M型钡铁氧体基永磁复合材料的制备及其性能研究

发布时间：2018-08-24 14:25

【摘要】：随着信息产业和无线通信技术的高速发展,电子设备变得更加高度集成化、多功能化和小型化。Kneller在1990年提出交换耦合机制后,永磁复合材料的研究主要集中在金属永磁复合材料,例如Nd-Fe-B和Sm-Co等,尽管其磁能积BH(max)相对于单相永磁材料有了大幅提高,但是由于成本高且不耐腐蚀,限制了金属永磁复合材料在工业生产中的应用。相比金属永磁复合材料,利用交换耦合原理制备的铁氧体永磁复合材料,不仅具有较高的剩磁(Br)、矫顽力(Hc)和磁能积BH(max)而且成本低、合成制备方法简单耐腐蚀性好。本论文选择M型钡铁氧体(Ba Fe12O19)为硬磁相,铁酸钴(Co Fe2O4)和钇铁石榴石(Y3Fe5O12)分别为软磁相,采用溶胶-凝胶法制备永磁复合粉体,并通过微波烧结法获得永磁复合陶瓷。运用X射线衍射仪(XRD)、显微共焦激光拉曼光谱仪(Raman Spectra)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)对试样的物相及化学组成和微观形貌进行分析;用精密阻抗分析仪和振动样品磁强计(VSM)对其介电和磁性能进行分析研究;用矢量网络分析仪对磁性复合粉体吸波性能进行测试研究,并对复合材料制备工艺和形成机理进行研究。该实验包括以下部分:(1)首先,采用溶胶-凝胶法制备Ba Fe12O19/Co Fe2O4永磁复合粉体,研究煅烧温度、螯合剂、p H值以及不同Co Fe2O4含量对永磁复合粉体物相组成的综合影响。其次,采用微波烧结法,成功制备出Ba Fe12O19/Co Fe2O4永磁复合陶瓷。实验结果表明,复合陶瓷物相组成清晰,晶粒分布均匀、烧结致密。通过研究Ba Fe12O19/Co Fe2O4永磁复合粉体磁滞回线,可以发现永磁复合粉体两相之间具有优异的交换耦合性。相比于纯相粉体材料,永磁复合粉体的饱和磁化强度和剩余磁化强度均有所提高,当Co Fe2O4含量达到10%时,永磁复合粉体的磁能积相比于纯相Ba Fe12O19提高了10%。通过对该材料吸波性能的研究发现,Co Fe2O4含量达到10%时,复合材料体系在17.66GHz出现了最大吸收峰-15.69 d B。此外,在13.2~18.17 GHz范围内,永磁复合粉体材料的吸收峰,始终大于纯相Ba Fe12O19的吸收峰。实验还对相应的烧结陶瓷材料的磁学性能及介电性能进行研究。研究表明,随着Co Fe2O4含量的增加,永磁复合陶瓷的饱和磁化强度以及剩余磁化强度均明显增大,而其介电常数有所下降,介电损耗角正切值(tan?)先增大后减小。(2)通过采用溶胶-凝胶法制备Ba Fe12O19/Y3Fe5O12永磁复合粉体,研究煅烧温度、螯合剂和p H值以及不同Y3Fe5O12含量对永磁复合粉体物相的影响。随后,应用微波烧结法将上述实验所得永磁复合粉体进行烧结,制备出Ba Fe12O19/Y3Fe5O12永磁复合陶瓷。实验结果表明,复合陶瓷两相之间分布均匀,化学相容性好。通过研究Ba Fe12O19/Y3Fe5O12永磁复合粉体磁滞回线,发现永磁复合粉体的两相之间具有优异的交换耦合性。相比于纯相粉体,永磁复合粉体的矫顽场和剩余磁化强度均有所提高,当Y3Fe5O12含量达到10%时,永磁复合粉体的磁能积为纯相Ba Fe12O19的2倍。通过对该材料吸波曲线的研究,当Y3Fe5O12含量达到10%时,在19.66 GHz出现了最大吸收峰-17.51 d B,吸收大于-8.47 GHz(Y3Fe5O12)的峰宽达到4.3 GHz,表明该组分粉体具有优异的吸波性能。在对烧结陶瓷材料的磁学性能及介电性能研究过程中,测试结果表明,随着Y3Fe5O12含量的增加,永磁复合陶瓷的矫顽场和剩余磁化强度增大,介电常数和介电损耗角正切值(tan?)均减小。
[Abstract]:With the rapid development of information industry and wireless communication technology, electronic devices have become more integrated, multifunctional and miniaturized. After Kneller proposed the exchange coupling mechanism in 1990, the research on permanent magnet composites has focused on metal permanent magnet composites, such as Nd-Fe-B and Sm-Co, although their magnetic energy product BH (max) is relative to single-phase. Permanent magnet materials have been greatly improved, but the high cost and non-corrosion resistance limit the application of metal permanent magnet composites in industrial production. Compared with metal permanent magnet composites, ferrite permanent magnet composites based on exchange coupling principle have not only higher remanence (Br), coercivity (Hc) and magnetic energy product BH (max), but also higher cost. In this paper, M-type barium ferrite (Ba Fe12O19) was chosen as hard magnetic phase, cobalt ferrite (Co Fe2O4) and yttrium iron garnet (Y3Fe5O12) as soft magnetic phase, and permanent magnet composite powders were prepared by sol-gel method. The composite ceramics were obtained by microwave sintering. X-ray diffractometer (XRD) and micro-copolymer were used. Raman Spectra, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to analyze the phase, chemical composition and micro-morphology of the samples, the dielectric and magnetic properties of the samples were analyzed by precision impedance analyzer and vibrating sample magnetometer (VSM), and the magnetic composite powder was absorbed by vector network analyzer. The experiment includes the following parts: (1) Firstly, Ba Fe12O19/Co Fe2O4 permanent magnet composite powders were prepared by sol-gel method. The effects of calcination temperature, chelating agent, P H value and different content of Co Fe2O4 on the phase composition of the composite powders were studied. Secondly, Ba Fe12O19/Co Fe2O4 permanent magnet composite ceramics were successfully prepared by microwave sintering. The experimental results show that the composite ceramics have clear phase composition, uniform grain distribution and compact sintering. By studying the hysteresis loops of Ba Fe12O19/Co Fe2O4 permanent magnet composite powders, excellent exchange coupling between the two phases can be found. The saturation magnetization and remanence magnetization of the composite powders were improved by 10% when the content of Co-Fe_2O_4 reached 10%, and the magnetic energy product of the composite powders was 10% higher than that of the pure phase Ba-Fe_12O_19. In addition, the absorption peak of the composite powders was always larger than that of the pure phase Ba Fe12O19 in the range of 13.2-18.17 GHz. The magnetic and dielectric properties of the sintered ceramics were also studied experimentally. The results show that with the increase of Co Fe2O4 content, the absorption peak of the composite ceramics is always larger than that of the pure phase Ba Fe12O19. The saturated magnetization and residual magnetization of Ba Fe12O19/Y3Fe5O12 composite powders were increased obviously, while the dielectric constant decreased, and the tangent value of dielectric loss angle (tan?) increased first and then decreased. (2) The effects of calcination temperature, chelating agent and P H value and Y3Fe5O12 content on the properties of Ba Fe12O19/Y3Fe5O12 composite powders were studied by sol-gel method. Afterwards, Ba Fe12O19/Y3Fe5O12 permanent magnet composite ceramics were prepared by microwave sintering method. The experimental results show that the two phases of the composite ceramics are uniformly distributed and have good chemical compatibility. The coercive field and residual magnetization of the composite powders are improved compared with those of pure phase powders. When the content of Y3Fe5O12 reaches 10%, the magnetic energy product of the composite powders is twice that of pure phase Ba Fe12O19. The maximum absorption peak appeared at 19.66 GHz - 17.51 D B, and the peak width of absorption larger than - 8.47 GHz (Y3Fe5O12) reached 4.3 GHz, indicating that the composite powder had excellent absorbing properties. During the study of magnetic and dielectric properties of sintered ceramics, the coercive field of permanent magnet composite ceramics increased with the increase of Y3Fe5O12 content. The dielectric constant and dielectric loss tangent (tan?) decrease with the increase of residual magnetization.
【学位授予单位】：陕西科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM277;TB33

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