Measurement of Hydrogen Content in Molten Metal by electrochemical cell based on oxide proton conductor.

首先，通过测定质子导电固体电解质CaZrO_3（+In_2O_3）的氢溶解度、总电导率和电子电导率，对其电化学性能进行了研究。通过这些测量，证实了CaZrO_3（+In_2O_3）的质子导电畴比SrCeO_3（Yb_2O_3）的质子导电畴延伸到更高的温度区域。然后，以该材料为电解液，构建了基于氢浓缩电池的铝液氢传感器，并对传感器的性能进行了研究。当电池被设计用于测量与熔融金属相平衡的气相氢势时，可以精确测量铝液中的氢势。研究了类似类型的熔铜氢传感器。结果表明，插入式传感器对熔融铜的检测效果良好。但在高温高氧势下，由于空穴电导为正，电动势值偏离了理论值。同时测量氧势发现是必要的，以评估正确的氢势在熔融铜。研制了一种测定金属中氢活度的仪器。这个装置是基于Sieverts的方法，其中氢的分压是用相同的质子导电固体电解质电化学测定的。并对该装置的性能进行了研究。因此，在这个研究项目开始时计划的所有项目都成功完成了。

At first, the electrochemical properties of the proton-conductive solid electrolyte to be used, CaZrO_3(+In_2O_3), were investigated by measuring the hydrogen solubility, the total conductivity, and the electronic conductivity. By these measurements, it was confirmed that the protonic-conductive domain of CaZrO_3(+In_2O_3) extends to the higher temperature region than that of SrCeO_3(Yb_2O_3). Then, the hydrogen sensor for molten aluminum based on the hydrogen concentration cell was constructed by using this material as the electrolyte and the performance of this sensor was investigated. The accurate measurement of the hydrogen potential in molten aluminum is possible when the cell was designed to measure the hydrogen potential of the gas phase equilibrated with the molten metals.The similar type of hydrogen sensor for molten copper was also studied. It was found that the insertion-type sensor operates well for molten copper. But, in these high temperature and high oxygen potential, the EMF values deviate from the theoretical one owing to the appearance of positive hole conductance. The simultaneous measurement of oxygen potential was found to be necessary to evaluate the correct hydrogen potential in molten copper.An apparatus to evaluate the hydrogen activity in metals were also developed. This apparatus is based on Sieverts' method, where the partial pressure of hydrogen is determined electrochemically using the same proton-coductive solid electrolyte. The performance of this apparatus were also studied.Consequently, all the items planned in the start of this research project were accomplished successfully.