硅钼蓝光度法快速测定硅在铜合金中的应用及理论探讨

The Application of Silicon-molybdenum-blue Photometric Method in Fast Determining Silicon in Copper Alloy and Its Theoretical Inquiry

试样以硝酸、氢氟酸溶解，加硼酸使过量的氢氟酸转变成为氟硼酸络合物，以免侵蚀玻璃器皿而影响硅的测定。氧化氮的存在使钼蓝的色泽不稳定，加尿素分解氧化氮消除之。在微酸性溶液中，正硅酸（或氟硅酸）与钼酸铵形成硅钼络离子，用硫酸调节酸度，在草酸铵存在下，用硫酸亚铁铵将其还原成硅钼蓝，借此进行硅的光度法测定。

After samples are dissolved with nitric acid and hydrofluoric acid, boric acid is added to change superfluous hydrofluoric acid into complex of fluorin-boric acid so as not to erode glassware to affect the determination of silicon. The presence of nitrogen oxide makes the colour and luster of molybdenum-blue unsteady so urea is added to decompose nitrogen oxide to eliminate it. In slight acidic solution, positive silicic acid （or fluorin silicic acid） and ammonium molybdate form complex ion of silicon and molybdenum, vitriol is used to adjust acidity. With the presence of ammonium oxalate, ferrous sulfate is used to reduce it into silicon-molybdenum-blueness, by which photometric method is used to determine silicon.