Preparation And Research Based On Fe 3 Si Thermistor

The intermetallic Fe3 Si and Mn(V)-doped Fe3 Si alloys were prepared by using the mechanical alloying method?cold pressing and vacuum sintering technology. XRD(X-ray diffraction)?density?resistivity at room temperature and TCR(temperature coefficient of resistance)were used to characterize and analyze the effect of the molding pressure and alloying element content on the properties of thermistor samples.Firstly, the influence of molding pressure on the electrical properties of Fe3 Si alloy was studied. Experimental results show that: when molding pressure were 100 KN ~ 300 KN(gradient of 50 KN), the single Fe3 Si phase was produced. The variation of average grain size and resistivity is just the opposite. The average crystal grain size is maximal, but the resistivity at room temperature is minimal at a pressure of 250 KN. When the molding pressure is 100 KN ~ 300 KN, the resistivity of the Fe3 Si alloy increases with the increase of temperature, and the thermal constant of the alloy reaches the maximum at F=250 KN.Secondly, XRD, density and room temperature resistivity were measured to analyze different doping Mn(V) content of Fe3 Si alloys. The results show that all experimental samples are the single phase Fe3 Si in different content of V or Mn, and the main phase peak of Fe3 Si alloys is shifted to the right with the increasing of the content of Mn(V). The density of doped Fe3 Si alloys are decreased with respect to the undoped alloy, and the value of density is the minimal at x=0.15. The variation of alloys density and resistivity is just opposite, and the room temperature resistivity of samples reaches the maximum in x=0.15.Finally, Fe3 Si alloys in different doped Mn and V contents were analyzed in thermal property. The results show that the thermal parameters of the samples slowly reduced with increase of the doping content of Mn element, but the thermal parameters of the samples increased first and then decreased with the increasing of V doping content. Thermal constants of samples are the highest at x = 0.05. For doped Mn alloys, the change rate of resistivity is decreased with the increasing of temperature. The change rate of(Fe0.8Mn0.2)3Si alloy's resistivity in the T=240? is 0, and in(Fe0.75Mn0.25)3Si alloy, the change rate of resistivity in 190? is approximately 0.