Method for determining contents of iron and nickel in iron-nickel alloy matrix by ICP-OES (Inductively Coupled Plasma-Optical

Abstract

The invention discloses a method for determining the contents of iron and nickel of matrix elements of an iron-nickel alloy by an ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer) method. The method is specifically implemented according to the following steps: step 1, carrying out three methods of sample pretreatment; 2, determining an analysis spectral line of iron and nickel; 3, internal standard elements and the adding amount of the internal standard elements are determined; and 4, calculating the content of iron and nickel through the relative strength. The method provided by the invention solves the problem of inaccurate measurement result in the existing method for measuring the contents of the matrix elements iron and nickel in the iron-nickel alloy, and has good accuracy and precision.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy material detection, and relates to a method for determining the content of iron and nickel elements in an iron-nickel alloy matrix by an ICP-OES method. Background Art

[0002] Commonly used high-temperature alloy materials are mainly nickel-based and iron-nickel-based. As iron-nickel is a matrix element, it has better wear resistance, pressure resistance, durability, physical and mechanical properties than other materials. It plays a key role in iron-nickel-based alloys and is widely used in engines in the aviation field. At present, when testing the chemical composition of iron-nickel content in iron-nickel alloys, the detection mainly includes chemical methods. The chemical method has high accuracy, but the process is cumbersome, time-consuming and consumable, and is not suitable for the modern fast-paced progress requirements; ICP-AES method, this method determines the nickel content of about 10%, FAAS method; direct reading spectroscopy, the detection of matrix elements uses the difference subtraction method, and the detection errors of other elements will bring matrix elements.

[0003] ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometer) is a chemical analysis instrument widely used for qualitative and quantitative analysis of metal elements and some non-metal elements. The internal standard method is to add a certain weight of pure substance as an internal standard to a certain amount of sample mixture to be analyzed, and calculate the content of the component to be tested according to the mass ratio of the test sample and the internal standard and the ratio of the corresponding spectral peak area and the relative correction factor. It is a commonly used analysis method for ICP-OES analysis. There are usually two methods. One is to directly add a quantitative internal standard to all standard curves and sample solutions to be tested, mix them evenly, and then pass them through the injection tube of the cross-flow nebulizer, and use argon gas atomization for detection. The advantage of this method is good stability, and the disadvantage is that the operation is cumbersome, and the internal standard solution is wasted, and it is easy to introduce human errors. The other method is to use a three-way tube to prepare an internal standard solution separately. The internal standard solution and the standard curve or the sample to be tested are injected at the same time, mixed through the three-way tube, and then passed through the injection tube of the cross-flow nebulizer. After argon gas atomization, the detection is carried out. The advantages of this method are simple and fast operation, and saving of internal standards. The disadvantage is that the mixing effect of the three-way tube is not good, and uneven mixing is prone to occur, resulting in large fluctuations in the results.

[0004] For the matrix elements iron and nickel, it is a challenge to determine their content by ICP-OES because their emission intensity is very high and their content is beyond the range that can be determined by ICP-OES. Combined with the chemical method to determine a small amount of major elements in high-temperature alloys, the experimental analysis steps are cumbersome and the experimental analysis cycle is long, which cannot meet the requirements for rapid analysis of the chemical composition of high-temperature alloys. Summary of the invention

[0005] The invention aims to provide a method for determining the content of iron and nickel in an iron-nickel alloy matrix element by ICP-OES, which solves the problem of inaccurate measurement results in the existing method for determining the content of iron and nickel in an iron-nickel alloy matrix element.

[0006] The technical solution adopted by the present invention is a method for determining the content of iron and nickel in an iron-nickel alloy matrix by ICP-OES, which is specifically implemented according to the following steps: Step 1: Sample pretreatment; Step 2, determining the analysis spectrum of iron and nickel; Step 3, determining the internal standard element and the amount of the internal standard element added; Step 4: Calculate the iron and nickel contents of the matrix elements through a linear range test.

[0007] The present invention is also characterized in that: Step 1 is specifically as follows: Step 1.1, preparing the analytical solution; Step 1.2, prepare a blank solution, and make a blank solution together with the sample in step 1.1; Step 1.3, preparing a series of working curve solutions; Step 1.4: Carry out testing on the machine and draw a working curve based on the element content and relative intensity.

[0008] Three dissolution methods were used in step 1.1: The first method is to weigh 0.1g of the iron-nickel alloy sample in step 1.1, accurate to 0.0001g, place the sample in a 150ml polytetrafluoroethylene beaker, add 5.0ml hydrochloric acid, 1.0ml nitric acid, and 0.5ml hydrofluoric acid in sequence, cover the polytetrafluoroethylene beaker with a lid, place the beaker on a low-temperature flat electric furnace, heat to dissolve, and after the sample is completely dissolved, remove and cool, transfer to a 50ml plastic volumetric flask, add 3.00ml of the internal standard solution, dilute to the scale with water, and shake well.

[0009] The second method is to weigh 0.1g of the iron-nickel alloy sample in step 1.1, accurate to 0.0001g, place the sample in a 150ml conical flask, add 5.0mlHCl and 1.0mlHNO3, place it on a low-temperature flat electric furnace to heat and dissolve, and after the sample is completely dissolved, remove it and add 10mlH2SO4, place it on a high-temperature flat electric furnace to evaporate until sulfuric acid smoke appears. If there is carbide, add nitric acid to remove the carbon, continue to emit sulfuric acid smoke, remove it and cool it, add appropriate amount of water to dissolve the salts, remove it and cool it, transfer it to a 100ml volumetric flask, add 3.00mlY internal standard solution, dilute it to the scale with water, and shake it well.

[0010] The third method is to weigh 0.1g of the iron-nickel alloy sample in step 1.1, accurate to 0.0001g, place the sample in a 150ml conical flask, add 10.0ml HCl and 1.0mlHNO3, place it on a low-temperature flat electric furnace to heat and dissolve, and after the sample is completely dissolved, remove it and add 5.0mlH2SO4+H3PO4, place it on a high-temperature flat electric furnace to evaporate until smoking, if there is carbide, add nitric acid to remove the carbon, continue to heat until smoking, remove it and cool it, add an appropriate amount of water to dissolve the salts, remove it and cool it, add 3.00mlY internal standard solution, transfer it to a 100ml volumetric flask, dilute it to the scale with water, and shake it well.

[0011] Hydrochloric acid was of premium grade with a ρ of 1.19 g / ml; nitric acid was of premium grade with a ρ of 1.42 g / ml; hydrofluoric acid was of premium grade with a ρ of 1.15 g / ml; sulfuric acid was of premium grade with a ρ of 1.84 g / ml; and phosphoric acid was of analytical grade with a ρ of 1.69 g / ml.

[0012] Step 1.3 is as follows: Step 1.3.1, draw a working curve using standard substances; Weigh an iron-nickel alloy standard sample with the same mass as the iron-nickel alloy sample, dissolve and fix the sample together with the sample according to the method for preparing the analytical solution in step 1.1, select 3 to 5 standard substances with content gradient for each element, and use an inductively coupled plasma emission spectrometer to measure the standard solution, equipped with a hydrofluoric acid-resistant injection system, and use the internal standard method. The measurement conditions are: incident power is 1150KW, cooling air flow is 12L / min, auxiliary gas flow is 0.5L / min, the number of repetitions is 3 times, the observation height is 12mm, and the internal standard line is 371.029nm. Draw the internal standard working curves of iron and nickel respectively; Step 1.3.2, draw a working curve using the standard solution; Prepare the analytical solution in step 1.1 and process 6 blank solutions in parallel. Transfer them into 6 50 ml volumetric flasks, one of which is used as a blank. Add alloy elements with contents close to those of the sample to be tested into the other 5 volumetric flasks. Add different amounts of standard solution of the element to be tested into the 5 volumetric flasks, add 3.00 ml of internal standard solution, dilute to the mark with water, and shake well.

[0013] Step 2 is specifically as follows: Step 2.1, select the spectral line through interference test of coexisting elements, sensitivity analysis of each spectral line and interference conditions beside the spectral line; Step 2.2, determine the sensitivity of each spectral line of iron and nickel; Step 2.3, calculate the intensity of iron and nickel at the same concentration under each spectral line; Step 2.4, obtain the interference lines next to the iron and nickel spectral lines; Step 2.5: Conduct interference test.

[0014] The principle of spectral line selection is to select spectral lines with no interference or little interference. The size of the interference is judged by the self-emission intensity of the analysis line and the interference line and the relative content in the sample; select spectral lines with high sensitivity and large self-emission intensity; select spectral lines with small self-absorption effect when the content of the analyzed element is relatively high; if the content of the measured element is high, select the secondary sensitive line; if the measured element is a large amount or major element in the sample, select the insensitive line.

[0015] Step 3 is as follows: Step 3.1, select yttrium as the internal standard element; Step 3.2, determine the inner mark line; Step 3. 3. Determine the amount of internal standard element to be added.

[0016] The beneficial effects of the present invention are as follows: the method for determining the content of iron and nickel in the matrix element of the iron-nickel alloy by the ICP-OES method of the present invention, the sample is dissolved and diluted with acid, the emission light intensity of each element analysis line in the test solution is measured on an inductively coupled plasma atomic emission spectrometer, yttrium is added as an internal standard element, the emission light intensity ratio of each element analysis line in the test solution is calculated, the intensity ratio is proportional to the content of each element, and the mass concentration of each analysis element is obtained from the working curve. The present invention adopts the internal standard method and uses the ICP-OES method to detect the relative intensity of the matrix element iron and nickel, which is fast and accurate, meets the daily analysis requirements, and has good accuracy and precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the internal standard working curve diagram of nickel in Example 4 of the present invention; Figure 2 It is the internal standard working curve diagram of iron in Example 4 of the present invention. DETAILED DESCRIPTION

[0018] The present invention is described in detail below in conjunction with specific implementation modes.

[0019] Example 1 The method for determining the content of iron and nickel in an iron-nickel alloy matrix by ICP-OES is specifically implemented according to the following steps: Step 1: Pre-treat the sample; Step 2, determining the analysis spectrum of iron and nickel; Step 3: Determine the internal standard element and the amount of the internal standard element added. By adding the internal standard element, the intensity of iron and nickel is converted into relative intensity, thereby improving the impact caused by slight changes in gas pressure, solution lifting amount, and atomization efficiency.

[0020] Step 4: Calculate the iron and nickel contents of the matrix elements through a linear range test.

[0021] Example 2 The method for determining the content of iron and nickel in an iron-nickel alloy matrix by ICP-OES is specifically implemented according to the following steps: Step 1: Pre-treat the sample; Step 1.1, preparing the analytical solution; In order to ensure the accurate determination of the elements to be tested, the dissolution of the sample must ensure that all the components to be tested are converted into the solution. According to the chemical properties of the elements to be tested in the iron-nickel-based alloy and the different test objects, the dissolution method of the sample will also be different.

[0022] Three dissolution methods are used in step 1.1 of the present invention: The first method is to weigh 0.1g of the iron-nickel alloy sample in step 1.1, accurate to 0.0001g, place the sample in a 150ml polytetrafluoroethylene beaker, add 5.0ml hydrochloric acid, 1.0ml nitric acid, and 0.5ml hydrofluoric acid in sequence, cover the polytetrafluoroethylene beaker with a lid, place the beaker on a low-temperature flat electric furnace, heat to dissolve, and after the sample is completely dissolved, remove it and cool it, transfer it to a 50ml plastic volumetric flask, add 3.00ml of the internal standard solution, dilute it to the scale with water, and shake it well.

[0023] The sample is dissolved by the salt nitric acid and hydrofluoric acid method to determine the content of elements such as Ni, Fe, Mn, Cr, Mo, Al, Ti, Co, Cu, Nb, Ta, Mg, Ca, Si, P, B, Hf, V, W, and Zr; The second method is to weigh 0.1g of the iron-nickel alloy sample in step 1.1, accurate to 0.0001g, place the sample in a 150ml conical flask, add 5.0mlHCl and 1.0mlHNO3, place it on a low-temperature flat electric furnace to heat and dissolve, and after the sample is completely dissolved, remove it and add 10ml of H2SO4 (1+1), place it on a high-temperature flat electric furnace to evaporate until sulfuric acid smoke appears. If there is carbide, add nitric acid to remove the carbon. If sulfuric acid smoke continues to appear, remove it and cool it, add an appropriate amount of water to dissolve the salts, remove it and cool it, transfer it to a 100ml volumetric flask, add 3.00mlY internal standard solution, dilute it to the scale with water, and shake it well.

[0024] The sample was dissolved by sulfuric acid fuming method. The sulfuric acid was high purity and ρ was 1.84 g / ml. The contents of elements such as Ni, Fe, Mn, Cr, Al, Ti, Co, Mo, Cu, Ta, Nb, V, and Zr were determined. The third method is to weigh 0.1g of the iron-nickel alloy sample in step 1.1, accurate to 0.0001g, place the sample in a 150ml conical flask, add 10.0ml HCl and 1.0ml HNO3, place it on a low-temperature flat electric furnace to heat and dissolve, and after the sample is completely dissolved, remove it and add 5.0ml H2SO4+H3PO4 (1+2), place it on a high-temperature flat electric furnace to evaporate until smoking, if there is carbide, add nitric acid to remove the carbon, continue to heat until smoking, remove it and cool it, add appropriate amount of water to dissolve the salts, remove it and cool it, add 3.00ml Y internal standard solution, transfer it to a 100ml volumetric flask, dilute it to the scale with water, and shake it well.

[0025] The sample was dissolved by the sulfur-phosphorus mixed acid fuming method. Phosphoric acid was analytical grade with a ρ of 1.69 g / ml. The contents of elements such as Ni, Fe, Mn, Cr, Al, Ti, Co, Mo, Cu, Ta, Nb, and W were determined.

[0026] Hydrochloric acid was of premium grade with a ρ of 1.19 g / ml; nitric acid was of premium grade with a ρ of 1.42 g / ml; hydrofluoric acid was of premium grade with a ρ of 1.15 g / ml; sulfuric acid was of premium grade with a ρ of 1.84 g / ml; and phosphoric acid was of analytical grade with a ρ of 1.69 g / ml.

[0027] In order to complete the determination of more elements by dissolving the sample once, the present invention selects the salt nitric acid + hydrofluoric acid method to dissolve the sample.

[0028] When using an inductively coupled plasma emission spectrometer to test samples dissolved by the saline nitric acid + hydrofluoric acid method, a hydrofluoric acid-resistant sample introduction system (polyethylene plastic atomizer + ceramic center tube) should be used, otherwise the atomization system can be easily corroded and damaged by hydrofluoric acid.

[0029] Step 1.2, prepare a blank solution, and make a blank solution together with the sample in step 1.1; Step 1.3, preparing a series of working curve solutions; Step 1.3.1, draw a working curve using standard substances; Weigh an iron-nickel alloy standard sample with the same mass as the iron-nickel alloy sample, dissolve and fix the volume together with the sample according to the method for preparing the analytical solution in step 1.1, select 3 to 5 standard substances with content gradient for each element, and measure the standard solution by inductively coupled plasma emission spectrometer equipped with a hydrofluoric acid-resistant injection system. The measurement conditions of the internal standard method are as follows: incident power of 1150KW, cooling air flow of 12L / min, auxiliary gas flow of 0.5L / min, repeated 3 times, observation height of 12mm, internal standard line of 371.029nm, and draw internal standard working curves for iron and nickel respectively.

[0030] Step 1.3.2, draw a working curve using the standard solution; Prepare the analytical solution in step 1.1 and process 6 blank solutions in parallel. Transfer them into 6 50 ml volumetric flasks, one of which is used as a blank. Add alloy elements with contents close to those of the sample to be tested into the other 5 volumetric flasks. Add different amounts of standard solution of the element to be tested into the 5 volumetric flasks, add 3.00 ml of internal standard solution, dilute to the mark with water, and shake well.

[0031] The amount of the standard solution of the element to be tested is calculated according to the content of the sample to be tested, so that the highest point among the six points of the working curve is higher than the sample to be tested.

[0032] Step 1.4: Carry out testing on the machine and draw a working curve based on the element content and relative intensity.

[0033] Step 2, determining the analysis spectrum of iron and nickel; Step 3: Determine the internal standard element and the amount of the internal standard element added. By adding the internal standard element, the intensity of iron and nickel is converted into relative intensity, thereby improving the impact caused by slight changes in gas pressure, solution lifting amount, and atomization efficiency.

[0034] Step 4: Calculate the iron and nickel contents through a linear range test.

[0035] The ICP-OES method for determining the content of iron and nickel in an iron-nickel alloy matrix comprises the following steps: dissolving a sample with hydrochloric acid, nitric acid and hydrofluoric acid, diluting the sample to a certain volume, measuring the emission light intensity of each element analysis line in the test solution under selected conditions on an inductively coupled plasma atomic emission spectrum, adding yttrium as an internal standard element, calculating the emission light intensity ratio of each element analysis line in the test solution, wherein the intensity ratio is proportional to the content of each element, and obtaining the mass concentration of each analysis element from a working curve, thereby expanding the determination range and improving the determination stability, so that the determination result has high sensitivity and is more accurate.

[0036] Example 3 The method for determining the content of iron and nickel in an iron-nickel alloy matrix by ICP-OES is specifically implemented according to the following steps: Step 1: Pre-treat the sample; Step 1.1, preparing the analytical solution; Three dissolution methods are used in step 1.1 of the present invention: The first method is to weigh 0.1g of the iron-nickel alloy sample in step 1.1, accurate to 0.0001g, place the sample in a 150ml polytetrafluoroethylene beaker, add 5.0ml hydrochloric acid, 1.0ml nitric acid, and 0.5ml hydrofluoric acid in sequence, cover the polytetrafluoroethylene beaker with a lid, place the beaker on a low-temperature flat electric furnace, heat to dissolve, and after the sample is completely dissolved, remove it and cool it, transfer it to a 50ml plastic volumetric flask, add 3.00ml of the internal standard solution, dilute it to the scale with water, and shake it well.

[0037] The sample is dissolved by the salt nitric acid and hydrofluoric acid method to determine the content of elements such as Ni, Fe, Mn, Cr, Mo, Al, Ti, Co, Cu, Nb, Ta, Mg, Ca, Si, P, B, Hf, V, W, and Zr; The second method is to weigh 0.1g of the iron-nickel alloy sample in step 1.1, accurate to 0.0001g, place the sample in a 150ml conical flask, add 5.0mlHCl and 1.0mlHNO3, place it on a low-temperature flat electric furnace to heat and dissolve, and after the sample is completely dissolved, remove it and add 10ml of H2SO4 (1+1), place it on a high-temperature flat electric furnace to evaporate until sulfuric acid smoke appears. If there is carbide, add nitric acid to remove the carbon. If sulfuric acid smoke continues to appear, remove it and cool it, add an appropriate amount of water to dissolve the salts, remove it and cool it, transfer it to a 100ml volumetric flask, add 3.00mlY internal standard solution, dilute it to the scale with water, and shake it well.

[0038] The sample was dissolved by sulfuric acid fuming method. The sulfuric acid was high purity and ρ was 1.84 g / ml. The contents of elements such as Ni, Fe, Mn, Cr, Al, Ti, Co, Mo, Cu, Ta, Nb, V, and Zr were determined. The third method is to weigh 0.1g of the iron-nickel alloy sample in step 1.1, accurate to 0.0001g, place the sample in a 150ml conical flask, add 10.0ml HCl and 1.0ml HNO3, place it on a low-temperature flat electric furnace to heat and dissolve, and after the sample is completely dissolved, remove it and add 5.0ml H2SO4+H3PO4 (1+2), place it on a high-temperature flat electric furnace to evaporate until smoking, if there is carbide, add nitric acid to remove the carbon, continue to heat until smoking, remove it and cool it, add appropriate amount of water to dissolve the salts, remove it and cool it, add 3.00ml Y internal standard solution, transfer it to a 100ml volumetric flask, dilute it to the scale with water, and shake it well.

[0039] The sample was dissolved by the sulfur-phosphorus mixed acid fuming method. Phosphoric acid was analytical grade with a ρ of 1.69 g / ml. The contents of elements such as Ni, Fe, Mn, Cr, Al, Ti, Co, Mo, Cu, Ta, Nb, and W were determined.

[0040] Hydrochloric acid was of premium grade with a ρ of 1.19 g / ml; nitric acid was of premium grade with a ρ of 1.42 g / ml; hydrofluoric acid was of premium grade with a ρ of 1.15 g / ml; sulfuric acid was of premium grade with a ρ of 1.84 g / ml; and phosphoric acid was of analytical grade with a ρ of 1.69 g / ml.

[0041] Step 1.2, prepare a blank solution, and make a blank solution together with the sample in step 1.1; Step 1.3, preparing a series of working curve solutions; Step 1.3.1, draw a working curve using standard substances; Weigh an iron-nickel alloy standard sample with the same mass as the iron-nickel alloy sample, dissolve and fix the volume together with the sample according to the method for preparing the analytical solution in step 1.1, select 3 to 5 standard substances with content gradient for each element, and measure the standard solution by inductively coupled plasma emission spectrometer equipped with a hydrofluoric acid-resistant injection system. The measurement conditions of the internal standard method are as follows: incident power of 1150KW, cooling air flow of 12L / min, auxiliary gas flow of 0.5L / min, repeated 3 times, observation height of 12mm, internal standard line of 371.029nm, and draw internal standard working curves for iron and nickel respectively.

[0042] Step 1.3.2, draw a working curve using the standard solution; Prepare the analytical solution in step 1.1 and process 6 blank solutions in parallel. Transfer them into 6 50 ml volumetric flasks, one of which is used as a blank. Add alloy elements with contents close to those of the sample to be tested into the other 5 volumetric flasks. Add different amounts of standard solution of the element to be tested into the 5 volumetric flasks, add 3.00 ml of internal standard solution, dilute to the mark with water, and shake well.

[0043] The amount of the standard solution of the element to be tested is calculated according to the content of the sample to be tested, so that the highest point among the six points of the working curve is higher than the sample to be tested.

[0044] Step 1.4: Carry out testing on the machine and draw a working curve based on the element content and relative intensity.

[0045] Step 2, determining the analysis spectrum of iron and nickel; Step 2.1, select the spectral line through interference test of coexisting elements, sensitivity analysis of each spectral line and interference conditions beside the spectral line; The principle of spectral line selection is to select spectral lines with no interference or little interference. The size of the interference is judged by the self-emission intensity of the analysis line and the interference line and the relative content in the sample; select spectral lines with high sensitivity and large self-emission intensity; select spectral lines with small self-absorption effect when the content of the analyzed element is relatively high; if the content of the measured element is high, select the secondary sensitive line; if the measured element is a large amount or major element in the sample, select the insensitive line.

[0046] Step 2.2, determine the sensitivity of each spectral line of iron and nickel; Step 2.3, calculate the intensity of iron and nickel at the same concentration under each spectral line; Step 2.4, obtain the interference lines next to the iron and nickel spectral lines; Step 2.5: Conduct interference test.

[0047] Step 3, determining the internal standard element and the amount of the internal standard element added; Step 3.1, select the internal standard element; The principles of internal standard elements are as follows: the evaporation characteristics of the internal standard element are similar to those of the element to be measured; the internal standard line corresponds to and matches the analysis line, and both are atomic lines or ion lines; the material to be measured cannot contain the internal standard element; the intensity difference is not large, there is no interference from adjacent spectral lines, and the self-absorption phenomenon is weak or non-existent.

[0048] Y (yttrium) element was selected as the internal standard element, and the concentration of the yttrium internal standard solution was prepared to be 0.15 mg / L. Specifically, 0.1905 g of yttrium oxide was weighed, and the mass fraction of Y2O3 was not less than 99.95%. The yttrium oxide was placed in a 250 ml conical flask, 40 ml of hydrochloric acid (1+1) was added, and the solution was heated at low temperature until completely dissolved. After cooling, the solution was transferred to a 1000 ml volumetric flask, 60 ml of hydrochloric acid (1+1) was added, and the solution was diluted to the scale with water and shaken well.

[0049] Step 3.2, determine the inner mark line; Step 3.3, determine the amount of internal standard element added; Step 4: Calculate the iron and nickel contents through a linear range test.

[0050] Example 4 The method for determining the content of iron and nickel in an iron-nickel alloy matrix by ICP-OES is specifically implemented according to the following steps: Step 1: Pre-treat the sample; The first dissolution method is adopted in step 1.1 of the present invention: 0.1g of the iron-nickel alloy sample is weighed in step 1.1, accurately to 0.0001g, the sample is placed in a 150ml polytetrafluoroethylene beaker, 5.0ml of hydrochloric acid, 1.0ml of nitric acid and 0.5ml of hydrofluoric acid are added in sequence, the polytetrafluoroethylene beaker cover is covered, the beaker is placed in a low-temperature flat electric furnace, heated to dissolve, after the sample is completely dissolved, removed and cooled, transferred to a 50ml plastic volumetric flask, 3.00ml of internal standard solution is added, diluted to the scale with water, and shaken well.

[0051] When using the saline nitric acid + hydrofluoric acid method (adding internal standard elements) to treat samples, the strength of trace elements must be considered. When the solution is diluted into a 50ml volumetric flask, the concentration of each element is doubled, which doubles the interference. The difficulty of detection also increases, and the operation requirements are relatively high.

[0052] The hydrochloric acid used was of high grade, with a ρ of 1.19 g / ml; the nitric acid used was of high grade, with a ρ of 1.42 g / ml; the hydrofluoric acid used was of high grade, with a ρ of 1.15 g / ml.

[0053] Step 1.2, prepare a blank solution, and make a blank solution together with the sample in step 1.1; Step 1.3, preparing a series of working curve solutions; Step 1.3.1, draw a working curve using standard substances; Weigh an iron-nickel alloy standard sample with the same mass as the iron-nickel alloy sample, dissolve and fix the sample together with the sample according to the method for preparing the analytical solution in step 1.1, select 3 to 5 standard substances with content gradient for each element, and use an inductively coupled plasma emission spectrometer to measure the standard solution, equipped with a hydrofluoric acid-resistant injection system, and use the internal standard method. The measurement conditions are: incident power is 1150KW, cooling air flow is 12L / min, auxiliary gas flow is 0.5L / min, repeated 3 times, observation height is 12mm, internal standard line is 371.029nm, and internal standard working curves of matrix elements iron and nickel are drawn respectively, with the content of iron and nickel as the horizontal axis and the relative intensity of iron and nickel as the coordinate to draw the working curve. Figure 1 As shown, the linear correlation coefficient R 2 is 0.99955, such as Figure 2 As shown, the linear correlation coefficient of iron is R 2 is 0.99989.

[0054] Step 1.3.2, draw a working curve using the standard solution; Prepare the analytical solution in step 1.1 and process 6 blank solutions in parallel. Transfer them into 6 50 ml volumetric flasks, one of which is used as a blank. Add alloy elements with contents close to those of the sample to be tested into the other 5 volumetric flasks. Add different amounts of standard solution of the element to be tested into the 5 volumetric flasks, add 3.00 ml of internal standard solution, dilute to the mark with water, and shake well.

[0055] The amount of the standard solution of the element to be tested is calculated according to the content of the sample to be tested, so that the highest point among the six points of the working curve is higher than the sample to be tested.

[0056] Step 1.4: Carry out testing on the machine and draw a working curve based on the element content and relative intensity.

[0057] Step 2, determining the analysis spectrum of iron and nickel; Step 2.1, select the spectral line through interference test of coexisting elements, sensitivity analysis of each spectral line and interference conditions beside the spectral line; Step 2.2, determine the sensitivity of each spectral line of iron and nickel; The sensitivities of the iron Fe spectral lines are 259.940nm, 238.204nm, 239.562nm, 240.488nm, 259.837nm, 261.187nm, 234.349nm, 371.994nm, and 233.280nm in order.

[0058] The sensitivities of each spectral line of nickel Ni are 221.647nm, 231.604nm, 341.476nm, 216.556nm, 232.003nm, 352.454nm, 361.939nm, 230.300nm, and 243.789nm in order.

[0059] Step 2.3, calculate the intensity of iron and nickel at the same concentration under each spectral line; A standard substance with an iron content of 1.0 mg / L was selected and the intensity under different spectral lines was calculated. The results are shown in Table 1.

[0060] Table 1 shows the intensity of iron at the same concentration under each spectral line

[0061] A standard substance with a nickel content of 0.50 mg / L was selected and the intensity under different spectral lines was calculated. The results are shown in Table 2.

[0062] Table 2 shows the intensity of nickel at the same concentration under each spectral line

[0063] Step 2.4, obtain the interference lines next to the iron and nickel spectral lines; The interference near each spectral line of iron was calculated using the spectrometer software. The results are shown in Table 3.

[0064] Table 3 shows the interference lines next to the iron spectrum line

[0065] The interference near each spectral line of nickel was calculated using the spectrometer software. The results are shown in Table 4.

[0066] Table 4 shows the interference lines next to the nickel spectrum

[0067] Step 2.5: Conduct interference test.

[0068] Since the interference of coexisting elements is extremely complex, it is far from enough to simply judge from the strength and the information provided by the software. The present invention makes a comprehensive judgment by performing interference tests and the content of each element in the test sample.

[0069] The specific process of using the representative content of each element to judge the interference situation of each spectral line is as follows; Step 2.5.1, the interference results of coexisting elements on different spectral lines of Fe are shown in Table 5; Table 5 shows the interference of coexisting elements on Fe

[0070] Step 2.5.2, the interference results of coexisting elements on different spectral lines of Ni are shown in Table 6; Table 6 shows the interference of coexisting elements on Ni

[0071] Since Fe and Ni are both matrix elements, their contents in the tested material are very high. Although there is interference from a certain element near some spectral lines, the interference can be ignored because the content of this interfering element in the tested sample is very low. According to the selection principle of spectral lines, in this embodiment, the non-sensitive line Fe259.837nm of Fe is selected as the analysis line of Fe; the sub-sensitive line Ni231.604nm of Ni is selected as the analysis line of Ni.

[0072] Step 3, determining the internal standard element and the amount of the internal standard element added; Step 3.1, select the internal standard element; The principles of internal standard elements are as follows: the evaporation characteristics of the internal standard element are similar to those of the element to be measured; the internal standard line corresponds to and matches the analysis line, and both are atomic lines or ion lines; the material to be measured cannot contain the internal standard element; the intensity difference is not large, there is no interference from adjacent spectral lines, and the self-absorption phenomenon is weak or non-existent.

[0073] The present invention is aimed at the detection of iron and nickel in nickel-based and iron-nickel-based materials, and selects Y (yttrium) element as the internal standard element.

[0074] Step 3.2, determine the inner mark line; The Y element is the same as other elements. The equipment software will give multiple spectral lines, including sensitive lines, sub-sensitive lines and insensitive lines. Select the sensitive line Y371.029nm as the internal standard line.

[0075] Step 3.3, determine the amount of internal standard element added; The effect of the amount of internal standard element Y added on the detection results of Fe is shown in Table 7; Table 7 shows the effect of internal standard addition on the determination results of Fe

[0076] The effect of the amount of internal standard element Y added on the detection results of Ni is shown in Table 8; Table 8 Effect of internal standard addition on Ni determination results

[0077] It can be concluded from the data in Tables 7 and 8 that when 0.15μg~0.60μg of internal standard is added, the detection results of Fe and Ni are very different; when 0.45μg of internal standard is added, the detection results of Fe17.20%, Fe18.54%, Fe38.40%, Ni52.27%, Ni53.35%, and Ni41.20% are relatively ideal; experiments show that when 0.40μg~0.45μg of Y internal standard is added, the linear coefficients and detection results of Fe and Ni meet the experimental requirements.

[0078] Step 4: Calculate the iron and nickel contents through a linear range test.

[0079] Since the standard sample contains alloy elements, this embodiment uses the standard sample to carry out the nickel and iron quantitative range test to determine the nickel and iron quantitative ranges. The results are shown in Tables 9 and 10.

[0080] Table 9 shows the quantitative range of nickel

[0081] Table 10 shows the quantitative range of iron

[0082] It can be seen from the data in Tables 10 and 11 that the nickel content is linear in the range of 24.4% to 57.5%, and the linear coefficient is greater than 0.9999%; the iron content is linear in the range of 17.20% to 49.6%, and the linear coefficient is greater than 0.9999%, which meets the test requirements.

[0083] Example 5 Based on Example 4, this example conducts a spike recovery test.

[0084] Add the same amount of nickel and iron standard solutions to different standard substances, and calculate the recovery rate based on the measured results. The calculation results are shown in Table 11: Table 11 shows the spike recovery test of nickel and iron

[0085] From the data in Table 11, it can be seen that the recovery rate of nickel is between 97.9% and 98.1%, and the recovery rate of iron is between 97.6% and 103%. The accuracy of the test data can meet the test requirements.

[0086] Example 6 Based on Example 4, this example conducts a precision test.

[0087] Use quality control samples for precision test. Weigh ten parts of quality control samples and place them in a polytetrafluoroethylene beaker. Add 5.0ml hydrochloric acid, 1.0ml nitric acid, and 0.5ml hydrofluoric acid. Dissolve the samples in a flat electric furnace at low temperature. After dissolution, cool to room temperature, transfer to a 50ml volumetric flask, add 3.0ml of Y internal standard solution, dilute to scale with water, and shake well.

[0088] Treat blank solution and series of standard solutions together with the samples.

[0089] The Ni and Fe contents were measured at Ni231.604nm and Fe259.837nm. The measurement results are shown in Table 12.

[0090] Table 12 shows the precision determination of Ni and Fe contents

[0091] From the data in Table 12, it can be seen that the RSD of Ni determination is 0.57%, and the RSD of Fe determination is 0.48%. Both RSDs are less than 1.0%, and the precision can meet the test standard requirements.

[0092] After adding the internal standard element, the high intensity value of the present invention is converted into a relative intensity value, and the value is reduced by an order of magnitude; within its linear range, the linear coefficient is greater than 0.9999; after the accuracy and precision tests, satisfactory results are obtained, and the method of the present invention is adopted to detect the iron and nickel content in daily iron-nickel-based materials, and the treated sample solution can also determine the content of elements such as Mn, Cr, Mo, Al, Ti, Co, Cu, Nb, Ta, Mg, Ca, Si, P, B, Hf, V, W, Zr, etc., which saves the detection cost to a great extent and is worthy of promotion.

[0093] The method for determining the content of iron and nickel in an iron-nickel alloy matrix element by ICP-OES adopts the ICP-OES internal standard method, firstly performs sample pretreatment, then determines the analysis spectrum of iron and nickel through interference test of coexisting elements, sensitivity analysis of each spectrum line and interference conditions beside the spectrum line, and solves the problem that the strength of iron and nickel as matrix elements is very high by adding internal standard elements, so that the strength of iron and nickel is converted into relative strength, thereby improving the influence caused by slight changes in gas pressure, solution lifting amount and atomization efficiency, and determining the internal standard elements and the addition amount of the internal standard elements, and the linear range test shows that the iron content is linearly related between 17.20% and 49.6%, and the linear coefficient is 0.99997, and the nickel content is linearly related between 24.4% and 57.5%, and the linear coefficient is 0.99996, and the recovery rate of iron is between 97.6% and 103%, and the recovery rate of nickel is between 97.9% and 98.1%, and it is verified that the accuracy of iron and nickel meets the test requirements. Through precision test, the RSD of iron is 0.48%, the RSD of nickel is 0.57%, and the RSD of iron and nickel is less than 1.0%, indicating that the detection precision of the method of the present invention is high and meets the daily detection needs. Therefore, the method of determining the content of iron and nickel in the matrix element of the iron-nickel alloy by the ICP-OES method of the present invention has the characteristics of wide linear range, high sensitivity, simple operation, fast analysis speed, accurate and reliable analysis results, and has good accuracy and precision in testing the content of iron and nickel in the iron-nickel alloy.

Claims

1. The method for determining the content of iron and nickel in an iron-nickel alloy matrix by ICP-OES is characterized in that: Follow the steps below to implement it: Step 1: Pre-treat the sample; Step 2, determining the analysis spectrum of iron and nickel; Step 3, determining the internal standard element and the amount of the internal standard element added; Step 4: Calculate the iron and nickel contents through a linear range test.

2. The method for determining the content of iron and nickel in an iron-nickel alloy matrix by ICP-OES according to claim 1, characterized in that: Step 1 is as follows: Step 1.1, preparing the analytical solution; Step 1.2, prepare a blank solution, and make a blank solution together with the sample in step 1.1; Step 1.3, preparing a series of working curve solutions; Step 1.4: Carry out testing on the machine and draw a working curve based on the element content and relative intensity.

3. The method for determining the content of iron and nickel in an iron-nickel alloy matrix by ICP-OES according to claim 2, characterized in that: Three dissolution methods were used in step 1.1: The first method is to weigh 0.1g of the iron-nickel alloy sample in step 1.1, accurate to 0.0001g, place the sample in a 150ml polytetrafluoroethylene beaker, add 5.0ml hydrochloric acid, 1.0ml nitric acid, and 0.5ml hydrofluoric acid in sequence, cover the polytetrafluoroethylene beaker with a lid, place the beaker on a low-temperature flat electric furnace, heat to dissolve, and after the sample is completely dissolved, remove and cool, transfer to a 50ml plastic volumetric flask, add 3.00ml of the internal standard solution, dilute to the scale with water, and shake well.

4. The method for determining the content of iron and nickel in an iron-nickel alloy matrix by ICP-OES according to claim 3, characterized in that: The second method is to weigh 0.1g of the iron-nickel alloy sample in step 1.1, accurate to 0.0001g, place the sample in a 150ml conical flask, add 5.0mlHCl and 1.0mlHNO3, place it on a low-temperature flat electric furnace to heat and dissolve, and after the sample is completely dissolved, remove it and add 10mlH2SO4, place it on a high-temperature flat electric furnace to evaporate until sulfuric acid smoke appears. If there is carbide, add nitric acid to remove the carbon, continue to emit sulfuric acid smoke, remove it and cool it, add appropriate amount of water to dissolve the salts, remove it and cool it, transfer it to a 100ml volumetric flask, add 3.00mlY internal standard solution, dilute it to the scale with water, and shake it well.

5. The method for determining the content of iron and nickel in an iron-nickel alloy matrix by ICP-OES according to claim 4, characterized in that: The third method is to weigh 0.1g of the iron-nickel alloy sample in step 1.1, accurate to 0.0001g, place the sample in a 150ml conical flask, add 10.0ml HCl and 1.0mlHNO3, place it on a low-temperature flat electric furnace to heat and dissolve, and after the sample is completely dissolved, remove it and add 5.0mlH2SO4+H3PO4, place it on a high-temperature flat electric furnace to evaporate until smoking, if there is carbide, add nitric acid to remove the carbon, continue to heat until smoking, remove it and cool it, add an appropriate amount of water to dissolve the salts, remove it and cool it, add 3.00mlY internal standard solution, transfer it to a 100ml volumetric flask, dilute it to the scale with water, and shake it well.

6. The method for determining the content of iron and nickel in an iron-nickel alloy matrix by ICP-OES according to claim 5, characterized in that: The hydrochloric acid was of premium grade with a ρ of 1.19 g / ml; the nitric acid was of premium grade with a ρ of 1.42 g / ml; the hydrofluoric acid was of premium grade with a ρ of 1.15 g / ml; the sulfuric acid was of premium grade with a ρ of 1.84 g / ml; and the phosphoric acid was of analytical grade with a ρ of 1.69 g / ml.

7. The method for determining the content of iron and nickel in an iron-nickel alloy matrix by ICP-OES according to claim 6, characterized in that: Step 1.3 is as follows: Step 1.3.1, draw a working curve using standard substances; Weigh an iron-nickel alloy standard sample with the same mass as the iron-nickel alloy sample, dissolve and fix the sample together with the sample according to the method for preparing the analytical solution in step 1.1, select 3 to 5 standard substances with content gradient for each element, and use an inductively coupled plasma emission spectrometer to measure the standard solution, equipped with a hydrofluoric acid-resistant injection system, and use the internal standard method. The measurement conditions are: incident power is 1150KW, cooling air flow is 12L / min, auxiliary gas flow is 0.5L / min, the number of repetitions is 3 times, the observation height is 12mm, and the internal standard line is 371.029nm. Draw the internal standard working curves of iron and nickel respectively; Step 1.3.2, draw a working curve using the standard solution; Prepare the analytical solution in step 1.1 and process 6 blank solutions in parallel. Transfer them into 6 50 ml volumetric flasks, one of which is used as a blank. Add alloy elements with contents close to those of the sample to be tested into the other 5 volumetric flasks. Add different amounts of standard solution of the element to be tested into the 5 volumetric flasks, add 3.00 ml of internal standard solution, dilute to the mark with water, and shake well.

8. The method for determining the content of iron and nickel in an iron-nickel alloy matrix by ICP-OES according to claim 7, characterized in that: Step 2 is specifically as follows: Step 2.1, select the spectral line through interference test of coexisting elements, sensitivity analysis of each spectral line and interference conditions beside the spectral line; Step 2.2, determine the sensitivity of each spectral line of iron and nickel; Step 2.3, calculate the intensity of iron and nickel at the same concentration under each spectral line; Step 2.4, obtain the interference lines next to the iron and nickel spectral lines; Step 2.5: Conduct interference test.

9. The method for determining the content of iron and nickel in an iron-nickel alloy matrix by ICP-OES according to claim 8, characterized in that: The principle of spectral line selection is to select spectral lines with no interference or little interference. The size of the interference is judged by the self-emission intensity of the analysis line and the interference line and the relative content in the sample; select spectral lines with high sensitivity and large self-emission intensity; select spectral lines with small self-absorption effect when the content of the analyzed element is relatively high; if the content of the measured element is high, select the secondary sensitive line; if the measured element is a large amount or major element in the sample, select the insensitive line.

10. The method for determining the content of iron and nickel in an iron-nickel alloy matrix by ICP-OES according to claim 9, characterized in that: Step 3 is as follows: Step 3.1, select yttrium as the internal standard element; Step 3.2, determine the inner mark line; Step 3.

3. Determine the amount of internal standard element to be added.

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