Abstract
In the case of determining silicon in iron and steels spectrophotometrically by molybdenum blue method, white cast iron is excluded from this application as it gives abnormally low analytical values.
The authors established a quantitative procedure for the determination of silicon in white cast iron without annealing of the sample. The results obtained agreed with those of the gravimetric analysis.
The procedure established was as follows. One tenth gram of white cast iron sample was dissolved in the mixed acid consisting of 15ml of (1+11) sulfuric acid and 5ml of 15% hydrogen peroxide, and the solution was made alkaline with 16ml of 10% ammonia water. After the solution was boiled for ten minutes and cooled, 15ml of the mixed acid was added in order to adjust the acid concentration. Subsequent procedure was followed by the usual analytical method.
By this procedure, we obtained the values agreeing with those by the coefficient of variation about 0.7%.
