A method for determining the content of copper and molybdenum in iron-based metallurgical powders

Abstract

This application provides a method for determining the content of copper and molybdenum in iron-based metallurgical powders. The method includes: preparing a test sample, dissolving the test sample to obtain a sample solution; preparing a blank solution without the analyte and several standard solutions containing known concentrations of the analyte; performing spectral measurements on the standard solutions using inductively coupled plasma optical emission spectrometry (ICP-OES) to plot a standard working curve; performing spectral measurements on the sample solution and the blank solution, obtaining the concentrations of the analyte in the sample solution and the blank solution from the standard working curve, and calculating the content of the analyte in the sample solution. The content detection method provided by this application has advantages such as simple sample preparation, convenient operation, short analysis time, high accuracy, low detection limit, small reagent consumption, environmental friendliness, and minimal matrix effect.

Description

Technical Field

[0001] This application relates to the field of elemental detection, and more specifically, to a method for determining the content of copper and molybdenum in iron-based metallurgical powders. Background Technology

[0002] Powder metallurgy is an industrial technology that uses metal powders (or mixtures of metal and non-metal powders) as raw materials, and through forming and sintering, produces metallic materials, composite materials, and various types of products. Iron-based powder metallurgy materials are widely used in various sectors of the national economy, especially the automotive industry, where they are commonly used in parts such as camshafts, exhaust valve seats, and various gears, playing a crucial role in the automotive field. With advancements in automotive deionization technology, the performance requirements for powder metallurgy parts are becoming increasingly stringent. Iron-based powder metallurgy often employs alloying elements such as carbon, copper, and molybdenum for strengthening. Adding copper enhances the material's friction and wear resistance, while adding molybdenum improves its strength. To strictly control the quality of iron-based powder metallurgy parts, it is necessary to accurately determine the copper and molybdenum content in the iron-based powder metallurgy.

[0003] Currently, no methods for the simultaneous detection of copper and molybdenum in iron-based powder metallurgy have been reported domestically or internationally. For the detection of copper and molybdenum in other materials, most methods employ spectrophotometry, iodometric titration, inductively coupled plasma atomic absorption spectrometry (ICP-AES), and ICP-AES mass spectrometry. Spectrophotometry and iodometric titration involve complex sample preparation processes, large reagent volumes, and long analysis times, requiring high levels of deionization expertise from analysts. Furthermore, neither of these methods can simultaneously determine multiple elements, thus limiting their application. ICP-AES and ICP-AES mass spectrometry suffer from limitations due to variations in sample preparation methods, interferences, and instrument conditions depending on the target analyte. Summary of the Invention

[0004] The purpose of this application is to provide a method for determining the content of copper and molybdenum in iron-based metallurgical powders, which can solve at least one of the aforementioned technical problems. The specific solution is as follows:

[0005] According to a specific embodiment of this application, this application provides a method for determining the content of copper and molybdenum elements in iron-based metallurgical powders, the method comprising:

[0006] S100. Prepare the test sample, then dissolve the test sample to prepare a sample solution; prepare a blank solution without the test element and several standard solutions containing the test element at known concentrations.

[0007] S200. Inductively coupled plasma atomic emission spectrometry (ICP-AES) is used to perform spectral measurements on the standard solution to obtain the integral value M of the spectral peak area of ​​the analyte in the standard solution.b Based on the known concentration C of the element to be measured in the standard solution b With M b The corresponding relationships are used to draw standard working curves;

[0008] S300. When the correlation coefficient of the standard working curve reaches 0.999 or higher, inductively coupled plasma atomic emission spectrometry (ICP-AES) is used to perform spectral measurements on the sample solution and blank solution. The background of the elemental spectral lines is checked and corrected to obtain the integral value M of the spectral peak area of ​​the analyte in the sample solution. s And the integral value M0 of the spectral peak area of ​​the element to be measured in the blank solution;

[0009] S400, according to M s Obtain the concentration C of the analyte in the corresponding sample solution from the standard working curve. s Based on M0, obtain the concentration C0 of the analyte in the corresponding blank solution from the standard working curve, and based on C... s The content of the element to be measured in the sample solution is calculated using C0.

[0010] This application employs an inductively coupled plasma atomic emission spectrometer (ICP-AES) to design a method for simultaneously determining the content of copper and molybdenum in iron-based powder metallurgy. The method includes preparing the test sample, preparing the sample solution, preparing the blank solution, preparing the standard solution, measuring with an ICP-AES, plotting a standard working curve of the concentration of the test element versus the integral value of the spectral peak area, and analyzing and calculating the results.

[0011] This application optimizes the preparation process of the test sample by using hydrochloric acid-nitric acid and sulfuric acid-phosphoric acid to dissolve the test sample, which can completely dissolve the test sample to meet the conditions for instrumental analysis.

[0012] Because inductively coupled plasma (ICP) light sources can excite a large number of emission lines, iron-based powder metallurgy may contain alloying elements such as phosphorus, manganese, chromium, nickel, and cobalt in addition to a large amount of iron matrix. During testing, not only is there matrix interference, but there may also be inter-element interference. This application addresses this by adding high-purity iron powder of the same amount as the test sample when preparing the standard solution, or by using an alloy steel standard with a composition similar to the test sample to plot a standard working curve. This effectively eliminates matrix differences between the standard working curve and the actual test sample. Furthermore, it allows for the simultaneous determination of the content of other alloying elements such as phosphorus, manganese, chromium, nickel, and cobalt in iron-based powder metallurgy. The prepared standard working curve can be stored and used long-term, simplifying the workflow and improving efficiency.

[0013] This invention optimizes the measurement conditions of inductively coupled plasma atomic emission spectrometry (ICP-AES) and determines the analytical spectral lines of copper and molybdenum. By selecting appropriate analytical spectral line wavelengths, adopting specific observation methods, and correcting background interference, the influence of spectral interference is eliminated, thereby improving the accuracy, sensitivity, and stability of the detection results.

[0014] In selecting the analytical spectral wavelengths, it is essential to ensure that the selected wavelengths possess characteristics such as low background concentration, low detection limit, high signal-to-noise ratio, and high sensitivity. Simultaneously, spectral interference from other spectral lines should be minimized. In the preliminary testing phase, several analytical spectral lines were selected and their spectral intensities measured. After multiple experiments, suitable analytical spectral wavelengths were finally determined: 327.393 nm for copper ions and 202.031 nm for molybdenum ions. The spectral peaks produced at these two wavelengths are sharp, with minimal spectral interference and low background. This also ensures that coexisting elements such as Cr, Co, Ni, W, and Si do not interfere with the analytes, and the iron matrix does not interfere with the selected wavelengths. However, raising the baseline can lead to an increase in background. Therefore, a matrix matching method is employed: adding the same amount of high-purity iron powder as the test sample to the standard solution; or using an alloy steel standard with a composition similar to the test sample to plot a standard working curve. This effectively eliminates matrix differences between the standard working curve and the actual test sample.

[0015] The inductively coupled plasma optical emission spectrometer (ICP) used in this application is an Optima 8300 model, which offers two observation modes: radial observation and axial observation. Radial observation collects light from the side of the plasma and measures the signal in the ion emission region (the optimal observation region). Axial observation, on the other hand, collects the signal from the entire analytical channel except for the exhaust flame. Therefore, the signal in the measurement region of radial observation is not as strong as the signal from the entire analytical channel in axial observation, resulting in lower sensitivity. However, the signal in this region provides the best signal-to-background ratio, which is particularly advantageous in the complex matrix of the test sample in this application, which contains matrix interference and interference from other alloying elements. Furthermore, radial observation does not collect the light signals from the atomized and atomic emission regions of the plasma, thus avoiding ionization interference. It has a very good linear range, very small matrix effect, and very low background, and is flexible and convenient. However, axial observation collects the signal from the entire analytical channel, including the atomized and atomic emission regions. Therefore, while axial observation improves sensitivity, it also increases background noise and matrix influence, introducing ionization interference. Furthermore, axial observation increases the observation area and also increases the self-absorption phenomenon of the emission spectral lines, thus affecting its linear range. This is especially true when determining complex elements in samples like those in this application, where the bending of the standard working curve can cause significant measurement errors. Therefore, this application uses standard solution excitation and tests the absolute intensity of the spectrum under both radial and axial observation methods, determining that the radial observation method is preferable.

[0016] In ICP spectral analysis, background interference is mainly caused by field emission, stray light effects, and ion-electron recombination processes. When the background light intensity varies with the content of the analyte in the sample, background correction can improve the analytical results, obtain the true spectral intensity of the analyte, and eliminate analytical errors caused by background interference. Experiments show that this method uses two-point correction to subtract background interference.

[0017] Compared with traditional methods, the content detection method provided in this application has advantages such as simple sample preparation, convenient operation, short analysis time, high result accuracy, low detection limit, small reagent consumption, environmental friendliness, and small matrix effect. The method recovery rate reaches 96-105%, and the RSD is less than 4.7%, which can meet the quality monitoring needs of materials used in automotive product development.

[0018] In some preferred embodiments, step S100 includes the preparation process of the test sample:

[0019] S111. Polish the sample surface to remove the adsorbate until the internal metal of the sample is exposed;

[0020] S112. The drill bit drills from the sample surface at a speed of 100-150 r / min to a thickness not exceeding 1 mm, removing the debris formed after drilling, thus completing the preparation of the test sample. The drill bit speed can be 100 r / min, 105 r / min, 110 r / min, 115 r / min, 120 r / min, 125 r / min, 130 r / min, 135 r / min, 140 r / min, 145 r / min, or 150 r / min; the drilling thickness can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1.0 mm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] In some preferred embodiments, step S100, the preparation process of the sample solution specifically includes the following steps:

[0022] S121. Weigh the sample to be tested, add deionized water, hydrochloric acid and nitric acid, and heat until the sample is completely dissolved to form a mixture.

[0023] S122. Add sulfuric acid and phosphoric acid to the mixture and continue heating until fumes are emitted;

[0024] S123. Take out the sample to be tested, cool it to room temperature, add deionized water, mix and heat to boiling;

[0025] S124. Take out the sample to be tested, cool it to room temperature, transfer it to a volumetric flask, add deionized water to dilute it, make up to the mark, mix well and set aside.

[0026] In some preferred embodiments, in step S121, 0.01-0.5g of the sample to be tested is weighed, for example, 0.01g, 0.05g, 0.1g, 0.15g, 0.2g, 0.25g, 0.3g, 0.35g, 0.4g, 0.45g or 0.5g, but not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0027] The amount of deionized water added is 10-50 mL, for example, 10 mL, 15 mL, 20 mL, 25 mL, 30 mL, 35 mL, 40 mL, 45 mL, or 50 mL; the amount of hydrochloric acid added is 1-20 mL, for example, 1 mL, 2 mL, 4 mL, 6 mL, 8 mL, 10 mL, 12 mL, 14 mL, 16 mL, 18 mL, or 20 mL; the amount of nitric acid added is 1-10 mL, for example, 1 mL, 2 mL, 3 mL, 4 mL, 5 mL, 6 mL, 7 mL, 8 mL, 9 mL, or 10 mL, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0028] In step S122, the amount of sulfuric acid added is 1-10 mL, for example, it can be 1 mL, 2 mL, 3 mL, 4 mL, 5 mL, 6 mL, 7 mL, 8 mL, 9 mL or 10 mL; the amount of phosphoric acid added is 1-5 mL, for example, it can be 1 mL, 1.5 mL, 2 mL, 2.5 mL, 3 mL, 3.5 mL, 4 mL, 4.5 mL or 5 mL, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0029] In some preferred embodiments, step S100, the preparation process of the standard solution includes:

[0030] S131. Weigh out several portions of high-purity iron powder equal to the amount of the test sample, add deionized water, hydrochloric acid and nitric acid and heat until the high-purity iron powder is completely dissolved.

[0031] S132. Add sulfuric acid and phosphoric acid to the dissolved mixture and continue heating until fumes are emitted;

[0032] S133. Take out the high-purity iron powder, cool it to room temperature, add deionized water, mix and heat to boiling;

[0033] S134. After removing the high-purity iron powder and cooling it to room temperature, transfer it into a volumetric flask.

[0034] S135. Add different volumes of copper standard solution and different volumes of molybdenum standard solution to the volumetric flask.

[0035] S136. Add deionized water to the volumetric flask to dilute, bring the volume to the mark, mix well and set aside.

[0036] In some preferred embodiments, step S200 specifically includes the following steps:

[0037] S211. Start the inductively coupled plasma atomic emission spectrometer. After the inductively coupled plasma atomic emission spectrometer is successfully initialized, ignite the plasma flame. After the plasma flame has stabilized for at least 20 minutes, perform the measurement.

[0038] S212. Adjust the settings of the inductively coupled plasma atomic emission spectrometer and perform spectral measurements on the standard solution at the selected measurement wavelength, in order of increasing concentration of the analyte in the standard solution.

[0039] S213. Plot the standard working curve by using the known concentration of the analyte in the standard solution as the abscissa and the integral value of the spectral peak area of ​​the analyte in the standard solution as the ordinate.

[0040] In some preferred embodiments, in step S212, the setting conditions of the inductively coupled plasma atomic emission spectrometer include:

[0041] The radio frequency power is set to 1000-1500W, for example, it can be 1000W, 1050W, 1100W, 1150W, 1200W, 1250W, 1300W, 1350W, 1400W, 1450W or 1500W, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] The plasma gas flow rate is set to 10-20 L / min, for example, it can be 10 L / min, 11 L / min, 12 L / min, 13 L / min, 14 L / min, 15 L / min, 16 L / min, 17 L / min, 18 L / min, 19 L / min or 20 L / min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] The atomizer airflow rate is set to 0.5-0.6 L / min, for example, it can be 0.5 L / min, 0.51 L / min, 0.52 L / min, 0.53 L / min, 0.54 L / min, 0.55 L / min, 0.56 L / min, 0.57 L / min, 0.58 L / min, 0.59 L / min or 0.6 L / min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] The auxiliary gas flow rate is set to 0.1-1 L / min, for example, it can be 0.1 L / min, 0.2 L / min, 0.3 L / min, 0.4 L / min, 0.5 L / min, 0.6 L / min, 0.7 L / min, 0.8 L / min, 0.9 L / min or 1.0 L / min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] The integration time is set to 5-20 seconds, for example, it can be 5s, 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 14s, 15s, 16s, 17s, 18s, 19s or 20s, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0046] The sample flow rate is set to 1-2 mL / min, for example, it can be 1.0 mL / min, 1.1 mL / min, 1.2 mL / min, 1.3 mL / min, 1.4 mL / min, 1.5 mL / min, 1.6 mL / min, 1.7 mL / min, 1.8 mL / min, 1.9 mL / min or 2.0 mL / min, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] The observation height is set to 10-20mm, for example, it can be 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm or 20mm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0048] The observation method used was radial observation, and the background correction method used was two-point correction.

[0049] In some preferred embodiments, in step S212, the setting conditions of the inductively coupled plasma atomic emission spectrometer include:

[0050] The radio frequency power was set to 1300W, the plasma gas flow rate was set to 15L / min, the nebulizer gas flow rate was set to 0.55L / min, the auxiliary gas flow rate was set to 0.5L / min, the integration time was set to 5-20s, the sample flow rate was set to 1.5mL / min, and the observation height was set to 15mm.

[0051] To obtain the optimal operating conditions for spectral analysis, this application first prepared several standard solutions and conducted optimization experiments on the operating conditions such as light source power, observation height, nebulizer airflow, plasma airflow, and auxiliary airflow. At the selected wavelength, the above operating conditions were changed step by step, and the spectral intensities of copper and molybdenum were measured. Finally, the optimal operating conditions for spectral analysis were determined. Within the range of operating conditions, the spectral line intensities of copper and molybdenum were the highest, and the sensitivity was the highest.

[0052] In some preferred embodiments, in step S212, the wavelength for measuring copper is 327.393 nm, and the wavelength for measuring molybdenum is 202.031 nm.

[0053] In some preferred embodiments, in step S400, according to C s The content of the element to be measured is calculated using C0, and the formula is as follows:

[0054] ;

[0055] Wherein, ꞷ represents the content of the element to be measured, %; C s C0 is the concentration of the analyte in the sample solution obtained from the standard working curve, in μg / mL; C0 is the concentration of the analyte in the blank solution obtained from the standard working curve, in μg / mL; V is the volume of the sample solution, in mL; and m is the mass of the test sample, in g.

[0056] For example, this application provides a method for determining the content of copper and molybdenum in iron-based metallurgical powders, specifically including the following steps:

[0057] S110. Prepare the test sample, specifically including:

[0058] S111. Polish the sample surface to remove the adsorbate until the internal metal of the sample is exposed;

[0059] S112. The drill bit drills at a speed of 100-150 r / min to cut a thickness of no more than 1 mm from the sample surface, removes the debris formed after drilling, and completes the preparation of the test sample.

[0060] S120. Preparation of sample solution, specifically including:

[0061] S121. Weigh 0.01-0.5g (accurate to 0.1mg) of the sample to be tested, add 10-50mL of deionized water, 1-20mL of hydrochloric acid and 1-10mL of nitric acid, and heat on a low-temperature electric furnace until the sample to be tested is completely dissolved to form a mixture.

[0062] S122. Add 1-10 mL of sulfuric acid and 1-5 mL of phosphoric acid to the mixture, and continue heating until it fumes for about 1 minute;

[0063] S123. Take out the sample to be tested and cool it to room temperature. Add 20-50 mL of deionized water and mix. Then place it on a low-temperature electric furnace and heat it to boiling.

[0064] S124. Take out the sample to be tested, cool it to room temperature, transfer it to a volumetric flask, add deionized water to dilute it, make up to the mark, mix well and set aside.

[0065] S130. Preparation of standard solutions, specifically including:

[0066] S131. Weigh out several portions of high-purity iron powder (mass fraction greater than 99.98%) equal to the amount of the sample to be tested, add 10-50 mL of deionized water, 1-20 mL of hydrochloric acid and 1-10 mL of nitric acid, and heat on a low-temperature electric furnace until the high-purity iron powder is completely dissolved to form a mixture.

[0067] S132. Add 1-10 mL of sulfuric acid and 1-5 mL of phosphoric acid to the mixture, and continue heating until fumes are emitted for about 1 minute;

[0068] S133. Take out the high-purity iron powder and cool it to room temperature. Add 20-50mL of deionized water and mix. Then place it on a low-temperature electric furnace and heat it to boiling.

[0069] S134. Take out the high-purity iron powder, cool it to room temperature, and transfer it into a volumetric flask;

[0070] S135. Add different volumes of copper standard solution and different volumes of molybdenum standard solution to the volumetric flask.

[0071] S136. Add deionized water to the volumetric flask to dilute, bring the volume to the mark, mix well and set aside.

[0072] S140. Prepare a blank solution, specifically including:

[0073] Weigh an equal amount of high-purity iron powder (mass fraction greater than 99.98%) into a volumetric flask, dilute with deionized water, bring the volume to the mark, mix well and set aside.

[0074] S210. Spectral measurement of standard solutions and plotting of standard working curves, specifically including:

[0075] S211. Start the inductively coupled plasma atomic emission spectrometer. After the inductively coupled plasma atomic emission spectrometer is successfully initialized, ignite the plasma flame. After the plasma flame has stabilized for at least 20 minutes, perform the measurement.

[0076] S212. Adjust the settings of the inductively coupled plasma atomic emission spectrometer, including: radio frequency power set to 1000-1500W, plasma gas flow rate set to 10-20L / min, nebulizer gas flow rate set to 0.5-0.6L / min, auxiliary gas flow rate set to 0.1-1L / min, integration time set to 5-20s, sample flow rate set to 1-2mL / min, and observation height set to 10-20mm.

[0077] The determination wavelengths for copper and molybdenum were selected: 327.393 nm for copper and 202.031 nm for molybdenum. The standard solutions were then subjected to spectral measurements in ascending order of analyte concentration to obtain the peak area integral value M for each analyte in the standard solutions. b ;

[0078] S213, using the known concentration C of the element to be measured in the standard solution. b The x-axis represents the integral value M of the spectral peak area of ​​the analyte in the measured standard solution. b Using the vertical axis as the ordinate, a standard working curve is plotted to obtain the linear regression equations for copper and molybdenum.

[0079] S300, spectral measurements of sample solution and blank solution, specifically including:

[0080] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to perform spectral measurements on the sample solution and blank solution. The background of the elemental spectral lines was checked and corrected to obtain the integral value M of the spectral peak area of ​​the analyte in the sample solution. s And the integral value M0 of the spectral peak area of ​​the element to be tested in the blank solution; when the content of the element to be tested in the sample solution exceeds the concentration range of this application, the dilution ratio of the sample solution can be appropriately increased so that the concentration of the element to be tested in the sample solution is within the range of the standard working curve.

[0081] S400, Result Analysis and Calculation, specifically including:

[0082] According to M s Obtain the concentration C of the analyte in the corresponding sample solution from the standard working curve. s Based on M0, obtain the concentration C0 of the analyte in the corresponding blank solution from the standard working curve, and based on C... s The content of the element to be measured is calculated using C0, and the formula is as follows:

[0083] ;

[0084] Wherein, ꞷ represents the content of the element to be measured, %; C sC0 is the concentration of the analyte in the sample solution obtained from the standard working curve, in μg / mL; C0 is the concentration of the analyte in the blank solution obtained from the standard working curve, in μg / mL; V is the volume of the sample solution, in mL; and m is the mass of the test sample, in g.

[0085] Compared with the prior art, the above-described solutions of this application have at least the following beneficial effects:

[0086] This application employs an inductively coupled plasma atomic emission spectrometer (ICP-AES) to design a method for simultaneously determining the content of copper and molybdenum in iron-based powder metallurgy. The method includes preparing the test sample, preparing the sample solution, preparing the blank solution, preparing the standard solution, measuring the concentration using an ICP-AES, plotting a standard working curve of the concentration of the test element versus the integral value of the spectral peak area, and analyzing and calculating the results.

[0087] This application optimizes the preparation process of the test sample by using hydrochloric acid-nitric acid and sulfuric acid-phosphoric acid to dissolve the test sample, which can completely dissolve the test sample to meet the conditions for instrumental analysis.

[0088] Because inductively coupled plasma (ICP) light sources can excite a large number of emission lines, iron-based powder metallurgy may contain alloying elements such as phosphorus, manganese, chromium, nickel, and cobalt in addition to a large amount of iron matrix. During testing, not only is there matrix interference, but there may also be inter-element interference. This application addresses this by adding high-purity iron powder of the same amount as the test sample when preparing the standard solution, or by using an alloy steel standard with a composition similar to the test sample to plot a standard working curve. This effectively eliminates matrix differences between the standard working curve and the actual test sample. Furthermore, it allows for the simultaneous determination of the content of other alloying elements such as phosphorus, manganese, chromium, nickel, and cobalt in iron-based powder metallurgy. The prepared standard working curve can be stored and used long-term, simplifying the workflow and improving efficiency.

[0089] This invention optimizes the measurement conditions of inductively coupled plasma atomic emission spectrometry (ICP-AES) and determines the analytical spectral lines of copper and molybdenum. By selecting appropriate analytical spectral line wavelengths, adopting specific observation methods, and correcting background interference, the influence of spectral interference is eliminated, thereby improving the accuracy, sensitivity, and stability of the detection results.

[0090] In selecting the analytical spectral wavelengths, it is essential to ensure that the selected wavelengths possess characteristics such as low background concentration, low detection limit, high signal-to-noise ratio, and high sensitivity. Simultaneously, spectral interference from other spectral lines should be minimized. In the preliminary testing phase, several analytical spectral lines were selected and their spectral intensities measured. After multiple experiments, suitable analytical spectral wavelengths were finally determined: 327.393 nm for copper ions and 202.031 nm for molybdenum ions. The spectral peaks produced at these two wavelengths are sharp, with minimal spectral interference and low background. This also ensures that coexisting elements such as Cr, Co, Ni, W, and Si do not interfere with the analytes, and the iron matrix does not interfere with the selected wavelengths. However, raising the baseline can lead to an increase in background. Therefore, a matrix matching method is employed: adding the same amount of high-purity iron powder as the test sample to the standard solution; or using an alloy steel standard with a composition similar to the test sample to plot a standard working curve. This effectively eliminates matrix differences between the standard working curve and the actual test sample.

[0091] The inductively coupled plasma optical emission spectrometer (ICP) used in this application is an Optima 8300 model, which offers two observation modes: radial observation and axial observation. Radial observation collects light from the side of the plasma and measures the signal in the ion emission region (the optimal observation region). Axial observation, on the other hand, collects the signal from the entire analytical channel except for the exhaust flame. Therefore, the signal in the measurement region of radial observation is not as strong as the signal from the entire analytical channel in axial observation, resulting in lower sensitivity. However, the signal in this region provides the best signal-to-background ratio, which is particularly advantageous in the complex matrix of the test sample in this application, which contains matrix interference and interference from other alloying elements. Furthermore, radial observation does not collect the light signals from the atomized and atomic emission regions of the plasma, thus avoiding ionization interference. It has a very good linear range, very small matrix effect, and very low background, and is flexible and convenient. However, axial observation collects the signal from the entire analytical channel, including the atomized and atomic emission regions. Therefore, while axial observation improves sensitivity, it also increases background noise and matrix influence, introducing ionization interference. Furthermore, axial observation increases the observation area and also increases the self-absorption phenomenon of the emission spectral lines, thus affecting its linear range. This is especially true when determining complex elements in samples like those in this application, where the bending of the standard working curve can cause significant measurement errors. Therefore, this application uses standard solution excitation and tests the absolute intensity of the spectrum under both radial and axial observation methods, determining that the radial observation method is preferable.

[0092] In ICP spectral analysis, background interference is mainly caused by field emission, stray light effects, and ion-electron recombination processes. When the background light intensity varies with the content of the analyte in the sample, background correction can improve the analytical results, obtain the true spectral intensity of the analyte, and eliminate analytical errors caused by background interference. Experiments show that this method uses two-point correction to subtract background interference.

[0093] Compared with traditional methods, the content detection method provided in this application has advantages such as simple sample preparation, convenient operation, short analysis time, high result accuracy, low detection limit, small reagent consumption, environmental friendliness, and small matrix effect. The method recovery rate reaches 96-105%, and the RSD is less than 4.7%, which can meet the quality monitoring needs of materials used in automotive product development. Attached Figure Description

[0094] Figure 1 A flowchart of the content detection method provided in a specific embodiment of this application is shown. Detailed Implementation

[0095] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0096] This embodiment provides a method for determining the content of copper and molybdenum in iron-based metallurgical powders, such as... Figure 1 Specifically, the process includes the following steps:

[0097] S110. Prepare the test sample, specifically including:

[0098] S111. Polish the sample surface to remove the adsorbate until the internal metal of the sample is exposed;

[0099] S112. The drill bit drills at a speed of 100-150 r / min to cut a thickness of no more than 1 mm from the sample surface, removes the debris formed after drilling, and completes the preparation of the test sample.

[0100] S120. Preparation of sample solution, specifically including:

[0101] S121. Weigh 0.10g (accurate to 0.1mg) of the sample to be tested, place it in a 150mL tall beaker, add 30mL of deionized water, 10mL of hydrochloric acid and 5mL of nitric acid, and heat on a low-temperature electric furnace until the sample to be tested is completely dissolved to form a mixture.

[0102] S122. Add 5 mL of sulfuric acid and 3 mL of phosphoric acid to the mixture, and continue heating until it starts to smoke for about 1 minute;

[0103] S123. Take out the sample to be tested and cool it to room temperature. Add 30 mL of deionized water and mix. Then place it on a low-temperature electric furnace and heat it to boiling.

[0104] S124. Take out the test sample and cool it to room temperature. Transfer it to a 100mL volumetric flask, add deionized water to dilute it, and make up to the mark. Mix well and set aside for later use.

[0105] Based on the volume of the sample solution corresponding to the test sample, a volumetric flask is appropriately selected with reference to this embodiment so that when the volume is adjusted to the mark, the solution concentration is maintained to be approximately the same as that in this embodiment.

[0106] It should be noted that the hydrochloric acid, nitric acid, and phosphoric acid used in the above steps were all of analytical grade.

[0107] S130. Preparation of standard solutions, specifically including:

[0108] S131. Weigh 6 equal portions of high-purity iron powder (mass fraction greater than 99.98%), each portion of high-purity iron powder is 0.10g (accurate to 0.1mg), place them in a 150mL tall beaker, add 30mL of deionized water, 10mL of hydrochloric acid and 5mL of nitric acid, and heat on a low-temperature electric furnace until the high-purity iron powder is completely dissolved to form a mixture.

[0109] S132. Add 5 mL of sulfuric acid and 3 mL of phosphoric acid to the mixture, and continue heating until it starts to smoke for about 1 minute;

[0110] S133. Take out the high-purity iron powder and cool it to room temperature. Add 30mL of deionized water and mix. Then place it on a low-temperature electric furnace and heat it to boiling.

[0111] S134. Take out 6 portions of high-purity iron powder, cool them to room temperature, and transfer them into 6 volumetric flasks of 100 mL each. The 6 volumetric flasks are labeled R1, R2, R3, R4, R5 and R6 respectively.

[0112] S135. Add copper standard solution (1000 μg / mL) and molybdenum standard solution (1000 μg / mL) to six volumetric flasks, respectively; wherein, add 0.10 mL of copper standard solution and 0.10 mL of molybdenum standard solution to R1, 0.50 mL of copper standard solution and 0.50 mL of molybdenum standard solution to R2, 1.00 mL of copper standard solution and 1.00 mL of molybdenum standard solution to R3, 3.00 mL of copper standard solution and 3.00 mL of molybdenum standard solution to R4, 5.00 mL of copper standard solution and 5.00 mL of molybdenum standard solution to R5, and 10.00 mL of copper standard solution and 10.00 mL of molybdenum standard solution to R6.

[0113] S136. Add deionized water to the 6 volumetric flasks to dilute, bring to the mark, mix well and set aside.

[0114] S140. Prepare a blank solution, specifically including:

[0115] Weigh 0.10 g (accurate to 0.1 mg) of high-purity iron (mass fraction greater than 99.98%) and add it to a 100 mL volumetric flask. Dilute with deionized water and bring the volume to the mark. Mix well and set aside.

[0116] S210. Spectral measurement of standard solutions and plotting of standard working curves, specifically including:

[0117] S211. Start the Optima 8300 inductively coupled plasma atomic emission spectrometer (PerkinElmer, USA; argon purity ≥99.996%). After the inductively coupled plasma atomic emission spectrometer is successfully initialized, ignite the plasma flame. After the plasma flame has stabilized for at least 20 minutes, perform the measurement.

[0118] S212. Adjust the settings of the inductively coupled plasma atomic emission spectrometer, including: radio frequency power set to 1300W, plasma gas flow rate set to 15L / min, nebulizer gas flow rate set to 0.55L / min, auxiliary gas flow rate set to 0.5L / min, integration time set to 5-20s, sample flow rate set to 1.5mL / min, observation height set to 15mm, observation mode set to axial observation, and correction mode set to background correction.

[0119] The determination wavelengths for copper and molybdenum were selected: 327.393 nm for copper and 202.031 nm for molybdenum. The standard solutions were then subjected to spectral measurements in ascending order of analyte concentration (R1 to R6) to obtain the spectral peak area integral value M for each analyte in the standard solutions. b ;

[0120] S213, using the known concentration C of the element to be measured in the standard solution. b The x-axis represents the concentration C from R1 to R6. b The concentrations were 1.0 μg / mL, 5.0 μg / mL, 10.0 μg / mL, 30.0 μg / mL, 50.0 μg / mL, and 100.0 μg / mL, respectively. The integral value M of the spectral peak area of ​​the analyte in the measured standard solutions R1 to R6 was used as the reference. bUsing the vertical axis as the ordinate, a standard working curve was plotted to obtain the linear regression equations for copper and molybdenum. The linear regression equation for copper is y = 109.0x - 749.6, and the linear regression equation for molybdenum is y = 46.2x + 277.1. The parameters of the standard working curve are shown in Table 1.

[0121] Table 1

[0122]

[0123] S300, spectral measurements of sample solution and blank solution, specifically including:

[0124] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to perform spectral measurements on the sample solution and blank solution. The background of the elemental spectral lines was checked and corrected to obtain the integral value M of the spectral peak area of ​​the analyte in the sample solution. s And the integral value M0 of the spectral peak area of ​​the element to be tested in the blank solution; when the content of the element to be tested in the sample solution exceeds the concentration range of this application, the dilution ratio of the sample solution can be appropriately increased so that the concentration of the element to be tested in the sample solution is within the range of the standard working curve.

[0125] S400, Result Analysis and Calculation, specifically including:

[0126] According to M s Obtain the concentration C of the analyte in the corresponding sample solution from the standard working curve. s Based on M0, obtain the concentration C0 of the analyte in the corresponding blank solution from the standard working curve, and based on C... s The content of the element to be measured is calculated using C0, and the formula is as follows:

[0127] ;

[0128] Wherein, ꞷ represents the content of the element to be measured, %; C s C0 is the concentration of the analyte in the sample solution obtained from the standard working curve, in μg / mL; C0 is the concentration of the analyte in the blank solution obtained from the standard working curve, in μg / mL; V is the volume of the sample solution, in mL; and m is the mass of the test sample, in g.

[0129] Following the above measurement methods and instrument operating conditions, standard solutions of copper and molybdenum were added to the test sample with known content of the elements to be measured, and recovery rate and precision tests were conducted. The results are shown in Table 2.

[0130] Table 2

[0131]

[0132] As can be seen from the test data provided in Table 2, the spiked recoveries of the two elements are between 96% and 105%, and the relative standard deviation is less than 4.7%. The method is accurate and has high precision, which can meet the detection requirements.

[0133] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for determining the content of copper and molybdenum in iron-based metallurgical powders, characterized in that, The content determination method includes: S100. Grind the sample surface to remove adsorbates until the internal metal is exposed. Drill the sample surface at a speed of 100-150 r / min to a thickness not exceeding 1 mm, removing the debris formed after drilling. This completes the preparation of the test sample. Then, dissolve the test sample by weighing it, adding deionized water, hydrochloric acid, and nitric acid, and heating until the test sample is completely dissolved to form a mixture. Add sulfuric acid and phosphoric acid to the mixture and continue heating until fuming. Remove the test sample and cool it to room temperature, add deionized water, mix, and heat to boiling. Remove the test sample and cool it to room temperature, transfer it to a volumetric flask, dilute with deionized water, and bring the volume to the mark. Mix well and set aside to obtain the sample solution. Prepare a blank solution without the analyte and several standard solutions containing the analyte at known concentrations. S200. Inductively coupled plasma atomic emission spectrometry (ICP-AES) is used to perform spectral measurements on the standard solution to obtain the integral value M of the spectral peak area of ​​the analyte in the standard solution. b Based on the known concentration C of the element to be measured in the standard solution b With M b The corresponding relationships are used to draw standard working curves; S300. When the correlation coefficient of the standard working curve reaches 0.999 or higher, inductively coupled plasma atomic emission spectrometry (ICP-AES) is used to perform spectral measurements on the sample solution and blank solution. The background of the elemental spectral lines is checked and corrected to obtain the integral value M of the spectral peak area of ​​the analyte in the sample solution. s And the integral value M0 of the spectral peak area of ​​the element to be measured in the blank solution; S400, according to M s Obtain the concentration C of the analyte in the corresponding sample solution from the standard working curve. s Based on M0, obtain the concentration C0 of the analyte in the corresponding blank solution from the standard working curve, and based on C... s The content of the element to be measured in the sample solution is calculated using C0.

2. The content determination method according to claim 1, characterized in that, In step S121, 0.01-0.5g of the sample to be tested is weighed. The amount of deionized water added is 10-50 mL, the amount of hydrochloric acid added is 1-20 mL, and the amount of nitric acid added is 1-10 mL. In step S122, the amount of sulfuric acid added is 1-10 mL, and the amount of phosphoric acid added is 1-5 mL.

3. The content determination method according to claim 1, characterized in that, In step S100, the preparation process of the standard solution includes: S131. Weigh out several portions of high-purity iron powder equal to the amount of the test sample, add deionized water, hydrochloric acid and nitric acid and heat until the high-purity iron powder is completely dissolved. S132. Add sulfuric acid and phosphoric acid to the dissolved mixture and continue heating until fumes are emitted; S133. Take out the high-purity iron powder, cool it to room temperature, add deionized water, mix and heat to boiling; S134. After removing the high-purity iron powder and cooling it to room temperature, transfer it into a volumetric flask. S135. Add different volumes of copper standard solution and different volumes of molybdenum standard solution to the volumetric flask. S136. Add deionized water to the volumetric flask to dilute, bring the volume to the mark, mix well and set aside.

4. The content determination method according to claim 1, characterized in that, In step S200, the spectral measurement process specifically includes the following steps: S211. Start the inductively coupled plasma atomic emission spectrometer. After the inductively coupled plasma atomic emission spectrometer is successfully initialized, ignite the plasma flame. After the plasma flame has stabilized for at least 20 minutes, perform the measurement. S212. Adjust the settings of the inductively coupled plasma atomic emission spectrometer and perform spectral measurements on the standard solution at the selected measurement wavelength, in order of increasing concentration of the analyte in the standard solution. S213. Plot the standard working curve by using the known concentration of the analyte in the standard solution as the abscissa and the integral value of the spectral peak area of ​​the analyte in the standard solution as the ordinate.

5. The content determination method according to claim 1, characterized in that, In step S212, the setting conditions for the inductively coupled plasma atomic emission spectrometer include: The radio frequency power was set to 1000-1500W, the plasma gas flow rate was set to 10-20L / min, the nebulizer gas flow rate was set to 0.5-0.6L / min, the auxiliary gas flow rate was set to 0.1-1L / min, the integration time was set to 5-20s, the sample flow rate was set to 1-2mL / min, the observation height was set to 10-20mm, the observation method was radial observation, and the background correction method was two-point correction.

6. The content determination method according to claim 1, characterized in that, In step S212, the setting conditions for the inductively coupled plasma atomic emission spectrometer include: The radio frequency power was set to 1300W, the plasma gas flow rate was set to 15L / min, the nebulizer gas flow rate was set to 0.55L / min, the auxiliary gas flow rate was set to 0.5L / min, the integration time was set to 5-20s, the sample flow rate was set to 1.5mL / min, and the observation height was set to 15mm.

7. The content determination method according to claim 1, characterized in that, In step S212, the wavelength for measuring copper is 327.393 nm, and the wavelength for measuring molybdenum is 202.031 nm.

8. The content determination method according to claim 1, characterized in that, In step S400, according to C s The content of the element to be measured is calculated using C0, and the formula is as follows: ； in, The content of the element to be measured; C s C0 is the concentration of the analyte in the sample solution obtained from the standard working curve; V is the volume of the sample solution; and m is the mass of the test sample.

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