New solid-state electrochemical method of measuring dissolved hydrogen in Al melt

A novel solid state electrochemical sensor having a heterojunction structure consisting of a solid proton conductor and a solid oxygen-ion conductor has been developed to measure hydrogen dissolved in aluminum melt. The sensor measures hydrogen concentration with reference to an oxygen at a reference compartment. To fix the oxygen partial pressure, two different methods were used. Either a mixture of CuO and Cu2O or else oxygen gas in air were employed to maintain a constant oxygen partial pressure at the reference electrode. The sensing mechanism of the heterojunction sensor is discussed and the characteristics of the sensor are reported in a hydrogen gas atmosphere at temperature ranging from 650 to 800 °C. The heterojunction hydrogen sensor was packaged and dipped into aluminum melt to measure hydrogen content during gassing and degassing processes.