极化电极电位滴定法直接测定镍基电热合金中镍

Direct Titration of Ni in Nickel Based Heat-Resisting Alloys by Polarised Electrodes Potentiometry

镍基合金中镍可以用丁二酮肟乙醇溶液直接滴定,以恒电流电位滴定法指示终点。所用的极化电极系统为,极电电流为2uA。滴定在PH11的氨性缓冲溶液中进行,温度保持在40～50℃左右。滴定曲线在等当点有—个尖锐的峰。大量的普通金属离子:Mn^(2+)、Fe^(2+)、Al^(3+)、Fe^(3+)、RE^(3+)、Ti^(4+)、Sn^(4+)、V(V)、Mo(Ⅵ)、W(Ⅵ)、Cr(Ⅵ)及适量的Cr^(3+)、Cu^(2+)、Co^(2+)以及阴离子均不干扰,滴定具有较高的选择性。

Ni in nickel based heat-resisting alloys can be titrated by polarised electrodes potentio-metry. Dimethylglyoxime is used ass the titrant, a Pt wire as anodic polarised indicator electrode, and a SiC rod as cathodic polarised reference electrode. The polarising current is 2 uA. Titration is performed in the ammonia buffer solution pH11, and at temperatures 40-50C. A differential type curve with a sharp peak at the equivalence point \s obtained. Large amounts of metal ions such as Mn2+ Fe2+ Fe3+, Al8, RE8+, Ti4+ Sn4+ Mo(VI), W(VI), Cr(VI), V(V) et al., and moderate amounts of Cr8+, Cu2+, Co3+, and anions do not interfere. This method proved to be simple, rapid, accurate and economical.