Research Of Ferrite Magnetostrictive Material And Its Application

With the popularity of electronic communication technology,the development of high-frequency ultrasonic transducer has put forward higher requirements for driving materials.Ultrasonic transducers on the market mainly use piezoelectric ceramic materials,but piezoelectric transducers in some mines,gas stations,chemical laboratories and other flammable and explosive gases used in special occasions,it is very easy to appear the dangerous phenomenon of high-voltage ignition explosion,thus limiting its application.NiCu ferrite,as a spinel ferrite,has good soft magnetic properties such as high resistivity p and low coercivity Hc,which is an ideal soft magnetic material for high frequency.Based on the soft magnetic properties of pure NiCu ferrite,this thesis prepares a material with high magnetostrictive coefficient and low coercivity by means of sintering temperature process and ion substitution,and designs a ferrite magnetostrictive ultrasonic transducer with this material as the driving element.In this thesis,by comparing the effects of different sintering temperatures on the properties of NiCu ferrite using the conventional solid-phase reaction process experiments,the best overall performance of the samples prepared at two sintering temperature points,1100℃ and 1150℃,was obtained.Then,Ni0.85(1-x)Cu0.15(1-x)CoxFe2O4(x=0,0.010,0.012,0.014)was used as the formulation to investigate the effect of Co3O4 substitution on the magnetic properties of NiCu ferrite.1100℃～1150℃ sintering conditions showed good microscopic morphological consistency and high densification of the samples,and the Coercive force was reduced by the substitution of Co content The overall performance of the sample is better at x=0.012,where ρ=5.319g/cm3,4πMs=2972Gs,Hc=6.2Oe,and λs=-31ppm.The magnetostrictive coefficient gradually becomes larger with the increase of Co substitution under the sintering condition at 1150℃,and the sample has the best overall performance at x=0.014,where p=5.207g/cm3,4πMs=2611Gs,Hc=20e,λs=-35ppm,and the high magnetostrictive coefficient and low coercivity material required for this experiment were obtained.The experimentally prepared NiCuCo ferrite material was used as a magnetostrictive rod to design an ultrasonic transducer with an intrinsic frequency of 26 kHz.In order to ensure the maximum enhancement of the magneto-mechanical conversion efficiency,an adjustable pre-stress structure was designed inside the device.The transducer was fabricated according to the design and tested with a high frequency AC power supply.Under the condition of pre-stressing,the vibration frequency of the transducer prototype reached resonance when high-frequency AC power was applied at 12 kHz,and the effective conversion of electromagnetic-mechanical energy could be achieved.A comprehensive analysis shows that the error may be caused by the ΔE effect,low density of ferrite rod pressing and forming,idealization of the simulation model for resonant frequency calculation and small magnetostriction coefficient of ferrite.