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本方法探讨了通过试验选择760℃时灼烧去除复合碳铁合金中游离碳,试样以硫磷混酸溶解后,加盐酸使铁转化为氯化铁,以氯化亚锡还原大部分三价铁,再以钨酸钠为指示剂,用三氯化钛将剩余三价铁全部还原为Fe2+后,过量的TiCl3溶液,可使作为指示剂钨酸钠中的六价钨还原成蓝色的五价钨化合物,故溶液呈蓝色。过量的TiCl3还原剂可在硫酸铜的催化下,借水中溶解氧及空气中的游离氧氧化使钨蓝色泽褪去,从而消除过量TiCl3的影响。在硫磷混酸介质中,以二苯胺磺酸钠为指示剂,用重铬酸钾标准溶液滴定TFe量,取得了令人满意的结果,相对标准偏差小于0.21%。
The method explores the removal of the free carbon in the composite carbon-iron alloy by burning at 760 ° C. after the test, dissolving the sample with parathion-phosphorous acid, adding hydrochloric acid to convert the iron to ferric chloride, and stannous chloride to reduce most of the ferric , And then sodium tungstate as an indicator, with titanium trichloride all the remaining ferric reduced to Fe2 +, the excess TiCl3 solution can be used as an indicator of sodium tungstate hexavalent tungsten reduced to five blue Tungsten compounds, so the solution was blue. Excess TiCl3 reductant can eliminate the influence of excessive TiCl3 under the catalysis of copper sulfate, by dissolving oxygen in water and oxidizing free oxygen in the air to fade the blue color of tungsten. In phosphoric acid and phosphoric acid mixed media, sodium diphenylamine sulfonate was used as the indicator to titrate TFe with potassium dichromate standard solution, and satisfactory results were obtained with the relative standard deviation of less than 0.21%.