Study On Gelcasting And Drying Method Of Multilayer PTCR

Gelcasting has been a novel colloidal forming method for integrating polymer chemistry into conventional ceramic technology. The forming method of ceramics is the most prospective method in making the near net shape and complicated ceramics.This paper introduced the process of producing the multilayer PTCR, including the forming of green body, sintering of sample and the lamination process of ceramic chip. Analyzing the foreground of multilayer PTCR, we put forward some advice about co-fire processing. In allusion to the advice, we carried out certain experiment and discussion.This paper mainly introduced the fundamental principle and technological process of gelcasting PTCR based on BaTiO3, including the preparation of slurry, the forming of green body, drying method and the sintering of sample. The advantage of using liquid desiccant was emphasized. We chose poly glycol as liquid desiccant, and investigated affect factors which influenced the drying rate, such as loading level of ceramic slurry, concentration of liquid desiccant and geometry of green body. We studied on modeling of liquid desiccant drying method for gelcasting ceramic green bodies, and compared with conventional drying methods.We discussed on forming technology of multilayer PTCR, and succeeded in fabricating multilayer thermistor based on BaTiO3 with high properties. The characteristic parameters are as follows: the number of layers: 3, size: 9.52 mm×7.56 mm×1.90 mm, room resistance: R25=4.34 ?, resistance rising rate:β=1.419E+5, temperature coefficient:α=9.76 %/℃.We attempted to prepare doped BaTiO3 ultra fine powders by hydrothermal method, in order to fabricate multilayer PTCR using Doctor Blade Method(DBM). The grain size can be 28.9 nm. We discussed on the affect factors which affected properties of BaTiO3 powder, such as Ba/Ti mol ratio, reaction temperature, reaction time and the amount of mineralizer KOH.