Method for detecting solid solution content of rare earth elements in steel and iron material

Abstract

The invention discloses a method for detecting the solid solution content of rare earth elements in a steel material, which comprises the following steps: firstly, electrolyzing a steel sample which is ground and polished until the surface has no macroscopic defects in a KCl or LiCl + tartaric acid (C4H6O6) aqueous solution, and filtering the electrolyzed suspension to realize the separation of solid-solution rare earth atoms from the rare earth elements in a second phase; then, concentrating the filtered solution, and cooling to a constant volume; and finally, measuring the concentration of the rare earth element in the solution by using an inductively coupled plasma mass spectrometer (ICP-MS), and calculating by using a formula to obtain the solid solubility of the rare earth element in the steel and iron material. The method can safely, reliably and cheaply measure the solid solubility of rare earth elements in steel and iron materials in laboratory research and production practice, and has the characteristics of high sensitivity, safe experimental process, efficient pretreatment process, cheap and easily available medicines and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of physical and chemical analysis, and particularly relates to a method for detecting the solid solution amount of rare earth elements in steel materials. Background Art

[0002] In the 1920s and 1930s, Germans began to add rare earth elements to steel materials and found that rare earth elements could reduce the sulfur content in steel and change the morphology of inclusions. After nearly a century of research and development, the advantageous effects of rare earth in steel materials have been summarized as: purifying molten steel, modifying inclusions, refining grains, and microalloying. Up to now, a large number of practices have shown that rare earth elements can significantly improve the low-temperature impact toughness, corrosion resistance, and high-temperature performance of steel. The key to making rare earth elements play an advantageous role in steel materials is to control the existence state of rare earth in steel materials. Especially under modern metallurgical conditions, high-purity molten steel with low oxygen and sulfur provides a good prerequisite environment for rare earth elements to exist in a solid solution state in steel and play a microalloying role. Therefore, how to accurately and efficiently detect the solid solubility of rare earth elements in steel is very important.

[0003] Since the 1970s, Kawamura Kazuo has used electrolysis to separate rare-earth inclusions in steel, and then subtracted the amount of rare-earth inclusions from the total amount of rare-earth in the steel to obtain the amount of rare-earth solid solution. This method belongs to the indirect method and is greatly affected by the recovery rate of rare-earth inclusions during use, making it difficult to accurately measure the solid solubility. In 1981, Li Wenbin used the internal friction method to measure the existence state and distribution of rare-earth in steel, but no quantitative analysis results were obtained. Patent CN1041653C discloses a method for analyzing the amount of rare-earth solid solution in steel by inductively coupled plasma spectroscopy. In this method, an ion-exchange column is used to adsorb rare-earth ions, and then the rare-earth ions are desorbed and collected. This process is greatly affected by the purity of the ion-exchange column and the reagents used, and it is easy to enrich the impurities introduced by the reagents and other factors, resulting in low detection accuracy. CN103063589A discloses a method for measuring the solid solubility of mixed rare-earth in steel materials. This method uses a spectrophotometer for detection, with low sensitivity and a complex solution preparation process, and is not suitable for large-scale detection. CN118275368A discloses a method for measuring the solid solubility of rare-earth elements in steel. In this method, when separating the electrolyte and inclusions after electrolysis, a method of placing filter paper in a Buchner funnel is used. Due to the large pore size of the filter paper and the limited bonding performance between the filter paper and the Buchner funnel, inclusions may leak into the filtrate, resulting in poor accuracy of the detection results, and low-temperature electrolysis is used. CN115144288A discloses a method for detecting the content of solid-solution rare-earth in steel and its application. In this method, after electrolysis, the electrolyte is filtered using a filter membrane with a pore size ≤0.15 μm. Due to the large amount of electrolyte used, the filtration process using the filter membrane is very slow, and the separation efficiency is too low. Moreover, when using an organic solvent as the electrolyte and directly measuring trace elements in the solution using an inductively coupled plasma mass spectrometer, the signal-to-noise ratio is low, and it is difficult to obtain accurate detection results. Summary of the Invention

[0004] The object of the present invention is to provide a method for detecting the amount of rare-earth elements in solid solution in steel materials. This analytical method can directly measure the amount of rare-earth elements in solid solution in steel materials under room temperature conditions, thereby accurately and conveniently completing the determination of the amount of rare-earth solid solution in steel materials.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for detecting the amount of rare-earth elements in solid solution in steel materials of the present invention includes the following steps:

[0007] (1) Cut the steel sample into a cuboid or cylindrical shape and polish its surface until it is bright and free of scratches and pit defects visible to the naked eye;

[0008] (2) Put the above steel sample into a beaker containing an aqueous solution of 2% - 8% KCl or LiCl + 0.2% - 0.6% tartaric acid (C4H6O6), and electrolyze at a temperature of 5°C - 45°C. After electrolysis is completed, filter the electrolyte solution;

[0009] (3) Collect the above filtered solution into a beaker, place it in a water bath and heat to evaporate the solvent and concentrate it to 1 / 2 - 1 / 3 of the original volume;

[0010] Cool the above concentrated solution to room temperature and then transfer it to a volumetric flask for volume fixation;

[0011] Use an inductively coupled plasma mass spectrometer (ICP-MS) to measure the concentration of rare earth elements in the solution after volume fixation, and then the solid solution amount of rare earth elements in the steel material can be calculated.

[0012] Further, electrolyze at a temperature of 20°C ± 5°C.

[0013] Further, electrolyze at room temperature.

[0014] Further, in the step (2): the electrolysis is constant current electrolysis, the anode is the sample, the cathode is stainless steel, the electrolysis current density is 15 - 3 mA / cm 2 , the electrolysis time is 1 - 2 h; and before electrolysis, put a semi-permeable membrane around the anode sample. The characteristics of the semi-permeable membrane are that solid particles cannot pass through and ions in the solution can pass through freely; after electrolysis, the rare earth atoms in the solid solution state dissolve into the electrolyte solution and exist in the form of ions, and the rare earth elements in the second phase exist in the form of anode precipitates. After filtration, the separation of the rare earth atoms in the solid solution state and the rare earth elements in the second phase is achieved.

[0015] Further, the semi-permeable membrane is made by mixing cellulose acetate and acetone in a ratio of 1:1.

[0016] Further, in the step (2): the filtration is specifically carried out in the following manner:

[0017] 1) The liquid in the semi-permeable membrane is filtered by vacuum acceleration with an organic filter membrane with a pore size of 0.01 μm - 0.2 μm in a sand core filter. After the first filtration is completed, add 5 mL - 10 mL of deionized water and continue to filter 3 - 5 times;

[0018] 2) The liquid in the beaker outside the semi-permeable membrane is filtered with 3 - 6 layers of quantitative slow filter paper. After the first filtration is completed, add 5 mL - 10 mL of deionized water and continue to filter 3 - 5 times.

[0019] Further, in the step (3): in the process of collecting the filtered solution into the beaker, after the first transfer of the solution, rinse the beaker 3 - 5 times with 10 mL - 15 mL of deionized water.

[0020] Further, in the step (3), the heating temperature is controlled between 70°C and 90°C to avoid losses caused by the solution boiling and splashing out of the container.

[0021] Further, in the step (4), after the solution is transferred for the first time, the beaker is rinsed 3 to 5 times with 10 mL to 15 mL of deionized water. Finally, the concave liquid level of the solution is made up to the calibration line of the volumetric flask with deionized water.

[0022] Further, in the step (5), after measuring the concentration with an inductively coupled plasma mass spectrometer, the quantification is carried out using formula (1):

[0023]

[0024] In the formula: W is the solid solution amount of rare earth elements in the steel material; C is the content of rare earth elements in the solution; V is the volume of constant volume; M1 is the mass of the sample before electrolysis; M2 is the mass of the sample after electrolysis.

[0025] Compared with the prior art, the beneficial technical effects of the present invention are:

[0026] Using the detection method of the present invention, the solid solution amount of rare earth elements in steel materials can be directly measured at room temperature, thereby accurately and conveniently obtaining the solid solution amount of rare earth elements in steel materials. Description of the Drawings

[0027] The present invention will be further described below in conjunction with the description of the drawings.

[0028] Figure 1 It is a flowchart of the detection method for the solid solution amount of rare earth elements in the steel material of the present invention. Detailed Embodiments

[0029] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0030] Embodiment 1

[0031] A detection method for the solid solution amount of rare earth elements in a steel material of the present invention includes the following steps:

[0032] (1) The surface of a weathering steel (the composition is shown in Table 1) hot-rolled plate sample with a length, width and height of 120 mm, 30 mm and 4 mm respectively is ground and polished brightly without defects such as scratches and pits visible to the naked eye;

[0033] (2) The above steel sample is placed in a beaker containing an aqueous solution of 5% KCl + 0.4% tartaric acid (C4H6O6), and electrolyzed at a temperature of 25°C ± 5°C. After electrolysis is completed, the electrolyte is filtered;

[0034] The electrolysis process is a constant-current electrolysis. The anode is the sample, the cathode is stainless steel, the electrolysis current density is 25 mA / cm², and the electrolysis time is 1 h. Before electrolysis, a semi-permeable membrane is put around the anode sample. The semi-permeable membrane is made by mixing cellulose acetate and acetone in a ratio of 1:1, and its characteristic is that solid particles cannot pass through while ions in the solution can pass through freely. After electrolysis, the rare-earth atoms in the solid solution state dissolve into the electrolyte and exist in the ionic state, and the rare-earth elements in the second phase exist in the form of anode precipitates. After filtration, the separation of the rare-earth atoms in the solid solution state and the rare-earth elements in the second phase is achieved.

[0035] The filtration process is carried out in the following way:

[0036] 1) The liquid in the semi-permeable membrane is filtered by vacuum acceleration using an organic filter membrane with a pore size of 0.2 μm in a sand core filter. After the first filtration, 10 mL of deionized water is added and the filtration is continued 4 times.

[0037] 2) The liquid in the beaker outside the semi-permeable membrane is filtered using a 5-layer quantitative slow filter paper. After the first filtration, 10 mL of deionized water is added and the filtration is continued 4 times.

[0038] Table 1 Composition of weathering steel (wt%)

[0039]

[0040] (3) The filtered solution above is collected into a beaker and placed in a water bath to heat and evaporate the solvent and concentrate it to 1 / 2 of the original volume.

[0041] During the process of collecting the filtered solution into the beaker, after the first transfer of the solution, the beaker is rinsed 4 times with 10 mL of deionized water.

[0042] During the process of heating and evaporating the solvent, the heating temperature is controlled at 75 °C to avoid losses caused by the solution boiling and splashing out of the container.

[0043] (4) After the concentrated solution above is cooled to room temperature, it is transferred to a volumetric flask for volume fixation.

[0044] After the first transfer of the solution, the beaker is rinsed 3 times with 10 mL of deionized water. Finally, the concave liquid level of the solution is made up to the calibration line of the volumetric flask with deionized water.

[0045] (5) The concentration of rare-earth elements in the solution after volume fixation above is measured by an inductively coupled plasma mass spectrometer (ICP-MS), and then the solid solution amount of rare-earth elements in the steel material can be calculated.

[0046] After measuring the concentration by an inductively coupled plasma mass spectrometer, quantitative analysis is carried out using formula (1):

[0047]

[0048] Wherein, W is the solid solution amount of rare earth elements in the steel material; C is the content of rare earth elements in the solution; V is the volume of constant volume; M1 is the mass of the sample before electrolysis; M2 is the mass of the sample after electrolysis.

[0049] Finally, the solid solution amount of rare earth Ce element in the above weathering steel can be obtained as 3.3 ppm.

[0050] Example Two

[0051] A detection method for the solid solution amount of rare earth elements in a steel material of the present invention includes the following steps:

[0052] (1) Polish the surface of a cylindrical sample of medium manganese steel (with the composition shown in Table 2) of Φ10×130 mm until it is bright and free of defects such as scratches and pits visible to the naked eye;

[0053] (2) Put the above steel sample into a beaker containing an aqueous solution of 2% LiCl + 0.5% tartaric acid (C4H6O6), and electrolyze at a temperature of 20°C ± 5°C. After electrolysis is completed, filter the electrolyte;

[0054] The electrolysis process is constant current electrolysis. The anode is the sample, the cathode is stainless steel, the electrolysis current density is 20 mA / cm2, and the electrolysis time is 70 min; and before electrolysis, put a semi-permeable membrane around the anode sample. The semi-permeable membrane is made by mixing cellulose acetate and acetone in a ratio of 1:1, and its characteristic is that solid particles cannot pass through and ions in the solution can pass through freely; after electrolysis, the solid solution state rare earth atoms dissolve into the electrolyte and exist in an ionic state, and the rare earth elements in the second phase exist in the form of anode precipitates. After filtration, the separation of solid solution state rare earth atoms and rare earth elements in the second phase is realized.

[0055] The filtration process is carried out in the following manner:

[0056] 1) The liquid in the semi-permeable membrane is filtered by vacuum acceleration with an organic filter membrane with a pore size of 0.2 μm in a sand core filter. After the first filtration is completed, add 10 mL of deionized water and continue to filter 3 times;

[0057] 2) The liquid in the beaker outside the semi-permeable membrane is filtered with 5 layers of quantitative slow filter paper. After the first filtration is completed, add 10 mL of deionized water and continue to filter 3 times.

[0058] Composition of medium manganese steel in Table 2 (wt%)

[0059]

[0060] (3) Collect the above filtered solution into a beaker, put it into a water bath and heat to evaporate the solvent and concentrate it to 1 / 2 of the original volume;

[0061] During the process of collecting the filtered solution into a beaker, after the first transfer of the solution, rinse the beaker 3 times with 10 mL of deionized water.

[0062] During the process of heating and evaporating the solvent, control the heating temperature at 70 °C to avoid losses caused by the solution boiling over and splashing out of the container.

[0063] (4) After cooling the above-concentrated solution to room temperature, transfer it to a volumetric flask for volume fixation.

[0064] After the first transfer of the solution, rinse the beaker 3 times with 10 mL of deionized water. Finally, use deionized water to make up the concave liquid level of the solution to the calibration line of the volumetric flask.

[0065] Measure the concentration of rare earth elements in the above-fixed volume solution with an inductively coupled plasma mass spectrometer (ICP-MS), and then the solid solution amount of rare earth elements in the steel material can be calculated.

[0066] After measuring the concentration with an inductively coupled plasma mass spectrometer, perform quantification using formula (1):

[0067]

[0068] In the formula, W is the solid solution amount of rare earth elements in the steel material; C is the content of rare earth elements in the solution; V is the fixed volume; M1 is the mass of the sample before electrolysis; M2 is the mass of the sample after electrolysis.

[0069] Finally, the solid solution amount of rare earth La element in the above medium manganese steel can be obtained as 29.1 ppm.

[0070] The present invention can relatively safely, reliably and inexpensively realize the determination of the solid solubility of rare earth elements in steel materials in laboratory research and production practice, and has the characteristics of high sensitivity, safe experimental process, efficient pretreatment process, and inexpensive and easily available drugs.

[0071] The above-described embodiments are only descriptions of the preferred modes of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for detecting the solid solution amount of rare earth elements in a steel material, characterized in that, It includes the following steps: (1) Cut the steel sample into a cuboid or cylinder shape, and polish its surface until it is bright and free of scratches and pit defects visible to the naked eye; (2) Put the above steel sample into a beaker containing an aqueous solution of 2% - 8% KCl or LiCl + 0.2% - 0.6% tartaric acid, and electrolyze at a temperature of 5°C - 45°C. After the electrolysis is completed, filter the electrolyte; (3) Collect the above filtered solution into a beaker, place it in a water bath to heat and evaporate the solvent and concentrate it to 1 / 2 - 1 / 3 of the original volume; Cool the above concentrated solution to room temperature and then transfer it to a volumetric flask for volume fixing; Measure the concentration of rare earth elements in the solution after volume fixing with an inductively coupled plasma mass spectrometer, and then the solid solution amount of rare earth elements in the steel material can be calculated; 2. The detection method of the solid solution amount of rare earth elements in steel materials according to claim 1, characterized in that Electrolyze at a temperature of 20°C ± 5°C.

3. The detection method for the solid solution amount of rare earth elements in steel materials according to claim 1, wherein, Electrolyze at room temperature.

4. The detection method for the solid solution amount of rare earth elements in steel materials according to claim 1, characterized in that, In the step (2): the electrolysis is carried out at a constant current, the anode is the sample, the cathode is stainless steel, and the electrolysis current density is 15 - 3 mA / cm 2 , and the electrolysis time is 1 - 2 h; before electrolysis, a semipermeable membrane is sleeved around the anode sample, and the characteristics of the semipermeable membrane are that solid particles cannot pass through and ions in the solution can pass through freely; after electrolysis, the rare earth atoms in the solid solution state dissolve into the electrolyte and exist in the form of ions, and the rare earth elements in the second phase exist in the form of anode precipitates, and then through filtration, the separation of the rare earth atoms in the solid solution state from the rare earth elements in the second phase is achieved.

5. The detection method for the solid solution amount of rare earth elements in steel materials according to claim 4, characterized in that, The semi-permeable membrane is made by mixing cellulose acetate and acetone in a ratio of 1:

1.

6. The detection method for the solid solution amount of rare earth elements in steel materials according to claim 1, characterized in that, In the step (2): The filtration is specifically carried out in the following way: 1) The liquid in the semi-permeable membrane is filtered under vacuum acceleration with an organic filter membrane with a pore size of 0.01μm - 0.2μm in a sand core filter. After the first filtration, add 5mL - 10mL of deionized water and continue to filter 3 - 5 times; 2) The liquid in the beaker outside the semi-permeable membrane is filtered with 3 - 6 layers of quantitative slow filter paper. After the first filtration, add 5mL - 10mL of deionized water and continue to filter 3 - 5 times.

7. The method for detecting the solid solution amount of rare earth elements in steel materials according to claim 1, wherein In the step (3): During the process of collecting the filtered solution into the beaker, after the first transfer of the solution, rinse the beaker 3 - 5 times with 10mL - 15mL of deionized water.

8. The detection method for the solid solution amount of rare earth elements in steel materials according to claim 1, characterized in that, In the step (3), the heating temperature is controlled between 70°C and 90°C to avoid losses caused by the solution boiling and splashing out of the container.

9. The method for detecting the solid solution amount of rare earth elements in steel materials according to claim 1, characterized in that, In the step (4), after the first transfer of the solution, rinse the beaker 3 - 5 times with 10mL - 15mL of deionized water. Finally, make up the concave liquid level of the solution to the calibration line of the volumetric flask with deionized water.

10. The detection method for the solid solution amount of rare earth elements in the steel material according to claim 1, characterized in that, In the step (5), after measuring the concentration with an inductively coupled plasma mass spectrometer, quantitative analysis is carried out using formula (1): In the formula: W is the solid solution amount of rare earth elements in the steel material; C is the content of rare earth elements in the solution; V is the fixed volume; M1 is the mass of the sample before electrolysis; M2 is the mass of the sample after electrolysis.

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