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NdFeB磁体的烧结过程研究 总被引:1,自引:0,他引:1
研究了在真空和氩气中烧结对NdFeB磁体磁性能和微观组织的影响.结果发现:经真空烧结的磁体磁性能有较大的个体差异,而在氩气中烧结的磁体磁性能则基本均匀一致,与前者相比,其剩磁平均值高0.05~0.09 T,内禀矫顽力要高1.6 MA/m左右,磁能积约高40 kJ/m3.SEM照片显示,在氩气气氛中烧结的磁体的微观组织更加均匀,而经真空烧结的磁体则有较多的缺陷. 相似文献
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采用速凝薄带加氢破碎法制备了烧结NdFeB永磁体,通过光学显微镜、扫描电镜以及AMT—4磁学特性测量仪表征了磁体的组织和性能,考察了烧结温度对磁体组织和性能的影响规律。结果表明:随着烧结温度的升高,磁体的致密度升高,剩磁、矫顽力、最大磁能积先增大后减小,其原因是随着烧结温度的升高,主晶相晶粒长大,富钕相分布更加均匀;当烧结温度超过某一值时,磁体的组织不均匀,富钕相发生团聚。 相似文献
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将烧结NdFeB磁体进行机械破碎,得到粒径大小运用于制备粘结磁体的磁粉,其矫顽力很低.在700~1050℃的温度范围内进行热处理.实验结果表明:适当地选取热处理温度,可以显著地提高磁粉矫顽力,使其成为各向异性的高性能磁粉.用光学显微镜及SEM对热处理前后磁粉的形态进行了观察.未经热处理的机械破碎磁粉,颗粒边缘地区很细碎,并且有很多裂纹,中心区域则相当完整.热处理后,磁粉的边缘区域裂纹明显减少并趋于平整,同时出现明显的稀土及其氧化物的富集区.这表明,热处理过程中磁粉可能发生了氧化,或者是将吸附的氧转化成了稀土氧化物. 相似文献
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试验探讨了粉末注射成形方法制备2∶17型SmCo磁体在烧结时Sm的挥发与氧化对烧结后组织的影响。结果表明:当烧结炉的真空度良好(≥5×10-3Pa)时,Sm的挥发使烧结组织呈现清晰的层状结构,外层成分严重偏离设计成分,X射线分析显示为Co0.7Fe0.3及Fe2O3结构,从而影响内部组织的致密化。而当烧结炉的真空度较低(<1×10-2Pa)时,Sm的挥发与内部氧化的共同作用,使组织形成多层结构,Sm与氧元素的分布规律基本一致,而挥发的Sm与氧结合生成白色粉末状的Sm氧化物沉积在烧结炉中。烧结组织中层状结构的存在抑制烧结过程中心部的致密化,是导致烧结坯体的致密度较低的重要原因。 相似文献
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结合国内烧结Nd-Fe-B磁体工业生产过程,研究了压制成型时生坯密度变化对烧结Nd—Fe—B磁体致密化程度、显微组织、取向度与磁性能的影响。试验结果表明,生坯密度的提高可促进烧结致密化过程,抑制烧结过程晶粒的不均匀长大,提高取向度,改善磁性能。 相似文献
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Nd-Fe-B磁体烧结致密化过程的研究 总被引:1,自引:0,他引:1
定量描述了Nd-Fe-B磁体的烧结致密化过程, 分析了有效稀土含量、合金粉末粒度与烧结致密化过程的关系, 讨论了Nd-Fe-B磁体烧结过程的致密化机制. Nd-Fe-B磁体烧结致密化过程可分为3个阶段, 即致密化过程迅速进行阶段、缓慢进行阶段、相对稳定阶段;随着烧结温度的上升, 第一阶段表现得更为突出, 第二阶段对应的烧结时间区段大大缩短. 有效稀土含量的提高、合金粉末粒度的减小显著促进Nd-Fe-B磁体烧结致密化过程. 主相颗粒重排以及主相颗粒长大与形状适位性变化是Nd-Fe-B磁体烧结过程的两类主要致密化机制, 而且后者对于Nd-Fe-B烧结磁体实现完全致密化起着决定性的作用. 相似文献
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研究了不同成分的烧结Nd-Fe-B磁体在恒定湿热和中性盐雾腐蚀环境中的腐蚀动力学行为,讨论了不同合金成分和腐蚀条件对磁体腐蚀速率的影响,探讨了烧结Nd-Fe-B磁体在不同介质中的电化学行为.结果表明:烧结Nd-Fe-B磁体在湿热环境中的重量变化表现出明显的抛物线衰减规律,而在盐雾腐蚀环境中的重量变化表现出先增后减的规律.以重稀土Dy替代少量Nd,并添加少量Co等元素,可以提高烧结Nd-Fe-B磁体的耐湿热和耐盐雾腐蚀性能. 相似文献
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Microstructure and corrosion resistance of sintered Nd15Dy1.2Fe77Al0.8B6 and Nd22Fe71B7 magnets modified by intergranular addition of MgO and ZnO were investigated. Both the remanence and sintering density of the magnets increased slightly with intergranular additions of MgO and ZnO. There was a remarkable increase in coercivity of Nd22Fe71B7 after addition. Besides, the effects on magnetic properties and an improved corrosion resistance were observed. Compared with the native magnets without addition, corrosion potential of the magnets with MgO and ZnO additives was more positive and the current density in the anodic branch of the polarization curve was reduced. Corrosion resistance resulting from autoclave testing (2×10^5 Pa of steam pressure, 120 ℃) showed that the corrosion rate of NdFeB magnets reduced with the increase of additive amount. Microstructure observation revealed that MgO and ZnO additives were incorporated into the intergranular phases in the magnets. With the introduction of MgO and ZnO, more intergranular phase with high oxygen content was formed while keeping the volume fraction of all the intergranular phases almost unchanged, which may contribute to improved corrosion resistance. Furthermore, addition of MgO and ZnO refined the grain size of Nd22Fe71B7. 相似文献
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In this work, the corrosion behavior of the surface parallel to the oriented c-axis(c‖) and perpendicular to c-axis(c⊥)in the(Ce_(0.15)Nd_(0.85))_(30)Fe_(bal)B dual main phase magnet was studied. With the addition of Ce,the volume fraction of RE-rich phase shown in the backscattered electron(BSE) images is basically approximate on the two surfaces. The free corrosion potential(E_(corr)) of the c‖ surface is more negative,which shows the worse corrosion resistance from the perspective of thermodynamics. While the reaction kinetics parameters with the smaller free corrosion current(i_(corr)) and the larger transfer resistance(R_(ct)) react the opposite conclusion in 3.5 wt% NaCl solution. Moreover, the c‖ surface performs smaller ions concentration of corrosion product and less damaged corrosion morphology compared to c⊥ surface after the free corrosion. The inconformity is not affected by the RE-rich phase, but by the anisotropy of the grains that the c‖ surface has larger density of the atoms and the lower ratio of(Nd, Ce)/Fe. 相似文献
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《粉末冶金学》2013,56(2):151-155
AbstractAs sintered parts are to be machined after sintering, the MnS powder is usually added to improve the machinability. Vibratory ball peening is used for deburring and improving the surface finish of sintered components in local PM industries. The effect of the MnS powder content and vibratory ball peening on the corrosion resistance of the sintered 316LSC alloys was investigated. Experimental results show that the addition of MnS powder slightly decreases the sintered density. The weight loss rate of the sintered specimens immersed in the 10%FeCl3 corrosion test solution increases slightly with increas- ing MnS content, but decreases with increasing sintering temperature. Vibratory ball peening effec- tively decreases the weight loss rate of the sintered stainless steels. The chromium atoms actively migrate across the phase boundary and diffuse into the MnS particles during sintering. This intensive chromium diffusion affects the corrosion performance of the sintered alloys with MnS added. The surface morphology of the as sintered and the ball peened specimens before and after the corrosion test were studied with a SEM. 相似文献
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Jinghui Di Shuai Guo Ling Chen Pengpeng Yi Guangfei Ding Kan Chen Ming Li Don Lee Aru Yan 《中国稀土学报(英文版)》2018,36(8):826-831
The effects of Ho substitution for Nd on the microstructure, corrosion resistance and thermal stability of the Nd-Fe-B magnets were investigated. The(Nd,Ho)-O phase was formed with increasing Ho substitution. The results of potentiodynamic polarization and highly accelerated stress test show improved corrosion resistance with increasing Ho substitution. The optimum mass loss 0.29 mg/cm~2 is achieved.Moreover, the average temperature coefficients for remanence and coercivity in the range of 25-150℃are both closer to zero, indicating improved thermal stability. The mechanisms for the improved corrosion resistance and thermal stability are discussed in relation to the microstructure featuring the(Nd,Ho)-O phase. 相似文献
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概述了烧结NdFeB系永磁材料矫顽力的影响因素及其理想微结构,并着重介绍了采用添加元素和新工艺提高其矫顽力的方法。 相似文献
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Nd-Fe-B permanent magnets with a small amount of Al nano-particles doping were prepared by conventional sintered method. Effect of Al content on magnetic property, corrosion resistance and oxidation properties of the magnets were studied. Investigation showed that the coercivity rose gradually, while the remanence decreased simultaneously with increase of Al doping amount. Further investigation revealed that most Al element diffused into the main phase and some Al element diffused into the Nd-rich phase. The autoclave test results showed that the corrosion rate of the magnets decreased with Al content increasing. After oxidation, the maximum energy product losses of the magnets with 0.0 wt.% and 0.2 wt.% Al nano-particles doping were 6.13% and 3.99%, respectively. Therefore, Al nano-particles doping was a promising way to enhance the coercivity and corrosion resistance of sintered Nd-Fe-B magnet. 相似文献
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电弧离子镀ZrN/TiN涂层对烧结NdFeB的耐腐蚀及磨损性能的影响 总被引:1,自引:0,他引:1
为了提高粉末烧结磁体NdFeB的耐腐蚀性能和耐磨损性能,采用电弧离子镀的方法在其上沉积制备了ZrN/TiN多层涂层。观察涂层的成分与显微组织,分析了涂层对烧结磁体耐腐蚀性能及磨损性能的影响。结果表明:电弧离子镀氮化物多层涂层与烧结磁体生成一过渡层,膜基结合强度高;涂层提高了磁体的耐腐蚀倾向,降低了腐蚀电流,腐蚀速率降低2个数量级;磁体在5%盐水中10h后才出现失重,涂层保护效果明显;磁体表面涂层的硬度15~20GPa,摩擦系数0.5,耐磨损性能提高。 相似文献
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《中国稀土学报(英文版)》2020,38(7):735-741
Sintered(Ce,Nd)-Fe-B magnets with high cost performance were prepared by substituting of Ce for Nd with the dual-main phase method.The corrosion behaviors of dual-main phase sintered(Ce_xNd_(1-x))_(30)Fe_(69)B_1(x=0.15 wt%,0.3 wt%) magnets,which were named as Ce15 and Ce30,were studied in 3.5 wt% NaCl,6.6 wt% Na_2 SO_4 and 3.0 wt% NaOH aqueous solutions,respectively.The galvanic corrosion of Ce30 is stronger than that of Ce15.However,the mass loss value of Ce30 is smaller than Ce15 after free corrosion for 33 d in NaCl solution.In the other two solutions,all the results show that the corrosion resistance of Ce30 is better than that of Ce15.The scanning electron microscope results show that the crack and shedding of the magnetic phase of Ce30 is less than that of Ce15.Combined above,the abnormal corrosion behavior shows that Ce30 magnets perform better corrosion resistance than Ce15,and the degradation degree of magnetic phase mainly affects the corrosion resistance of magnets. 相似文献
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A.Ali A.Ahmad K.M.Deen 《中国稀土学报(英文版)》2009,27(6):1003-1007
Sintered NdFeB magnets have complex microstructure that makes them susceptible to corrosion in active environments.The current paper evaluated the anticorrosion characteristics of multilayer titanium nitride ceramic coating applied through cathodic arc physical vapour deposition(CAPVD) for protection of sintered NdFeB permanent magnets.The performance of ceramic coating was compared to the electrodeposited nickel coating having a copper interlayer.Electrochemical impedance spectroscopy(EIS) and cyclic polar... 相似文献