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試剂:标准钽溶液:称取金屬钽(純度99.9%)250毫克于白金皿中,加氫氟酸10毫升,加硝酸,加热溶解,加1:1硫酸5毫升,蒸发至冒白烟,冷却,于量瓶中用1:1硫酸稀釋至500毫升。取溶液4毫升,加1:1硫酸8毫升,用4%草酸銨溶液稀釋至100毫升,每毫升含钽20微克。硫酸——草酸溶液:1:1硫酸12毫升,以4%草酸銨溶液。稀釋到100毫升。方法:钢铁試样: (a)不含硼钢样:称取試样0.05～0.5克,加1:1硫酸6毫升及少量水,加热溶解,加过氧
Reagents: Standard tantalum solution: Weigh 250 mg of tantalum (purity 99.9%) in platinum dish, add 10 ml of hydrofluoric acid, add nitric acid, dissolve by heating, add 5 ml of 1: 1 sulfuric acid and evaporate to white smoke, Cool and dilute to 500 mL with 1: 1 sulfuric acid in a measuring flask. Take 4 ml of solution, add 8 ml of 1: 1 sulfuric acid and dilute to 100 ml with 4% ammonium oxalate solution, containing 20 micrograms of tantalum per ml. Sulfuric acid - oxalic acid solution: 1: 1 sulfuric acid 12 ml, 4% ammonium oxalate solution. Dilute to 100 ml. Methods: Steel samples: (a) boron-free steel sample: Weigh 0.05 to 0.5 grams of sample, add 1: 1 sulfuric acid 6 ml and a small amount of water, heated to dissolve, add peroxide