Thermistor ceramics is a kind of functional ceramics. The development of functional ceramics began in the 1930s. It has experienced the development process from dielectric ceramics → piezoelectric ferroelectric ceramics → semiconductor ceramics → fast ion conductor ceramics → high temperature superconducting ceramics. It has developed into a large class of advanced ceramic materials with diverse properties, wide variety, wide application and high market share. In recent decades, driven by the urgent needs of human society for modern technologies such as energy, computers, information, automobiles, and home appliances, thermistors have developed rapidly as a temperature or current-sensitive component.

PTC is the abbreviation of Positive Temperature Coefficient, which means positive temperature coefficient, which generally refers to semiconductor materials or components with a large positive temperature coefficient. Usually the PTC we refer to refers to the positive temperature coefficient thermistor, referred to as the PTC thermistor. PTC thermistor is a typical temperature-sensitive semiconductor resistor. When the temperature exceeds a certain temperature (Curie temperature), its resistance value will increase in steps with the increase of temperature. The currently used PTC materials are mainly divided into two types: ceramic-based PTC materials and polymer-based PTC materials. Ceramic materials are usually used as excellent insulators with high resistance, while ceramic PTC thermistors are based on barium titanate and doped with other polycrystalline ceramics (mainly doped BaTiO3 series ceramics), which have lower resistance and semiconducting properties. BaTiO3 is a ferroelectric and has been widely used as high-capacity capacitors and piezoelectric ceramics. However, by doping with BaTiO3 and controlling the sintering atmosphere (oxidizing atmosphere), PTC thermosensitive ceramics with fully semiconducting grains and proper electrical insulation at the grain boundaries can be obtained. This can prevent the heated towel rack thermostat from freezing and clogging the heating towel rack thermostat in cold areas or under low temperature conditions, and solve the problem of easy clogging of the thermostat nozzle under low temperature conditions.