JPH05157698A - Quantitative analysis of steel for nickel - Google Patents

Abstract

PURPOSE:To obtain an ICP method by which steel can be quantitatively analyzed for nickel with high sensitivity in order to quantitatively recognize the relation between the compounded composition and characteristics of the steel containing Ni, Cr, Mo, and V. CONSTITUTION:In the title quantitative analysis, a cutting-dust steel sample is thermally dissolved in aqua regia after the sample is degreased and dried and a filtrate is obtained by filtrating the dissolved solution after cooling. Then ion-exchanged water is added to the filtrate until the mixture reached a fixed amount after strontium is added as a standard reference material. By using the mixture as a sample solution, the luminance intensity of the nickel contained in the sample is measured by using an inductively coupled plasma method and the nickel content of the sample is determined by an internal standard method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for quantitative analysis of nickel in alloys, especially in Ni-Cr-Mo-V steel, by high frequency inductively coupled plasma emission method (hereinafter referred to as ICP method).

[0002]

2. Description of the Related Art A high-speed rotary generator is a gas turbine that burns gas to turn a generator to generate electricity. The heat generated at this time heats hot water to 90% of the original amount of energy.
It is intended to increase the efficiency of%.

When this high-speed rotary generator is used, the conventional 600 rpm is rotated at a high speed of 30,000 rpm, so that centrifugal force is also considerably applied, and conventional materials cannot be used in terms of strength. For this reason, miniaturization is being considered in consideration of safety in terms of rotational speed and centrifugal force.

Further, since the rotation speed increases, the temperature also rises, which may increase up to about 350 ° C. as compared with the conventional 180 ° C. Therefore, high strength at high temperature is required.

Ni-Cr used especially for rotor bar materials
-Mo-V steel has a track record as a gas turbine for thermal power generation and is characterized by high strength at high temperatures, but this special steel is a custom-made product by an external manufacturer or the like, and JIS Since it is out of the standard, Ni-Cr-Mo-
It is necessary to clearly and quantitatively grasp the relationship between the alloy composition and characteristics of V to improve quality control and process control. Therefore, it is essential to establish a method for analyzing trace Ni.

[0006]

SUMMARY OF THE INVENTION The present invention was devised by focusing on such problems, and Ni-Cr-
The present invention provides an ICP method for quantifying nickel in Mo-V steel with high sensitivity.

[0007]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention is to degrease and dry shavings of steel, add aqua regia to heat and decompose, and then cool and filter the decomposed solution. After adding strontium as a standard substance to the obtained filtrate, a fixed amount of ion-exchanged water was used, and this was used as a sample solution to measure the emission intensity of nickel using the high frequency inductively coupled plasma emission method. Quantifying is the solution.

[0008]

According to such a quantitative analysis method, when the powdered steel is decomposed by heating with aqua regia, the residual amount of other coexisting substances in the sample solution is small and nickel can be decomposed almost completely.

When nickel emission intensity of the sample solution is measured by the ICP method and quantified by the internal standard method, aqua regia and reagents have a negative effect. The same reagent concentration can be used to suppress the influence of the presence of aqua regia and reagents.

Further, both the coefficient of variation and the recovery rate when the synthetic solution was measured were sufficiently satisfactory in practical use, and as a result, nickel in steel was quantified with high sensitivity. A method for analyzing trace amounts of nickel in Mo-V steel has been established, and the relationship between the composition and properties of steel can be clarified.

[0011]

EXAMPLES Ni-Cr-Mo-V according to the present invention will be described below.
A specific example of the method for analyzing Ni in steel will be described.

First, the basic operation procedure of this embodiment will be described with reference to the flow chart of FIG.

First, in step 101, a swarfed Ni-Cr-Mo-V steel used as a sample is degreased with chloroform and well dried, and then in step 102, aqua regia is added in a conical beaker for thermal decomposition at a predetermined temperature. To do. In order to carry out the analysis with higher accuracy, it is preferable to measure the reagents used with a whole pipette, a micropipette or the like.

Next, after cooling this decomposition liquid, step 10
No. 3 Filter using 5C filter paper and receive in a 200 ml volumetric flask. Next, 2.0 g of strontium as a standard substance is added to the filtrate obtained in step 104, and a fixed amount of 200 ml is made with ion-exchanged water. Step this
In 105, the sample solution is used in the quantitative analysis method of nickel in steel by the ICP method.

In the following, Ni- by the ICP method according to the present invention
Details of a quantitative analysis method of nickel in Cr-Mo-V steel will be described based on Examples.

[1] Operating procedure of analysis method [1-1 Composition of sample] Sample Ni-Cr-Mo-
Table 1 shows the composition of V steel.

[0017]

[Table 1]

[1-2 Decomposition of Sample and Preparation Method of Sample Solution] Debris-like Ni-Cr-Mo-V steel is degreased with chloroform and dried to obtain a sample. This sample is subjected to aqua regia decomposition and aqua regia- The residue was decomposed by perchloric acid decomposition method, and the residue after decomposition was examined. In addition, a part was subjected to a blank test.

(1) Method for decomposing aqua regia A sample of 1.0 g was taken in a conical beaker, and 40 m of aqua regia
1 is added and the mixture is decomposed by heating using a burner. After cooling down, N
Filter with o5C filter paper.

(2) Aqua regia-perchloric acid decomposition method 1.0 g of a sample was sampled in a conical beaker and aqua regia 40 m
1, 20 ml of perchloric acid were added, and the mixture was heated to the point of dryness, dissolved in nitric acid, and then added with NO. Filter with 5C filter paper.

(3) 0.5 g of a blank sample was treated with NO. It was filtered through 5C filter paper.

[2] Analyzing device, measurement conditions and reagents [2-1 Analyzing device] ICP emission spectroscopic device is IC manufactured by Shimadzu
PS-1000-2 type was used.

[2-2 Measurement Conditions] Table 2 shows the measurement conditions.

[0024]

[Table 2]

[2-3 Reagents] Table 3 shows a list of reagents used in the experiment.

[0026]

[Table 3]

[2-4 Measurement Method] The peak search internal standard method was used.

[3] Result of Decomposition Test FIGS. 2 and 3 are graphs showing the residue of the sample subjected to the aqua regia decomposition method. According to the aqua regia method, it was observed that the main components, iron and chromium, remained slightly.

FIGS. 4 and 5 are graphs showing the residue after decomposition by the aqua regia-perchloric acid decomposition method. Although nickel, chromium, molybdenum and vanadium which are measurement items were not detected, A small amount of silicon Si remained. FIG. 6 is a graph showing the residue of the sample used in the blank test.

Here, if perchloric acid remains in the sample,
The correction for removing the influence of the viscosity of perchloric acid when applying the ICP method becomes complicated. Therefore, in order to remove perchloric acid, it is dried to dryness after the decomposition, but this dryness may cause chromium to volatilize.

[4] Verification of aqua regia-perchloric acid decomposition method It was examined how much chromium was volatilized by the above-mentioned (2) aqua regia-perchloric acid decomposition method.

[4-1 Method] 20 mg of chromium (1000 ppm standard solution for atomic absorption measurement) in a conical beaker
Are collected, and 40 ml of aqua regia and 20 ml of perchloric acid are added and heated. White smoke is generated and heating is stopped just before drying.
After cooling, dissolve in 20 ml of nitric acid (1 + 1) to obtain 200 ml
After determining a fixed amount, chromium is measured by the ICP method.

[4-2 Result] Table 4 shows the result of measuring chromium after the above operation.

[0034]

[Table 4]

Table 4 shows the results of three times of the volatilization test of chromium, and it was found that chromium was considerably volatilized during the decomposition process as expected. From this result, it was found that simultaneous analysis of nickel, chromium, molybdenum and vanadium is difficult by the aqua regia-perchloric acid decomposition method.

From the above results, the aqua regia decomposition method was adopted for the decomposition of the sample, and the residue was melted with the flux.
That is, a sample of 1.0 g was taken in a conical beaker, 40 ml of aqua regia was added to decompose by heating, and about 50 ml of water was left after cooling.
In addition, the mixture was filtered through No5C filter paper, 2 g of strontium as a standard substance was added to the filtrate, and ion-exchanged water was added to make a fixed amount of 200 ml, which was used as a sample solution in the nickel quantitative analysis method by the ICP method.

[5] Experiments and Results [5-1 Selection of Analysis Line] In order to select the most suitable wavelength for nickel analysis, a single solution of each element constituting the Ni-Cr-Mo-V steel and an internal standard. The analytical line was qualitatively selected using strontium as a substance. The results are shown in FIGS.

The concentration of each element in the sample solution was 3 for Ni.
60ppm, Cr 200ppm, Mo 40ppm,
V is 10ppm, Mn is 30ppm, Sr is 10pp
m and Fe are 10000 ppm. Then, three wavelengths having high emission intensity of nickel were selected and an analysis line was selected.

FIG. 7 shows an emission spectrum at a wavelength of 231.604 nm, FIG. 8 shows an emission spectrum at a wavelength of 341.477 nm, and FIG. 9 shows an emission spectrum at a wavelength of 221.674 nm. The emission spectra of coexisting substances are all base at any wavelength. It is supposed to be on the line and not interfere with nickel.

Therefore, as the analysis line, 221.674 nm, which has high sensitivity in the first priority of the wavelength of nickel, was adopted.

[5-2 Selection of Sensitivity (HV)] Sensitivity (H
V) is a high voltage applied to Photomal, and an optimum HV exists depending on the concentration.

Therefore, an optimum HV was selected using a solution having a nickel concentration of 360 ppm. The results are shown in Figs.
It shows in FIG. Since HV is preferably as high as possible so long as it is not saturated, here, from the results shown in FIG.
It was adopted.

[5-3 Selection of Internal Standard Material and Its Wavelength] Strontium is adopted as an internal standard material, and in order to select an analysis line of this strontium, three typical wavelengths of strontium (407.771 nm, 421.
552 nm, 216.596 nm) profile was measured and qualitatively determined. The results are shown in FIGS. 13 to 15. Wavelength 407.771 nm and wavelength 421.552n
As for m, as shown in FIGS. 13 and 14, only the emission line of strontium was present and all the coexisting substances were on the baseline, and no interference with strontium was observed. Figure 15
At the wavelength of 216.5596 nm shown in, the emission line of Fe, which is the main component of the coexisting substance, overlaps the emission line of strontium, and the emission line of nickel is also close. Therefore, since interference by these substances is expected, it is unsuitable as an analytical line.

From the above results, the analysis lines of strontium which is an internal standard substance have wavelengths of 407.771 nm and 4
Although 21.552 nm can be used, a wavelength of 421.552 nm having a high emission intensity as an analysis line is adopted here.

[5-4 Accuracy of Calibration Curve] The concentration of nickel in the sample solution is about 360 ppm. Therefore, the accuracy of the calibration curve was confirmed in the nickel concentration range of 0 to 540 ppm. The result is shown in FIG. From this figure, the calibration curve almost passes through the origin, and the correlation coefficient is 0.99999777,
It can be seen that the standard deviation is 1.2042758 ppm, which is a very good precision.

[Influence of 5-5 Reagent] Nickel Concentration 36
Hydrochloric acid and nitric acid, which are decomposition reagents, were added stepwise to the 0 ppm solution to quantitatively investigate the effect. The result is shown in FIG. It shows in FIG.

The determination as to whether there is any influence is made by the recovery rate (measured value x 1
00 / prepared value) ± 2%, and the allowable range is shown by a broken line in the figure.

Both hydrochloric acid and nitric acid showed negative effects. This means that the presence of aqua regia increases the viscosity of the sample solution,
This is because the amount of sample sucked was reduced and the apparent emission intensity was lowered.

Therefore, it was decided to make the concentration of the reagents in the calibration curve preparation solution and the sample solution the same to suppress the influence of the presence of aqua regia.

[5-6 Effect of Coexisting Elements] Iron, chromium, molybdenum, vanadium, manganese, copper, phosphorus, silicon, and strontium as an internal standard substance are added in stages to a solution having a nickel concentration of 180 ppm, and the coexisting elements are added. The effect was investigated quantitatively.

The results are shown in FIGS. The determination of the presence or absence of these influences was within ± 2% of the nickel recovery rate, and the allowable range is shown by a broken line in the figure.

As a result, it was found that chromium, molybdenum, vanadium, manganese, copper, phosphorus, silicon and strontium all have no effect within the allowable range shown by the broken line. However, it was found that iron, which is the main component, has a negative effect as shown in FIG. It is considered that this is because the presence of iron increased the viscosity of the sample solution and decreased the amount of suction of the sample, resulting in a lower apparent emission intensity. Therefore, the concentration of iron in the solution for preparing the calibration curve and the concentration of iron in the sample solution were made the same to suppress the negative influence of iron.

[5-7 Effect of Reagent on Strontium Internal Standard Material] A solution having a strontium concentration of 10 ppm was added stepwise with hydrochloric acid and nitric acid, which are decomposition reagents, to quantitatively investigate the effect. The results are shown in FIGS. 28 and 29.

As a result, it was found that both hydrochloric acid and nitric acid had negative effects. That is, as the amounts of hydrochloric acid and nitric acid added increased, the recovery rate of strontium decreased. It is considered that this is because the viscosity of the sample solution increased due to the presence of hydrochloric acid and nitric acid as described above.

Therefore, the concentration of the reagent in the solution for preparing the calibration curve and the concentration of the reagent in the sample solution were made equal to suppress the above-mentioned negative influence.

[Effect of Coexisting Element on Internal Standard Material Strontium] Strontium Concentration 10 ppm
Iron, chromium, molybdenum, vanadium, manganese, copper, phosphorus, silicon and nickel were added stepwise to the solution to quantitatively investigate the effect of each element on strontium. The results are shown in FIGS.

Chromium, molybdenum, vanadium, manganese, copper, phosphorus, silicon and nickel were within the permissible range shown by the broken line and had no effect on strontium.

However, it has been found that iron, which is the main component, has a negative effect as shown in FIG. It is considered that this is because the presence of iron increased the viscosity of the sample solution and decreased the amount of suction of the sample due to the presence of iron, and the apparent emission intensity decreased. Therefore, the concentration of iron in the solution for preparing the calibration curve and the concentration of iron in the sample solution were made the same to suppress the negative influence of iron.

[5-9 Verification of Analytical Accuracy Using Synthetic Solution] In order to verify analytical accuracy under the conditions examined above, five synthetic solutions were prepared and carried out. Table 5 shows the composition of the synthetic solution, and Table 6 shows the measurement results.

[0060]

[Table 5]

[0061]

[Table 6]

From Table 6, the average measured nickel value is 20.
3.0 ppm, recovery rate is 101.5%, coefficient of variation (C
V) was 0.98, which was a sufficient accuracy for practical use.

The solution for preparing the calibration curve was prepared as shown below.

That is, 2 ml of aqua regia in a 100 ml volumetric flask.
0 ml, strontium 1.0 mg and ferric chloride 2.
4 g was added, and 0 to 30 mg of nickel was added stepwise to make a fixed amount of 100 ml with ion-exchanged water.

It is also possible to use a standard solution for preparing a mixed calibration curve in which chromium, molybdenum and vanadium are added in stages.

[6] Consideration From the above results, Ni- by the ICP method according to this embodiment is
The following findings were obtained by examining the analysis method of nickel in Cr-Mo-V steel.

(6-1) Sample Decomposition Method Nickel can be easily decomposed by adding aqua regia to the chipped sample and heating it.

(6-2) Analysis line As a result of examining the interference of coexisting elements on the analysis line 221.647 nm with high emission intensity and high sensitivity, no interference peak was observed.

(6-3) Influence and suppression of degrading reagent The degrading reagent aqua regia showed negative interference. It is considered that this is because the viscosity of the sample solution increased due to the coexistence of aqua regia and the suction amount of the sample decreased, so in order to suppress this effect, the reagent concentration in the sample solution and the calibration curve preparation solution should be the same. In addition, it was possible to suppress the above-mentioned influence by further measuring by using the strontium internal standard method.

(6-4) Analytical accuracy The recovery rate when 5 synthetic solutions were measured was 101.5%, and the coefficient of variation was 0.98%, which were all sufficiently satisfactory for practical use.

[0071]

EFFECT OF THE INVENTION Ni-Cr by the ICP method according to the present invention
According to the method for analyzing nickel in -Mo-V steel, by thermally decomposing a swarf-like alloy with aqua regia, there is little residual of other coexisting substances in the sample solution, and nickel is almost completely decomposed. can do.

When the luminescence intensity of nickel was measured by the ICP method in the sample solution and quantified by the internal standard method, aqua regia and reagents showed a negative effect, but in the calibration curve preparation solution and the sample solution. It became possible to suppress the influence of the presence of aqua regia and reagents by keeping the same reagent concentration. In addition, the sample solution
Both the coefficient of variation and the recovery rate when measured by the CP method were sufficiently satisfactory for practical use, and the result was N
A method for analyzing a trace amount of Ni in i-Cr-Mo-V steel has been established to clarify the relationship between the composition and properties of steel, and
Quality control and process control can be improved.

[Brief description of drawings]

FIG. 1 is a flowchart showing a basic operation procedure of a method for quantitatively analyzing nickel in steel according to the present invention.

FIG. 2 is a graph showing the residue of the sample subjected to the aqua regia decomposition method.

FIG. 3 is a graph showing the residue of the sample subjected to the aqua regia decomposition method.

FIG. 4 is a graph showing a residue of a sample subjected to an aqua regia-perchloric acid decomposition method.

FIG. 5 is a graph showing a residue of a sample subjected to an aqua regia-perchloric acid decomposition method.

FIG. 6 is a graph showing the residue of the sample used in the blank test.

FIG. 7 is a graph showing emission spectra of various elements at a wavelength of 231.604 nm.

FIG. 8 is a graph showing emission spectra of various elements at a wavelength of 341.477 nm.

FIG. 9 is a graph showing emission spectra of various elements at a wavelength of 221.647 nm.

FIG. 10: Wavelength 221.647 nm, nickel concentration 36
The graph which selected HV (in the case of HV10) using a 0 ppm solution.

FIG. 11: Wavelength 221.647 nm, nickel concentration 36
The graph which selected HV (in the case of HV20) using a 0 ppm solution.

FIG. 12: Wavelength 221.647 nm, nickel concentration 36
The graph which selected HV (in the case of HV30) using a 0 ppm solution.

FIG. 13 is a graph showing profiles of coexisting substances at a wavelength of 407.771 nm of strontium as an internal standard substance and each element in the sample after aqua regia decomposition.

FIG. 14 is a graph showing profiles of coexisting substances at a wavelength of 421.552 nm of strontium as an internal standard substance and each element in the sample after aqua regia decomposition.

FIG. 15 is a graph showing profiles of coexisting substances at a wavelength of 216.5596 nm of each element in the sample after decomposition of aqua regia and strontium as an internal standard substance.

FIG. 16 is a graph showing a calibration curve of nickel.

FIG. 17 is a graph showing the effect of hydrochloric acid as a decomposition reagent.

FIG. 18 is a graph showing the effect of nitric acid as a decomposition reagent.

FIG. 19 is a graph quantitatively showing an allowable range of nickel recovery rate due to the influence of Fe.

FIG. 20 is a graph quantitatively showing the allowable range of nickel recovery rate due to the influence of Cr.

FIG. 21 is a graph quantitatively showing the allowable range of nickel recovery rate due to the effect of Mo.

FIG. 22 is a graph quantitatively showing the allowable range of nickel recovery rate due to the influence of V.

FIG. 23 is a graph quantitatively showing the allowable range of nickel recovery rate due to the influence of Mn.

FIG. 24 is a graph quantitatively showing an allowable range of nickel recovery rate due to the influence of Cu.

FIG. 25 is a graph quantitatively showing an allowable range of nickel recovery rate due to the influence of P.

FIG. 26 is a graph quantitatively showing an allowable range of nickel recovery rate due to the influence of Si.

FIG. 27 is a graph quantitatively showing the allowable range of nickel recovery rate due to the influence of Sr.

FIG. 28 is a graph showing the influence of a reagent (hydrochloric acid) on strontium.

FIG. 29 is a graph showing the influence of a reagent (nitric acid) on strontium.

FIG. 30 is a graph quantitatively showing the allowable range of the recovery rate of strontium due to the influence of Fe.

FIG. 31 is a graph quantitatively showing the allowable range of the recovery rate of strontium due to the influence of Cr.

FIG. 32 is a graph quantitatively showing the allowable range of the recovery rate of strontium due to the influence of Mo.

FIG. 33 is a graph quantitatively showing the allowable range of the recovery rate of strontium due to the influence of V.

FIG. 34 is a graph quantitatively showing the allowable range of the strontium recovery rate due to the influence of Mn.

FIG. 35 is a graph quantitatively showing the allowable range of the strontium recovery rate due to the influence of Cu.

FIG. 36 is a graph quantitatively showing the allowable range of the recovery rate of strontium due to the influence of P.

FIG. 37 is a graph quantitatively showing the allowable range of the recovery rate of strontium due to the influence of Si.

FIG. 38 is a graph quantitatively showing the allowable range of the recovery rate of strontium due to the influence of Ni.

Claims (2)

[Claims] 1. A strontium ion as a standard substance is added to a filtrate obtained by degreasing and drying swarfed steel, drying it by adding aqua regia and then heating and decomposing it, and then filtering this decomposing solution. Quantitative analysis of nickel in steel, characterized in that a fixed amount of exchanged water is used as a sample solution, the emission intensity of nickel is measured using the high frequency inductively coupled plasma emission method, and nickel is determined by the internal standard method. Method. 2. The method for quantitative analysis of nickel in steel according to claim 1, wherein the sample steel is a Ni—Cr—Mo—V system.