Method for determining chromium content in a tungsten matrix with added chromium or simultaneously added chromium and vanadium

摘要

A method for determining chromium content in a tungsten matrix with singly or simultaneously added chromium and vanadium, characterized in that a test sample is subjected to melting with sodium peroxide and hot water leaching; meanwhile said sodium peroxide is also used as an oxidizing agent to oxidize all the chromium to high valences; the main body of tungsten is coordinated by ammonium hydrogen fluoride to prevent tungstic acid from precipitating; precipitation and turbidity are avoided throughout the analysis, titration can be carried out in a quite clear condition with accurate and reliable results. In this invention, the clearness of the solution when titrating is very important for the accuracy of titrimetric analysis; the solution is always clear throughout the determination, ensuring that the interference with determination of chromium from vanadium is accurately and quantitatively eliminated; the interference from vanadium is eliminated by subtraction method, by means of titrating with ferrous ammonium sulfate standard solution after oxidation with potassium permanganate. In this invention, the determination method allows the determination to be carried out in the quite clear condition, and eliminates the interference from vanadium completely and quantitatively, thus the accuracy and speed of the determination of chromium content in a tungsten matrix with singly or simultaneously added chromium and vanadium are improved.