Ptc Recipe And Process Research

BaTiO₃ ceramic is a typical kind of ferroelectric ceramic. By adding trace amounts of rare earth elements, the room temperature resistivity of BaTiO₃ ceramic will drop significantly, which is called the PTC (Positive Temperature Coefficient) effect.The development direction of the PTC material is to meet the demand of high voltage, high temperature, low resistivity, high reliability, chip and other aspects.To meet the application requirements, the properties of the PTC materials must be modified and optimized according to the usage. Generally the ways include the following:1 adjusting the Curie temperature;2 reducing the room temperature resistivity of materials;3 increasing the lift-drag ratio and the temperature coefficience;4 improving the capacity of withstand voltage and reliability of the resistance;5 strengthening the abilities to resist the current impact.In order to improve the performance of the PTC material, the cores and the keys are optimizing the formula of PTC ceramic, improving and optimizing the processing conditions, and optimizing the technical Standardization through evaluating the performance.In this paper, the PTC ceramic using BaTiO₃ as the main crystal phase is chosen as the research object. The doping technology and the processing technology are researched and optimized results shows that both the formulation of PTC ceramic material and the processing technology have an effect on the performance of the product.It lays a good foundation for the process and the key technology to make the PTC ceramic products meeting the parameters and the reliability requirements ultimately.The main contents and targets of the research are:1 the influence that the adulterant has on the material properties and microscopic structure;The adulterant can improve the grain structure and PTC properties of the materials. 2 the influence that the processing technology (synthesis temperature, sintering temperature, ect. ) has on the material properties and the microscopic structure; The rational synthetic temperature and sintering temperature can meet the conventional electrical properties; improve the microscopic structure and the PTC properties of the materials.3 to obtain a kind of low resistivity PTC material based on the research of 1) and 2): zero power resistivity 30⁴5?·cm, withstanding voltage≥250v/mm, temperature coefficience≥12%/℃.The main component formation of the research: Ba 68.28mol%, Ti 102.00mol%, Sr 14.59 mol%, Y₂O₃ 0.191 mol%, Si 0.497%(w/w), Ca 17 mol%, Mn 0.014%(w/w)The main processing technology conditions: Synthesis temperature and time: 1210℃3hours Sintering temperature and time: 1330℃1² hours...