Study on Thermal Control Behavior by Using BaTiO₃-Based PTC Materials With Room Temperature Curie Point

Thermal management has become an important issue to be solved in the miniaturization and weight reduction of electronic equipment, especially in the aerospace field. The doped BaTiO₃, as a self-regulating heating material, exhibits an attractive application perspective on the thermal control of electrical devices, resulting from its positive temperature coefficient (PTC) property. However, the Curie temperature of most of the doped BaTiO₃ material at present is much higher than the operating temperature of the electrical equipment. On this basis, this paper focuses on the controlling of the Curie temperature and thermal control performance of the BaTiO₃-based heating component. The polycrystalline Ba_1-xSr_xTiO₃ was synthesized by solid solution reaction. The Curie temperature is tuned by the content of the strontium element, simultaneously the elements Y and Mn are doped to reduce the room temperature resistivity and improve the PTC effect. The X-ray diffraction demonstrates that the bulk phase of the Ba_1-xSr_xTiO₃ generates in the presintering process, while the crystallization of composition has completed during the sintering. Importantly, the Curie temperature of doped Ba_1-xSr_xTiO₃ for x = 0.3 with average particle size of 4.86 μm has shifted to around 38°C, beyond that exhibiting a 2.8-orders magnitude of PTCR jump.

Results of the thermal control experiment show that, in contrast to the ordinary resistor heater, the heating element based on the BaTiO₃ PTC material can achieve lower equilibrium temperature without any auxiliary control methods. Compared to the traditional thermal control system composed by the ordinary resistor, sensor and controller, the novel thermal control system based on PTC heating unit possesses simple structure, lightweight and excellent reliability.