Sample preparation method of silicon nitride for ICP-OES analysis

Abstract

The invention provides a silicon nitride sample preparation method for ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer) analysis. A microwave digestion method comprises the following steps: (1) mixing silicon nitride with a composite acid solution to obtain a mixed material; (2) carrying out microwave digestion treatment on the mixed material, and carrying out constant volume treatment to obtain a sample preparation solution; wherein the composite acid solution comprises concentrated nitric acid, hydrofluoric acid and concentrated sulfuric acid. According to the sample preparation method, silicon nitride can be fully dissolved, and then Si and impurity elements in the ceramic material silicon nitride can be tested at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of analysis and testing, and relates to a sample preparation method of silicon nitride for ICP-OES analysis. Background Art

[0002] Silicon nitride is an important structural ceramic material. It is a superhard material that has lubricity and wear resistance. It is an atomic crystal and has anti-oxidation properties at high temperatures. Silicon nitride is a superhard material that is difficult to dissolve. It has lubricity and wear resistance. The proportion of various elements in silicon nitride has a great influence on its performance.

[0003] CN118329821A discloses a method for identifying and testing the lattice oxygen content of silicon nitride materials. The method comprises: (1) introducing helium and argon into a nitrogen oxygen analyzer as a working carrier gas and a power gas for oxygen and nitrogen testing, respectively; (2) placing silicon nitride material powder in a graphite crucible, and using the nitrogen oxygen analyzer in a step-by-step power heating reaction stage, according to set analysis parameters, using infrared absorption spectroscopy and thermal conductivity method to respectively measure the oxygen and nitrogen contents released from the silicon nitride material powder.

[0004] CN118343689A discloses a high-purity silicon nitride powder and a preparation method thereof, which detects the carbon and oxygen contents in the silicon nitride powder by means of gravimetric method, titration method, atomic absorption spectrometry, X-ray fluorescence spectrometry and the like.

[0005] The above-mentioned method for detecting the element content in silicon nitride requires a large amount of reagents, takes a long time, and has large deviations in the detection results, making it difficult to accurately analyze the content of each element in silicon nitride. Summary of the invention

[0006] The object of the present invention is to provide a sample preparation method for silicon nitride for ICP-OES analysis. The sample preparation method of the present invention can fully dissolve silicon nitride, and thus can simultaneously test Si and impurity elements in the ceramic material silicon nitride.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing silicon nitride for ICP-OES analysis, the method comprising the following steps:

[0009] (1) mixing silicon nitride and a composite acid solution to obtain a mixed material;

[0010] (2) subjecting the mixed material to microwave digestion treatment and then to constant volume to obtain a sample preparation solution;

[0011] Wherein, the composite acid solution comprises concentrated nitric acid, hydrofluoric acid and concentrated sulfuric acid.

[0012] The invention uses a composite acid solution of concentrated nitric acid, hydrofluoric acid and concentrated sulfuric acid to mix with silicon nitride and then perform microwave digestion, so that silicon nitride can be completely dissolved, and Si and impurity elements in the ceramic material silicon nitride can be tested simultaneously. The method is rapid, safe and efficient, uses a small amount of reagents, and is fully dissolved, meeting the detection standard of ICP-OES machine.

[0013] Preferably, the silicon nitride in step (1) is in powder form.

[0014] Preferably, the silicon nitride is washed and dried before the mixing in step (1).

[0015] Preferably, the washing comprises acid washing and ethanol washing.

[0016] Preferably, the pickling detergent comprises dilute hydrochloric acid and / or dilute nitric acid.

[0017] Preferably, the mass concentration of the dilute hydrochloric acid is 10% to 20%, for example, 10%, 12%, 15%, 18% or 20%, etc., not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] Preferably, the mass concentration of the dilute nitric acid is 20% to 30%, for example, 20%, 22%, 25%, 28% or 30%, etc., not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] Preferably, the ethanol washing time is 5 min to 15 min, for example, 5 min, 8 min, 10 min, 12 min or 15 min, etc., not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0020] Preferably, the volume ratio of concentrated nitric acid, hydrofluoric acid and concentrated sulfuric acid in the composite acid solution of step (1) is 1:(0.5-1.5):(0.5-1.5), for example: 1:0.5:1, 1:0.8:1.2, 1:1:1, 1:1.5:0.5 or 1:1.5:1.5, etc., not limited to the listed values, other values ​​not listed within the numerical range are also applicable.

[0021] Preferably, the mass concentration of the concentrated nitric acid is 65% to 68%, for example, 65%, 65.5%, 66%, 67% or 68%, etc., not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] Preferably, the mass concentration of the hydrofluoric acid is 40% to 50%, for example, 40%, 42%, 45%, 48% or 50%, etc., and is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0023] Preferably, the mass concentration of the concentrated sulfuric acid is 90% to 98%, for example, 90%, 92%, 95%, 96% or 98%, etc., not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0024] Preferably, the mass volume ratio of the silicon nitride to the composite acid solution in step (1) is 10 g / L to 15 g / L, for example: 10 g / L, 11 g / L, 12 g / L, 14 g / L or 15 g / L, etc., not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] Preferably, the temperature of the microwave digestion treatment in step (2) is 220°C to 230°C, for example, 220°C, 222°C, 225°C, 228°C or 230°C, etc., not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0026] Preferably, the power of the microwave digestion treatment in step (2) is 300W to 500W, for example, 300W, 350W, 400W, 450W or 500W, etc., not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] Preferably, the time of the microwave digestion treatment in step (2) is 30 min to 90 min, for example, 30 min, 50 min, 60 min, 80 min or 90 min, etc., not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] As a preferred embodiment of the present invention, the sample preparation method comprises the following steps:

[0029] (1) washing silicon nitride with acid and ethanol, and then mixing it with a composite acid solution at a mass volume ratio of 10 g / L to 15 g / L to obtain a mixed material, wherein the composite acid solution comprises concentrated nitric acid, hydrofluoric acid and concentrated sulfuric acid at a volume ratio of 1:(0.5-1.5):(0.5-1.5);

[0030] (2) The mixed material is subjected to microwave digestion at a temperature of 220° C. to 230° C. and a power of 300 W to 500 W for 30 min to 90 min to obtain a clarified solution, and the clarified solution is subjected to constant volume treatment to obtain a sample preparation solution.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The sample preparation method of the present invention can fully dissolve silicon nitride, and thus can simultaneously test Si and impurity elements in the ceramic material silicon nitride.

[0033] (2) The sample preparation method described in the present invention has a stable dissolution process, no solution splashing, and a low component loss rate, which can improve the accuracy of the test results.

[0034] (3) The silicon nitride sample preparation method for ICP-OES analysis of the present invention can obtain a silicon measurement deviation of the sample within 23.56%. By controlling the conditions and feed amount during the sample preparation process, the silicon measurement deviation of the sample can be within 1.2%, and the material deviation of impurities can be within 6.67%, or even 0. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0036] Example 1

[0037] This embodiment provides a method for preparing silicon nitride for ICP-OES analysis, the method comprising the following steps:

[0038] (1) washing silicon nitride with dilute hydrochloric acid and then with ethanol for 10 minutes, drying to obtain pretreated silicon nitride, mixing 3 mL of 68% concentrated nitric acid, 3 mL of 45% hydrofluoric acid and 3 mL of 98% concentrated sulfuric acid to obtain a composite acid solution, taking 0.1 g of the pretreated silicon nitride and mixing it with the composite acid solution to obtain a mixed material;

[0039] (2) The mixed material is subjected to microwave digestion at a temperature of 225° C. and a power of 400 W for 60 min to obtain a clarified solution, and the clarified solution is fixed to volume to obtain a sample preparation solution.

[0040] Example 2

[0041] This embodiment provides a method for preparing silicon nitride for ICP-OES analysis, the method comprising the following steps:

[0042] (1) washing silicon nitride with dilute nitric acid and then with ethanol for 10 minutes, drying to obtain pretreated silicon nitride, mixing 4 mL of 65% concentrated nitric acid, 2 mL of 50% hydrofluoric acid and 4 mL of 90% concentrated sulfuric acid to obtain a composite acid solution, taking 0.1 g of the pretreated silicon nitride and mixing it with the composite acid solution to obtain a mixed material;

[0043] (2) The mixed material is subjected to microwave digestion at a temperature of 220° C. and a power of 300 W for 90 min to obtain a clarified solution, and the clarified solution is subjected to a constant volume treatment to obtain a sample preparation solution.

[0044] Example 3

[0045] This embodiment provides a method for preparing silicon nitride for ICP-OES analysis, the method comprising the following steps:

[0046] (1) washing silicon nitride with dilute nitric acid and then with ethanol for 10 minutes, drying to obtain pretreated silicon nitride, mixing 3 mL of 66% concentrated nitric acid, 4.5 mL of 40% hydrofluoric acid and 2.5 mL of 98% concentrated sulfuric acid to obtain a composite acid solution, taking 0.1 g of the pretreated silicon nitride and mixing it with the composite acid solution to obtain a mixed material;

[0047] (2) The mixed material is subjected to microwave digestion at a temperature of 230° C. and a power of 500 W for 30 min to obtain a clarified solution, and the clarified solution is subjected to a constant volume treatment to obtain a sample preparation solution.

[0048] Example 4

[0049] This embodiment provides a method for preparing silicon nitride for ICP-OES analysis, the method comprising the following steps:

[0050] (1) washing silicon nitride with dilute hydrochloric acid and then with ethanol for 10 minutes, drying to obtain pretreated silicon nitride, mixing 5 mL of 68% concentrated nitric acid, 2 mL of 45% hydrofluoric acid and 2 mL of 98% concentrated sulfuric acid to obtain a composite acid solution, taking 0.1 g of the pretreated silicon nitride and mixing it with the composite acid solution to obtain a mixed material;

[0051] (2) The mixed material is subjected to microwave digestion at a temperature of 225° C. and a power of 400 W for 60 min to obtain a clarified solution, and the clarified solution is fixed to volume to obtain a sample preparation solution.

[0052] Example 5

[0053] This embodiment provides a method for preparing silicon nitride for ICP-OES analysis, the method comprising the following steps:

[0054] (1) washing silicon nitride with dilute hydrochloric acid and then with ethanol for 10 minutes, drying to obtain pretreated silicon nitride, mixing 2 mL of 68% concentrated nitric acid, 3.5 mL of 45% hydrofluoric acid and 3.5 mL of 98% concentrated sulfuric acid to obtain a composite acid solution, taking 0.1 g of the pretreated silicon nitride and mixing it with the composite acid solution to obtain a mixed material;

[0055] (2) The mixed material is subjected to microwave digestion at a temperature of 225° C. and a power of 400 W for 60 min to obtain a clarified solution, and the clarified solution is fixed to volume to obtain a sample preparation solution.

[0056] Example 6

[0057] This embodiment provides a method for preparing silicon nitride for ICP-OES analysis, the method comprising the following steps:

[0058] (1) washing silicon nitride with dilute hydrochloric acid and then with ethanol for 10 minutes, drying to obtain pretreated silicon nitride, mixing 2 mL of 68% concentrated nitric acid, 2 mL of 45% hydrofluoric acid and 2 mL of 98% concentrated sulfuric acid to obtain a composite acid solution, taking 0.1 g of the pretreated silicon nitride and mixing it with the composite acid solution to obtain a mixed material;

[0059] (2) The mixed material is subjected to microwave digestion at a temperature of 225° C. and a power of 400 W for 60 min to obtain a clarified solution, and the clarified solution is fixed to volume to obtain a sample preparation solution.

[0060] Example 7

[0061] This embodiment provides a method for preparing silicon nitride for ICP-OES analysis, the method comprising the following steps:

[0062] (1) washing silicon nitride with dilute hydrochloric acid and then with ethanol for 10 minutes, drying to obtain pretreated silicon nitride, mixing 4 mL of 68% concentrated nitric acid, 4 mL of 45% hydrofluoric acid and 4 mL of 98% concentrated sulfuric acid to obtain a composite acid solution, taking 0.1 g of the pretreated silicon nitride and mixing it with the composite acid solution to obtain a mixed material;

[0063] (2) The mixed material is subjected to microwave digestion at a temperature of 225° C. and a power of 400 W for 60 min to obtain a clarified solution, and the clarified solution is fixed to volume to obtain a sample preparation solution.

[0064] Example 8

[0065] This embodiment provides a method for preparing silicon nitride for ICP-OES analysis, the method comprising the following steps:

[0066] (1) washing silicon nitride with dilute hydrochloric acid and then with ethanol for 10 minutes, drying to obtain pretreated silicon nitride, mixing 3 mL of 68% concentrated nitric acid, 3 mL of 45% hydrofluoric acid and 3 mL of 98% concentrated sulfuric acid to obtain a composite acid solution, taking 0.1 g of the pretreated silicon nitride and mixing it with the composite acid solution to obtain a mixed material;

[0067] (2) The mixed material is subjected to microwave digestion at a temperature of 200° C. and a power of 400 W for 60 min to obtain a clarified solution, and the clarified solution is fixed to volume to obtain a sample preparation solution.

[0068] Comparative Example 1

[0069] This comparative example provides a method for preparing silicon nitride for ICP-OES analysis, the method comprising the following steps:

[0070] (1) washing silicon nitride with dilute hydrochloric acid and then with ethanol for 10 min and drying to obtain pretreated silicon nitride, mixing 4.5 mL of 68% concentrated nitric acid and 4.5 mL of 45% hydrofluoric acid to obtain a composite acid solution, taking 0.1 g of the pretreated silicon nitride and mixing it with the composite acid solution to obtain a mixed material;

[0071] (2) The mixed material was digested by microwave at a temperature of 225° C. and a power of 400 W. The solution boiled and the sample could not be prepared.

[0072] Comparative Example 2

[0073] This comparative example provides a method for preparing silicon nitride for ICP-OES analysis, the method comprising the following steps:

[0074] (1) washing silicon nitride with dilute hydrochloric acid and then with ethanol for 10 min and drying to obtain pretreated silicon nitride, mixing 3 mL of 68% concentrated nitric acid, 3 mL of 45% hydrofluoric acid and 3 mL of 98% concentrated sulfuric acid to obtain a composite acid solution, taking 0.1 g of the pretreated silicon nitride and mixing it with the composite acid solution to obtain a mixed material;

[0075] (2) The mixture is stirred at 225° C. for 60 min, filtered to obtain a clear solution, and the clear solution is fixed to volume to obtain a sample preparation solution.

[0076] Performance Test:

[0077] The sample solutions obtained in the above examples and comparative examples were measured by ICP-OES analysis, wherein the impurities measured included iron and aluminum. The test results are shown in Table 1, wherein the calculation method of the deviation is: Deviation = |actual value - measured value | / actual value × 100%:

[0078] Table 1

[0079]

[0080]

[0081] As can be seen from Table 1, from Examples 1-3, the silicon measurement deviation of the sample obtained by the sample preparation method of silicon nitride for ICP-OES analysis of the present invention can be within 23.56%, and by controlling the conditions and feed amount in the sample preparation process, the silicon measurement deviation of the sample can be within 1.2%, and the material deviation of impurities can be within 6.67%, and can even reach 0.

[0082] By comparing Example 1 with Examples 4-5, it can be seen that in the sample preparation process of the silicon nitride of the present invention for ICP-OES analysis, the volume ratio of concentrated nitric acid, hydrofluoric acid and concentrated sulfuric acid in the composite acid solution will affect the sample preparation effect. The volume ratio of concentrated nitric acid, hydrofluoric acid and concentrated sulfuric acid in the composite acid solution is controlled to be 1:(0.5-1.5):(0.5-1.5), and the sample preparation effect is better. If it exceeds the above range, the dissolution effect will be significantly reduced, and if the proportion of concentrated sulfuric acid is too small, the temperature is insufficient, resulting in incomplete dissolution of the sample.

[0083] By comparing Example 1 with Examples 6-7, it can be seen that in the sample preparation process of ICP-OES analysis using silicon nitride described in the present invention, the mass volume ratio of silicon nitride to the composite acid solution will affect the sample preparation effect. When the mass volume ratio of silicon nitride to the composite acid solution is controlled at 10-15 g / L, the sample preparation effect is better. If the amount of silicon nitride added is too high, the sample is not completely dissolved. If the amount of silicon nitride added is too low, the data deviation is large and the repeatability is poor.

[0084] By comparing Example 1 and Example 8, it can be seen that in the sample preparation process of the silicon nitride of the present invention for ICP-OES analysis, the temperature of microwave digestion will affect the sample preparation effect. When the temperature of microwave digestion is controlled at 220°C to 230°C, the sample preparation effect is better. If the temperature of microwave digestion is too low, the sample will not be completely dissolved. If it is too high, boiling will easily occur and the sample cannot be prepared.

[0085] By comparing Example 1 with Comparative Example 1, it can be seen that the addition of concentrated sulfuric acid to the composite acid solution can increase the temperature of microwave digestion, thereby completely dissolving silicon nitride. If concentrated sulfuric acid is not added, the microwave temperature cannot reach the dissolution state. If the microwave digestion temperature is too low, silicon nitride cannot be completely dissolved, resulting in a significant deviation in the test results.

[0086] From the comparison between Example 1 and Comparative Example 2, it can be seen that the conventional method adopts open heating dissolution, which causes a large amount of silicon to volatilize. The microwave digestion method adopted in the present invention is a sealed digestion, which can retain the silicon in the silicon nitride to the greatest extent.

[0087] The applicant declares that the above 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 shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing silicon nitride for ICP-OES analysis, characterized in that: The sample preparation method comprises the following steps: (1) mixing silicon nitride and a composite acid solution to obtain a mixed material; (2) subjecting the mixed material to microwave digestion treatment and then to constant volume to obtain a sample preparation solution; Wherein, the composite acid solution comprises concentrated nitric acid, hydrofluoric acid and concentrated sulfuric acid.

2. The sample preparation method according to claim 1, characterized in that: The silicon nitride in step (1) is in powder form.

3. The sample preparation method according to claim 1 or 2, characterized in that: The silicon nitride is washed and dried before mixing in step (1); Preferably, the washing comprises acid washing and ethanol washing; Preferably, the pickling detergent comprises dilute hydrochloric acid and / or dilute nitric acid; Preferably, the mass concentration of the dilute hydrochloric acid is 10% to 20%; Preferably, the mass concentration of the dilute nitric acid is 20% to 30%; Preferably, the ethanol washing time is 5 min to 15 min.

4. The sample preparation method according to any one of claims 1 to 3, characterized in that: The volume ratio of concentrated nitric acid, hydrofluoric acid and concentrated sulfuric acid in the composite acid solution of step (1) is 1:(0.5-1.5):(0.5-1.5).

5. The sample preparation method according to any one of claims 1 to 4, characterized in that: The mass concentration of the concentrated nitric acid is 65% to 68%; Preferably, the mass concentration of the hydrofluoric acid is 40% to 50%; Preferably, the mass concentration of the concentrated sulfuric acid is 90% to 98%.

6. The sample preparation method according to any one of claims 1 to 5, characterized in that: The mass volume ratio of the silicon nitride to the composite acid solution in step (1) is 10 g / L to 15 g / L.

7. The sample preparation method according to any one of claims 1 to 6, characterized in that: The temperature of the microwave digestion treatment in step (2) is 220°C to 230°C.

8. The sample preparation method according to any one of claims 1 to 7, characterized in that: The power of the microwave digestion treatment in step (2) is 300W to 500W.

9. The sample preparation method according to any one of claims 1 to 8, characterized in that: The microwave digestion treatment time in step (2) is 30 min to 90 min.

10. The sample preparation method according to any one of claims 1 to 9, characterized in that: The sample preparation method comprises the following steps: (1) washing silicon nitride with acid and ethanol, and then mixing it with a composite acid solution at a mass volume ratio of 10 g / L to 15 g / L to obtain a mixed material, wherein the composite acid solution comprises concentrated nitric acid, hydrofluoric acid and concentrated sulfuric acid at a volume ratio of 1:(0.5-1.5):(0.5-1.5); (2) The mixed material is subjected to microwave digestion at a temperature of 220° C. to 230° C. and a power of 300 W to 500 W for 30 min to 90 min to obtain a clarified solution, and the clarified solution is subjected to constant volume treatment to obtain a sample preparation solution.

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