灼烧除碳——重铬酸钾滴定法测定复合碳铁合金中TFe

Determination of the TFe in Composite Carbon Iron Alloy by Burning Carbon Removal and Potassium Dichromate Titration Method

实验选择760℃灼烧去除复合碳铁合金中的游离碳后,试样以硫磷混酸溶解,加盐酸,用SnCl2还原大部分的Fe3+为Fe2+,再用TiCl3定量还原剩余的Fe3+,用钨酸钠指示还原终点;再以二苯胺磺酸钠为指示剂,用重铬酸钾标准溶液滴定TFe量,测定结果满意,相对标准偏差≤0.21%(n=6)。

After being burned at 760℃selected by test for removing free carbon in carbon iron alloy, the sample was dissolved by the mixture solution of sulfuric acid and phosphoric acid. Adding hydrochloric acid, the most Fe3＋was reduced to Fe2＋by SnCl2, and then the residual Fe3＋was reduced quantitatively by TiCl3, at the same time, sodium tungstate was used to indicate the reducing end. With sodium diphenylamine sulfonate as indicator, the TFe content was titrated by potassium dichromate standard solution. The satisfactory results were obtained and the relative standard deviation≤0.21%（n=6）.