Method for analyzing content of phosphorus in lanthanum-iron alloy

Abstract

The invention discloses a method for analyzing the content of phosphorus in a lanthanum-iron alloy, which comprises the following steps: dissolving a sample with nitric acid, oxidizing phosphorus in the sample into orthophosphoric acid with potassium permanganate, adding ammonium molybdate in the presence of bismuth salt to generate phosphorus-bismuth-molybdenum ternary heteropoly acid, reducing the phosphorus-bismuth-molybdenum ternary heteropoly acid into phosphorus-bismuth-molybdenum blue with ascorbic acid by taking ethanol as a stabilizer, and carrying out gradient elution on the phosphorus-bismuth-molybdenum blue to obtain the content of phosphorus in the lanthanum-iron alloy. Measuring the absorbance at 700nm by using a spectrophotometer; and converting by using standard samples with similar types and contents. According to the method for analyzing the phosphorus content in the lanthanum-iron alloy, the phosphorus content in the lanthanum-iron alloy is determined through design of the analysis method, and data support is provided for development, application and process optimization of rare earth iron alloy. The method is used for production practice, and the determination process is simple, rapid and accurate.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical analysis, and in particular relates to an analysis method for phosphorus content in lanthanum-iron alloy. Background Art

[0002] Lanthanum-iron alloys have important applications in many fields. They can be used as permanent magnet materials in motors, generators and other equipment, can improve the electrochemical properties of alloys, and can be used as catalysts to improve the rates of certain chemical reactions. In order to increase the strength and hardness of the material, phosphorus elements are considered to be added to the composition design. However, excessive phosphorus content will cause material segregation, prone to cold brittleness, and lead to a decrease in its mechanical properties, mainly involving toughness, ductility, plasticity, impact resistance and other properties. Therefore, it is necessary to ensure that the phosphorus content of the materials produced by the enterprise is within the national standard range. Therefore, it is necessary to study the analysis method of phosphorus content in lanthanum-iron alloys. Summary of the invention

[0003] The purpose of the present invention is to provide an analytical method for the phosphorus content in lanthanum ferroalloys, and to design and determine the phosphorus content in lanthanum ferroalloys by analytical method design, so as to provide data support for the development, application and process optimization of rare earth ferroalloys. This method has been used in production practice, and the determination process is simple, fast and accurate.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The invention discloses a method for analyzing phosphorus content in a lanthanum-iron alloy. The method comprises the following steps: dissolving a sample with nitric acid, oxidizing phosphorus in the sample into orthophosphoric acid with potassium permanganate, adding ammonium molybdate in the presence of a bismuth salt to generate a phosphorus-bismuth-molybdenum ternary heteropoly acid, using ethanol as a stabilizer, reducing the phosphorus-bismuth-molybdenum ternary heteropoly acid into phosphorus-bismuth-molybdenum blue with ascorbic acid, and measuring the absorbance of the phosphorus-bismuth-molybdenum blue at 700 nm with a spectrophotometer.

[0006] Convert with standard samples of the same type and with similar content:

[0007]

[0008] Where: W(P)(%) 标 : Phosphorus mass percentage of standard sample

[0009] A 试 : Sample absorbance value

[0010] A 标 : Absorbance value of standard sample.

[0011] 2. The method for analyzing phosphorus content in lanthanum-iron alloy according to claim 1 is characterized in that it specifically comprises: placing the weighed sample in a 50mL steel volumetric flask, adding 15mL nitric acid-bismuth nitrate solution to heat and dissolve the sample, adding potassium permanganate solution until the sample is completely dissolved until manganese dioxide precipitates, boiling for 2-3min, removing and cooling to room temperature; adding 5mL sodium thiosulfate-anhydrous sodium sulfite solution, 5mL ammonium molybdate-potassium sodium tartrate solution, 10mL ascorbic acid ethanol solution, coloring at room temperature for more than 20min, then diluting with water to the scale, and shaking well; adjusting the spectrophotometer to 700nm, selecting an appropriate absorption dish, and measuring the absorbance with water as a reference;

[0012] calculate:

[0013] Use the same type of standard sample with similar content to convert:

[0014]

[0015] Where: W(P)(%) 标 : Phosphorus mass percentage of standard sample

[0016] A 试 : Sample absorbance value

[0017] A 标 : Absorbance value of standard sample.

[0018] Furthermore, each time the reagent is added, it should be shaken well.

[0019] Furthermore, the nitric acid-bismuth nitrate solution contains 10 g / L bismuth nitrate.

[0020] Furthermore, the concentration of the potassium permanganate solution is 40 g / L).

[0021] Furthermore, the sodium thiosulfate-anhydrous sodium sulfite solution contains: 0.2 g of sodium thiosulfate and 1 g of anhydrous sodium sulfite in 100 mL of water.

[0022] Furthermore, the ammonium molybdate-sodium potassium tartrate solution contains 3.5 g of ammonium molybdate and 6.5 g of sodium potassium tartrate in 100 mL of water.

[0023] Furthermore, the ascorbic acid-ethanol solution is prepared by adding 2 g of ascorbic acid to 100 mL of ethanol.

[0024] Furthermore, a 722N spectrophotometer was used.

[0025] Compared with the prior art, the beneficial technical effects of the present invention are:

[0026] The invention provides an analytical method for determining the phosphorus content in a lanthanum-iron alloy. The ascorbic acid reduction-phosphorus bismuth molybdenum blue spectrophotometry is used to determine the phosphorus content in the lanthanum-iron alloy. The detection result is accurate, and an accurate and efficient analytical method is provided for relevant scientific research institutes to detect and analyze the phosphorus content in the field of rare earth iron alloys, which is helpful to improve the production qualification rate and application reliability of the lanthanum-iron alloy, and promote the sustainable development of the green economy of enterprises. DETAILED DESCRIPTION

[0027] A method for analyzing phosphorus content in lanthanum-iron alloy, comprising:

[0028] 1 Scope

[0029] This method is suitable for the determination of phosphorus content in ferrolanthanum, ferrocerium, ferromolybdenum and other alloys.

[0030] 2 Principle

[0031] The sample is dissolved with nitric acid, and the phosphorus in the sample is oxidized to orthophosphoric acid with potassium permanganate. In the presence of bismuth salt, ammonium molybdate is added to generate phosphobum-bismuth-molybdenum ternary heteropoly acid. With ethanol as a stabilizer, ascorbic acid is used to reduce the phosphobum-bismuth-molybdenum ternary heteropoly acid to phosphobum-bismuth-molybdenum blue, and its absorbance is measured at 700nm with a spectrophotometer.

[0032] 3 Main reagents and instruments

[0033] 3.1 Nitric acid-bismuth nitrate solution: 10 g / L bismuth nitrate in nitric acid (1+5).

[0034] 3.2 Potassium permanganate solution (40g / L).

[0035] 3.3 Sodium thiosulfate-anhydrous sodium sulfite solution: 100 mL of water contains 0.2 g of sodium thiosulfate and 1 g of anhydrous sodium sulfite.

[0036] 3.4 Ammonium molybdate-potassium sodium tartrate solution: 100mL of water contains 3.5g of ammonium molybdate and 6.5g of potassium sodium tartrate.

[0037] 3.5 Ascorbic acid-ethanol solution: Add 2 g of ascorbic acid to 100 mL of ethanol (1+1).

[0038] 3.6722N spectrophotometer.

[0039] 4. Instrument Preparation

[0040] Before analysis, the 722N spectrophotometer was preheated to ensure that the instrument reached a stable state, the analysis wavelength was adjusted to 700 nm, and the zero point was adjusted with water.

[0041] 5 Analysis steps

[0042] 5.1 Sample size

[0043] Weigh 0.1000 g of the sample.

[0044] 5.2 Blank test

[0045] Carry out a blank test along with the sample.

[0046] 5.3 Determination

[0047] Place the weighed sample in a 50mL steel volumetric flask, add 15mL nitric acid-bismuth nitrate solution (3.1) and heat to dissolve the sample. When the sample is completely dissolved, add potassium permanganate solution (3.2) until manganese dioxide precipitates. Boil for 2-3 minutes, remove and cool to room temperature. Add 5mL sodium thiosulfate-anhydrous sodium sulfite solution (3.3), 5mL ammonium molybdate-potassium sodium tartrate solution (3.4), 10mL ascorbic acid ethanol solution (3.5) (shake well each time adding reagents), color at room temperature for more than 20 minutes, then dilute with water to the scale and shake well. Adjust the spectrophotometer to 700nm, select an appropriate absorption dish, and measure the absorbance with water as the reference.

[0048] 6 Calculation

[0049] Convert with standard samples of the same type and with similar content:

[0050]

[0051] Where: W(P)(%) 标 : Phosphorus mass percentage of standard sample

[0052] A 试 : Sample absorbance value

[0053] A 标 : Standard sample absorbance value

[0054] 7 Results and discussion

[0055] 7.1 Precision test

[0056] Due to the lack of lanthanum-iron alloy standard samples, steel standard samples were added with lanthanum trioxide for 10 independent measurements during the experiment. The measurement results are as follows.

[0057] Table 1 Precision experiment

[0058]

[0059] 7.2 Sample determination

[0060] According to 6.3 to 1 # , 2 # The oxygen content in the samples and standard substances was measured and the results are shown in Table 2.

[0061] Table 2 Sample determination

[0062] Sample No. Measured value (%) Standard value YSBC11233-99 0.031 0.031 <![CDATA[1 # ]]> 0.026 / <![CDATA[2 # ]]> 0.058 /

[0063] 7.3 Conclusion

[0064] This method can be used to accurately determine the phosphorus content in lanthanum-iron alloys. It is simple and fast to operate, can meet production testing needs, and has good promotion and application value.

[0065] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for analyzing phosphorus content in lanthanum-iron alloy, characterized in that: The sample is dissolved with nitric acid, and the phosphorus in the sample is oxidized to orthophosphoric acid with potassium permanganate. In the presence of bismuth salt, ammonium molybdate is added to generate phospho-bismuth-molybdenum ternary heteropoly acid. With ethanol as a stabilizer, ascorbic acid is used to reduce the phospho-bismuth-molybdenum ternary heteropoly acid to phospho-bismuth-molybdenum blue, and its absorbance is measured at 700 nm with a spectrophotometer; Convert with standard samples of the same type and with similar content: Where: W(P)(%) 标 : Phosphorus mass percentage of standard sample A 试 : Sample absorbance value A 标 : Absorbance value of standard sample.

2. The method for analyzing phosphorus content in lanthanum-iron alloy according to claim 1, characterized in that: Specifically, the method comprises: placing the weighed sample in a 50mL steel volumetric flask, adding 15mL nitric acid-bismuth nitrate solution to heat and dissolve the sample, adding potassium permanganate solution dropwise until manganese dioxide precipitates after the sample is completely dissolved, boiling for 2-3 minutes, removing and cooling to room temperature; adding 5mL sodium thiosulfate-anhydrous sodium sulfite solution, 5mL ammonium molybdate-potassium sodium tartrate solution, and 10mL ascorbic acid ethanol solution, coloring at room temperature for more than 20 minutes, then diluting with water to the scale, and shaking well; adjusting the spectrophotometer to 700nm, selecting an appropriate absorption dish, and measuring the absorbance with water as a reference; calculate: Convert with standard samples of the same type and with similar content: Where: W(P)(%) 标 : Phosphorus mass percentage of standard sample A 试 : Sample absorbance value A 标 : Absorbance value of standard sample.

3. The method for analyzing phosphorus content in lanthanum-iron alloy according to claim 2, characterized in that: Shake well each time you add reagent.

4. The method for analyzing phosphorus content in lanthanum-iron alloy according to claim 2, characterized in that: The nitric acid-bismuth nitrate solution contains 10 g / L bismuth nitrate.

5. The method for analyzing phosphorus content in lanthanum-iron alloy according to claim 2, characterized in that: The concentration of the potassium permanganate solution is 40 g / L).

6. The method for analyzing phosphorus content in lanthanum-iron alloy according to claim 2, characterized in that: The sodium thiosulfate-anhydrous sodium sulfite solution: 100 mL of water contains 0.2 g of sodium thiosulfate and 1 g of anhydrous sodium sulfite.

7. The method for analyzing phosphorus content in lanthanum-iron alloy according to claim 2, characterized in that: The ammonium molybdate-sodium potassium tartrate solution contains 3.5 g of ammonium molybdate and 6.5 g of sodium potassium tartrate in 100 mL of water.

8. The method for analyzing phosphorus content in lanthanum-iron alloy according to claim 2, characterized in that: The ascorbic acid-ethanol solution: 2 g of ascorbic acid is added to 100 mL of ethanol.

9. The method for analyzing phosphorus content in lanthanum-iron alloy according to claim 2, characterized in that: A 722N spectrophotometer was used.

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