Research For Solid Electrolytic Type Of Hydrogen Concentration And Its Performance

Based on the mechanism of Proton Solid Electrolyte Fuel Cell, a solid electrolyte type of hydrogen concentration sensor working in the temperature range of 300-600℃is developed, which could be used for the instant accurate measurement and real-time control of hydrogen concentration, in a specific environment such as gas nitriding and so on.Combining the mechanism of Proton Solid Electrolyte Fuel Cell, the overall structure of the sensor is designed. And the sensor's fabrication process has been studied, which mainly include the preparation process of solid electrolyte, sealing materials and their process selection, internal and external electrode design and fabrication process.When gas nitriding, as the non-decomposed ammonia in furnace gas has a corrosive effect on the platinum electrode, which would affect the sensor's usage performance and life seriously, electrode protection layer must be sprayed on platinum electrode surface. Testing on the properties involving permeability, adhesive strength, thermal shock resistance and corrosion resistance have been done on electrode protection layer of different formula and different sintering process. The results show that the electrode protection layer, with the formula 80%a—Al2O3,2% diatomite,18% high clay, sintering process 850℃and thermal insulation 20min, has good permeability, high adhesive strength, excellent corrosion resistance.A series of output characteristics testing on hydrogen concentration sensor has been made, the results show that, the developed sensor has the properties of good sensitivity, short response time, good selectivity and high stability. And the corresponding relation of the sensor's output potential and hydrogen concentration under different temperature has been measured.Finally, applying the hydrogen sensor to gas nitriding process, by measuring and control the hydrogen content in the nitriding furnace to control ammonia decomposition rate, thus achieve the control of hydrogen potential in the furnace. Through conversion, the corresponding relations of the ammonia decomposition rate, the hydrogen concentration and the sensor's out potential's under different temperature are obtained. Take this result as a basis for nitriding process, following this process, processing 40Cr steel parts with 15 times furnace nitriding, testing results show that, both nitrided layer depth and surface hardness achieve the drawing's technical conditions'needs, and the nitriding quality is stability and reliability.