Study On Preparation Technology Of Lead Barium Titanate Based Thermal Ceramics By Two-step Synthesis

The lead titanate-based thermal ceramic material is a high-temperature PTCR?Positive Temperature Coefficient Resistance?ceramic material.Because of its good PTC?Positive Temperature Coefficient?effect and high Curie temperature,it is often used as a high-power heating material,with various fields such as transportation,home appliances,and communication.For the increase of the frequency of use of strong electricity,people put forward higher requirements on the electric strength of lead-tantalate-based thermal ceramic materials,and the electrical strength of the material is related to the average size and distribution of the internal crystal grains of the material.The smaller the particle size,the tighter the grain distribution and the higher the electrical strength of the material.The traditional PTCR ceramic material synthesis method requires pre-baking lead titanate and other raw materials,which causes a large amount of volatilization of lead titanate during calcination.The volatilization of lead during the synthesis process causes the grain inside the material to grow larger.The electrical strength of the lead titanate-based thermal ceramic material is reduced,and the reliability of the material is deteriorated.In order to improve the electrical strength of the material,it is necessary to refine the crystal grains.In this thesis,the two-step synthesis method is the main research object.The formulation,pre-sintering temperature and sintering temperature are optimized to realize lead titanate-based thermal ceramics.The microcrystallization of the material improves the electrical strength of the material.In the aspect of formula adjustment,the mechanism of donor acceptor doping was deeply studied and analyzed,and the effects of liquid additive and CaCO₃ on material properties and microstructure were studied.In the aspect of synthesis technology,the two-step synthesis method was studied.The lead titanate-based thermal ceramic materials were studied from the two aspects of calcination temperature and sintering temperature.Finally,the powder was pre-fired at 1050°C.Sintering at°C and the preparation by the two-step synthesis method is the best,and a circular sheet sample having a height of 2 mm and?13 can be obtained.At this time,the ceramic material sample has a Curie temperature of 260°C,a room temperature resistivity of 3000?/cm,a lift-to-drag ratio of8×103,and a breakdown voltage of 1000 V or more.