Study Of The Materials Of Piece Type Limiting Current Oxygen Sensor With Dense Diffusion Barrier

With the development of the technology for automobile and manufacture craft of sensors, automobile oxygen sensors are consummating constantly with a wide developing foreground. To overcome the disadvantage of the traditional current type oxygen sensor and optimize the testing performances of sensor, using solid state electronic-ion mixed conductor as the material of the preparation of limiting current oxygen sensor with a dense diffusion barrier is studied in this article. This kind of oxygen sensor has a better oxygen sensitive characteristic then broadened a sensor measures range. It has many merits such as inexpensive, simple structure, respond quickly and work reliable. So it is the one kind of the limiting current oxygen sensor which has a good prospect.In this thesis, a new gel-casting method has been studied: mix the Y2O3 stabilized ZrO2 powder body with organic monomer, coupler, dispersant and the plasticizing agent according to a certain proportion. Then pour the slurry into a model after drop little initiator and accelerating agent in it. Then it has prepared the materials of each part in the oxygen sensor, carried on the material modification and analyzed the results.Electrolyte material: prepared the Y2O3 stabilized ZrO2 ceramics by a new gel-casting method. YSZ sintered at 1400℃has became the cubic fluorite structure, and sintered at 1500℃whose relative density can reach 95.1%, using gel-casting method can reduce the sinter temperature by 100～200℃. The samples which mixed with Al2O3 have lower rate of contraction, higher volume density, and good sintering character.Dense diffusion barrier material: the best sintering temperature of La0.8Sr0.2MnO3 material is determined 1000℃, synthetic reaction can finish at this temperature. The samples sintered at 1200℃whose relative density can reach 97%. As increasing of strontium in La1-xSrxMnO3, the volume density of the samples decrease and the sintering character descend.Conductive ceramics material: the electrical resistivity of ZnO ceramic will decrease slowly when increasing of the Al2O3, and the electrical resistivity reaches the least when the quality percent of Al2O3 is 0.5%; and the electrical resistivity descend quickly when the sintering temperature raise up. The electrical resistivity of ZnO conductive ceramic mixed with Y2O3 sintered at 1000℃is the biggest which reaches 220Ω·cm . And the electrical resistivity descend when the sintering temperature raise up. When the sintering temperature between 1000℃and 1200℃, the electrical resistivities of the ZnO samples fall over 90%.