Preparation And Characterization Of Magnetic Damping Rubber Composites

In the present work, pilot-scale preparation of strontium ferrite powders and strontiumferrite/NBR magnetic damping rubber composites were studied. The calcination process ofstrontium ferrite in the pilot scale and damping mechanism of magnetic damping rubbercomposites were discussed. In the part of preparation of strontium ferrite powders, firstly, theeffect of different Fe/Sr mole ratio, calcination temperature, mixing ways between flux andprecursor, calcination oxygen pressure and relevant characterization. Then, calcinationtemperature, calcination oxygen pressure and their interaction were further investigated. Atlast, the optimum calcination time of strontium ferrite powders was determined. In thepreparation part of magnetic damping rubber composites, the pilot-scale strontium ferriteloading which has great influence on the magnetic and damping properties was investigated.The storage modulus, loss modulus and loss factor of the composites before and aftermagnetizing process were compared. Damping response of the rubber composites at certaintemperature, frequency and amplitude range were analysed.The results of pilot-scale study of the strontium ferrite showed that the optimum Fe/Srmole ratio, calcination temperature, calcination oxygen pressure, calcination time, mixingways between flux and precursor were10,850℃,0.02MPa,4h and mixing with grinder,respectively. Under such process conditions, the saturation magnetization, remanentmagnetization and coercivity of the powders reached57.06emu/g,29.98emu/g and4590.1Oe, respectively. The XRD patterns showed intact characteristic peaks and FI-IRmeasurement showed that Si-69successfully compounded with the powders.The XRD measurements of the magnetic damping rubber composites at different ferriteloading showed the whole characteristic peaks of strontium ferrite. The results of the magnetic properties showed that the saturation magnetization and remanent magnetizationincreased with increasing ferrite loading. However, the coercivity was relatively independentof the ferrite loading. The results of dynamic damping properties showed that the magnetizingprocess had great influence on the storage modulus, loss modulus and loss factor at differentferrite loading. The damping properties reached the top at strontium ferrite loading of90phr.In the testing range of0~100℃, the storage modulus at this ferrite loading increased and theloss peak of tanδ became wider after magnetizing. In the frequency range of0~100Hz, thestorage modulus decreased after magnetizing and loss peak of loss modulus and loss factorappeared in the range of40~80Hz. In the amplitude range of0~50μm, the storage modulusdecreased and the loss modulus and loss factor increased after magnetizing. These phenomenawere attributed to the joint effect of electromagnetic loss and the interaction between themagnetic powders and the rubber matrix. Finally, the result of demagnetization study showedthat the surface magnetic field intensity of the rubber composite did not fade in30days. Itwas a kind of superior permanent magnetic rubber composite.