Method for measuring chromium content in tungsten substrate added with chromium or simultaneously added with chromium and vanadium

Abstract

The invention relates to a method of mensurating the content of chrome in tungsten matrix which is added with the chrome and vanadium separately or synchronously. The method is characterized in that a sample is melted by sodium dioxide and is soaked in hot water; meanwhile, the sodium dioxide is also used as oxidant to oxidize the chrome into high valence chrome; ammonium bifluoride is used for complexing main body tungsten and avoiding tungstenic acid cementing out; the whole analysis process avoids the occurrence of precipitation and opacification; titration can be carried out under completely limpid and transparent state; and titration result is exact and reliable. The limpid and transparent solution during the titration is very important to the accuracy of titration analysis. The solution is always limpid and transparent during the whole mensuration process, thereby ensuring that the interference of the vanadium is eliminated exactly and quantitatively when the chrome is mensurated. After the interference of the vanadium is oxidized by potassium permanganate, ferrous ammonium sulphate standard solution is used for titrating to eliminate by a subtraction method. The mensurating method ensures that the mensuration is carried out under the completely limpid and transparent state, and the method eliminates the interference of the vanadium completely and quantitatively and improves the accuracy and the speed for detecting the content of the chrome in the tungsten matrix which is added with the chrome and the vanadium separately or synchronously.

Description

technical field [0001] The invention relates to a method for determining the chromium content in a tungsten substrate with chromium added or simultaneously added with chromium and vanadium. [0002] The term "optimization of analysis conditions" in the present invention refers to a brand-new redox system, which makes the classic redox titration method successfully applied to the accurate determination of constant chromium in the tungsten system, and the method is simple, accurate and fast. At the same time, after the analysis conditions are optimized, the interference between chromium and vanadium can be accurately and quantitatively eliminated during analysis, and the accurate determination of the content of chromium and vanadium in the tungsten matrix that is simultaneously added with chromium and vanadium can be completed. [0003] The term "matrix" in this specification is also called "medium" or "matrix". [0004] The term "tungsten matrix" in this specification means th...

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Problems solved by technology

[0055] However, there are some problems in this method in practical application: (1) the sample solution produces a large amount of precipitation during the oxidation-reduction process, and this precipitation makes: 1. During titration, it seriously affects the judgment of the end point, and it is very easy to cause excessive titration, resulting in high results. And the reproducibility is not good; 2. The precipitate does not quantitatively adsorb a small amount of measured element ions, resulting in low results and poor reproducibility; 3. Part of the vanadium and the precipitate co-precipitate to completely eliminate the interference of vanadium on chromium 4. The sample solution is in a heated state for a long time during oxidation and reduction, and the sediment is easy to splash and lose the test solution, leading to retesting

In order to avoid sample splashing, the operator must always stand beside the heating furnace and keep shaking the triangular flask, which is very labor-intensive

(2) Whether the excess oxidizing agent and reducing agent have been completely destroyed during redox is completely determined by experience, if there is any residue, it will significantly affect the result

(3) Long analysis time and low efficiency

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