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可锻铸铁中加入微量铋,可防止铸件最厚部分产生灰口倾向,提高铸件性能,同时又缩短了退火周期,节约了燃料。为了快速测定铋含量,可在溶样后直接用抗坏血酸掩蔽铁,加碘化钾使与铋形成黄色络合物(BiI_4~-),马钱子碱能与此络合物成盐,可用氯仿萃取,进行比色测定。这样提高了分析速度,时间由原来2小时(用二氧化锰共沉淀法)减少到半小时左右,满足了炉前分析的需要。实验部分一、仪器及试剂:1.72型分光光度计。2.硫酸:1∶9,及1%。3.高锰酸钾溶液:3%。4.抗坏血酸溶液:
The addition of trace amounts of bismuth in malleable iron prevents the tendency of the thickest parts of the castings to produce gray castings and improves the performance of castings while shortening the annealing cycle and saving fuel. In order to quickly determine the content of bismuth, iron can be directly masked with ascorbic acid after the sample is dissolved, potassium iodide is added to make a yellow complex with bismuth (BiI_4 ~ -), and strychnine can form a salt with the complex, which can be extracted with chloroform, Colorimetric assay was performed. This increased the speed of analysis, the time from the original 2 hours (with manganese dioxide coprecipitation method) reduced to about half an hour, to meet the needs of the furnace analysis. Experimental part A, instruments and reagents: 1.72 spectrophotometer. 2. Sulfuric acid: 1: 9, and 1%. 3 potassium permanganate solution: 3%. Ascorbic acid solution: