Fabrication Of Limiting-current Type Oxygen Sensors By A Technology Of Multilayered Lamination

Solid electrolyte oxygen sensor has been popularly used in automotive industry and planar limiting-current oxygen sensor is valued for its characters of high precision, quick response, durability and no reference air, which make up the core component of oxygen device. According to the relevant research at home and abroad, the oxygen sensor was studied from the aspects of Solid electrolyte material, structural design, screen printing, stacking hot pressing and sintering process. Further more, the signals of sensor were detected in detail.In the experiment, 5mol% yttrium stabilized zirconia ceramics and 8mol% yttrium stabilized zirconia ceramics, which had been sintered, were investigated by shrinkage rate, thermal expansion instrument, digital microscope and AC impedance. Furtherly the resistance of Grain boundary and resistance of Grain were calculated by the AC impedance spectroscopy below 550℃. Meanwhile, activation energy of grain and Grain boundary were gained in the fitting curve of Arrhenius.A thin-film limiting-current type oxygen sensor using 5mol% yttrium stabilized zirconia (5YSZ) was developed successfully through the technology of tape casting. It was made from tape-casting layers by screen printing, stacking hot pressing and multilayered cofiring process. Meanwhile the physical characteristics were investigated by SEM and digital microscope. The response time and I-V curve of oxygen sensor sample were tested at 923K in a mixture of the N2-O2 with the oxygen concentration between 1100ppm and 90%. Further more, the influence of the ambient pressure and the temperature of solid electrolyte were also developed. Finally, two test systems of oxygen sensors were introduced with their different applications in detection. The result distinctly shows that stable current platforms of the sensor prepared by multilayered cofiring are formed in the scope of the oxygen concentration mentioned previously, and a good linear relationship between the limiting current and oxygen concentration is illustrated according to Normal diffusion model; Simultaneously it is indicated that the sensor has good repeatability at 923K with the oxygen concentration varying from 5.06% to 21.24% and the response time is within 1 second,which is able to meet the need of basic application in oxygen detection.