of oxide for each type is determined from the amount of oxygen for each type of oxide.

(4) The analysis sample is heated in an inert atmosphere and reacted with a carbon source while controlling the temperature rising rate, and CO gas which is sequentially generated when oxygen in the analysis sample reacts with the carbon source. Is extracted into an inert gas stream, the amount of the extracted CO gas is sequentially measured by an infrared absorption method, and the peak of the generated CO amount is detected from the generated CO amount data thus obtained. The generated CO amount data is accumulated in time series while decreasing the flow rate of the inert gas flow every time the peak appears, and the oxygen amount for each type of oxide in the analysis sample is determined from the accumulated generated CO amount data. A method for analyzing oxides in an analysis sample, wherein a type-specific oxide amount is determined from the oxide type-specific oxygen amount.

(5) an analysis sample heating means for heating the analysis sample in an inert atmosphere while controlling the temperature rising rate; a carbon source supply means for supplying a carbon source to be reacted with oxygen in the analysis sample; An inert gas flow generating means for generating an inert gas flow for extracting and transporting a CO gas generated by a reaction between oxygen in the analysis sample and the carbon source, and CO transported and transported by the inert gas flow Reaction oxygen amount measuring means for sequentially analyzing the gas by an infrared absorption method to obtain the reaction oxygen amount, and reaction oxygen amount peak detecting means for detecting the reaction oxygen amount peak from the reaction oxygen amount data sequentially obtained from the reaction oxygen amount measurement means And an inert gas flow control means for reducing the flow rate of the inert gas flow every time a peak of the reactive oxygen amount detected by the reactive oxygen amount peak detecting means appears. Oxygen analyzer for each type of oxide in the sample.

(6) an analysis sample heating means for heating the analysis sample in an inert atmosphere while controlling the rate of temperature rise; a carbon source supply means for supplying a carbon source to be reacted with oxygen in the analysis sample; Inert gas flow generating means for generating an inert gas flow for extracting and transporting a CO gas generated by a reaction between oxygen in the analysis sample and the carbon source, and CO extracted and transported by the inert gas flow Generated C that measures the amount of gas by the infrared absorption method and obtains the amount of CO generated sequentially
O amount measuring means, generated CO amount peak detecting means for detecting a peak of the generated CO amount from the generated CO amount data sequentially obtained by the generated CO amount measuring means, and generated CO amount detected by the generated CO amount peak detecting means. Analysis comprising: an inert gas flow control means for reducing the flow rate of the inert gas flow each time a peak of the amount appears; and a reactive oxygen amount calculating means for obtaining a reactive oxygen amount from the generated CO amount data. Oxygen analyzer for each type of oxide in the sample.

(7) Analysis sample heating means for heating the analysis sample in an inert atmosphere while controlling the temperature rising rate; carbon source supply means for supplying a carbon source to be reacted with oxygen in the analysis sample; An inert gas flow generating means for generating an inert gas flow for extracting and transporting a CO gas generated by a reaction between oxygen in the analysis sample and the carbon source, and CO transported and transported by the inert gas flow Reaction oxygen amount measuring means for sequentially analyzing the gas by an infrared absorption method to obtain the reaction oxygen amount, and reaction oxygen amount peak detecting means for detecting the reaction oxygen amount peak from the reaction oxygen amount data sequentially obtained from the reaction oxygen amount measurement means An inert gas flow control means for reducing the flow rate of the inert gas flow each time a peak of the reactive oxygen amount detected by the reactive oxygen amount peak detecting means, and the reactive oxygen amount measuring means An analyzer for calculating the amount of oxide for each type from the amount of reactive oxygen obtained in time series from the data.

(8) An analysis sample heating means for heating the analysis sample in an inert atmosphere while controlling the rate of temperature rise, a carbon source supply means for supplying a carbon source to be reacted with oxygen in the analysis sample, Inert gas flow generating means for generating an inert gas flow for extracting and transporting a CO gas generated by a reaction between oxygen in the analysis sample and the carbon source, and CO extracted and transported by the inert gas flow Generated C that measures the amount of gas by the infrared absorption method and obtains the amount of CO generated sequentially
O amount measuring means, generated CO amount peak detecting means for detecting a peak of the generated CO amount from the generated CO amount data sequentially obtained by the generated CO amount measuring means, and generated CO amount detected by the generated CO amount peak detecting means. Inert gas flow rate control means for reducing the flow rate of the inert gas flow every time a peak of the amount appears, and calculating means for obtaining a type-specific oxide amount from generated CO amount data obtained in time series from the generated CO amount measuring means An analyzer for an oxide in an analysis sample, comprising:

[0019]

According to the present invention, first, an analysis sample is heated in an inert atmosphere to react with a carbon source, and CO gas generated by the reaction of oxygen in the analysis sample with the carbon source is converted into an inert gas stream. It is based on a technique for measuring the amount of reactive oxygen by measuring and analyzing the extracted CO gas by an infrared absorption method. The carbon source is not particularly limited, but a graphite crucible, graphite powder, carbon contained in a graphite capsule, an analysis sample, or the like can be used as the carbon source.

Among them, it is practical to use a graphite crucible as a carbon source, put an analysis sample into the graphite crucible, heat and melt it to generate CO gas. A method may be used in which graphite powder is used as a carbon source, mixed with an analysis sample, and heated.

One of the features of the present invention is that, based on the above-described technology, a reaction with a carbon source is performed while controlling the rate of temperature rise of an analysis sample, and sequentially generated CO gas is extracted into an inert gas stream. The CO gas is sequentially analyzed to determine the amount of reactive oxygen or the generated C
The point is that the amount of O is determined, and the reaction oxygen amount data or the generated CO amount data is accumulated in time series. The oxygen amount or oxide amount for each type of oxide can be calculated from the thus obtained reaction oxygen amount data or generated CO amount data.

That is, it is considered that the oxide and the carbon source in the analysis sample cause a reaction of MO + C = M + CO (M: metal, O: oxygen, C: carbon). Since the reaction temperature of the above-mentioned reaction differs for each type of oxide, the present inventor heated and reacted with the carbon source while precisely controlling the rate of temperature rise of the analysis sample, thereby obtaining the type of oxide. It has been found that the CO gas can be extracted by reacting at different timings for each time. In this way,
Calculating the amount of oxygen derived from the type of oxide or the amount of this type of oxide that has reacted at a certain timing by transporting the CO gas extracted at a different timing by an inert gas flow and successively measuring and analyzing the CO gas Can be.

Means for calculating or calculating the amount of oxygen or the amount of oxide for each type of oxide is roughly divided into the following. And the generated CO amount data are stored in chronological order, and the generated C
There is a method of obtaining from O amount data.

As a method of obtaining from the reaction oxygen amount data accumulated in time series, a reaction time corresponding to a reaction timing of each type of oxide (according to a method represented by the following waveform, an appearance timing of each waveform). The data inside may be integrated to determine the amount of oxygen or the amount of oxide for each type of oxide. Also,
The sequential reaction oxygen data is accumulated, and the total oxide amount or oxygen amount is calculated.

As a method of obtaining from the generated CO amount data accumulated in time series, a reaction timing corresponding to the reaction timing of each type of oxide (the appearance timing of each oxide according to the method represented by the following waveform). Data over time can be integrated, and the amount of oxygen or the amount of oxide can be calculated from the amount of CO gas generated in the reduction reaction for each oxide obtained. Further, the sequential reaction CO data is accumulated, and the total oxide amount or oxygen amount is calculated.

FIG. 1 shows an example of a graph in which the amount of extracted oxygen (corresponding to the amount of extracted CO gas) obtained by the method and the apparatus of the embodiment of the present invention is displayed in time series. For example, if n types of oxides are contained in the analysis sample, a first waveform having a first peak and a second waveform having a second peak in the order of oxides that are easily reduced are referred to as a second waveform having a second peak. A waveform having n peaks in the form is obtained.

Specifically, the control of the rate of temperature rise of the analysis sample is performed by gradually increasing the temperature and maintaining a constant from the appearance of the first peak of the amount of extracted oxygen or the amount of extracted CO gas to the end of the first waveform. Temperature and gradually rises from the end of the first waveform to the appearance of the second peak, and further, from the appearance of the second peak to the end of the second waveform, to a constant temperature, from the end of the second waveform The temperature is gradually increased until the appearance of the third peak, and the temperature is kept constant from the appearance of the third peak to the end of the third waveform, and the temperature is gradually increased from the end of the third waveform to the appearance of the fourth peak. Thus, a repetitive pattern of raising the temperature and keeping the temperature constant is preferable.

More specifically, for example, in the case of analyzing a bearing steel containing four types of oxide-based inclusions, the rate of temperature rise from the starting point of heating the sample to the peak appearance point of the first waveform Is set to 1 ° C./sec, the temperature rising rate from the peak appearance point of the first waveform to the end point of the first waveform is set to 0 ° C./sec, and then from the end point of the first waveform to the second peak appearance point. Is set to 1 ° C./sec again, and the temperature rising rate from the second peak appearance point to the end point of the second waveform is set to 0 ° C./sec.
And Next, the temperature rising rate from the end point of the second waveform to the third peak appearance point is 1 ° C./sec, and the temperature rising rate from the third peak appearance point to the end point of the third waveform is 0 ° C.
/ Sec. Next, the heating rate from the end point of the third waveform to the fourth peak appearance point is again set to 1 ° C./sec, and the heating rate from the fourth peak appearance point to the end point of the fourth waveform is 0 ° C. / Sec. From the end point of the fourth waveform to the end of the analysis, the temperature is again set to 1 ° C./sec. By this operation, four types of inclusions corresponding to each of the four types of inclusions included
Get two peaks. What is necessary is to control as follows.

If the temperature at which the waveform of each peak starts to be generated is too high, the temperature range of the reaction between the first oxide and the second oxide becomes too close, and it becomes difficult to separate the waveforms. In addition, it is considered that the slower the heating rate, the closer to the thermodynamic equilibrium condition. On the other hand, if the heating rate is too slow, the analytical efficiency will be poor, and it is not suitable for analyzing practical steel. From these points, the rate of temperature rise of the analysis sample is 0.01 ° C./s or more and 20 ° C.
/ S or less is recommended.

The type of the oxide to be used in the present invention is not particularly limited. For example, Al ₂ O ₃ , SiO _{2
2, CaO, MgO, MnO,} Cr 2 O 3, TiO 2,
And complex oxide-based inclusions thereof.
Looking at a steel material, which is a typical example of an analysis sample to be analyzed by the present invention, it can be seen that Al ₂ O ₃ as an oxide-based inclusion in the steel material
, SiO ₂ , CaO, MgO, MnO and the like. In addition, they exist not only as a single substance but also in various forms such as those in a complex form such as MgO.Al ₂ O ₃ .

Next, another feature of the present invention is that the CO gas extracted sequentially is analyzed sequentially while controlling the temperature rising rate of the analysis sample as described above, and the amount of reactive oxygen or the amount of generated CO is determined. The peak of the amount of reactive oxygen or the amount of generated CO is detected from the thus obtained data of the amount of reactive oxygen or the amount of generated CO, and CO gas is extracted every time the detected peak of the amount of reactive oxygen or the amount of generated CO appears. The point is that the analysis is performed while reducing the flow rate of the active gas flow.

That is, as described above, the temperature at which the oxide decomposes differs depending on the type of the oxide.
It has been found that the decomposition temperature of each oxide is affected by the CO partial pressure of the atmosphere during the reaction between each oxide and the carbon source. As a result of the study, as shown in FIG. 2, the relationship between the reaction temperature of the oxide and the CO partial pressure could be estimated or measured based on the thermodynamic equilibrium calculation and the actual measurement results.

As can be seen from FIG. 2 which shows the relationship between the decomposition temperature for each type of oxide and the CO partial pressure (corresponding to the amount of oxygen constituting the oxide) shown in FIG.
It is thought that it changes with the partial pressure. Therefore, depending on the CO partial pressure when each oxide is decomposed, the decomposition temperature of the oxide may be the same even if the type of the oxide is different. In such a case, each of the oxides shown in FIG. Are considered to overlap. In this case, the type of the oxide cannot be identified.

This can be expressed by the following equation.

The ΔG = -RTlnP _CO ... (1) where, .DELTA.G the free energy, R represents the gas constant of the oxide, T is temperature, P _CO is minute CO gas when the oxide is reduced by carbon Pressure, which corresponds to the oxygen content of each oxide.

The waveforms of the above-mentioned extracted oxygen amount (extracted CO gas amount) curves can be extracted more precisely for each oxide as they are separated from each other without overlapping each other.

Thus, based on such findings, the present inventor thought that it was necessary to take measures to control the CO partial pressure of the atmosphere during the CO gas extraction in order to solve the problems of the present invention. The CO partial pressure can be expressed as in the following equation 2.

{(CO gas amount) / (inert gas amount + CO gas amount)} = CO partial pressure (2) Here, the value of the numerator in Expression 2 is a value that is necessarily determined by the oxygen amount in the analysis sample. It is. By changing the amount of the inert gas in the value of the denominator, the CO partial pressure at the time of analysis can be arbitrarily controlled.

That is, by the method of changing the amount of inert gas, the decomposition temperature for each type of oxide at the time of analysis can be arbitrarily controlled, and the separability of each waveform of the CO gas extraction curve for each oxide can be significantly improved. It is.

Thus, the peak of the amount of reactive oxygen or the amount of generated CO is detected from the sequentially obtained data of the amount of reactive oxygen or the amount of generated CO, and the CO gas is extracted every time the detected peak of the amount of reactive oxygen or the amount of generated CO is generated. The analysis method of the present invention has been developed in which the analysis is performed while reducing the flow rate of the inert gas flow.

Means for detecting the peak of the amount of reactive oxygen or the amount of generated CO from the data of the amount of reactive oxygen or the amount of generated CO is, for example, a coulometric method, a conductivity method, a gas chromatograph method, an infrared absorption method, or a non-aqueous solvent method. Can be used.

Further, the detected reaction oxygen amount or the generated CO
As the inert gas flow control means for reducing the flow rate of the inert gas flow for extracting the CO gas every time the amount of the peak appears,
For example, a flow meter and an inert gas flow control valve may be used to adjust the flow rate arbitrarily.

Further, the flow rate of the inert gas for extracting the CO gas is preferably 2000 cc / min or less.
This is because the inert gas flow rate for extracting CO gas is 2000
If it exceeds cc / min, the variation in the detected gas amount tends to be large, though it depends on the means for detecting the peak. For example, in the case of the apparatus of the present invention shown in FIG. 3, the flow rate of the inert gas may be adjusted by the gas flow controllers 8 and 9 in the figure.

Furthermore, the present inventor has obtained a new finding that the amount of dissolved analysis sample is also important when performing analysis by an inert gas transport-infrared absorption method. That is, for example, in the case of an analysis sample such as a metal having an extremely low oxygen content, or in the case of an analysis sample having a low total oxygen content and many types of oxides, the amount of oxygen generated from each oxide is extremely small. The extracted waveform of oxygen overlaps with noise peculiar to the apparatus, which is not related to the oxygen amount, and it tends to be difficult to separate only the oxygen amount generated from the oxide in the analysis sample. In order to prevent this, the amount of the sample to be dissolved may be increased, but from the viewpoint of the analysis efficiency and the uniform dissolution, the amount is preferably about 5 g or less.

The infrared CO absorption detector 10 shown in FIG.
The reference cell 21 is filled with nitrogen or the like having no infrared absorption, and the detector 22 is filled with a high concentration of the component gas to be measured. The detector 22 is divided into two rooms by a thin partition 23, and a metal plate attached to the partition 23 serves as one pole of the condenser 24. When the component to be measured is present in the sample, the amount of light entering the detector 22 is reduced by the amount absorbed by the sample, and a pressure difference is generated between the two chambers of the detector 22 to displace the diaphragm 23, and the capacitor 24 The capacity changes. By measuring this change in capacity, the concentration of the component to be measured can be known.

The sensitivity of the infrared CO absorption detector 10 depends on the light quantity difference between the reference cell 21 and the measurement cell 25. To increase the light quantity difference, the optical path length L of the infrared CO absorption detection device
Is important. If the optical path length L exceeds 50 mm, it depends on the combination with the intensity of the infrared light source 26, but it becomes difficult to discriminate the signal of extracted waveform from noise or a normal waveform cannot be obtained. If the optical path length L is too short, the reference cell 2
The difference between 1 and the light quantity of the measurement cell 25 is less likely to appear. For this reason, the optical path length L of the infrared CO absorption detection device of the present invention is preferably ≦ 50 mm.

The infrared CO used in the present invention
There are various types and structures of the absorption detection device such as a cross-flow type, but these types, structures and types are not particularly limited as long as they satisfy the above-described measurement principle.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described together with comparative examples with reference to the drawing of FIG.

FIG. 3 schematically shows the structure of a main part of a sample analyzer to which the method of the present invention is applied. In FIG. 1, reference numeral 1 denotes a direct current type extraction furnace, in which an upper electrode and lower electrodes 3 and 4 for holding a crucible 2 for accommodating a sample and electrically heating the crucible 2 are provided. An AC power supply 5 has one end connected to the upper electrode 3 via the ammeter 6 and the other end connected to the lower electrode 4. Reference numeral 7 denotes a voltmeter for measuring the voltage between the electrodes 3 and 4.

Reference numeral 16 denotes a gas flow path of the sample analyzer.
A flow controller 8 for adjusting the flow rate of the gas introduced into the extraction furnace 1 and a flow controller 9 for adjusting the flow rate of the gas to the infrared CO absorption detection device 10 are connected to this gas flow path. The oxygen in the sample is analyzed by the detection device 10. After the infrared CO absorption detector 10, the room temperature oxidizer 11 for converting the CO ₂ selectively oxidize CO in the gas, to selectively remove only CO ₂ generated by the ambient temperature oxidizer C
O ₂ remover 12, H for selectively removing H ₂ O in gas
_A heat conduction type analyzer 14 is connected via a ₂ O remover 13, and is configured to analyze nitrogen in a sample.

Reference numeral 17 denotes an electric signal control circuit which sends an extraction gas signal to a microcomputer 15;
A signal for controlling the He amount of the atmospheric gas is sent to the gas flow control valves 8 and 9.

Numeral 15 denotes an arithmetic control unit such as a microcomputer, which performs arithmetic processing on an extracted gas signal from the sample to determine the amount of oxygen and the amount of nitrogen for each type of oxide-based inclusion.

Using the analyzer shown in FIG. 3, the following examples and comparative examples were analyzed. Table 1 shows the outline of each example together with the results.

[0055]

[Table 1]

Comparative Example 1 is an example of analysis using an artificially prepared oxide powder. The amount of the powder dissolved was 0.5 g, and the amount of oxygen as Al ₂ O ₃ therein was 0.141.
mg, the amount of oxygen as MgO is 0.040 mg, CaO
Al ₂ so that the oxygen amount as
O ₃ powder, MgO powder, and CaO powder were accurately weighed using a microbalance. These three powders are mixed, and 2773K in advance, He gas flow rate is 2000 ml.
/ Min into the graphite crucible 2 degassed. The He amount of the atmosphere gas flowing through the gas flow controllers 8 and 9 during gas extraction was 400 ml / min. The extracted gas is passed through the gas flow path 16 to the infrared CO absorption detector (optical path length 50 m).
m), measured by the infrared CO absorption mechanism described above, and the microcomputer 15 calculates the amount of oxygen gas. The heating rate of the sample is 10 ° C./s. As a result of the measurement, a plurality of waveforms as shown in FIG. 1, in this case, three waveforms were not separated, and only the first waveform appeared. The total oxygen amount was 0.201 mg, and most of the inserted oxygen amount could be recovered.

The object of analysis in Example 1 is the same subject having the same powder type and mixed amount shown in Comparative Example 1. The analysis conditions other than the flow rate of the inert gas were the same as in Comparative Example 1. The control of the inert gas flow rate was as follows. Until the first waveform peak appeared, the amount of the atmosphere gas flowing through the gas flow controllers 8 and 9 was set to 600 ml / min. Thereafter, after the peak appearance of the first waveform was completed, the atmospheric gas flowing through the gas flow controllers 8 and 9 was reduced to 500 ml / min. Then, the second waveform appeared separately from the first waveform.

The amount of the atmosphere gas flowing through the gas flow controllers 8 and 9 was set to 500 ml / min until the second waveform peak appeared.
Left. After the appearance of the second waveform peak, the temperature was further increased and the amount of the atmosphere gas flowing through the gas flow controllers 8 and 9 was increased to 400 m.
1 / min. Then, the third waveform appeared separately from the second waveform. The amount of the atmosphere gas flowing through the gas flow controllers 8 and 9 is set to 4 until the peak of the third waveform appears.
After the peak of the third waveform appeared, the temperature was further increased to reduce the amount of the atmosphere gas flowing through the gas flow controllers 8 and 9 to 300 ml / min. The next waveform did not appear and the gas extraction was completed.

The first waveform is a waveform indicating the amount of oxygen corresponding to the Al ₂ O ₃ oxide, and the amount of oxygen was 0.141 mg. The second waveform is a waveform indicating the amount of oxygen corresponding to the MgO oxide, and the amount of oxygen was 0.040 mg. The third waveform is a waveform indicating the amount of oxygen corresponding to the CaO oxide, and the amount of oxygen was 0.028 mg. As described above, when the flow rate of the inert gas at the time of analysis is reduced in the order of appearance of the waveform, the CO partial pressure at the time of gas extraction increases, the decomposition temperature of the oxide changes to a high temperature side, and each waveform has It is considered that the separability was improved. As described above, by controlling the flow rate of the inert gas at the time of analysis, it became possible to analyze the three types of oxides in the powder sample by oxygen.

Comparative Example 2 is an example of analysis using steel for bearings. The composition of the inclusions in the bearing steel is Al ₂ O ₃ ,
It is composed of MgO and CaO. The amount of oxygen for each composition of the inclusions was quantified in advance by the extraction separation method of inclusions, and the amount of oxygen corresponding to Al ₂ O ₃ was 2.5 p.
pm, oxygen equivalent to MgO is 1.5 ppm, CaO
Was 1.0 ppm. The analysis conditions such as the rate of temperature rise of the sample, the flow rate of the inert gas, and the optical path length of the infrared CO absorption detector are the same as those in Comparative Example 1. The extracted waveform was one waveform without being separated into three, and the total amount of extracted oxygen was 4.9 ppm.

The subject of analysis in Example 2 is the same as the bearing steel shown in Comparative Example 2. The analysis conditions other than the flow rate of the inert gas were the same as those in Comparative Example 2. The control of the inert gas flow rate was as follows. Until the peak of the first waveform appears, the amount of the atmosphere gas flowing through the gas flow controllers 8 and 9 is reduced to 600 ml /
min. After the peak of the first waveform appears, the amount of the atmosphere gas flowing through the gas flow controllers 8 and 9 is reduced to 500 ml.
/ Min. Then, the second waveform appeared clearly separated from the first waveform. Until the peak of the second waveform appeared, the amount of the atmosphere gas flowing through the gas flow controllers 8 and 9 was kept at 500 ml / min. After the appearance of the peak of the second waveform, the temperature was further increased and the amount of the atmosphere gas flowing through the gas flow controllers 8 and 9 was reduced to 400 ml / min. Then, the third waveform appeared clearly separated from the second waveform. The gas flow controller 8, until the third waveform peak appears,
9 was kept at 400 ml / min, and after the peak of the third waveform appeared, the temperature was further increased and the amount of the atmosphere gas flowing through the gas flow controllers 8 and 9 was 300 ml / min.
Reduced to. The next waveform did not appear and the gas extraction was completed. The first waveform is an extraction curve of oxygen corresponding to Al ₂ O ₃ inclusions, which showed 2.49 ppm. The second waveform is an extraction curve of oxygen corresponding to MgO inclusions, and showed 1.48 ppm. The third waveform is an extraction curve of oxygen corresponding to CaO inclusions, showing 0.96 ppm.

As described above, when the flow rate of the inert gas at the time of analysis is reduced in the order of appearance of the waveform, the CO partial pressure in the crucible 2 at the time of gas extraction increases as in the case of the analysis of the powder sample. It is considered that the decomposition temperature of the oxide changed to a higher temperature side as compared with the case where the flow rate of the atmospheric gas was constant, and the separability of each waveform was improved. As described above, by controlling the flow rate of the inert gas at the time of analysis, it became possible to analyze the three types of oxides of the bearing steel sample by oxygen.

Example 3 is the same bearing steel as Comparative Example 2 and Example 2. The dissolved amount of the sample was increased to 3 g with respect to the dissolved amount of 1 g of the sample of Comparative Example 2 and Example 2. Other dissolution and gas flow conditions are exactly the same as in the second embodiment. As compared with Example 2, the absolute amount of oxygen generated from each oxide increases, and the separability of the first waveform, the second waveform, and the third waveform is further improved. Quantitative values improved.

Example 4 is not shown in Table 1, but is an example in which 1 g of bearing steel was used to simultaneously control the heating rate and the gas flow rate and analyzed. The composition of the inclusions in this bearing steel is SiO
₂ , Al ₂ O ₃ , MgO, and CaO.
When the amount of oxygen for each composition of the inclusions was quantified in advance by the extraction separation method of inclusions, the amount of oxygen corresponding to SiO ₂ was 0.8 ppm, the amount of oxygen corresponding to Al ₂ O ₃ was 2.1 ppm, and the amount of MgO was 2.1 ppm. The amount of oxygen corresponding to is 1.4 pp
The amount of oxygen corresponding to m and CaO was 1.0 ppm.
The heating rate between the peak appearance point of the first waveform from the start of heating the sample is 1 ° C./s, and the heating rate from the peak appearance point of the first waveform to the end point of the first waveform is 0 ° C./s. And Until the first waveform peak appears at this time, the gas flow controller 8,
The atmosphere gas amount flowing through 9 was 600 ml / min.
Thereafter, from the appearance of the first waveform peak to the appearance of the second waveform peak, the amount of the atmosphere gas flowing through the gas flow controllers 8 and 9 was reduced to 500 ml / min. Then, the second waveform appeared clearly separated from the first waveform. The temperature rising rate from the end point of the first waveform to the appearance point of the second peak was 1 ° C./s.

The heating rate from the peak appearance point of the second waveform to the end point of the second waveform was again set to 0 ° C./s. When the peak of the second waveform appears, the gas flow controllers 8, 9
Was reduced to 400 ml / min until the peak of the third waveform appeared. Then, the third waveform appeared clearly separated from the second waveform. The temperature rising rate from the end point of the second waveform to the peak appearance point of the third waveform was 1 ° C./s.

The heating rate from the peak appearance point of the third waveform to the end point of the third waveform was again set to 0 ° C./s. When the peak of the third waveform appears, the gas flow controllers 8, 9
Was reduced to 350 ml / min until the peak of the fourth waveform appeared. Then, the fourth waveform appeared clearly separated from the third waveform. The temperature rising rate from the end point of the third waveform to the peak appearance point of the fourth waveform was 1 ° C./s.

The heating rate from the peak appearance point of the fourth waveform to the end point of the fourth waveform was again set to 0 ° C./s. When the peak of the fourth waveform appears, the gas flow controllers 8, 9
The amount of the atmosphere gas flowing through is reduced to 300 ml / min, and the heating rate is again increased to 1 ° C. from the fourth waveform end point.
/ S, gas extraction was not observed thereafter until the end of the analysis. The first waveform is an oxygen extraction curve corresponding to SiO ₂ , showing 0.79 ppm. The second waveform is Al
It is an extraction curve of oxygen corresponding to O ₂ O ₃ , which is 2.1 pp.
m. The third waveform is an extraction curve of oxygen corresponding to MgO, showing 1.4 ppm. The fourth waveform is C
It is an extraction curve of oxygen corresponding to aO and was 1.0 ppm. When the temperature rise rate and the gas flow rate are simultaneously controlled and analyzed in this manner, an extremely good agreement can be obtained with the result of previously quantifying the oxygen content for each composition of the inclusions. Further, the peak position of the waveform could be clearly discriminated as compared with the result of only the gas flow control.

As for the separability of each waveform, the effect of the embodiment is further improved as the rate of temperature rise of the sample during gas extraction is reduced.

The gas flow rates of the flow controller 8 and the flow controller 9 may be the same. However, there is a case where the amount of the extracted gas is large and the display of the extracted waveform peaks out. It is advisable to reduce the flow rate.

As described above, the apparatus of the present invention was applied to the analysis of oxygen by oxygen gas by the inert gas melting / transporting-infrared absorption method, whereby oxide-based inclusions in the sample were accurately separated by type. Could be analyzed.

[0071]

As described above, according to the analysis method or apparatus of the present invention, the amount of oxygen or the amount of oxide for each type of oxide, such as oxide-based inclusions, in the analysis sample can be reduced. It is possible to measure and analyze accurately and quickly even in a small amount, and the effect is extremely large. Further, the present invention is a very useful invention that meets the needs of the industry, such as in the field of steelmaking, where it is desired to precisely control the form and amount of oxides, the amount of oxygen, and the like.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an extracted oxygen amount curve for each type of oxide-based inclusions.

FIG. 2 is a conceptual diagram showing the relationship between the decomposition temperature and the CO partial pressure (the amount of oxygen constituting the oxide) for each type of oxide, obtained from thermodynamic calculations.

FIG. 3 is an apparatus configuration diagram schematically showing a sample analyzer according to an embodiment of the present invention.

FIG. 4 is an explanatory view schematically showing an infrared CO absorption detection device.

[Explanation of symbols]

A to F: Types of oxides 1: Extraction furnace of direct current type 2. Crucible 3. Upper electrode 4. Lower electrode 5. AC power supply 6. Ammeter 7. Voltmeter 8, 9, Gas flow control valve 10. Infrared ray CO absorption detector 11 ... ambient temperature oxidizer 12 ... CO ₂ remover 13 ... H ₂ O remover 14 ... heat conduction type analyzer 15 ... microcomputer 16 ... gas channel 17 ... electric signal control circuit 21 ... reference cell 22 ... Detector 23 ... Separator 24 ... Condenser 25 ... Sample cell 26 ... Light source 27 ... Concave mirror 28 ... Sample gas inlet 29 ... Sample gas outlet 30 ... Interference gas cell 31 ... Rotating sector

Claims (8)

[Claims] 1. An analytical sample is heated in an inert atmosphere,
Reaction with a carbon source while controlling the rate of temperature rise, oxygen in the analysis sample reacts with the carbon source to extract sequentially generated CO gas into an inert gas stream, and the extracted CO gas is subjected to infrared absorption. The reactive oxygen amount is determined by sequential analysis according to the method, the peak of the reactive oxygen amount is detected from the thus obtained reactive oxygen amount data, and the flow rate of the inert gas flow is reduced each time the detected reactive oxygen amount peak appears. Oxidation in an analysis sample characterized by analyzing while accumulating reaction oxygen amount data in time series and obtaining the oxygen amount for each type of oxide in the analysis sample from the accumulated reaction oxygen amount data. Oxygen analysis method by type. 2. An analytical sample is heated in an inert atmosphere,
Reaction with a carbon source while controlling the rate of temperature rise, the CO in the analysis sample reacts with the carbon source to extract sequentially generated CO gas into an inert gas stream, and the amount of the extracted CO gas is measured by infrared rays. Measured sequentially by the absorption method, the peak of the generated CO amount is detected from the generated CO amount data thus obtained,
Generated CO amount data is accumulated in time series while decreasing the flow rate of the inert gas flow every time the detected generated CO amount peaks appear, and from the accumulated generated CO amount data, oxides in the analysis sample are accumulated. What is claimed is: 1. An oxygen analysis method for each type of oxide in an analysis sample, which comprises determining an oxygen amount for each type. 3. An analysis sample is heated in an inert atmosphere,
Reaction with a carbon source while controlling the rate of temperature rise, oxygen in the analysis sample reacts with the carbon source to extract sequentially generated CO gas into an inert gas stream, and the extracted CO gas is subjected to infrared absorption. The reactive oxygen amount is determined by sequential analysis according to the method, the peak of the reactive oxygen amount is detected from the thus obtained reactive oxygen amount data, and the flow rate of the inert gas flow is reduced each time the detected reactive oxygen amount peak appears. The reaction oxygen data is accumulated in a time series by analyzing while performing, and the oxygen amount for each type of oxide in the analysis sample is obtained from the accumulated reaction oxygen data, and the oxygen amount for each type is determined from the oxygen amount for each oxide type. A method for analyzing an oxide in an analysis sample, comprising determining an amount of the oxide. 4. An analytical sample is heated in an inert atmosphere,
Reaction with a carbon source while controlling the rate of temperature rise, the CO in the analysis sample reacts with the carbon source to extract sequentially generated CO gas into an inert gas stream, and the amount of the extracted CO gas is measured by infrared rays. Measured sequentially by the absorption method, the peak of the generated CO amount is detected from the generated CO amount data thus obtained,
Generated CO amount data is accumulated in time series while decreasing the flow rate of the inert gas flow every time the detected generated CO amount peaks appear, and from the accumulated generated CO amount data, oxides in the analysis sample are accumulated. A method for analyzing an oxide in an analysis sample, wherein an oxygen amount for each type is obtained, and an oxygen amount for each type is obtained from the oxygen amount for each oxide type. 5. An analysis sample heating means for heating an analysis sample in an inert atmosphere while controlling a temperature rising rate; a carbon source supply means for supplying a carbon source to be reacted with oxygen in the analysis sample; An inert gas flow generating means for generating an inert gas flow for extracting and conveying a CO gas generated by a reaction between oxygen in the sample and the carbon source, and a CO gas carried out and carried by the inert gas flow Reacting oxygen amount measuring means for analyzing by an infrared absorption method and sequentially obtaining the reacting oxygen amount,
A reactive oxygen amount peak detecting means for detecting a peak of the reactive oxygen amount from the reactive oxygen amount data sequentially obtained from the reactive oxygen amount measuring means, and the reaction oxygen amount peak detected by the reactive oxygen amount peak detecting means, An apparatus for controlling the flow rate of an inert gas flow by means of an inert gas flow rate control means for reducing the flow rate of an inert gas flow. 6. An analysis sample heating means for heating an analysis sample in an inert atmosphere while controlling a heating rate, a carbon source supply means for supplying a carbon source to be reacted with oxygen in the analysis sample, Inert gas flow generating means for generating an inert gas flow for extracting and transporting a CO gas generated by a reaction between oxygen in a sample and the carbon source, and CO gas extracted and transported by the inert gas flow A generated CO amount measuring means for measuring the amount by an infrared absorption method to obtain a generated CO amount sequentially, and a generated CO amount for detecting a peak of the generated CO amount from the generated CO amount data sequentially obtained by the generated CO amount measuring means Peak detection means, inert gas flow control means for reducing the flow rate of the inert gas flow each time a peak of the generated CO amount detected by the generated CO amount peak detection means, and the generated CO amount data A means for calculating the amount of reactive oxygen from the data, and an oxygen analyzer for each type of oxide in the analysis sample. 7. An analysis sample heating means for heating an analysis sample in an inert atmosphere while controlling a heating rate, a carbon source supply means for supplying a carbon source to be reacted with oxygen in the analysis sample, An inert gas flow generating means for generating an inert gas flow for extracting and conveying a CO gas generated by a reaction between oxygen in the sample and the carbon source, and a CO gas carried out and carried by the inert gas flow Reacting oxygen amount measuring means for analyzing by an infrared absorption method and sequentially obtaining the reacting oxygen amount,
A reactive oxygen amount peak detecting means for detecting a peak of the reactive oxygen amount from the reactive oxygen amount data sequentially obtained from the reactive oxygen amount measuring means, and the reaction oxygen amount peak detected by the reactive oxygen amount peak detecting means, Inert gas flow rate control means for reducing the flow rate of the inert gas flow, and arithmetic means for calculating the type-specific oxide amount from the reactive oxygen amount data obtained in time series from the reactive oxygen amount measuring means, For analyzing oxides in the analysis sample. 8. An analysis sample heating means for heating an analysis sample in an inert atmosphere while controlling a temperature rising rate; a carbon source supply means for supplying a carbon source to be reacted with oxygen in the analysis sample; Inert gas flow generating means for generating an inert gas flow for extracting and transporting a CO gas generated by a reaction between oxygen in a sample and the carbon source, and CO gas extracted and transported by the inert gas flow A generated CO amount measuring means for measuring the amount by an infrared absorption method to obtain a generated CO amount sequentially, and a generated CO amount for detecting a peak of the generated CO amount from the generated CO amount data sequentially obtained by the generated CO amount measuring means Peak detection means, inert gas flow control means for reducing the flow rate of the inert gas flow each time a peak of the generated CO amount detected by the generated CO amount peak detection means, and the generated CO amount meter Calculating means for calculating the amount of oxides by type from the generated CO amount data obtained in time series from the measuring means.