Synthesis and characterization of material for NTC fire safety sensor

The ceramic powder prepared from the mixture of SiO₂, KNO₂ and KNO₃ have been characterized for NTC behavior and the same have been used as sensor material in the form of a thin metal cable to detect over-heating. These materials have mega ohm resistance at room temperature and showed exponential drop in resistance with the rise in temperature over a temperature range of 100–400 ˚C. The material was sintered at 800˚C for 2 h resulting in good bonding strength. The electrical characters were tested by plotting graph between temperature and resistance being main parameters of entire sensor system in the temperature range of 110˚C to 370˚C. Several other important characteristics like B value, Activation energy, Temperature co-efficient were also calculated for checking the electrical characterization of sensor material. The material characterization was also conducted with help of different techniques. XRD result confirmed about the spinal type crystal structure of the sample mandatory for electrical behavior required for NTC sensors. SEM study showed the morphology of material which is discrete grains good for conductivity at high temperatures. The ceramic material thus synthesized can be used in over heating detection application in several fields.