Analysis Of Factors Affecting The Zero Point Of NO_x Sensor And Optimization Of Ceramic Chip Process

With the rapid development of the world economy,the problem of automobile exhaust pollution has become the focus of attention all over the world,and the NO_x sensor is an important device for automobile exhaust purification.At present,diesel engines mainly use selective catalytic reduction technology to purify exhaust gas.As an important part of the SCR aftertreatment system,the NO_x sensor monitors and feeds back the concentration of nitrogen oxides in the exhaust gas during engine operation,so as to control nitrogen oxide emissions to meet the national requirements.Based on the understanding of the preparation process and working principle of the NO_x sensor,this paper designs a NO_x sensor calibration system.The system has low cost,simple and convenient structure,wide application range,and overall good accuracy and stability.The results show that the design of the calibration system of the NO_x sensor can accurately and quickly monitor the concentration of nitrogen oxides in the exhaust gas,which is of great significance to the research and development of the sensor.Analyzed and studied the influencing factors of NO_x sensor to measure the pump zero point.By analyzing the structure of the chip,the test principle and the preparation process of the slit,the signal test of the chip is carried out,and the relationship between the slits of different thickness and width,the different oxygen concentration and the pump current and the influence on the zero point of the measuring pump are obtained.It shows that the zero point of the measuring pump can be made smaller by reducing the thickness of the slit,the width of the slit and the oxygen concentration,so as to improve the accuracy,sensitivity and stability of the sensor.The effect of different dispersants on the dispersion and performance of zirconia powder was studied.Designed a variety of dispersants and zirconia powder to improve optimization experiments,through the sedimentation height and the morphology observation and analysis of the sediment with SEM scanning electron microscope,the results show that the minimum experimental sedimentation height of fish oil is 3.5cm,and the morphological particles are uniform and have no pores,which is most suitable as the optimal dispersant for this experiment.Experiments have analyzed the effects of additives on the properties of cast blanks under different formulations.Design different formulas to obtain multiple sets of casting pastes,and obtain the blanks by ball milling,printing and casting,which are laminated and sintered using unique sintering temperature and time.The pinhole width,the number of folds and the sintering shrinkage rate obtained by the test are analyzed and cast.The mechanical properties of the green sheet such as the superimposability and strength and toughness,the results show that: when the casting glue is 7g and the dispersant is 3g,the green sheet has the best superimposability and strength and toughness,moreover,the sintering shrinkage rate of the blank sample is the most consistent with the theoretical shrinkage rate value of zirconia.