The electrothermal conversion mechanism of the PTC heating element has a unique operating mode at the microscopic level. The following is a detailed introduction.
First, from the perspective of material structure, the PTC heating element is mainly composed of semiconductor ceramic materials with a positive temperature coefficient effect. There are a large number of grain boundaries and grains inside this material. When the power is not turned on, there are potential barriers at the grain boundaries, which hinder the free movement of electrons. When the current passes through the PTC heating element, the electrons begin to move in a directional manner under the action of the electric field, trying to cross these grain boundary barriers.
Secondly, in the microscopic electrothermal conversion process, as the current passes, the electrons interact with the lattice. When the electrons cross the grain boundaries, they will transfer part of the energy to the lattice, causing the lattice vibration to intensify, which is manifested as an increase in temperature on a macroscopic level. At the same time, due to the positive temperature coefficient characteristics of the PTC material, as the temperature increases, the barrier height at the grain boundary will further increase. This increase in barrier height will lead to a decrease in electron mobility, thereby limiting the further increase in current.
Furthermore, from the perspective of energy conversion, when the kinetic energy of the electrons is transferred to the lattice, the energy of the lattice vibration is dissipated in the form of heat energy, realizing the conversion of electrical energy to thermal energy. Moreover, since the PTC material can automatically adjust the resistance according to the temperature, when the temperature rises to a certain level, the resistance increases sharply and the current decreases, thereby achieving the effect of automatic temperature control. At the microscopic level, this is because the increase in temperature leads to enhanced electron scattering at the grain boundary, the electron migration path becomes more tortuous, the resistance increases, and the generation of current and heat is limited.
Finally, during the entire electrothermal conversion process, the microstructure and electron behavior inside the PTC heating element interact and influence each other. The migration of electrons, the vibration of the lattice, and the change of the grain boundary barrier together constitute a dynamically balanced system, which enables the PTC heating element to stably realize electrothermal conversion under different temperature conditions and maintain good temperature control performance. This microscopic operating mechanism is the key to the efficient and stable heating of the PTC heating element, and also provides a solid foundation for its wide application in many fields.
