Rapid determination method of molybdenum content in iron and alloys

A rapid determination and alloy technology, applied in the preparation of test samples, color/spectral characteristic measurement, etc., can solve the problems of poor repeatability, time-consuming, inaccurate results, etc., to achieve less reagents, easy operation, stable color solution Effect

Active Publication Date: 2013-03-13
GUIZHOU AEROSPACE PRECISION PRODS
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  • Abstract
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AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved by the present invention is to overcome the defects of long time-consuming or poor repeatability and inaccurate results of the existing determination methods of molybdenum content, and to provide a rapid determination method of molybdenum content in iron and alloys

Method used

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Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0011] 1. Reagents

[0012] Nitric acid (65-68%), phosphoric acid (≥85%), sulfuric acid (95-98%), sulfuric acid-phosphoric acid mixed acid (1:1), perchloric acid (70-72%), phosphoric acid-perchloric acid mixture acid (2:1), ascorbic acid solution (100g / L), ammonium thiocyanate solution (100g / L), thiourea solution (30g / L),

[0013] Molybdenum standard solution: Weigh 0.25g of pure molybdenum with a mass fraction above 99.9%, put it in a 250mL beaker, add 2-4mL of nitric acid and heat to dissolve, add 5mL of phosphoric acid solution and 5mL of sulfuric acid, heat until sulfuric acid fumes are emitted, remove and cool slightly, Add 20mL of water, heat to dissolve the salts, cool to room temperature, transfer to a 500mL volumetric flask, dilute to the mark with water, and mix well to obtain a standard solution containing 0.5mg / mL of molybdenum.

[0014] 2. Instrument: UV-Vis spectrophotometer.

[0015] 3. Sample: Process the iron or alloy sample into chips with a thickness not g...

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Abstract

The invention discloses a rapid determination of molybdenum content in iron and alloys. According to the method, an iron or alloy sample is adopted. A phosphoric acid-perchloric acid mixed solution is employed to dissolve and oxidize the sample. In a sulfuric acid-phosphoric acid medium, an ascorbic acid is used as a reducing agent to prepare a sample solution, a working curve technique is employed to calculate the molybdenum content, so that molybdenum (V) cannot be reduced to lower valence molybdenum, and the result can have good repeatability. Due to the oxidation effect of a lot of perchloric acid, the unstable color development and large determination result error phenomena arising in dissolution of a tungsten and vanadium-containing sample by sulfuric acid-phosphoric acid or reduction of the sample by stannous chloride. In the sulfuric acid-phosphoric acid medium, the color development solution is stable, and reduction needs no adding of iron as the conditioning agent, thus eliminating the influence brought by iron in the solution. During sample dissolution, there is no need to add nitric acid at the time of smoking to destroy a carbide. The analysis time is only 1 / 5-1 / 4 of that of the alpha-Benzoin oxime gravimetric method. Fewer instruments and reagents are used, thus reducing the determination cost. Compared with conventional spectrophotometry, the method broadens the mass fraction measurement range.

Description

technical field [0001] The invention relates to a method for determining the content of molybdenum, in particular to a method for rapidly determining the content of molybdenum in iron and alloys. Background technique [0002] In the chemical analysis industry, there are two methods for determining the high content of molybdenum in steel and alloys. One is the α-benzoin oxime gravimetric method. analyze. Another kind is to adopt sulfuric acid-phosphoric acid to dissolve sample, stannous chloride is made reducing agent, adds iron base sample simultaneously, but this method may reduce molybdenum (VI) to molybdenum (V) with strong reducing agent stannous chloride simultaneously Low-priced molybdenum is generated, which makes the repeatability of the results poor, and the addition of iron base samples will also affect the test results. Contents of the invention [0003] The technical problem to be solved by the present invention is to overcome the defects of long time-consumi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/31G01N1/28G01N1/44G01N1/38
Inventor 李正权
Owner GUIZHOU AEROSPACE PRECISION PRODS
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