Microwave digestion method and application of Ni-based alloy

Abstract

The invention provides a microwave digestion method and application of Ni-based alloy. The microwave digestion method comprises the following steps: (1) mixing Ni-based alloy, concentrated hydrochloric acid and concentrated nitric acid to obtain a mixture; wherein the Ni base alloy comprises a NiPt alloy or a NiCr alloy; (2) sequentially carrying out first-stage microwave digestion, second-stage microwave digestion and third-stage microwave digestion on the mixture to obtain a digested solution; wherein the temperature of the first-stage microwave digestion is more than the temperature of the second-stage microwave digestion and is less than the temperature of the third-stage microwave digestion; the heat preservation time of the first-stage microwave digestion is more than the heat preservation time of the second-stage microwave digestion and less than the heat preservation time of the third-stage microwave digestion. The Ni-based alloy can be completely dissolved by adopting a mixture of concentrated hydrochloric acid and concentrated nitric acid, and meanwhile, the dissolution rate can be obviously increased through a specific microwave digestion mode, so that rapid dissolution is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of testing and relates to a microwave digestion method and application of a Ni-based alloy. Background Art

[0002] At present, one method for detecting elements in NiPt alloy or NiCr alloy is X-ray fluorescence spectroscopy (XRF) analysis, but this method has low accuracy and large deviation. In order to improve accuracy and reduce deviation, inductively coupled plasma optical emission spectrometer (ICP-OES) can be used for detection. ICP-OES can be used to detect most metal elements and some non-metal elements, with less interference, stable signal and simple operation; when testing the element content of the alloy, the alloy can be digested into acid solution by acid dissolution and then tested on the machine.

[0003] However, the existing acid dissolution methods have poor dissolution effects on NiPt alloys or NiCr alloys, the reaction is extremely slow, and a clear solution cannot be obtained quickly.

[0004] Therefore, it is necessary to find a method to quickly dissolve NiPt alloy or NiCr alloy to obtain a sample for ICP-OES testing. Summary of the invention

[0005] In view of the shortcomings of the prior art, the object of the present invention is to provide a microwave digestion method and application of Ni-based alloys. The present invention uses a mixture of concentrated hydrochloric acid and concentrated nitric acid to completely dissolve the Ni-based alloy, and at the same time, the dissolution rate of the Ni-based alloy can be increased by microwave digestion. The temperature of the microwave digestion is set to increase step by step, and the holding time of the microwave digestion is increased step by step, so that the sample can be dissolved more thoroughly and the dissolution rate can be further increased. Therefore, the method of the present invention can quickly dissolve NiPt alloy or NiCr alloy, and safely and efficiently obtain samples for ICP-OES testing.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a microwave digestion method for a Ni-based alloy, the microwave digestion method comprising:

[0008] (1) A Ni-based alloy, concentrated hydrochloric acid and concentrated nitric acid are mixed to obtain a mixture; wherein the Ni-based alloy comprises a NiPt alloy or a NiCr alloy.

[0009] (2) subjecting the mixture to primary microwave digestion, secondary microwave digestion and tertiary microwave digestion in sequence to obtain a digestion solution; wherein the temperature of the primary microwave digestion is less than the temperature of the secondary microwave digestion and less than the temperature of the tertiary microwave digestion; and the insulation time of the primary microwave digestion is less than the insulation time of the secondary microwave digestion and less than the insulation time of the tertiary microwave digestion.

[0010] The invention adopts a mixture of concentrated hydrochloric acid and concentrated nitric acid to completely dissolve a Ni-based alloy (such as a NiPt alloy or a NiCr alloy), and simultaneously improves the dissolution rate of the Ni-based alloy by microwave digestion, and sets the temperature of microwave digestion to be gradually increased, and the holding time of microwave digestion to be gradually increased, and has the advantages that: firstly, by gradually increasing the temperature, thermal stress generated by a sudden temperature rise in the initial stage of the Ni-based alloy sample can be avoided, and the sample can be protected from damage; secondly, the gradient temperature rise helps to gradually release the gas and volatile components in the sample, and prevents boiling and splashing caused by sudden temperature rise; finally, by controlling the temperature at different stages, the reaction conditions can be optimized, and the sufficiency and repeatability of the reaction can be ensured.

[0011] In summary, the method of the present invention can quickly dissolve NiPt alloy or NiCr alloy, and the dissolution process is stable, no solution splashing occurs, and the component loss rate is low, so that samples for ICP-OES testing can be obtained safely and efficiently, and the accuracy of the test results can be improved.

[0012] ICP-OES can be used to detect Ni and Pt in NiPt alloys, or Ni and Cr in NiCr alloys.

[0013] Preferably, the volume ratio of concentrated hydrochloric acid to concentrated nitric acid is (2-10):1, for example, it can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 3:1.

[0014] In the present invention, when the volume ratio of concentrated hydrochloric acid to concentrated nitric acid is 3:1, the mixture of the two is called aqua regia. Aqua regia has the best solubility for Ni-based alloys (such as NiPt alloys or NiCr alloys) and can increase the dissolution rate.

[0015] Preferably, the mass concentration of the concentrated hydrochloric acid is 36-38%, for example, 36%, 37% or 38%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0016] Preferably, the mass concentration of the concentrated nitric acid is 65-68%, for example, 65%, 66%, 67% or 68%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] Preferably, the ratio of the mass of the Ni-based alloy to the total volume of the concentrated hydrochloric acid and concentrated nitric acid is 1g:(80-120)mL, for example, it can be 1g:80mL, 1g:85mL, 1g:90mL, 1g:95mL, 1g:100mL, 1g:105mL, 1g:110mL, 1g:115mL or 1g:120mL, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0018] The reagent used in the invention is small, and when the ratio of the mass of the Ni-based alloy to the total volume of concentrated hydrochloric acid and concentrated nitric acid meets 1g:(80-120)mL, the requirement of completely dissolving the Ni-based alloy can be met.

[0019] Preferably, the power of the primary microwave digestion is 350-450 W, for example, 350 W, 360 W, 370 W, 380 W, 390 W, 400 W, 410 W, 420 W, 430 W, 440 W or 450 W, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] Preferably, the heating rate of the primary microwave digestion is 10-30°C / min, for example, 10°C / min, 15°C / min, 20°C / min, 25°C / min or 30°C / min, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] Preferably, the temperature of the primary microwave digestion is 130-170°C, for example, it can be 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C or 170°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0022] Preferably, the holding time of the primary microwave digestion is 8-12 min, for example, 8 min, 9 min, 10 min, 11 min or 12 min, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0023] In the present invention, when the temperature and holding time of the primary microwave digestion meet the above ranges, it is beneficial to avoid thermal stress caused by a sudden temperature rise in the sample in the initial stage and protect the sample from damage.

[0024] Preferably, the power of the secondary microwave digestion is 350-450 W, for example, 350 W, 360 W, 370 W, 380 W, 390 W, 400 W, 410 W, 420 W, 430 W, 440 W or 450 W, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] Preferably, the heating rate of the secondary microwave digestion is 10-30°C / min, for example, it can be 10°C / min, 15°C / min, 20°C / min, 22°C / min, 24°C / min, 26°C / min, 28°C / min or 30°C / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the temperature of the secondary microwave digestion is 160-200°C, for example, it can be 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C or 200°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] Preferably, the holding time of the secondary microwave digestion is 13-17 min, for example, 13 min, 14 min, 15 min, 16 min or 17 min, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] In the present invention, when the temperature and holding time of the secondary microwave digestion meet the above ranges, it is beneficial to gradually release the gas and volatile components in the sample and prevent boiling and splashing caused by sudden temperature increase.

[0029] Preferably, the power of the three-stage microwave digestion is 350-450 W, for example, 350 W, 360 W, 370 W, 380 W, 390 W, 400 W, 410 W, 420 W, 430 W, 440 W or 450 W, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] Preferably, the heating rate of the three-stage microwave digestion is 10-30°C / min, for example, it can be 10°C / min, 15°C / min, 20°C / min, 22°C / min, 24°C / min, 26°C / min, 28°C / min or 30°C / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] Preferably, the temperature of the three-stage microwave digestion is 180-220°C, for example, it can be 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C or 220°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] Preferably, the insulation time of the three-stage microwave digestion is 35-45 min, for example, it can be 35 min, 36 min, 37 min, 38 min, 39 min, 40 min, 41 min, 42 min, 43 min, 44 min or 45 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] In the present invention, when the temperature and holding time of the three-stage microwave digestion meet the above ranges, it is beneficial to allow the sample to have sufficient time and temperature to undergo rapid reaction digestion to obtain a clear solution.

[0034] In summary, when the temperature and holding time of the first-stage microwave digestion, the second-stage microwave digestion and the third-stage microwave digestion all meet the specified range, it is beneficial to accelerate the dissolution of Ni-based alloys (such as NiPt alloys or NiCr alloys), and the dissolution process is stable, no solution splashing occurs, and the component loss rate is low. It can achieve high efficiency and speed while improving the accuracy of the detection results.

[0035] Preferably, the powers of the first-stage microwave digestion, the second-stage microwave digestion and the third-stage microwave digestion are equal.

[0036] Preferably, in step (2), after the three-stage microwave digestion, cooling and volume fixing steps are performed in sequence.

[0037] Specifically, the microwave digestion method comprises the following steps:

[0038] (I) Mixing a Ni-based alloy, concentrated hydrochloric acid and concentrated nitric acid to obtain a mixture; wherein the volume ratio of the concentrated hydrochloric acid to the concentrated nitric acid is 3:1; the mass concentration of the concentrated hydrochloric acid is 36-38%; the mass concentration of the concentrated nitric acid is 65-68%; wherein the Ni-based alloy is a NiPt alloy or a NiCr alloy, and the ratio of the mass of the Ni-based alloy to the total volume of the concentrated hydrochloric acid and the concentrated nitric acid is 1 g:(80-120) mL.

[0039] (II) placing the mixture into a microwave digestion apparatus, and performing primary microwave digestion, secondary microwave digestion and tertiary microwave digestion in sequence at a power of 350-450 W, and then cooling and fixing the volume to obtain a digestion solution; wherein the heating rate of the primary microwave digestion is 10-30° C. / min, the temperature is 130-170° C., and the insulation time is 8-12 min; the heating rate of the secondary microwave digestion is 10-30° C. / min, the temperature is 160-200° C., and the insulation time is 13-17 min; the heating rate of the tertiary microwave digestion is 10-30° C. / min, the temperature is 180-220° C., and the insulation time is 35-45 min; the temperature of the primary microwave digestion is less than the temperature of the secondary microwave digestion and less than the temperature of the tertiary microwave digestion.

[0040] In a second aspect, the present invention provides an application of the microwave digestion method as described in the first aspect, wherein the microwave digestion method is applied in the field of element detection.

[0041] The equipment for element detection includes ICP-OES.

[0042] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The invention adopts a mixture of concentrated hydrochloric acid and concentrated nitric acid to completely dissolve a Ni-based alloy (such as a NiPt alloy or a NiCr alloy), and simultaneously improves the dissolution rate of the Ni-based alloy by microwave digestion, and sets the temperature of microwave digestion to be gradually increased, and the holding time of microwave digestion to be gradually increased, and has the advantages that: firstly, by gradually increasing the temperature, thermal stress generated by a sudden temperature rise in the initial stage of the Ni-based alloy sample can be avoided, and the sample can be protected from damage; secondly, the gradient temperature rise helps to gradually release the gas and volatile components in the sample, and prevents boiling and splashing caused by sudden temperature rise; finally, by controlling the temperature at different stages, the reaction conditions can be optimized, and the sufficiency and repeatability of the reaction can be ensured.

[0045] In summary, the method of the present invention can quickly dissolve NiPt alloy or NiCr alloy, and the dissolution process is stable, no solution splashing occurs, and the component loss rate is low, so that samples for ICP-OES testing can be obtained safely and efficiently, and the accuracy of the test results can be improved. DETAILED DESCRIPTION

[0046] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0047] Example 1

[0048] This embodiment provides a microwave digestion method for NiPt alloy, comprising the following steps:

[0049] Weigh 0.1 g of NiPt alloy into a polytetrafluoroethylene tube, then take 7.5 mL of concentrated hydrochloric acid with a mass concentration of 37% and 2.5 mL of concentrated nitric acid with a mass concentration of 66% into the polytetrafluoroethylene tube, then place the polytetrafluoroethylene tube in a microwave digestion instrument, and perform primary microwave digestion, secondary microwave digestion and tertiary microwave digestion in sequence at a power of 400 W. The specific procedure is as follows: first, heat to 150° C. at a rate of 15° C. / min and keep warm for 10 min, then heat to 180° C. at a rate of 15° C. / min and keep warm for 15 min, and finally heat to 200° C. at a rate of 15° C. / min and keep warm for 40 min; after the procedure is completed, cool to constant volume to obtain a digestion solution.

[0050] Example 2

[0051] This embodiment provides a microwave digestion method for NiPt alloy, comprising the following steps:

[0052] Weigh 0.1 g of NiPt alloy into a polytetrafluoroethylene tube, then take 6 mL of concentrated hydrochloric acid with a mass concentration of 37% and 2 mL of concentrated nitric acid with a mass concentration of 66% into the polytetrafluoroethylene tube, then place the polytetrafluoroethylene tube in a microwave digestion instrument, and perform primary microwave digestion, secondary microwave digestion and tertiary microwave digestion in sequence at a power of 420 W. The specific procedure is as follows: first, heat to 160° C. at a rate of 15° C. / min and keep warm for 9 minutes, then heat to 190° C. at a rate of 15° C. / min and keep warm for 14 minutes, and finally heat to 210° C. at a rate of 15° C. / min and keep warm for 38 minutes; after the program is completed, cool to constant volume to obtain a digestion solution.

[0053] Example 3

[0054] This embodiment provides a microwave digestion method for NiPt alloy, comprising the following steps:

[0055] Weigh 0.1 g of NiPt alloy into a polytetrafluoroethylene tube, then take 9 mL of concentrated hydrochloric acid with a mass concentration of 37% and 3 mL of concentrated nitric acid with a mass concentration of 66% into the polytetrafluoroethylene tube, then place the polytetrafluoroethylene tube in a microwave digestion instrument, and perform primary microwave digestion, secondary microwave digestion and tertiary microwave digestion in sequence at a power of 380 W. The specific procedure is as follows: first, heat to 140°C at a rate of 15°C / min and keep warm for 11 minutes, then heat to 170°C at a rate of 15°C / min and keep warm for 16 minutes, and finally heat to 190°C at a rate of 15°C / min and keep warm for 42 minutes; after the program is completed, cool to constant volume to obtain a digestion solution.

[0056] Example 4

[0057] The difference between this embodiment and embodiment 1 is that the volume of concentrated hydrochloric acid is 4.5 mL, and the volume of concentrated nitric acid is 1.5 mL.

[0058] The remaining parameters remain the same as those in Example 1.

[0059] Example 5

[0060] The difference between this embodiment and embodiment 1 is that the temperature of the third-stage microwave digestion is 190° C. and the insulation time is 45 min.

[0061] The remaining parameters remain the same as those in Example 1.

[0062] Example 6

[0063] The difference between this embodiment and embodiment 1 is that the time of the third-stage microwave digestion is 30 minutes.

[0064] The remaining parameters remain the same as those in Example 1.

[0065] Example 7

[0066] The difference between this embodiment and embodiment 1 is that the NiPt alloy is replaced by the NiCr alloy.

[0067] The remaining parameters remain the same as those in Example 1.

[0068] Comparative Example 1

[0069] This comparative example provides a method for dissolving a NiPt alloy, comprising the following steps:

[0070] Weigh 0.1 g of NiPt alloy into a polytetrafluoroethylene tube, then take 7.5 mL of concentrated hydrochloric acid with a mass concentration of 37% and 2.5 mL of concentrated nitric acid with a mass concentration of 66% into the polytetrafluoroethylene tube, then place the polytetrafluoroethylene tube in a normal atmospheric environment for natural digestion, and then fix the volume after digestion to obtain a digestion solution.

[0071] test

[0072] (1) The mass percentage contents of nickel and platinum in the digestion solutions provided in Examples 1-6 and Comparative Example 1 were analyzed and determined by ICP-OES. The obtained measured values ​​are shown in Table 1.

[0073] In Table 1, the actual values ​​are the actual mass percentages of nickel and platinum in the NiPt alloy. The calculation method of the deviation is: deviation = |actual value - measured value| / actual value × 100%.

[0074] (2) The mass percentage contents of nickel and chromium in the digestion solution provided in Example 7 were analyzed and determined by ICP-OES. The obtained measured values ​​are shown in Table 2.

[0075] In Table 2, the actual values ​​are the actual mass percentages of nickel and chromium in the NiCr alloy. The calculation method of the deviation is: deviation = |actual value - measured value| / actual value × 100%.

[0076] Table 1

[0077]

[0078] Table 2

[0079]

[0080] analyze:

[0081] (1) Comprehensive analysis of the data in Table 1 and Table 2 shows that the dissolution process of the method provided by the present invention is stable, no solution splashing occurs, the component loss rate is low, and the requirements for equipment can be reduced.

[0082] (2) Comprehensive analysis of the data of Example 1 and Examples 4-6 shows that there are certain requirements for the amount of acid, power, temperature and reaction time when using microwave digestion to digest samples.

[0083] (3) Comprehensive analysis of Example 1 and Comparative Example 1 shows that the digestion time required for the natural digestion method in Comparative Example 1 is longer, and the deviation of Comparative Example 1 is larger than that of Example 1, that is, the natural digestion method is prone to solution splashing and the component loss rate is high.

[0084] In summary, the sample preparation method provided by the present invention has a stable dissolution process, no solution splashing, a low component loss rate, can greatly shorten the sample dissolution time, achieve high efficiency and speed, and can improve the accuracy of the test results.

[0085] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A microwave digestion method for Ni-based alloys, characterized in that: The microwave digestion method comprises: (1) mixing a Ni-based alloy, concentrated hydrochloric acid and concentrated nitric acid to obtain a mixture; wherein the Ni-based alloy comprises a NiPt alloy or a NiCr alloy; (2) subjecting the mixture to primary microwave digestion, secondary microwave digestion and tertiary microwave digestion in sequence to obtain a digestion solution; wherein the temperature of the primary microwave digestion is less than the temperature of the secondary microwave digestion and less than the temperature of the tertiary microwave digestion; and the insulation time of the primary microwave digestion is less than the insulation time of the secondary microwave digestion and less than the insulation time of the tertiary microwave digestion.

2. The microwave digestion method according to claim 1, characterized in that: The volume ratio of the concentrated hydrochloric acid to the concentrated nitric acid is (2-10):1, preferably 3:

1.

3. The microwave digestion method according to claim 1 or 2, characterized in that: The mass concentration of the concentrated hydrochloric acid is 36-38%; Preferably, the mass concentration of the concentrated nitric acid is 65-68%.

4. The microwave digestion method according to any one of claims 1 to 3, characterized in that: The ratio of the mass of the Ni-based alloy to the total volume of the concentrated hydrochloric acid and concentrated nitric acid is 1 g: (80-120) mL.

5. The microwave digestion method according to any one of claims 1 to 4, characterized in that: The power of the first-level microwave digestion is 350-450W; Preferably, the heating rate of the primary microwave digestion is 10-30°C / min; Preferably, the temperature of the primary microwave digestion is 130-170°C; Preferably, the insulation time of the primary microwave digestion is 8-12 min.

6. The microwave digestion method according to any one of claims 1 to 5, characterized in that: The power of the secondary microwave digestion is 350-450W; Preferably, the heating rate of the secondary microwave digestion is 10-30°C / min; Preferably, the temperature of the secondary microwave digestion is 160-200°C; Preferably, the holding time of the secondary microwave digestion is 13-17 min.

7. The microwave digestion method according to any one of claims 1 to 6, characterized in that: The power of the three-stage microwave digestion is 350-450W; Preferably, the heating rate of the three-stage microwave digestion is 10-30°C / min; Preferably, the temperature of the three-stage microwave digestion is 180-220°C; Preferably, the insulation time of the three-stage microwave digestion is 35-45 min.

8. The microwave digestion method according to any one of claims 1 to 7, characterized in that: The power of the first-stage microwave digestion, the second-stage microwave digestion and the third-stage microwave digestion are equal.

9. The microwave digestion method according to any one of claims 1 to 8, characterized in that: In step (2), after the three-stage microwave digestion, cooling and volume fixing steps are performed in sequence.

10. An application of the microwave digestion method according to any one of claims 1 to 9, characterized in that: The microwave digestion method is applied in the field of element detection.

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