Method for measuring content of corrosion inhibitor boron nitride in gunpowder

Abstract

The invention discloses a method for determining the content of a corrosion inhibitor boron nitride in gunpowder, and belongs to the technical field of analysis and detection. In order to accurately detect the content of boron nitride in gunpowder, the invention provides a method for determining the content of a corrosion inhibitor boron nitride in gunpowder, which comprises the following steps: digesting gunpowder with the mass of m, pouring a digesting solution into a G6 filter cup with the mass of m1, washing, carrying out suction filtration, drying the G6 filter cup to constant weight, weighing the total mass m2 of residues and the G6 filter cup, and calculating the content of the corrosion inhibitor boron nitride in the gunpowder. And calculating the content of the corrosion inhibitor boron nitride in the gunpowder. By optimizing the gunpowder pretreatment process and the filter cup, complete digestion of the gunpowder is guaranteed, the content of the corrosion inhibitor boron nitride in the gunpowder can be rapidly and accurately detected, adjustment of gunpowder production process parameters can be guided, and accurate data can be provided for monitoring of product quality.

Description

Technical Field

[0001] The invention belongs to the technical field of analysis and detection, and in particular relates to a method for determining the content of boron nitride, a corrosion inhibitor, in gunpowder. Background Art

[0002] Commonly used corrosion inhibitors include 801, calcium carbonate, etc. With the research of new formula gunpowder, the original corrosion inhibitors can no longer meet the corrosion inhibitor needs of new formula gunpowder. Boron nitride (BN) is an important inorganic non-metallic material with a crystal structure similar to that of carbon materials. Boron nitride is used as a corrosion inhibitor material in gunpowder, which has good electrical insulation, thermal conductivity, and chemical stability. At the same time, boron nitride is antioxidant, corrosion-resistant, has good high-temperature stability, and is slightly soluble in hot acid and insoluble in cold water. Corrosion inhibitors can prevent or slow down material corrosion. The amount of corrosion inhibitor used is very small, but the effect is significant. When used in large-scale gunpowder production, precise addition is conducive to controlling material corrosion indicators and costs. Therefore, boron nitride has a good development prospect in gunpowder, and accurate detection and determination of the boron nitride content in gunpowder is of great significance for guiding the quality of gunpowder.

[0003] CN102650614A discloses a method for determining the content of boron nitride in steel, and the determination steps are as follows: 1) weigh 1.0000g to 2.0000g of a sample and place it in a 150mL quartz beaker, add 20mL of water, 8mL to 12mL of hydrochloric acid, and 8mL to 12mL of nitric acid, heat to dissolve the sample, and after the reaction is calm, remove it, filter it with a glass sand core funnel covered with a filter membrane (or filter it with a glass funnel covered with slow quantitative filter paper), wash the precipitate with hot high-purity water for 8 to 10 times, and wash the precipitate on the filter membrane into ( Or transfer the filter paper and the precipitate into a 150mL quartz beaker, add 2mL~3mL of nitric acid (if there is filter paper, add 5mL~10mL of nitric acid to fully carbonize the filter paper), dissolve at low temperature, add 2mL~4mL of perchloric acid, continue to heat and dissolve until white perchloric acid smoke comes out and it becomes wet salt, remove it, add 100mL (1+1) of nitric acid to dissolve the salt, transfer it into a 50mL volumetric flask, dilute it to the scale with water, shake it well, take it with a reagent blank, and use an inductively coupled plasma mass spectrometer to determine the boron in boron nitride, and convert the boron nitride content in steel.

[0004] CN104155267A discloses a chemical analysis method for boron nitride content in a nickel-based powder material, comprising the following steps:

[0005] (1) Sample selection: Take powder with a particle size of less than 40 mesh as the analysis sample; (2) Preparation of test solution: Use acid solution to separate the boron nitride of the test sample, and use anhydrous sodium carbonate to melt the boron nitride to prepare a sodium borate solution; (3) Preparation of standard solution: Weigh the same amount of anhydrous sodium carbonate as that for the sample preparation, melt it and dissolve it in water, add mixed acid to prepare a reagent blank solution, transfer 10.00 mL of the reagent blank respectively, and add the boron standard solution to prepare five standard solutions of different concentrations; (4) ICP analysis method to measure the boron nitride content: Start the isoelectric inductively coupled plasma emission spectrometer, select the B182.641 analysis line, analyze no less than 5 standard solutions of different concentrations, test the intensity value, establish the intensity-concentration curve, and then test the test solution, calculate the boron content according to the intensity-concentration curve, and thus obtain the boron nitride content.

[0006] The existing technologies all measure the boron nitride content in stable samples such as alloys, but the analysis of the boron nitride content in gunpowder is a constant analysis, which cannot be completely treated with acid or alkali, and the next step of measurement cannot be performed. Therefore, these methods are not suitable for measuring the content of the corrosion inhibitor boron nitride in gunpowder. Therefore, it is necessary to develop a method for measuring the content of the corrosion inhibitor boron nitride in gunpowder. Summary of the invention

[0007] The purpose of the present invention is to develop a method for determining the content of the corrosion inhibitor boron nitride in gunpowder, so as to fill the blank of the detection of the content of boron nitride in gunpowder and better guide the production of gunpowder.

[0008] To achieve the above object, the present invention provides a method for determining the content of boron nitride as a corrosion inhibitor in gunpowder, which comprises the following steps:

[0009] A. Accurately weigh a gunpowder sample with a mass of m, digest it, and obtain a digestion solution;

[0010] B. Accurately weigh the mass of the G6 filter cup (G6 filter plate pore size is 1.2μm to 2.0μm) that has been constant, record it as m 1 ; Pour the digestion solution into the G6 filter cup, wash the digestion container with water, pour the washing solution into the G6 filter cup, filter, wash and filter the G6 filter cup with water until it is neutral, then wash it alternately with ether acetone mixed solution and water, and finally wash and filter with water until the G6 filter cup has no solvent odor;

[0011] C. Dry the washed G6 filter cup at 110℃~120℃ to constant weight, accurately weigh the total mass of the residue and G6 filter cup, record it as m 2 ;

[0012] D. Through the formula Calculate the content of the corrosion inhibitor boron nitride in the gunpowder; where W is the mass percentage of boron nitride in the gunpowder, m 2is the total mass of the residue and G6 filter cup, m 1 is the mass of the G6 filter cup, and m is the mass of the gunpowder sample;

[0013] In step A, the specific steps of digestion are:

[0014] When the gunpowder sample does not contain graphite, the gunpowder sample and concentrated nitric acid are mixed at a mass volume ratio of 1g: 10-15ml, and digested at 150℃-250℃ (during the heating process, the solution first gradually turns black, and then the solution gradually becomes almost clear due to the small amount of boron nitride in the gunpowder). After the digestion is complete, water is added to the system at a mass volume ratio of 1g: 20-30ml of the gunpowder sample and water, heated to boiling, and then cooled to obtain a digestion solution;

[0015] When the gunpowder sample contains graphite, the gunpowder sample and concentrated nitric acid are mixed at a mass volume ratio of 1g:10-15ml, and digested at 150℃-250℃. After complete digestion, cool, add perchloric acid aqueous solution to the system at a mass volume ratio of the gunpowder sample to perchloric acid aqueous solution of 1g:5-7.5ml, heat at 400-600℃ until the graphite is completely decomposed, cool, add water to the system at a mass volume ratio of the gunpowder sample to water of 1g:20-30ml, heat to boiling, cool, check to see if there is any residual graphite, and obtain a digestion solution.

[0016] Among them, in the above-mentioned method for determining the content of corrosion inhibitor boron nitride in gunpowder, the specific operation of nitric acid digestion is: heating to 150°C ~ 250°C, removing the digestion container when the reaction starts, and reheating to 150°C ~ 250°C when the reaction is about to stop, and repeating this process until the sample in the digestion container is completely decomposed, and then heating at 150°C ~ 250°C for 30min ~ 40min. During the digestion process, if the remaining solution in the digestion container is less than 1 / 2 of the initial solution volume, add 2.5~5ml of concentrated nitric acid per gram of gunpowder sample.

[0017] Among them, in the above-mentioned method for determining the content of corrosion inhibitor boron nitride in gunpowder, when checking residual graphite, if there is floating residual graphite in the system, add perchloric acid aqueous solution according to the mass volume ratio of gunpowder sample and perchloric acid aqueous solution of 1g:2.5~3.75ml, and heat at 400~600℃ until the graphite is completely decomposed.

[0018] Among them, in the above method for determining the content of corrosion inhibitor boron nitride in gunpowder, in step A, before digestion, the size of the gunpowder sample is first processed: the gunpowder sample with a combustion layer thickness not exceeding 0.7 mm is not processed; the gunpowder sample with a combustion layer thickness greater than 0.7 mm is cut into small pieces with a diameter not greater than 5 mm, or processed by a crusher, passed through a double-layer sieve of 3 mm and 5 mm, and the 3 mm sieve-surface material is taken.

[0019] Among them, in the above method for determining the content of corrosion inhibitor boron nitride in gunpowder, in step A, the perchloric acid aqueous solution is obtained by mixing perchloric acid with a mass fraction of 70% and water in a volume ratio of 2:1.

[0020] Among them, in the above method for determining the content of corrosion inhibitor boron nitride in gunpowder, in step A, an electric furnace or a hot plate is used for heating during digestion.

[0021] Wherein, in the above method for determining the content of the corrosion inhibitor boron nitride in the gunpowder, in step B, a mixed solution of ether and acetone and water are used for alternate washing 3 to 5 times.

[0022] Among them, in the above method for determining the content of corrosion inhibitor boron nitride in gunpowder, in step C, the specific operation of drying to constant weight is: every 0.5 to 1 hour, take out the G6 filter cup in drying, place it in a dryer to cool to room temperature and then weigh it until the difference between two consecutive weighings does not exceed 0.0005g, which means it is dried to constant weight. In step B, the same method can be used to dry the G6 filter cup to constant weight.

[0023] Since perchloric acid is highly oxidizing and corrosive, it is easy to cause the danger of combustion and explosion when mixed with gunpowder. Therefore, in the present invention, when detecting a gunpowder sample containing graphite, concentrated nitric acid is first used for digestion, and when the concentrated nitric acid cannot decompose the graphite-containing sample, a perchloric acid aqueous solution is added for digestion, so as to ensure the accuracy of the detection result and ensure safety.

[0024] In the present invention, the concentrated nitric acid used is commercially available concentrated nitric acid, and its concentration is generally 68%; the perchloric acid is also commercially available perchloric acid, and its concentration is generally 70%.

[0025] Beneficial effects of the present invention:

[0026] The present invention optimizes the gunpowder pretreatment process to ensure that the gunpowder is completely digested, and then optimizes the filter cup, so that the content of the corrosion inhibitor boron nitride in the gunpowder can be quickly and accurately detected. The method has the characteristics of less reagent types and dosage, time saving, simple and convenient operation, high data precision and accuracy, stability, high safety, etc., can guide the adjustment of gunpowder production process parameters, and provide accurate data for monitoring product quality. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below by way of examples, but the protection scope of the present invention is not limited to the scope of the examples.

[0028] Filter Cup Selection Test

[0029] The first step is to weigh 2g (accurate to 0.0002g) of blank gunpowder sample without boron nitride, cut it into small pieces no larger than 5mm, add boron nitride, add 20mL of concentrated nitric acid, and heat at about 200℃ to completely digest until the solution is almost clear. Add 50ml of distilled water and continue to heat until boiling, then cool. Slowly pour the solution obtained after digestion into constant G4, G5, and G6 filter cups, wash the conical flask with distilled water, pour the washing liquid into the filter cup and filter it, and wash the filter cup with distilled water until it is neutral. Wash it alternately with a mixed solution of ether and acetone and distilled water for three to five times, then wash it with distilled water, filter it until the filter cup has no solvent smell, and set it aside;

[0030] Step 2: Place the filter cup in an oven at 120°C to dry, cool, and weigh until the difference between two consecutive weighings is no more than 0.0005g. Finally, dry and weigh, calculate W according to the formula, and conduct an additive linear recovery test. The results are shown in Tables 1, 2, and 3.

[0031] Table 1 G4 filter cup test recovery

[0032] Serial number Boron nitride addition amount / g Filter plate aperture Recovery rate 1 0.0646 4-7μm(G4) 92.8％ 2 0.0517 4-7μm(G4) 96.3％ 3 0.0310 4-7μm(G4) 96.7％ 4 0.0246 4-7μm(G4) 95.1％

[0033] Table 2 G5 filter cup recovery rate

[0034] Serial number Boron nitride addition amount / g Filter plate aperture Recovery rate 1 0.0826 2-4μm(G5) 96.8％ 2 0.0719 2-4μm(G5) 98.0％ 3 0.0617 2-4μm(G5) 96.7％ 4 0.0501 2-4μm(G5) 100.2％ 5 0.0410 2-4μm(G5) 100.2％ 6 0.0312 2-4μm(G5) 99.3％ 7 0.0202 2-4μm(G5) 98.5％ 8 0.0114 2-4μm(G5) 99.1％

[0035] Table 3G6 filter cup recovery rate

[0036]

[0037]

[0038] As shown in Tables 1 to 3, when using the G6 filter cup, the recovery rate can be stably less than 3%, and the test result is the most accurate; when using the G5 filter cup, the recovery rate is unstable; when using the G4 filter cup, the accuracy is poor. Therefore, the present invention selects the G6 filter cup.

[0039] Example 1

[0040] Step 1: Cut the sample into small pieces no larger than 5mm, accurately weigh 2.0006g of gunpowder sample, add 20mL of concentrated nitric acid, heat at about 200℃ to completely digest until the solution is almost clear, add 50ml of distilled water and continue to heat until boiling, then cool, slowly pour the solution obtained after digestion into a G6 filter cup with a constant weight of 46.7416g, wash the conical flask with distilled water, pour the washing liquid into the filter cup and filter, wash the filter cup with distilled water until it is neutral. Wash alternately with ether acetone mixed solution and distilled water three to five times, then wash with distilled water, filter until the filter cup has no solvent smell, and set aside;

[0041] Step 2: Place the filter cup in a 120°C oven to dry, cool, and weigh until the difference between two consecutive weighings is no more than 0.0005g. The final dry weight is 46.7636g. Calculate according to the formula: W = (m 2 -m 1 ) / m×100%=1.099%.

[0042] Example 2

[0043] Step 1: Cut the sample into small pieces no larger than 5mm, accurately weigh 2.0019g of gunpowder sample, add 20mL of concentrated nitric acid, heat at about 200℃ to completely digest until the solution is almost clear, add 50ml of distilled water and continue to heat until boiling, then cool, slowly pour the solution obtained after digestion into a G6 filter cup with a constant weight of 47.1307g, wash the conical flask with distilled water, pour the washing liquid into the filter cup and filter, wash the filter cup with distilled water until it is neutral. Wash alternately with ether acetone mixed solution and distilled water three to five times, then wash with distilled water, filter until the filter cup has no solvent smell, and set aside;

[0044] Step 2: Dry, cool and weigh the filter cup in an oven at 120°C until the difference between two consecutive weighings is no more than 0.0005g. The final dry weight is 47.1811g. Calculate according to the formula: W = (m 2 -m 1 ) / m×100%=2.517%.

[0045] Example 3

[0046] Step 1: Cut the sample into small pieces no larger than 5mm, accurately weigh 2.0763g of gunpowder sample, add 20mL of concentrated nitric acid, heat at about 200℃ to completely digest until the solution is almost clear, add 50ml of distilled water and continue to heat until boiling, then cool, slowly pour the solution obtained after digestion into a G6 filter cup with a constant weight of 46.2084g, wash the conical flask with distilled water, pour the washing liquid into the filter cup and filter, wash the filter cup with distilled water until it is neutral. Wash alternately with ether acetone mixed solution and distilled water three to five times, then wash with distilled water, filter until the filter cup has no solvent smell, and set aside;

[0047] Step 2: Dry, cool and weigh the filter cup in an oven at 120°C until the difference between two consecutive weighings is no more than 0.0005g. The final dry weight is 46.2284g. Calculate according to the formula: W = (m 2 -m 1 ) / m×100%=0.963%.

[0048] Example 4

[0049] Step 1: Cut the sample into small pieces no larger than 5mm, accurately weigh 2g (accurate to 0.0002g) of gunpowder sample, add 20ml concentrated nitric acid, heat at about 200℃ to completely digest until the solution is almost clear, add 50ml distilled water and continue to heat until boiling, then cool, slowly pour the solution obtained after digestion into a constant G6 filter cup, wash the conical flask with distilled water, pour the washing liquid into the filter cup and filter, wash the filter cup with distilled water until it is neutral. Wash with ether acetone mixed solution and distilled water alternately three to five times, then wash with distilled water, filter until the filter cup has no solvent smell, and set aside;

[0050] Step 2: Place the filter cup in an oven at 120°C to dry, cool, and weigh until the difference between two consecutive weighings is no more than 0.0005g. Finally, dry and weigh, and calculate W according to the formula. Ten samples were processed, and the data are shown in Table 4 below.

[0051] Table 4 Analysis and test results

[0052]

[0053] Recovery test

[0054] The first step is to weigh 2g (accurate to 0.0002g) of blank gunpowder sample without boron nitride, cut it into small pieces no larger than 5mm, add boron nitride, add 20mL of concentrated nitric acid, and heat at about 200℃ to completely digest until the solution is almost clear. Add 50ml of distilled water and continue to heat until boiling, then cool. Slowly pour the solution obtained after digestion into a constant G6 filter cup, wash the conical flask with distilled water, pour the washing liquid into the filter cup and filter it, and wash the filter cup with distilled water until it is neutral. Wash it alternately with a mixed solution of ether and acetone and distilled water for three to five times, then wash it with distilled water, filter it until the filter cup has no solvent smell, and set it aside;

[0055] Step 2: Place the filter cup in an oven at 120°C to dry, cool, and weigh until the difference between two consecutive weighings is no more than 0.0005g. Finally, dry and weigh, calculate W according to the formula, and conduct an additive linear recovery test. The data are shown in Table 5 below.

[0056] Table 5 Addition linear recovery

[0057] Serial number Boron nitride addition content Boron nitride addition amount / g Recycling mass / g Recovery rate 1 0.5％ 0.0102 0.0101 99.1％ 2 1.0％ 0.0203 0.0201 99.0％ 3 1.5％ 0.0302 0.0302 100％ 4 2.0％ 0.0406 0.0405 99.7％ 5 2.5％ 0.0501 0.0502 100.1％ 6 3.0％ 0.0608 0.0609 100.1％

[0058] It can be seen from the above embodiments and recovery rate experiments that the present invention is simple to operate and can accurately detect the content of the corrosion inhibitor boron nitride in the gunpowder, thereby being able to quickly guide the production of gunpowder and monitor the quality of gunpowder.

Claims

1. A method for determining the content of boron nitride as a corrosion inhibitor in gunpowder, characterized in that: The following steps are involved: A. Accurately weigh a gunpowder sample with a mass of m, digest it, and obtain a digestion solution; B. Accurately weigh the constant mass of the G6 filter cup and record it as m1; Pour the digestion solution into the G6 filter cup, wash the digestion container with water, pour the washing solution into the G6 filter cup, filter, wash and filter the G6 filter cup with water until it is neutral, then wash it alternately with ether acetone mixed solution and water, and finally wash and filter with water until the G6 filter cup has no solvent smell; C. Dry the washed G6 filter cup at 110℃~120℃ to constant weight, accurately weigh the total mass of the residue and G6 filter cup, recorded as m2; D. Through the formula Calculate the content of the corrosion inhibitor boron nitride in the gunpowder; where W is the mass percentage of boron nitride in the gunpowder, m2 is the total mass of the residue and the G6 filter cup, m1 is the mass of the G6 filter cup, and m is the mass of the gunpowder sample; In step A, the specific steps of digestion are: When the gunpowder sample does not contain graphite, the gunpowder sample and concentrated nitric acid are mixed at a mass volume ratio of 1g:10-15ml, and digested at 150℃-250℃. After the digestion is complete, water is added to the system at a mass volume ratio of the gunpowder sample and water of 1g:20-30ml, heated to boiling and then cooled to obtain a digestion solution; When the gunpowder sample contains graphite, the gunpowder sample and concentrated nitric acid are mixed at a mass volume ratio of 1g:10-15ml, and digested at 150℃-250℃. After complete digestion, cool, add perchloric acid aqueous solution to the system at a mass volume ratio of the gunpowder sample to perchloric acid aqueous solution of 1g:5-7.5ml, heat at 400-600℃ until the graphite is completely decomposed, cool, add water to the system at a mass volume ratio of the gunpowder sample to water of 1g:20-30ml, heat to boiling, cool, check to see if there is any residual graphite, and obtain a digestion solution.

2. The method for measuring the content of the corrosion inhibitor boron nitride in gunpowder according to claim 1, characterized in that: The specific operation of nitric acid digestion is: heat to 150℃~250℃, remove the digestion container when the reaction starts, reheat to 150℃~250℃ when the reaction is about to stop, and repeat this process until the sample in the digestion container is completely decomposed, and then heat at 150℃~250℃ for 30min~40min. During the digestion process, if the remaining solution in the digestion container is less than 1 / 2 of the initial solution volume, add 2.5~5ml of concentrated nitric acid per gram of gunpowder sample.

3. The method for measuring the content of corrosion inhibitor boron nitride in gunpowder according to claim 1, characterized in that: When checking for residual graphite, if there is floating residual graphite in the system, add more perchloric acid aqueous solution at a mass volume ratio of 1g of gunpowder sample to perchloric acid aqueous solution: 2.5-3.75ml, and heat at 400-600℃ until the graphite is completely decomposed.

4. The method for measuring the content of corrosion inhibitor boron nitride in gunpowder according to claim 1, characterized in that: In step A, before digestion, the size of the gunpowder sample is processed: the gunpowder sample with a combustion layer thickness not exceeding 0.7 mm is not processed; the gunpowder sample with a combustion layer thickness greater than 0.7 mm is cut into small pieces with a diameter not greater than 5 mm, or processed by a crusher, passed through a double-layer sieve of 3 mm and 5 mm, and the 3 mm sieve material is taken.

5. The method for measuring the content of corrosion inhibitor boron nitride in gunpowder according to claim 1, characterized in that: The perchloric acid aqueous solution is obtained by mixing perchloric acid with a mass fraction of 70% and water in a volume ratio of 2:

1.

6. The method for measuring the content of corrosion inhibitor boron nitride in gunpowder according to claim 1, characterized in that: In step A, during digestion, heating is performed using an electric furnace or a hot plate.

7. The method for measuring the content of corrosion inhibitor boron nitride in gunpowder according to claim 1, characterized in that: In step B, a mixed solution of ether and acetone and water are used for alternate washing 3 to 5 times.

8. The method for determining the content of the corrosion inhibitor boron nitride in gunpowder according to any one of claims 1 to 7, characterized in that: In step C, the specific operation of drying to constant weight is: every 0.5 to 1 hour, take out the G6 filter cup being dried, place it in a dryer to cool to room temperature, and then weigh it until the difference between two consecutive weighings does not exceed 0.0005g, which means it is dried to constant weight.

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