Dissolution method for icp-oes detection of nichrome alloy nicsi

Abstract

This invention discloses a method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection, comprising the following steps: mixing the NiCrPSi nickel alloy sample to be tested with hydrochloric acid aqueous solution, concentrated nitric acid, and hydrofluoric acid aqueous solution, digesting at 120-140℃ for 1.5-2.5h, and then evaporating the solution to dryness at 220-260℃; then adding nitric acid aqueous solution and heating until the solid is completely dissolved, and then diluting with water to obtain the NiCrPSi nickel alloy test solution. The dissolution method of this invention can completely dissolve NiCrPSi nickel alloy powder without elemental loss, providing an accurate sample solution for ICP-OES detection; and it eliminates the need for specialized equipment such as microwave digesters or electrothermal digesters, as well as special reagents such as perchloric acid and tartaric acid, using only conventional acid reagents and general experimental equipment, thus reducing costs, simplifying operation, and enhancing versatility.

Description

Technical Field

[0001] This invention relates to the field of chemical analysis technology for metallic materials, and in particular to a method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection. Background Technology

[0002] NiCrPSi nickel alloy powder, due to its excellent high-temperature resistance, corrosion resistance, and good fatigue performance, is a core material for critical structures such as hot-end components of aerospace engines and precision joints in high-end industrial equipment. Its purity and elemental content (such as the oxidation resistance of Cr) directly determine the safety performance and service life of the end product. Therefore, accurate testing of the elemental composition of this alloy powder is a crucial step in ensuring material compliance and engineering reliability.

[0003] Currently, inductively coupled plasma atomic emission spectrometry (ICP-OES) is the mainstream technology for detecting the elemental content of nickel alloy powders. This method offers advantages such as simultaneous multi-element detection, low detection limits, and high accuracy. However, the accuracy of the results depends entirely on the effectiveness of sample dissolution during pretreatment. Incomplete dissolution (resulting in undissolved alloy particles or oxide residues) or an unstable solution system after dissolution can directly lead to spectral signal distortion, resulting in elemental content detection deviations and consequently misleading material quality assessments. Currently, hydrochloric acid and / or nitric acid are commonly used for low-temperature heating dissolution, but this method is designed for conventional nickel-based alloys and is not suitable for self-fluxing alloys containing special phases, such as NiCrPSi nickel alloys.

[0004] Because P and Si in NiCrPSi nickel alloys form extremely stable phosphide phases (such as Ni3P), and a dense SiO2 passivation film easily forms on the silicon surface during acid dissolution, phosphate ions combine with nickel and chromium ions to form insoluble phosphate precipitates, which in turn form a dense, phosphorus-rich passivation film on the surface, hindering further dissolution and leading to incomplete sample dissolution. The hydrochloric acid-nitric acid system lacks sufficient oxidizing and complexing power, and the low-temperature heating cannot provide enough energy to destroy these stable structures or penetrate the passivation film, ultimately leading to dissolution failure and the formation of insoluble precipitates, affecting the accuracy of the detection results. Furthermore, other existing dissolution methods for NiCrPSi nickel alloys often rely on equipment such as microwave digestion and high-risk reagents such as perchloric acid, resulting in high costs and risks, and thus poor versatility. Summary of the Invention

[0005] Based on the technical problems existing in the background technology, this invention proposes a NiCrPSi nickel alloy dissolution method for ICP-OES detection. The dissolution method of this invention can completely dissolve NiCrPSi nickel alloy powder without element loss, providing an accurate sample solution for ICP-OES detection. Furthermore, it eliminates the need for specialized equipment such as microwave digesters and electrothermal digesters, as well as special reagents such as perchloric acid and tartaric acid. It only uses conventional acid reagents and general experimental equipment, reducing costs, simplifying operation, and enhancing versatility.

[0006] This invention proposes a method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection, comprising the following steps: mixing the NiCrPSi nickel alloy sample to be tested with hydrochloric acid aqueous solution, concentrated nitric acid, and hydrofluoric acid aqueous solution, digesting at 120-140℃ for 1.5-2.5h, and then heating to 220-260℃ to evaporate the solution to dryness; then adding nitric acid aqueous solution and heating until the solid is completely dissolved, and then diluting with water to obtain the NiCrPSi nickel alloy test solution.

[0007] More preferably, the digestion is carried out at 130°C for 2 hours, and then the temperature is raised to 240°C to evaporate the solution to dryness.

[0008] Preferably, the hydrochloric acid aqueous solution is a mixture of equal volumes of concentrated hydrochloric acid and water; the nitric acid aqueous solution is a mixture of equal volumes of concentrated nitric acid and water. Concentrated nitric acid is a nitric acid aqueous solution with a mass fraction of 65-68%; concentrated hydrochloric acid is a hydrochloric acid aqueous solution with a mass fraction of 36-38%; and hydrofluoric acid aqueous solution is a hydrofluoric acid aqueous solution with a mass fraction of 38-42%.

[0009] Preferably, the ratio of the NiCrPSi nickel alloy sample to hydrochloric acid aqueous solution, concentrated nitric acid, and hydrofluoric acid aqueous solution is 0.1g:3-5mL:4-6mL:1.5-2.5mL; The ratio of the NiCrPSi nickel alloy sample to the nitric acid aqueous solution was 0.1g:4-6mL.

[0010] This invention uses hydrochloric acid aqueous solution, concentrated nitric acid, and hydrofluoric acid aqueous solution in appropriate proportions, combined with a low-temperature digestion treatment at 120-140℃, which can promote the initial dissolution of elements such as Ni and Cr in NiCrPSi nickel alloy and inhibit the violent reaction of hydrofluoric acid; then the solution is evaporated to dryness at 220-260℃. During this process, hydrofluoric acid can effectively destroy the silicate structure, ensuring complete dissolution of Si, and can also destroy the phosphide structure, and promote the stable existence of phosphoric acid without volatilization.

[0011] Preferably, in the NiCrPSi nickel alloy test solution, the ratio of the NiCrPSi nickel alloy test sample to the final volume is 0.1g:100-1000mL.

[0012] Each 0.1g of NiCrPSi nickel alloy sample can be diluted with water to a final volume of 100mL. When detecting a single element in the NiCrPSi nickel alloy sample, if the content of that element is ≥5% (such as Cr), the dilution can also be such that each 0.1g of NiCrPSi nickel alloy sample can be diluted with water to a final volume of 1000mL. This ensures that the concentration of the element being tested is within the linear detection range of ICP-OES.

[0013] Preferably, an aqueous nitric acid solution is added, and the mixture is heated at 240-260°C until the solid is completely dissolved.

[0014] Preferably, in the NiCrPSi nickel alloy, the Si content is 3.0-5.0% and the P content is 5.0-7.0%.

[0015] Preferably, the composition of the NiCrPSi nickel alloy, by mass percentage, includes: Cr 28.0-30.0%, Si 3.0-5.0%, P 5.0-7.0%, Fe < 0.05%, Cu < 0.05%, Al < 0.05%, with the balance being Ni.

[0016] More preferably, the composition of the NiCrPSi nickel alloy, by mass percentage, includes: Cr 28.5-29.5%, Si 3.5-4.5%, P 5.5-6.5%, Fe < 0.05%, Cu < 0.05%, Al < 0.05%, with the balance being Ni.

[0017] Preferably, the ICP-OES conditions for detecting the NiCrPSi nickel alloy test solution are as follows: RF generator power of 1000-1200W, atomizing gas flow rate of 0.7-0.8L / min, cooling gas flow rate of 14-16L / min, auxiliary gas flow rate of 0.7-0.9L / min, peristaltic pump injection rate of 1.4-1.6mL / min, and radial observation method.

[0018] More preferably, the ICP-OES conditions for detecting the NiCrPSi nickel alloy test solution are as follows: RF generator power of 1100W, atomizing gas flow rate of 0.75L / min, cooling gas flow rate of 15L / min, auxiliary gas flow rate of 0.8L / min, peristaltic pump injection volume of 1.5mL / min, and radial observation method.

[0019] Preferably, when using ICP-OES for detection, the analytical lines for silicon, chromium, iron, copper, and aluminum are as follows: silicon 251.612 nm, chromium 267.716 nm, iron 238.204 nm, copper 324.754 nm, and aluminum 237.312 nm.

[0020] Preferably, the content of each component other than P in the NiCrPSi nickel alloy is calculated using the external standard method.

[0021] The water mentioned above is deionized water.

[0022] The reagents used above were of analytical grade, and the NiCrPSi nickel alloy test solution was prepared in a container made of polytetrafluoroethylene.

[0023] This invention employs a composite acid system of "hydrochloric acid aqueous solution-concentrated nitric acid-hydrofluoric acid" combined with stepwise gradient heating treatment: On one hand, hydrofluoric acid can effectively dissolve the dense SiO2 passivation film formed on the silicon surface, generating soluble fluorosilicates and opening up the contact channel between the acid solution and the alloy matrix; on the other hand, the strong oxidizing properties of nitric acid and hydrochloric acid work synergistically, with nitric acid oxidizing the stable phosphide phase to orthophosphoric acid, while simultaneously utilizing the Cl- in hydrochloric acid... - Coordination ability and Ni 2+ Cr 3+ The process combines various methods to prevent phosphate precipitation from re-encapsulating the sample. Furthermore, gradient heating is employed: low-temperature digestion inhibits violent reactions, while the high-temperature stage provides sufficient energy to destroy the phosphate structure and ensure the stable existence of phosphoric acid without volatilization, reducing elemental loss. Finally, nitric acid is added for secondary dissolution, completely eliminating insoluble residues. This approach balances dissolution efficiency and completeness, achieving complete dissolution of the NiCrPSi nickel alloy and completely eliminating the black residue of insoluble components. It addresses the core defect of incomplete dissolution in existing methods, providing an accurate sample basis for ICP-OES detection.

[0024] This invention does not require specialized equipment such as microwave digesters or electrothermal digesters, nor does it require special reagents such as perchloric acid or tartaric acid. It only uses conventional acid reagents and general experimental equipment, which reduces experimental costs and operational barriers. It is suitable for various laboratory scenarios and has strong versatility. Attached Figure Description

[0025] Figure 1 Photograph of NiCrPSi nickel alloy test solution 1.

[0026] Figure 2 This is the final photograph of the sample dissolved in Comparative Example 1.

[0027] Figure 3 This is the final photograph of the sample dissolved in Comparative Example 2.

[0028] Figure 4 This is the final photograph of the sample dissolved in Comparative Example 3.

[0029] Figure 5 This is the final photograph of the sample dissolved in Comparative Example 4.

[0030] Figure 6 This is the final photograph of the sample dissolved in Comparative Example 5.

[0031] Figure 7 This is the final photograph of the sample dissolved in Comparative Example 6.

[0032] Figure 8 This is the final photograph of the sample dissolved in Comparative Example 7. Detailed Implementation

[0033] The technical solution of the present invention will now be described in detail through specific embodiments.

[0034] Example 1 A method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection includes the following steps: Take a NiCrPSi nickel alloy sample (its composition by mass percentage includes: Cr 29.0%, Si 4.0%, P 6.0%, Fe < 0.05%, Cu < 0.05%, Al < 0.05%, with the balance being Ni), accurately weigh 0.1001 g, and add it to a polytetrafluoroethylene beaker. Then, add 4 mL of hydrochloric acid aqueous solution (a mixture of equal volumes of 36% hydrochloric acid aqueous solution and water), 5 mL of concentrated nitric acid (68% nitric acid aqueous solution), and finally add 2 mL of hydrofluoric acid aqueous solution (40% hydrofluoric acid aqueous solution). Immediately cover the beaker with a polytetrafluoroethylene watch glass and gently shake the beaker for 1-2 minutes to ensure that the sample and acid solution are fully mixed (observe small bubbles appearing in the beaker and the surface of the sample gradually becoming wet). Then, place the beaker on a hot plate preheated to 130°C and maintain the temperature for 2 hours for digestion. Next, raise the hot plate temperature to 240°C and maintain the temperature for 5-6 hours until the solution in the beaker evaporates completely. Stop heating and allow the beaker to cool slightly. Then, add 5 mL of nitric acid solution (a mixture of equal volumes of 68% nitric acid and water) around the beaker wall to rinse away any remaining solid residue. Next, heat at 240°C for 2 hours until the solid is completely dissolved (at this point, the solution will be a characteristic yellow-green color, indicating that Cr has dissolved into Cr). 3+ (The form is completely dissolved). Finally, rinse the watch glass and the inner wall of the beaker three times with deionized water. Transfer the rinsing solution and the solution in the beaker to a 100mL plastic volumetric flask, dilute to volume with deionized water, and shake well to obtain NiCrPSi nickel alloy test solution 1. Figure 1 Photograph of NiCrPSi nickel alloy test solution 1, by Figure 1 It can be seen that the NiCrPSi nickel alloy test solution 1 is clear and free of solid impurities.

[0035] Accurately measure 10 mL of the above NiCrPSi nickel alloy test solution 1 to 100 mL into a plastic volumetric flask, dilute to volume with deionized water, and shake well to obtain NiCrPSi nickel alloy test solution 2.

[0036] Example 2 A method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection includes the following steps: Take a NiCrPSi nickel alloy sample (its composition by mass percentage includes: Cr 28.5%, Si 4.5%, P 5.5%, Fe < 0.05%, Cu < 0.05%, Al < 0.05%, with the balance being Ni), accurately weigh 0.1001 g, and add it to a polytetrafluoroethylene beaker. Then, add 3 mL of hydrochloric acid aqueous solution (a mixture of equal volumes of 36% hydrochloric acid aqueous solution and water), 6 mL of concentrated nitric acid (68% nitric acid aqueous solution), and finally add 1.5 mL of hydrofluoric acid aqueous solution (40% hydrofluoric acid aqueous solution). Immediately cover the beaker with a polytetrafluoroethylene watch glass and gently shake the beaker for 1-2 minutes to ensure that the sample and acid solution are fully mixed (observe small bubbles appearing in the beaker and the surface of the sample gradually becoming wet). Then, place the beaker on a preheated hot plate at 140°C and maintain the temperature for 1.5 hours for digestion. Next, raise the hot plate temperature to 260°C and maintain the temperature for 5-6 hours until the solution in the beaker evaporates completely. Stop heating and allow the beaker to cool slightly. Then, add 4 mL of nitric acid solution (a mixture of equal volumes of 68% nitric acid and water) around the beaker wall to rinse away any remaining solid residue. Finally, heat at 250°C for 2 hours until the solid is completely dissolved (at this point, the solution will be a characteristic yellow-green color, indicating that Cr has dissolved into Cr). 3+ (The form is completely dissolved). Finally, rinse the watch glass and the inner wall of the beaker three times with deionized water. Transfer the rinsing solution and the solution in the beaker to a 100mL plastic volumetric flask, dilute to volume with deionized water, and shake well to obtain NiCrPSi nickel alloy test solution 1, which is clear and free of solid impurities. When detecting Cr, carefully measure 10 mL of the above NiCrPSi nickel alloy test solution 1 to 100 mL into a plastic volumetric flask, dilute to volume with deionized water, and shake well to obtain NiCrPSi nickel alloy test solution 2.

[0037] Example 3 A method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection includes the following steps: Take a NiCrPSi nickel alloy sample (its composition by mass percentage includes: Cr 29.5%, Si 3.5%, P 6.5%, Fe < 0.05%, Cu < 0.05%, Al < 0.05%, with the balance being Ni), accurately weigh 0.1001 g, and add it to a polytetrafluoroethylene beaker. Then, add 5 mL of hydrochloric acid aqueous solution (a mixture of equal volumes of 36% hydrochloric acid aqueous solution and water), 4 mL of concentrated nitric acid (68% nitric acid aqueous solution), and finally add 2.5 mL of hydrofluoric acid aqueous solution (40% hydrofluoric acid aqueous solution). Immediately cover the beaker with a polytetrafluoroethylene watch glass and gently shake the beaker for 1-2 minutes to ensure that the sample and acid solution are fully mixed (small bubbles will appear in the beaker, and the surface of the sample will gradually become wet). Then, place the beaker on a preheated hot plate at 120°C and maintain the temperature for 2.5 hours for digestion. Next, raise the hot plate temperature to 220°C and maintain the temperature for 5-6 hours until the solution in the beaker evaporates completely. Stop heating and allow the beaker to cool slightly. Then, add 6 mL of nitric acid solution (a mixture of equal volumes of 68% nitric acid and water) around the beaker wall to rinse away any remaining solid residue. Finally, heat at 260°C for 2 hours until the solid is completely dissolved (at this point, the solution will be a characteristic yellow-green color, indicating that Cr has dissolved into Cr). 3+ (The form is completely dissolved). Finally, rinse the watch glass and the inner wall of the beaker three times with deionized water. Transfer the rinsing solution and the solution in the beaker to a 100mL plastic volumetric flask, dilute to volume with deionized water, and shake well to obtain NiCrPSi nickel alloy test solution 1, which is clear and free of solid impurities. When detecting Cr, carefully measure 10 mL of the above NiCrPSi nickel alloy test solution 1 to 100 mL into a plastic volumetric flask, dilute to volume with deionized water, and shake well to obtain NiCrPSi nickel alloy test solution 2.

[0038] Comparative Example 1 A method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection includes the following steps: Take 0.1002 g of the NiCrPSi nickel alloy sample to be tested (its composition is the same as in Example 1), accurately weigh it, and add it to a polytetrafluoroethylene beaker. Then, add 4 mL of hydrochloric acid aqueous solution (the hydrochloric acid aqueous solution is a mixture of equal volumes of 36% hydrochloric acid aqueous solution and water) and 5 mL of concentrated nitric acid (68% nitric acid aqueous solution). Immediately cover the beaker with a polytetrafluoroethylene watch glass and gently shake the beaker for 1-2 minutes to ensure that the sample and acid solution are fully mixed (small bubbles are observed in the beaker and the surface of the sample gradually becomes wet). The beaker was then placed on a preheated hot plate at 130°C and kept warm for 2 hours for digestion. The hot plate temperature was then increased to 240°C and maintained for 5-6 hours until the solution in the beaker evaporated completely. Heating was then stopped, and the beaker was allowed to cool slightly. 5 mL of a nitric acid solution (a mixture of equal volumes of 68% nitric acid and water) was then added in a circular motion along the beaker wall to rinse away any remaining solid residue. Heating at 240°C for 3 hours revealed that the solid could not be completely dissolved. (See photograph below.) Figure 2 As shown.

[0039] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 does not contain hydrofluoric acid aqueous solution.

[0040] Comparative Example 2 A method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection includes the following steps: Take 0.1000 g of the NiCrPSi nickel alloy sample to be tested (its composition is the same as in Example 1), add it to a polytetrafluoroethylene beaker, then add 5 mL of concentrated nitric acid (68% nitric acid aqueous solution), and finally add 2 mL of hydrofluoric acid aqueous solution (40% hydrofluoric acid aqueous solution); immediately cover with a polytetrafluoroethylene watch glass, and gently shake the beaker for 1-2 minutes to ensure that the sample and acid solution are fully mixed (small bubbles are observed in the beaker, and the surface of the sample gradually becomes wet). The beaker was then placed on a preheated hot plate at 130°C and kept warm for 2 hours for digestion. The hot plate temperature was then increased to 240°C and maintained for 5-6 hours until the solution in the beaker evaporated completely. Heating was then stopped, and the beaker was allowed to cool slightly. 5 mL of a nitric acid solution (a mixture of equal volumes of 68% nitric acid and water) was then added in a circular motion along the beaker wall to rinse away any remaining solid residue. Heating at 240°C for 3 hours revealed that the solid could not be completely dissolved. (See photograph below.) Figure 3 As shown.

[0041] The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 does not add hydrochloric acid aqueous solution.

[0042] Comparative Example 3 A method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection includes the following steps: Take 0.1002 g of the NiCrPSi nickel alloy sample to be tested (its composition is the same as in Example 1), accurately weigh it, and add it to a polytetrafluoroethylene beaker. Then add 4 mL of hydrochloric acid aqueous solution (the hydrochloric acid aqueous solution is an equal volume mixture of 37% hydrochloric acid aqueous solution and water), and finally add 2 mL of hydrofluoric acid aqueous solution (35.5% hydrofluoric acid aqueous solution). Immediately cover it with a polytetrafluoroethylene watch glass and gently shake the beaker for 1-2 minutes to ensure that the sample and acid solution are fully mixed (small bubbles are observed in the beaker, and the surface of the sample gradually becomes wet). The beaker was then placed on a preheated hot plate at 130°C and kept warm for 2 hours for digestion. The hot plate temperature was then increased to 240°C and maintained for 5-6 hours until the solution in the beaker evaporated completely. Heating was then stopped, and the beaker was allowed to cool slightly. 5 mL of a nitric acid solution (a mixture of equal volumes of 68% nitric acid and water) was then added in a circular motion along the beaker wall to rinse away any remaining solid residue. Heating at 240°C for 3 hours revealed that the solid could not be completely dissolved. (See photograph below.) Figure 4 As shown.

[0043] The difference between Comparative Example 3 and Example 1 is that Comparative Example 3 does not contain concentrated nitric acid.

[0044] Comparative Example 4 A method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection includes the following steps: Take 0.1001 g of the NiCrPSi nickel alloy sample to be tested (its composition is the same as in Example 1), accurately weigh it, and add it to a polytetrafluoroethylene beaker. Then, add 1.5 mL of hydrochloric acid aqueous solution (a mixture of equal volumes of 37% hydrochloric acid aqueous solution and water), 9 mL of concentrated nitric acid (68% nitric acid aqueous solution), and finally add 0.5 mL of hydrofluoric acid aqueous solution (35.5% hydrofluoric acid aqueous solution). Immediately cover the beaker with a polytetrafluoroethylene watch glass and gently shake the beaker for 1-2 minutes to ensure that the sample and acid solution are fully mixed (small bubbles are observed in the beaker, and the surface of the sample gradually becomes wet). The beaker was then placed on a preheated hot plate at 130°C and kept warm for 2 hours for digestion. The hot plate temperature was then increased to 240°C and maintained for 5-6 hours until the solution in the beaker evaporated completely. Heating was then stopped, and the beaker was allowed to cool slightly. 5 mL of a nitric acid solution (a mixture of equal volumes of 68% nitric acid and water) was then added in a circular motion along the beaker wall to rinse away any remaining solid residue. Heating at 240°C for 3 hours revealed the presence of a small amount of solid, consisting of fine black particles, as shown in the photograph. Figure 5 As shown.

[0045] The difference between Comparative Example 4 and Example 1 is that in Comparative Example 4, the ratio of the amount of NiCrPSi nickel alloy sample to hydrochloric acid aqueous solution, concentrated nitric acid and hydrofluoric acid aqueous solution is 0.1g:1.5mL:9mL:0.5mL.

[0046] Comparative Example 5 A method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection includes the following steps: Take 0.1000 g of the NiCrPSi nickel alloy sample to be tested (its composition is the same as in Example 1), accurately weigh it, and add it to a polytetrafluoroethylene beaker. Then, add 6 mL of hydrochloric acid aqueous solution (a mixture of equal volumes of 37% hydrochloric acid aqueous solution and water), 1 mL of concentrated nitric acid (68% nitric acid aqueous solution), and finally add 4 mL of hydrofluoric acid aqueous solution (35.5% hydrofluoric acid aqueous solution). Immediately cover the beaker with a polytetrafluoroethylene watch glass and gently shake the beaker for 1-2 minutes to ensure that the sample and acid solution are fully mixed (small bubbles are observed in the beaker, and the surface of the sample gradually becomes wet). The beaker was then placed on a preheated hot plate at 130°C and kept warm for 2 hours for digestion. The hot plate temperature was then increased to 240°C and maintained for 5-6 hours until the solution in the beaker evaporated completely. Heating was then stopped, and the beaker was allowed to cool slightly. 5 mL of a nitric acid solution (a mixture of equal volumes of 68% nitric acid and water) was then added in a circular motion along the beaker wall to rinse away any remaining solid residue. After heating at 240°C for 3 hours, a very small amount of black solid was observed to settle at the bottom after standing for a period of time. (See photo below.) Figure 6 As shown.

[0047] The difference between Comparative Example 5 and Example 1 is that in Comparative Example 5, the ratio of the amount of NiCrPSi nickel alloy sample to hydrochloric acid aqueous solution, concentrated nitric acid and hydrofluoric acid aqueous solution is 0.1g:6mL:1mL:4mL.

[0048] Comparative Example 6 A method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection includes the following steps: Take 0.1003 g of the NiCrPSi nickel alloy sample to be tested (its composition is the same as in Example 1), accurately weigh it, and add it to a polytetrafluoroethylene beaker. Then, add 4 mL of hydrochloric acid aqueous solution (a mixture of equal volumes of 37% hydrochloric acid aqueous solution and water), 5 mL of concentrated nitric acid (68% nitric acid aqueous solution), and finally add 2 mL of hydrofluoric acid aqueous solution (35.5% hydrofluoric acid aqueous solution). Immediately cover the beaker with a polytetrafluoroethylene watch glass and gently shake the beaker for 1-2 minutes to ensure that the sample and acid solution are fully mixed (small bubbles are observed in the beaker, and the surface of the sample gradually becomes wet). The beaker was then placed on a preheated hot plate at 130°C and kept warm for 2 hours for digestion. It was then heated at this temperature until the solution in the beaker evaporated completely. Heating was stopped, and after the beaker cooled slightly, 5 mL of a nitric acid solution (a mixture of equal volumes of 68% nitric acid and water) was added in a circular motion along the beaker wall to rinse away any remaining solid residue. Heating at 240°C for 3 hours revealed that some solid powder still remained, as shown in the photograph. Figure 7 As shown.

[0049] The difference between Comparative Example 6 and Example 1 is that in Comparative Example 6, the digestion was carried out at 130°C for 2 hours, and then heated at this temperature until the solution in the beaker was evaporated to dryness; Comparative Example 6 did not have a high-temperature evaporation process.

[0050] Comparative Example 7 A method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection includes the following steps: Take 0.1003 g of the NiCrPSi nickel alloy sample to be tested (its composition is the same as in Example 1), accurately weigh it, and add it to a polytetrafluoroethylene beaker. Then, add 4 mL of hydrochloric acid aqueous solution (a mixture of equal volumes of 37% hydrochloric acid aqueous solution and water), 5 mL of concentrated nitric acid (68% nitric acid aqueous solution), and finally add 2 mL of hydrofluoric acid aqueous solution (35.5% hydrofluoric acid aqueous solution). Immediately cover the beaker with a polytetrafluoroethylene watch glass and gently shake the beaker for 1-2 minutes to ensure that the sample and acid solution are fully mixed (small bubbles are observed in the beaker, and the surface of the sample gradually becomes wet). The beaker was then placed on a hot plate preheated to 240°C for 2 hours of digestion. During this digestion process, the solution boiled and evaporated violently, resulting in insufficient reaction time and a reduction in acid content. Consequently, the sample could not be digested to the maximum extent, as shown in the photograph. Figure 8 As shown.

[0051] The difference between Comparative Example 7 and Example 1 is that in Comparative Example 7, the digestion was carried out at 240°C for 2 hours, and then heated at this temperature until the solution in the beaker evaporated to dryness; Comparative Example 7 did not have a low-temperature digestion step.

[0052] As can be seen from Example 1 and Comparative Examples 1-7, a composite acid system consisting of hydrochloric acid aqueous solution, concentrated nitric acid, and hydrofluoric acid in appropriate amounts is required. This system, combined with stepwise gradient heating treatment, can completely dissolve the NiCrPSi nickel alloy, avoid sample loss, save resources to the greatest extent, reduce acid consumption, and ensure the accuracy and reliability of the analytical results.

[0053] Example 4 ICP-OES method was used to detect NiCrPSi nickel alloy; The ICP-OES conditions were as follows: RF generator power 1100W, nebulizing gas (99.999% high-purity argon) flow rate 0.75L / min, cooling gas (99.999% high-purity argon) flow rate 15L / min, auxiliary gas (99.999% high-purity argon) flow rate 0.8L / min, peristaltic pump injection rate 1.5mL / min, and radial observation method. The analytical lines for silicon, chromium, iron, copper, and aluminum are as follows: silicon 251.612 nm, chromium 267.716 nm, iron 238.204 nm, copper 324.754 nm, and aluminum 237.312 nm. Solution preparation: Blank solution: Take 4 mL of hydrochloric acid aqueous solution (hydrochloric acid aqueous solution is an equal volume mixture of 36% hydrochloric acid aqueous solution and water), 5 mL of concentrated nitric acid (68% nitric acid aqueous solution), 2 mL of hydrofluoric acid aqueous solution (40% hydrofluoric acid aqueous solution), and 5 mL of nitric acid aqueous solution (nitric acid aqueous solution is an equal volume mixture of 68% nitric acid aqueous solution and water) into a 100 mL plastic volumetric flask, dilute to volume with deionized water, and shake well to obtain the blank solution.

[0054] Standard solutions: Take stock solutions of Cr, Si, Fe, Cu, and Al with a concentration of 1000 μg / mL (purchased from the National Nonferrous Metals and Electronic Materials Analysis and Testing Center). Accurately measure an appropriate amount of each stock solution and add 4 mL of hydrochloric acid aqueous solution (a mixture of equal volumes of 36% hydrochloric acid aqueous solution and water), 5 mL of concentrated nitric acid (68% nitric acid aqueous solution), and 2 mL of hydrofluoric acid aqueous solution (40% hydrofluoric acid aqueous solution). Dilute to volume with deionized water to obtain a series of standard solutions with a gradient distribution of concentrations. The concentrations of Cr and Si are 10, 20, 30, 40, and 50 μg / mL, and the concentrations of Fe, Cu, and Al are 0.1, 0.2, 0.3, 0.4, and 0.5 μg / mL.

[0055] The above standard solutions were sampled and linear detection was performed. The results are shown in Table 1.

[0056] Table 1. Linear equations and correlation coefficients of element standard curves

[0057] Note: In the linear equation, y represents the analytical line intensity of each element, and x represents the concentration of each element.

[0058] Take a NiCrPSi nickel alloy sample to be tested (its composition by mass percentage includes: Cr 29.0%, Si 3.7%, P 6%, Fe 0.033%, Cu 0.009%, Al 0.019%, with the balance being Ni) and prepare NiCrPSi nickel alloy test solutions 1 and 2 according to the method in Example 1, and inject the samples for detection.

[0059] The above NiCrPSi nickel alloy test solutions 1 and 2 were tested three times. The content of each element in the nickel alloy was calculated according to the linear equation in Table 1, and the precision was examined. The results are shown in Table 2.

[0060] When the element content is ≤5%, the element content is calculated based on the test results of NiCrPSi nickel alloy test solution 1; when the element content is >5%, the element content is calculated based on the test results of NiCrPSi nickel alloy test solution 2.

[0061] Table 2 Precision test results

[0062] As can be seen from Table 2, the sample dissolution method provided by the present invention can accurately detect the content of elements other than P in NiCrPSi nickel alloy, and can reduce the detection deviation to below 1.5%, with high precision and good reproducibility.

[0063] The above-mentioned NiCrPSi nickel alloy sample (its composition by mass percentage includes: Cr 29.0%, Si 3.7%, P 6%, Fe 0.033%, Cu 0.009%, Al 0.019%, with the balance being Ni) was taken. Cr, Si, Fe, Cu, and Al were added to each element to increase the mass percentage by 1% (i.e., the added amount was 1%). Then, NiCrPSi nickel alloy test solutions 1 and 2 were prepared according to the method in Example 1, and the samples were injected for detection. The content of each element in the nickel alloy was calculated according to the linear equation in Table 1, and the recovery rate was examined. The results are shown in Table 3.

[0064] Table 3 Recovery rate test results

[0065] As can be seen from Table 3, the detection accuracy of Cr, Si, Fe, Cu and Al is relatively high. The NiCrPSi nickel alloy test solution prepared by the sample dissolution method described in this invention can completely dissolve the sample without causing element loss, thus improving the accuracy of the detection results.

[0066] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection, characterized in that, The process includes the following steps: the NiCrPSi nickel alloy sample to be tested is mixed with hydrochloric acid aqueous solution, concentrated nitric acid and hydrofluoric acid aqueous solution, digested at 120-140℃ for 1.5-2.5h, and then heated to 220-260℃ to evaporate the solution to dryness; then nitric acid aqueous solution is added and heated until the solid is completely dissolved, and then diluted with water to obtain the NiCrPSi nickel alloy test solution.

2. The method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection according to claim 1, characterized in that, Hydrochloric acid aqueous solution is a mixture of equal volumes of concentrated hydrochloric acid and water; nitric acid aqueous solution is a mixture of equal volumes of concentrated nitric acid and water. Concentrated nitric acid is a nitric acid aqueous solution with a mass fraction of 65-68%; concentrated hydrochloric acid is a hydrochloric acid aqueous solution with a mass fraction of 36-38%; and hydrofluoric acid aqueous solution is a hydrofluoric acid aqueous solution with a mass fraction of 38-42%.

3. The method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection according to claim 1 or 2, characterized in that, The ratio of the NiCrPSi nickel alloy sample to hydrochloric acid aqueous solution, concentrated nitric acid, and hydrofluoric acid aqueous solution is 0.1g:3-5mL:4-6mL:1.5-2.5mL; The ratio of the NiCrPSi nickel alloy sample to the nitric acid aqueous solution was 0.1g:4-6mL.

4. The method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection according to claim 1 or 2, characterized in that, In the NiCrPSi nickel alloy test solution, the ratio of the NiCrPSi nickel alloy test sample to the final volume is 0.1g:100-1000mL.

5. The method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection according to claim 1 or 2, characterized in that, Add nitric acid aqueous solution and heat at 240-260℃ until the solid is completely dissolved.

6. The method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection according to claim 1 or 2, characterized in that, In NiCrPSi nickel alloy, the Si content is 3.0-5.0% and the P content is 5.0-7.0%.

7. The method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection according to claim 1 or 2, characterized in that, The composition of NiCrPSi nickel alloy, by mass percentage, includes: Cr 28.0-30.0%, Si 3.0-5.0%, P 5.0-7.0%, Fe < 0.05%, Cu < 0.05%, Al < 0.05%, with the balance being Ni.

8. The method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection according to claim 1 or 2, characterized in that, The ICP-OES conditions for detecting NiCrPSi nickel alloy test solutions were as follows: RF generator power of 1000-1200W, atomizing gas flow rate of 0.7-0.8L / min, cooling gas flow rate of 14-16L / min, auxiliary gas flow rate of 0.7-0.9L / min, peristaltic pump injection rate of 1.4-1.6mL / min, and radial observation method.

9. The method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection according to claim 1 or 2, characterized in that, When using the ICP-OES method, the analytical lines for silicon, chromium, iron, copper, and aluminum are as follows: silicon 251.612 nm, chromium 267.716 nm, iron 238.204 nm, copper 324.754 nm, and aluminum 237.312 nm.

10. The method for dissolving NiCrPSi nickel alloy samples for ICP-OES detection according to claim 1 or 2, characterized in that, The content of each component other than P in NiCrPSi nickel alloy was calculated using the external standard method.

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