Method for detecting silicon content in vanadium-aluminum alloy

The invention provides a method for detecting the silicon content in a vanadium-aluminum alloy. The method comprises the steps of: establishing a silicon standard solution concentration-absorbance working curve; decomposing a sample to be detected with hydrochloric acid and nitric acid; adding sodium sulfite into the obtained solution to be detected so as to reduce the solution to blue, conducting cooling, and setting the constant volume of the solution in a standard volumetric flask; getting two solutions of certain amount from the standard volumetric flask for detecting, with one solution used as a color developing solution and the other solution used as a reference solution; adjusting the color developing solution to chromogenic acidity, adding excess ammonium molybdate, and disposing the solution for 5-30min so as to generate silicomolybdenum yellow heteropoly acid, then adding a mixed acid of oxalic acid and sulfuric acid, and adding ammonium ferrous sulfate immediately to reduce the silicomolybdenum yellow heteropoly acid generated during reaction to silicomolybdenum blue heteropoly acid, and carrying out dilution to a scale; adjusting the reference solution to chromogenic acidity, adding a mixed acid of oxalic acid and sulfuric acid, ammonium molybdate and ammonium ferrous sulfate, and carrying out dilution to the scale; measuring absorbance at a position of 680nm at a spectrophotometer, looking up the working curve according to the obtained absorbance value of the color developing solution, and calculating the silicon content in the vanadium-aluminum alloy.