| 摘要 |
PURPOSE:To determine a nitrogen amount, by a method wherein, after a steel foil, which is soft-nitrided, is heated and molten in hydrochloric acid, sodium hydroxide is added to the solution, and an ammonia electrode is immersed in the solution containing ammonia gas. CONSTITUTION:A give amount of steel foil, which is gas-softened, is weighed. The steel foil is placed in a conical beaker, and HCl is added for heating and analysis to replace nitrogen in the steel foil into ammonium ion. After the ammonium ion is cooled, it is trnsferred to a measuring flask, and is diluted withwater to add 20% NaOH solution thereto. The mixture is diluted with water again to the pH at 1.28. In the sample liquid, nitrogen in a nitriding layer, which is replaced into ammonium ion, exists in a state that it is further replaced into ammonia gas. The concentration of the ammonia gas is detected by an ammonia electrode immersed in a sample liquid. The ammonia electrode is constituted such that a glass electrode for measuring pH is covered with high molecular film, and an internal liquid of, for example, NH4Cl, is poured between a glass film for pH response and the high molecular film. |
