固化温度和时间对快淬粘结磁体性能的影响

用E20环氧树脂加入固化剂顺丁烯二酸酐制备了快淬（Nd，Pr）FeCoZrB粘结磁体，研究了固化温度和时间对粘结磁体抗压强度和磁性能的影响。随固化温度升高，固化时间增加，粘结磁体的交联反应充分进行，抗压强度明显增加；但由于聚合交联反应生成的水腐蚀磁粉，以及高温固化时磁体空隙中的氧气与磁粉发生了氧化，使磁体磁性能显著降低。     

模压成形各向异性NdFeB粘结磁体性能研究

采用模压成形方法制备各向异性粘结NdFeB磁体,主要研究了粉末粒度以及取向磁场强度对粘结磁体磁性能和力学性能的影响.试验结果表明,随着磁粉粒度的减小,粘结磁体的剩磁有所增加,但矫顽力下降明显.随着取向磁场强度的增大,粘结磁体剩磁进一步提高,各向异性明显;粘结磁体密度及抗压强度随磁粉粒度的减小略有提高.经粒度配比后制备的粘结磁体获得了较高的磁性能和抗压强度,其B_r、H_(ci)及σ_(bc)分别为0.81T、828kA/m及204MPa.     

成形工艺对粘结NdFeB磁体结构和磁性能的影响

在粘结NdFeB磁体模压成形过程中存在较大的压力损失，引起磁体密度分布不均匀，致使磁体密度减小。本文研究了压制压强、预压成形和压制方式等对粘结NdFeB磁体结构和磁性能的影响及机理。研究表明：随着压制压强提高，粘结NdFeB磁体的密度和磁性能显著增大；粒度配合、预压成形和双向压制等办法均可增大粘结NdFeB磁体的密度和磁性能；在适当的压制压强下，将粒度配合、预压成形及双向压制工艺结合，制备出密度达到6．5g／cm^3、磁能积达到104kJ／m^3的粘结NdFeB磁体。     

粘结剂含量对粘结NdFeB磁体磁性能和抗压强度的影响

用环氧树脂粘结剂制备了NdFeB粘结磁体,探讨了粘结剂含量对粘结磁体磁性能和抗压强度的影响规律及机理.当粘结剂含量为1%(质量分数,下同)时,磁粉不能完全被包覆、粘结,磁体密度、磁性能和抗压强度低;当粘结剂含量为5%时,粘结剂体积分数大,稀释了磁体的磁性能,多余的粘结剂也使磁体抗压强度降低.粘结剂含量为2.5%时磁体具有较佳的性能:剩磁Br=0.616T;内禀矫顽力Hcj=784kA/m;最大磁能积(BH)m=58kJ/m3;抗压强度为236MPa.     

粉末注射成形在永磁材料中的应用

讨论了粉末注射成形在粘结磁体生产中的应用和烧结磁体研究开发的现状。介绍了注射成形用磁粉的多种制造方法,常用注射成形粘结磁体和杂合磁体的基本性能及应用。分析了影响注射成形磁体性能的技术关键。指出了粉末注射成形在生产低成本、高精度、高性能磁体的技术优势。     

粘结磁体助剂对模压成型NdFeB粘结磁体性能的影响

采用模压设备制备了NdFeB粘结磁体,并研究了粘结助剂(粘结剂和偶联剂)对快淬NdFeB粘结磁体力学性能,包括密度和抗压强度以及磁性能的影响.研究结果表明,添加偶联剂可以提高粘结磁体的性能.使用E-51环氧树脂粘结剂所获得的磁体密度、剩磁、矫顽力、最大磁能积以及抗压强度比用E-44粘结剂的磁体性能要高.随着粘结剂含量的增加,磁体的密度在逐渐降低,磁体的抗压强度在不断变大.而剩磁随着粘结剂含量的增加在不断下降.对矫顽力这个性能来说,1.5%的粘结剂含量为最佳用量.     

注射成形钕铁硼粘结磁体研究的现状及前景

论述了注射成形钕铁硼粘结磁体的特点及发展趋势,分析了其生产工艺中的4个关键因素,包括磁粉、粘结剂与藕联剂、注射过程、充磁过程,并对这4个关键因素的研究状况作了综合评述,认为今后注射成形钕铁硼粘结磁体的研究开发将主要集中在以下4个方面研究:各向异性粉末和各向异性粘结磁体,研发合适的粘结体系及注射成形工艺参数,开发磁能积更高的磁体,开发耐热钕铁硼粘结磁体。     

压机对粘结NdFeB磁体质量的影响

模压成形是粘结NdFeB磁体制造的最主要方法。分析了粘结NdFeB磁体的特点;在实验研究和大量生产实践的基础上,介绍了模具结构、压机结构和压制成形动作对磁体质量的重要影响;总结了控制粘结NdFeB磁体质量的关键技术。     

粘结剂和温压工艺对粘结钕铁硼材料性能的影响

为了获得高性能的粘结钕铁硼(NdFeB)磁体,对含偶联剂和粘结剂的钕铁硼粉体进行了温压压制实验。在70~110℃温度范围内,探索了温压压力、温度、粘结剂及其含量对粘结钕铁硼磁体的密度和性能影响。结果表明:含0.5%偶联剂和0.6%粘结剂(均为质量分数)的钕铁硼粉体的压制规律符合黄培云压制方程,压制模量为3.57 MPa,非线性指数为0.21;随着压力和温度的升高,粘结磁体的密度和最大磁能积先升高然后下降。当粘结剂含量大于1.0%(质量分数)后,磁体密度迅速下降;在相同的温度、压力和粘结剂含量下,加入半固体的E44粘结剂比加入E51和CYD粘结剂的磁体密度大。在温压温度为80℃条件下,获得了密度6.7 g/cm~3,磁能积104 kJ/m~3的粘结钕铁硼永磁材料。     

NdFeB粘结磁体加工性能

应用高压毛细管流变仪和HAAKE转矩流变仪，研究了粘结剂尼龙．6质量分数10％时的NdFeB粘结磁体流变和加工性能。结果表明：NdFeB粘结磁性材料的喂料体系的流动为非牛顿型假塑性液体，具有超高的熔体粘度；润滑剂能有效地降低喂料流动粘度，改善加工条件；而偶联剂会恶化其加工性能；磁粉的粒度分布对喂料的粘度和加工性能有明显的影响。本实验结果可为NdFeB粘结磁体注射、挤出成型的工艺参数确定、模具和机械设计以及加工质量的控制等提供技术依据。     

连铸喷淋冷却结晶器的应用及研究

涟钢三炼钢厂小方坯连铸机采用了喷淋冷却结晶器,研究分析了拉速、中间罐浇铸温度、水压与水流量对该结晶器平均热流量的影响,以及水质对喷淋冷却结晶器的影响。使用这种结晶器后,连铸的产量及铸坯质量大大提高。     

Influence of Aspect Ratio on Fluid Flow and Heat Transfer in Mould when Using Swirl Flow during Casting

Mathematical modelling was used to study the effect of a changed aspect ratio of a continuous casting mould on the resulting flow field in the upper part of the mould when using a swirl flow in the nozzle. Model predictions were initially compared to physical modelling data. More specifically, the predicted axial velocities were found to differ only at the most ~3 mm/s from the measured data. Thus, the model was concluded to be sound. By changing the aspect ratio of a billet mould from 1 to 3 systematically, a numerical analysis of the mould region of a billet continuous caster was performed with a novel injection concept using swirling flow in the immersion nozzle in order to control the heat and mass transfer in the continuous casting mould. The predictions showed that the aspect ratio of the mould has a large influence on the flow field in the upper part of the mould. The meniscus temperature was found to increase with an increasing aspect ratio from 1 to 2, but the maximum temperature was found to decrease when the aspect ratio was increased above 2.     

Structure and Magnetic Properties of Sm2Fe17Nx Sintering Magnets Prepared by Spark Plasma Sintering

Bulk Sm2Fe17Nx sintering magnet was fabricated by spark plasma sintering(SPS) technique. The effects of sintering pressure and sintering temperature on the magnetic properties of the Sm2Fe17Nx magnet were investigated. As a result, the density of the magnet is obviously improved with the increase of sintering pressure, but the coercivity drops since Sm2Fe17Nx has decomposed into SmN, α-Fe and N2. When sintering temperature was only above 200 ℃ under 1 GPa sintering pressure, the coercivity even begins to decrease, which indicates that high pressure promotes the decomposition of the Sm2Fe17Nx at lower temperature. The decomposition is also proved by the decrease of nitrogen and increase of α-Fe in the magnets.     

Three-dimensional analysis and design of petal-like mould for continuous casting of steels

Abstract

Understanding the shrinkage behaviour of a steel billet is very important for designing the continuous casting mould, and conversely, a well designed mould is beneficial when matching the shrinkage behaviour of the billet. The shrinkage behaviour of a billet is hard to measure in situ during continuous casting but can be calculated by numerical simulation. A three-dimensional finite element model has been built to simulate the thermal and stress fields of the billet in the mould. The dynamic thermal boundary condition, the effect of ferrostatic pressure and the temperature dependent thermophysical parameters have been considered in the model. The shrinkage of billet when considering ferrostatic pressure is on average 0·08 mm smaller than when not considering ferrostatic pressure. The temperature and stress distributions are analysed in the present paper, and based on this analysis, a novel petal-like mould was designed and its taper determined. The designed mould has been tested in industrial practice showing better lifetime and billet quality.     

新型锌基塑料模具合金的研制开发

通过合金成分的改变,添加钛、铬、硼、稀土变质元素,开发了新型锌基塑料模具合金,探讨了合金的金相组织、性能、耐蚀性及尺寸稳定性等。结果表明,变质元素可细化合金组织,新合金具有较好的综合机械性能,较高的软化温度(150℃以上),低的线收缩率(0.81%～0.90%),耐晶间腐蚀,尺寸变化约为0.0405%,用做注塑模的使用寿命在1.8万次以上。     

Effect of Heavy Rare Earth Dopants on Hydrogen Incorporation in SmCo 2:17 Type Magnet

Previous studies showed that the temperature coefficient of obviously decreases with increasing the content of heavy rare earth element in SmCo magnet. But the investigation on the hydrogen incorporation in SmCo magnet is limited. In this paper, we would like to report the effect of heavy rare earth dopant on hydrogen incorporation in SmCo 2:17 type magnet. The relationship between temperature and pressure in hydrogenatied magnet is studied using XRD, DTA, and magnetic measurement. Based on the experimental results, the initial hydrogenation temperature decreases with increasing the content of heavy rare earth, however, the initial saturation pressure enhances. During the hydrogenation, the temperature region shrinks with increasing heavy rare earth doping.     

成形压力对烧结Nd-Fe-B磁体微观组织与磁性能的影响

在于法制备烧结钕铁硼生产线上,研究了11.54 MPa和9.23 MPa两种成形压力对Φ9.5mm烧结钕铁硼磁体(/%:31.00Pr+Nd、1.20B、0.20Al、余Fe)微观组织与磁性能的影响。结果表明,成形压力增大可以改善晶粒分布的不均匀性,提高取向度,从而提高剩磁与磁能积;但成形压力增大易使晶粒尺寸增大,从而使矫顽力降低。     

Study on Fabrication Process of Anisotropic Injection Bonded Nd-Fe-B Magnets

This study is on the injection molding process for the fabricating anisotropic Nd-Fe-B bonded magnets. The effects of powder loading, particle size of the magnetic powder, polymer binder and the fabricating process on the magnetic and the mechanical properties of anisotropic Nd-Fe-B magnets were investigated. The proper powder loading, particle size and binder are 60%(vol%), 75–106 μm and PA 1010, respectively. The optimum condition for good magnetic properties of anisotropic injection bonded Nd-Fe-B magnets is mixing the binder and the chemicals in the temperature between 205–215 °C, injection temperature of 265 °C, the injection pressure of 5–6 MPa, the press time of 5 second, and molding temperature of 80 °C. The magnetic properties of anisotropic bonded Nd-Fe-B magnets made in above conditions from d-HDDR powder were: B_r=0.72 T, _iH_c=983 kA/m, (BH)_max=75 kJ/m^c.     

高纯Mg-Cu-Y合金熔炼工艺研究

在真空中频感应熔炼炉中制取高纯镁基Mg-Cu-Y合金。根据荧光光谱分析结果,考察中间合金、保温时间以及浇铸模具对合金成分均匀性的影响。结果表明,中间合金的熔炼对于合金成分的均匀有决定性的影响,保温时间越长越有利于合金元素分布均匀,浇铸模具影响合金在凝固过程中的偏析程度,保护气体可以抑制合金液的挥发,对合金成分均匀性影响较小。