Preparation And Properties Of Bonded Rare Earth Magnetostrictive Composites

Bonded rare earth magnetostrictive composite material is a kind of material prepared by adding binder after grinding the rare earth giant magnetostrictive material into powder.In this paper,we studied the process and properties of bonded rare-earth giant magnetostrictive materials prepared by oriented textured alloy powders.We discussed the influence of process parameters on the magnetic properties and the AC loss characteristics of giant magnetostrictive composites.The paper provides reference for the practical application of giant magnetostrictive composites.In this paper,oriented textured TbDyFe alloy powder was used to prepare magnetostrictive composite material with phenolic and polyurethane as binders by powder metallurgy.The microstructure and properties of the material was investigated by SEM,SRD,resistance strain gauge,impedance analyzer,and soft magnetic AC measurement system.Orthogonal test method was used to analyze the effect of the preparation process on the material properties from the powder size,the content and type of the insulating binder,the molding pressure,and the coupling agent content.The results shows that:?1?The paper started from the loss theory,separated the hysteresis loss and the eddy current loss of the material.The effect of the material preparation process on the material loss was analyzed in combination with the alternating magnetic hysteresis loop of the material,and the ratio of the hysteresis loss and the eddy current loss of the material was calculated.The analysis shows that while at frequencies below 20kHz,the eddy current loss of the composite material accounts for less than 30%.Compared with the alloy material,the loss of the composite material reduced successfully.?2?The permeability of TbDyFe alloy was low?the permeability is 8¹1?,and the permeability of the bonded magnetostrictive material was lower?about 4?.This paper explored the use of adding high magnetic permeability soft magnetic alloy powder to improve the magnetization characteristics of the composite material.By adding FeNi50 soft magnetic powder,the magnetic permeability and the magnetization characteristics of the material was improved.?3?The maximum saturated magnetostrictive coefficient of the phenolic bonded material was 870×10^-6,the peak value of d₃₃ was 2.75nm/A,the density was 7g/cm3,and the permeability was 4.5.The maximum saturation magnetostrictive coefficient was 810×10^-6 for polyurethane bonded magnetostrictive composites,the peak value of d₃₃ was 2.96nm/A,the density was 7.3g/cm³,and the permeability was 4.7.The permeability of phenolic bonding material increased from 4.51 to 6.96,up 54%,after adding 35wt%soft magnetic powder.?4?The hysteresis loss of the phenolic bonded material was 0.033sW/kg in each period of the magnetic field,and the eddy current loss can be described as,the coefficient was about 1.27×10^-4;By 16 kHz magnetic field,magnetic induction was 700 Gs,the total loss was 640 W/kg of the material shaped under 1000MPa pressure,which was 50%lower than the alloy material;For polyurethane bonded magnetostrictive composites,p_h/f was 0.031sW/k,the eddy current loss coefficient b was 1.02×10^-4,and the total material loss was 642 W/kg;After adding 35wt%soft magnetic powder the hysteresis loss p_h/f of the phenolic material was 0.018sW/kg,eddy loss coefficient b was 0.0006,the total material loss was reduced from 655W/kg to 369W/kg.