Method for measuring content of boron element in cobalt-based alloy

Abstract

The invention discloses a method for determining the content of a boron element in a cobalt-based alloy, which adopts inductively coupled plasma atomic emission spectrometry for determination and comprises the following steps: preparing a solution to be determined, preparing a standard solution, drawing a standard working curve, determining the solution to be determined and processing data, a preparation method of the to-be-detected solution comprises the following steps: weighing 0.4000 g of a sample in a boron-free quartz flask, adding hydrochloric acid, slowly adding a hydrogen peroxide solution until the reaction is complete, evaporating to be nearly dry at the temperature of below 180 DEG C, supplementing hydrochloric acid and nitric acid, heating and dissolving at the temperature of below 180 DEG C until the reaction is stopped, adding (1 + 1) mixed acid of sulfuric acid and phosphoric acid and mannitol, heating at the temperature of 280-300 DEG C until smoking, taking down after 30 minutes, slightly cooling, adding hydrochloric acid, and stirring for 30 minutes to obtain the to-be-detected solution. Boiling until salt is completely dissolved, cooling, and diluting with water to a constant volume in a 100mL plastic volumetric flask. The method disclosed by the invention has relatively high accuracy and good repeatability and stability.

Description

Technical Field

[0001] The invention relates to a method for determining the content of boron in a cobalt-based alloy, and belongs to the technical field of metallurgical analysis. Background Art

[0002] Cobalt-based alloys are hard alloys resistant to various types of wear and corrosion, as well as high-temperature oxidation. With cobalt as its primary component and containing elements such as Cr, Ni, and Fe, they exhibit high strength, excellent resistance to thermal fatigue, hot corrosion, and abrasion at temperatures above 980°C, and good weldability. They are suitable for manufacturing guide vanes and nozzle guide vanes for aircraft jet engines, industrial gas turbines, and shipboard gas turbines, as well as diesel engine nozzles. To effectively improve the performance of cobalt-based alloys, certain essential elements are added and their content is controlled to effectively monitor their quality.

[0003] However, currently, methods for elemental analysis in cobalt-based alloys are not comprehensive. Domestically, there are no relevant chemical analysis standards for cobalt alloys, with the sole exception of YS / T 1330-2019, "Chemical Analysis Methods for Cobalt-Chromium Ceramic Alloys." Internationally, the only chemical analysis method for cobalt-based high-temperature alloys is ASTM E1473-09. This lack of cobalt-based alloy standards poses significant challenges for the accurate determination of elements in cobalt-based alloys. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for determining the boron content in cobalt-based alloys, which adopts inductively coupled plasma atomic emission spectrometry and has high accuracy, good repeatability and stability.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for determining the boron content in a cobalt-based alloy using inductively coupled plasma atomic emission spectrometry includes preparing a test solution, preparing a standard solution, drawing a standard working curve, determining the test solution, and processing data. The details are as follows:

[0007] (1) Preparation of test solution

[0008] Weigh 0.4000g of sample into a boron-free quartz flask, add 5mL~10mL of hydrochloric acid, slowly add 1mL~2mL of hydrogen peroxide solution until the reaction is complete, evaporate to near dryness below 180℃, add 3mL~5mL of hydrochloric acid and 1mL~2mL of nitric acid, heat and dissolve below 180℃ until no reaction occurs, add 10mL~15mL of (1+1) sulfuric acid and phosphoric acid mixture and 0.5mL~1mL of mannitol, heat at 280~300℃ until smoking, remove and cool slightly after 30min, add 4mL~6mL of hydrochloric acid, boil until the salts are completely dissolved, cool, dilute with water and make up to volume in a 100mL plastic volumetric flask.

[0009] (2) Preparation of standard solution

[0010] Weigh 6 parts of high-purity cobalt and dissolve them according to the preparation method of the test solution. After complete dissolution, transfer them to a 100mL plastic volumetric flask. Then, add a standard solution of an element with a mass fraction of more than 5% (excluding the matrix cobalt) to the volumetric flask to match the mass percentage of the corresponding element in the sample to be tested. Finally, add different volumes of boron standard solution and adjust the volume to prepare a series of standard solutions with a concentration gradient.

[0011] The standard solution contains a matrix cobalt element concentration of 35wt% to 55wt%, a chromium element concentration of 18wt% to 25wt%, a nickel element concentration of 10wt% to 30wt%, a tungsten element concentration of 6wt% to 15wt%, a molybdenum element concentration of 5wt% to 10wt%, and an iron element concentration of 10wt% to 30wt%.

[0012] (3) Drawing of standard working curve

[0013] Using an inductively coupled plasma emission spectrometer, the elements to be measured are measured from low to high concentrations, and a calibration curve is drawn with the concentration of the elements to be measured as the horizontal axis and the emission intensity as the vertical axis. The concentration unit is wt%, and the emission intensity unit is c / s.

[0014] The measurement conditions of the inductively coupled plasma emission spectrometer shown are: RF emission power: 1200KW; cooling gas flow rate: 15L / min; nebulizing gas flow rate: 0.75L / min; auxiliary gas flow rate: 1L / min; pump speed: 12r / min; observation mode: axial; observation height: 12mm; integration time: 18s; and the analytical line wavelength of the element to be measured is: 182.577nm.

[0015] (4) Test solution determination and data processing

[0016] The solution to be tested is introduced into an inductively coupled plasma atomic emission spectrometer, and the emission intensity of the solution to be tested is measured using the same measurement conditions as the standard working curve. The content of the element to be tested in the solution to be tested is obtained according to the standard working curve, and then the content of the boron element in the cobalt-based alloy is calculated.

[0017] The detection range of the method of the present invention is 0.0020wt% to 0.030wt%.

[0018] The inventive principle of the technical solution of the present invention is:

[0019] Cobalt-based alloys are acid-dissolved, in which boron usually exists in the solution in the form of boric acid or borate ions. Mannitol is a polyhydroxy compound containing multiple hydroxyl groups in its molecules. These hydroxyl groups can react with boric acid or borate ions to form stable five-membered or six-membered ring complexes. This complexation reduces the possibility of boron existing in the form of volatile boric acid, etc., and enhances the stability of boron in the solution, thereby avoiding the loss of boron due to the volatilization of boric acid and other substances during the acid-dissolution process, ensuring that boron can be well retained in the solution system, facilitating subsequent operations such as accurate analysis of boron in cobalt-based alloys.

[0020] The beneficial effects of adopting the above technical solution are:

[0021] (1) The determination method provided by the present invention overcomes the defect of boron volatility and can efficiently determine the boron content in cobalt-based alloys. It has high detection accuracy, good repeatability and stability, and is suitable for daily sample detection.

[0022] (2) The present invention adopts a matrix matching method to eliminate the influence of the matrix effect, which greatly improves the efficiency and accuracy of the detection of the boron content in cobalt-based alloys and is suitable for the determination of the boron content in various brands of cobalt-based alloys.

[0023] (3) The detection method provided by the present invention has a wide dynamic linear range and high analytical precision, which can make up for the shortcomings of traditional wet chemistry, save manpower and material resources, and realize rapid analysis and detection. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below with reference to specific embodiments.

[0025] The reagents and instruments used in the present invention are as follows:

[0026] 1. Reagents

[0027] The water used in the present invention is laboratory water of grade 2 or above as specified in GB / T 6682;

[0028] Hydrochloric acid, extra-pure (ρ1.19 g / mL);

[0029] Nitric acid, extra pure (ρ1.42 g / mL);

[0030] Hydrogen peroxide, high purity (ρ1.10 g / mL);

[0031] Sulfuric acid, high purity (ρ1.84 g / mL):

[0032] Phosphoric acid, high purity (ρ1.79 g / mL);

[0033] Mannitol, analytical grade;

[0034] High-purity cobalt (purity ≥99.99%, Central Iron and Steel Research Institute);

[0035] Cr, Ni, tungsten, and molybdenum single element standard stock solutions (10 mg / mL, Central Iron and Steel Research Institute);

[0036] Boron standard stock solution (1 mg / mL, Central Iron and Steel Research Institute); Boron standard working solution (0.1 mg / mL) was prepared by serial dilution of the standard stock solution.

[0037] 2. Instruments

[0038] Varian 725-ES inductively coupled full spectrum direct reading plasma optical emission spectrometer (Agilent, USA) with a minimum resolution of 0.007 nm and a spectral line test range of 167–785 nm; Sartorius CPA124S electronic balance.

[0039] Example 1

[0040] This example measures the boron content in a standard sample of cobalt-based alloy grade GH5188. The determination method is as follows:

[0041] (1) Preparation of cobalt-based alloy sample solution

[0042] Weigh 0.4000g of sample into a boron-free quartz flask, add 10mL of hydrochloric acid, slowly add 2mL of hydrogen peroxide solution until the reaction is complete, evaporate to near dryness below 180℃, add 5mL of hydrochloric acid and 2mL of nitric acid, heat to dissolve below 180℃ until no reaction occurs, add 15mL of (1+1) sulfuric acid and phosphoric acid mixture and 0.5mL of mannitol, heat at 290℃ under a stable heat source until smoking, remove from the heat after 30min, cool slightly, add 6mL of hydrochloric acid, boil until the salts are completely dissolved, cool, dilute with water and make up to volume in a 100mL plastic volumetric flask.

[0043] (2) Prepare standard solution

[0044] According to GB / T 14992-2005, the chemical composition of the GH5188 sample is shown in Table 1.

[0045] Table 1 Chemical composition of GH5188 sample

[0046]

[0047] Weigh 6 portions of 0.16 g high-purity cobalt, with a matrix cobalt element concentration of about 40%, and dissolve them according to the cobalt-based alloy sample solution preparation process in step (1). After complete dissolution, transfer them into 100 mL plastic volumetric flasks.

[0048] According to the chemical composition of the GH5188 sample shown in Table 1, standard solutions of each element with a mass fraction of 5% or greater were added to a volumetric flask. The concentrations of chromium, nickel, and tungsten were approximately 20%, 20%, and 15%, respectively, to serve as the matrix solutions for the standard solutions. Different volumes of the boron standard working solution were pipetted into the matrix solution volumetric flask to prepare a series of standard solutions with a concentration gradient. The boron concentrations in the standard solutions are shown in Table 2.

[0049] Table 2 Concentration of boron in standard solution (μg / mL)

[0050]

[0051] (3) Draw the standard working curve

[0052] Set the instrument parameters on the inductively coupled plasma spectrometer according to Table 3, select the analytical line wavelength of the element to be measured as 182.577 nm, measure the spectral intensity of the element to be measured in the standard solution in turn, and draw the standard working curve with the concentration of the element to be measured as the horizontal axis and the emission intensity as the vertical axis.

[0053] Table 3 Measurement instrument conditions

[0054]

[0055] (4) Sample analysis and data processing

[0056] The solution to be tested is introduced into the inductively coupled plasma atomic emission spectrometer, and the emission intensity of the element to be tested in the solution to be tested is measured using the same measurement conditions as the working curve. The content of the element to be tested in the solution to be tested is obtained according to the standard working curve; then the content of the boron element in the sample to be tested can be calculated according to the following formula.

[0057]

[0058] Where: ω is the mass percentage of boron in the sample to be tested, %;

[0059] ω0 is the concentration of the element to be measured calculated according to the working curve, μg / mL;

[0060] V0 is the volume of the solution to be tested, mL;

[0061] m0 is the mass of the sample, g.

[0062] (5) Precision test

[0063] The samples were measured 11 times using the same method. The results and relative standard deviations (RSDs) are shown in Table 4.

[0064] Table 4 Example 1 precision test results (%)

[0065]

[0066] (6) Accuracy test

[0067] In order to verify the accuracy of the method, the spike recovery method was used for determination. The results are shown in Table 5.

[0068] Table 5 Accuracy test results of Example 1 (%)

[0069]

[0070] Example 2

[0071] This example determines the content of boron in the cobalt-based alloy standard sample GH6159. The determination method is as follows:

[0072] (1) Preparation of cobalt-based alloy sample solution

[0073] Weigh 0.4000g of sample into a boron-free quartz flask, add 8mL of hydrochloric acid, slowly add 2mL of hydrogen peroxide solution until the reaction is complete, evaporate below 180℃ to near dryness, add 4mL of hydrochloric acid and 2mL of nitric acid, heat below 180℃ to dissolve until no reaction occurs, add 12mL of (1+1) sulfuric acid and phosphoric acid mixture and 1mL of mannitol, heat at 280℃ under a stable heat source until smoking, remove from the heat after 30min, cool slightly, add 5mL of hydrochloric acid, boil until the salts are completely dissolved, cool, dilute with water to the volume in a 100mL plastic volumetric flask.

[0074] (2) Prepare standard solution:

[0075] According to GB / T 14992-2005, the chemical composition of the standard sample of brand GH6159 is shown in Table 6.

[0076] Table 6 Chemical composition of GH6159 standard sample

[0077]

[0078] Weigh 6 portions of 0.12 g high-purity cobalt, with a matrix cobalt element concentration of about 30%, and dissolve them according to the cobalt-based alloy sample solution preparation process in step (1). After complete dissolution, transfer them into 100 mL plastic volumetric flasks.

[0079] According to the chemical composition of the GH6159 standard sample shown in Table 6, standard solutions of the elements with a mass fraction of 5% or greater were added to volumetric flasks. The concentrations of chromium, nickel, molybdenum, and iron were approximately 18%, 25%, 7%, and 9%, respectively, to serve as the matrix solutions for the standard solutions. Different volumes of the boron standard working solution were pipetted into the matrix solution volumetric flasks to prepare a series of standard solutions with a concentration gradient. The boron concentrations in the standard solutions are shown in Table 7.

[0080] Table 7 Concentration of boron in standard solution (μg / mL)

[0081]

[0082] (3) Draw the standard working curve

[0083] Set the instrument parameters on the inductively coupled plasma spectrometer according to Table 3, select the analytical line wavelength of the element to be measured as 182.577 nm, measure the spectral intensity of the element to be measured in the standard solution in turn, and draw the standard working curve with the concentration of the element to be measured as the horizontal axis and the emission intensity as the vertical axis.

[0084] (4) Sample analysis and data processing

[0085] The solution to be tested is introduced into the inductively coupled plasma atomic emission spectrometer, and the emission intensity of the element to be tested in the solution to be tested is measured using the same measurement conditions as the working curve. The content of the element to be tested in the solution to be tested is obtained according to the standard working curve; then the content of the boron element in the sample to be tested can be calculated according to the following formula.

[0086]

[0087] Where: ω is the mass percentage of boron in the sample to be tested, %;

[0088] ω0 is the concentration of the element to be measured calculated according to the working curve, μg / mL;

[0089] V0 is the volume of the solution to be tested, mL;

[0090] m0 is the mass of the sample, g.

[0091] (5) Precision test

[0092] The samples were measured 11 times using the same method. The measurement results and relative standard deviations (RSDs) are shown in Table 8.

[0093] Table 8 Example 2 precision test results (%)

[0094]

[0095] (6) Accuracy test

[0096] In order to verify the accuracy of the method, the spike recovery method was used for determination. The results are shown in Table 9.

[0097] Table 9 Example 2 Accuracy test results (%)

[0098]

[0099] Example 3

[0100] This example determines the content of boron in the cobalt-based alloy standard sample GH6783. The determination method is as follows:

[0101] (1) Preparation of cobalt-based alloy sample solution

[0102] Weigh 0.4000g of sample into a boron-free quartz flask, add 5mL of hydrochloric acid, slowly add 1mL of hydrogen peroxide solution until the reaction is complete, evaporate below 180℃ to near dryness, add 3mL of hydrochloric acid and 1mL of nitric acid, heat below 180℃ to dissolve until no reaction occurs, add 10mL of (1+1) sulfuric acid and phosphoric acid mixture and 1mL of mannitol, heat at 300℃ under a stable heat source until smoking, remove from the flask after 30min and cool slightly, add 4mL of hydrochloric acid, boil until the salts are completely dissolved, cool, dilute with water and make up to volume in a 100mL plastic volumetric flask.

[0103] (2) Prepare standard solution:

[0104] According to GB / T 14992-2005, the chemical composition of the standard sample of brand GH6783 is shown in Table 10.

[0105] Table 10 Chemical composition of GH6783 standard sample

[0106]

[0107] Weigh 6 portions of 0.12 g high-purity cobalt, with a matrix cobalt element concentration of about 30%, and dissolve them according to the cobalt-based alloy sample solution preparation process in step (1). After complete dissolution, transfer them into 100 mL plastic volumetric flasks.

[0108] According to the chemical composition of the GH6783 standard sample shown in Table 10, add standard solutions of each element with a mass fraction of 5% or greater to a volumetric flask. The concentrations of aluminum, nickel, and iron are approximately 5%, 30%, and 25%, respectively, to serve as the matrix solutions for the standard solutions. Pipette different volumes of the boron standard working solution into the matrix solution volumetric flask to prepare a series of standard solutions with a concentration gradient. The boron concentrations in the standard solutions are shown in Table 11.

[0109] Table 11 Concentration of Boron in Standard Solutions (μg / mL)

[0110]

[0111] (3) Draw the standard working curve

[0112] Set the instrument parameters on the inductively coupled plasma spectrometer according to Table 3, select the analytical line wavelength of the element to be measured as 182.577 nm, measure the spectral intensity of the element to be measured in the standard solution in turn, and draw the standard working curve with the concentration of the element to be measured as the horizontal axis and the emission intensity as the vertical axis.

[0113] (4) Sample analysis and data processing

[0114] The solution to be tested is introduced into the inductively coupled plasma atomic emission spectrometer, and the emission intensity of the element to be tested in the solution to be tested is measured using the same measurement conditions as the working curve. The content of the element to be tested in the solution to be tested is obtained according to the standard working curve; then the content of the boron element in the sample to be tested can be calculated according to the following formula.

[0115]

[0116] Where: ω is the mass percentage of boron in the sample to be tested, %;

[0117] ω0 is the concentration of the element to be measured calculated according to the working curve, μg / mL;

[0118] V0 is the volume of the solution to be tested, mL;

[0119] m0 is the mass of the sample, g.

[0120] (5) Precision test

[0121] The samples were measured 11 times using the same method. The measurement results and relative standard deviation (RSD) are shown in Table 12.

[0122] Table 12 Example 3 precision test results (%)

[0123]

[0124] (6) Accuracy test

[0125] In order to verify the accuracy of the method, the spike recovery method was used for determination. The results are shown in Table 13.

[0126] Table 13 Accuracy test results of Example 3 (%)

[0127]

[0128] It can be seen from the above experimental results that the method provided by the present invention can accurately determine the content of boron in cobalt-based alloys and has good test precision and accuracy.

[0129] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining the boron content in a cobalt-based alloy, characterized in that: The determination was carried out by inductively coupled plasma atomic emission spectrometry, including preparation of a test solution, preparation of a standard solution, drawing of a standard working curve, determination of the test solution and data processing. The test solution preparation method was as follows: 0.4000 g of a sample was weighed and placed in a boron-free quartz flask, 5 mL to 10 mL of hydrochloric acid was added, 1 mL to 2 mL of hydrogen peroxide solution was slowly added until the reaction was complete, the solution was evaporated to near dryness below 180° C., 3 mL to 5 mL of hydrochloric acid and 1 mL to 2 mL of nitric acid were added, and the solution was heated to dissolve below 180° C. until no further reaction occurred, 10 mL to 15 mL of a (1+1) mixed acid of sulfuric acid and phosphoric acid and 0.5 mL to 1 mL of mannitol were added, and the solution was heated at 280 to 300° C. until smoke appeared. After 30 minutes, the solution was removed and cooled slightly, 4 mL to 6 mL of hydrochloric acid was added, and the solution was boiled until the salts were completely dissolved. After cooling, the solution was diluted with water to a fixed volume in a 100 mL plastic volumetric flask.

2. The method for determining the boron content in a cobalt-based alloy according to claim 1, wherein: The standard solution preparation method is as follows: weigh 6 parts of high-purity cobalt, dissolve it according to the preparation method of the test solution, and transfer it to a 100 mL plastic volumetric flask after complete dissolution; then, add a standard solution of an element with a mass fraction of more than 5% excluding the matrix cobalt to the volumetric flask to match the mass percentage of the corresponding element in the sample to be tested; finally, add different volumes of boron standard solution and adjust the volume to prepare a series of standard solutions with a concentration gradient.

3. The method for determining the boron content in a cobalt-based alloy according to claim 2, wherein: The standard solution contains a matrix cobalt element concentration of 35wt% to 55wt%, a chromium element concentration of 18wt% to 25wt%, a nickel element concentration of 10wt% to 30wt%, a tungsten element concentration of 6wt% to 15wt%, a molybdenum element concentration of 5wt% to 10wt%, and an iron element concentration of 10wt% to 30wt%.

4. The method for determining the boron content in a cobalt-based alloy according to claim 1, wherein: The method for drawing the standard working curve is as follows: using an inductively coupled plasma emission spectrometer, the element to be measured is measured from low to high concentration, and a calibration curve is drawn with the concentration of the element to be measured as the horizontal axis and the emission intensity as the vertical axis. The unit of the concentration is wt%, and the unit of the emission intensity is c / s.

5. The method for determining the boron content in a cobalt-based alloy according to claim 1, wherein: The measurement conditions of the inductively coupled plasma emission spectrometer are as follows: RF emission power: 1200 kW; cooling gas flow rate: 15 L / min; atomizing gas flow rate: 0.75 L / min; auxiliary gas flow rate: 1 L / min; pump speed: 12 r / min; observation mode: axial; observation height: 12 mm; and integration time: 18 s.

6. The method for determining the boron content in a cobalt-based alloy according to claim 1, wherein: The analytical line wavelength of the boron element is 182.577 nm.

7. The method for determining the boron content in a cobalt-based alloy according to claim 1, wherein: The test solution determination and data processing are as follows: the test solution is introduced into an inductively coupled plasma atomic emission spectrometer, the emission intensity of the test solution is measured using the same measurement conditions as the standard working curve, the content of the test element in the test solution is obtained according to the standard working curve, and the content of the boron element in the cobalt-based alloy is determined by calculation.

8. The method for determining the boron content in a cobalt-based alloy according to claim 1, wherein: The detection range of the method is 0.0020 wt% to 0.040 wt%.

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