The Study Of Class ? Ceramic Preperation And Performance For 200?-202 MLCC

The application of high temperature series of multilayer ceramic capacitors?MLCC?in the areas of aerospace,aviation,ocean shipping,new weapons is more and more extensive because of its wide range of working temperature?working temperature is 150?,175?,200?even 250??.The research on high temperature porcelain is urgent in order to solve the demand of high temperature porcelain which for high temperature multilayer ceramic capacitor,to realize the localization of dielectric material,to ensure that the demand of the military equipment for high temperature multilayer ceramic capacitor products.The successful development of 200?high temperature ceramic materials using in military high temperature multilayer ceramic capacitors?MLCC?will end the pattern of MLCC products relying on imports,will hedge the risks of Chinese trade.Firstly,the structure and modification mechanism of barium titanate crystal are analyzed.Then,the thesis introduces the preparation process and test method of ceramic powder.We did the formula research of X9U-202 high temperature porcelain from three aspects:the technology of stable dielectric constant value within the range of working temperature for BaTiO₃-based ceramic;raising high-temperature insulation resistance of Ba TiO₃ ceramic material system;decreasing the sintering temperature of Ba TiO₃ system ceramic material.Nb₂O₅,PbTiO₃,Bi₂?SnO₂?₃,Bi₂O₃ are doped together to improve the temperature characteristic of the ceramic material;MnO₂,ZnO,Dy₂O₃are used to raise its high-temperature insulation resistance;also we did the research on the effect of sintering temperature adding Bi₂O₃ or glass system.The paper does some improvements on the development of lead-free environmental protection,the introduction of Bi₂?SnO₂?is new,it is relatively rare in the previous literature.In addition,we also did research on testing the accuracy of the particle size from adding quantity of dispersant and ultrasonic time,the influence on various electrical property from different time of ball-milling is studied.Then we found that the longer ball-milling caused the smaller particle size,the smaller dielectric constant,the greater insulation resistance and electric strength,finally the best time of ball-milling was concluded.Finally,we got the high temperature ceramic material with meeting development goals.Its performance parameters are as follows:dielectric constant,1905²123;dielectric loss tangent value,0.0085⁰.0089;insulation resistance?25??:?5²0?310¹¹?;insulation resistance?200??:?4¹5?310⁹?;capacitance with temperature change rate?%?:-42.3⁺7.5;electric strength:7.1¹1.2k V/mm;sintering temperature:1140?.