河北工业大学
95215232
硕士学位论文
双合金法制备高性能烧结钕铁硼工艺研究 姓名:张志清 申请学位级别:硕士
专业:材料工程
指导教师:崔春翔;田藏韬
20070501
双合金法制备高性能烧结钕铁硼工艺研究
摘 要
烧结NdFeB作为第三代稀土永磁材料,自1983年被发现以来,以其高性能(理论磁能 积为64MGOe 、高性价比得到迅猛发展。我国是稀土大国,稀土资源占世界储量的80%,这 是我们 发展稀土永磁材料的最大优势。然而,我国大多数企业的生产技术水平远远落后于 日本和欧美,产品档次也不高,在市场竞争中处于不利的地位,因此,提高烧结NdFeB磁 体的性能档次,是许多烧结NdFeB生产企业必须面对的问题。在公司现有设备条件下,如 何使烧结NdFeB磁体性能达到最高,这是本课题研究的出发点。 本课题从 NdFeB 合金铸锭的组织分析入手,采用双合金工艺,制粉采用氢爆工艺,有 效控制工艺参数,以获得磁性能最佳的烧结磁体。
柴油机起动器对 NdFeB 合金铸锭的组织分析表明, 现有的冶炼设备生产的铸锭, 在稀土含量降低时,
析出大量α-Fe。铸锭中α-Fe相的存在,不仅减少了铸锭中Nd 2 Fe
14
B相生成数量,还对后续
热镀锌合金的制粉、成型工序产生不良影响,特别是严重危害烧结钕铁硼磁体的性能,具体表现在磁 体的剩磁、磁能积没有因合金中稀土含量的减少而提高,磁体内禀矫顽力亦受到影响。为 此,
采用真空高温退火的方式消除铸锭中α-Fe。用退火后的铸锭直接制备烧结磁体,磁 体的剩磁、磁能积显著提高,但内禀矫顽力比较低。
为此,采用双合金工艺提高磁体的矫顽力。主合金成分接近Nd 2 Fe
14
B相,辅合金是富钕
相。主合金经高温退火消除α-Fe。主、辅合金经氢爆破碎后,按一定的比例进行混合后, 气流磨制粉,磁场取向成型,烧结、回火,制成烧结磁体。
通过对氢爆工艺粉末及磁体组织的分析,采用氢爆破碎,有效改善粉末的性质,提高 磁体性能。
对双合金磁体的烧结、回火工艺的研究,双合金磁体的烧结温度高于传统磁体的烧结 温度,确定最佳的烧结温度为 1105℃,最佳回火温度为 520℃。
对主、辅合金混合比例对磁性能的影响进行分析,当比例为 93:7时,双合金的名义
paas系统
成分为Nd 30.23 Pr
1.05
Dy
220v交流稳压器
0.7
B
1.07
Nb
0.279
Al
0.186
Cu
0.07
Fe
66.415菌类生产
(wt% 时, 双合金磁体达到了磁能积 45MGOe,
内禀矫顽力 13.8kOe的最佳磁性能。
关键词 :双合金, 烧结钕铁硼 ,氢爆 ,磁性能
i
ABSTRACT
Since sintered Nd-Fe-B alloys have been found in 1983, as the third generation of rare-earth permanent-magnet material, because of its high performance (the theoretical magnetic energy product is 64MOeand the high cost performance ratio it has been devel
oped rapidly. we are rare-earth rich country, which occupates 80 percents of the world storage capacity, and which is our biggest dominance in the development of rare-earth permanent-magnet material. However, the manufacturing technique in most of our industry fall behind of Japan and America, and the products quality is not so good, which leads to the disadvantage in the market competition. As a result, increasing the performance of sintered Nd-Fe-B magnets is a problem that many industry must face. On the base of the existing equipments, how to improve the performance of sintered Nd-Fe-B magnets is the departure point of this article.
In order to obtain the best magnetic performance sintered magnets ,At beginning of this article the structure of Nd-Fe-B alloy cast ingots were analysied. Binary alloy technology ,controlling the technology parameter effectively and HD process were also empolyed.
The analyse on the structure of Nd-Fe-B alloy cast ingots indicates that the cast ingots produced by existing melting equipments will precipitate much α-Fe when the percentage composition of rare-earth depresses.The existence of α-Fe in cast ingots,not only decrea
ses the numerical measure of Nd2Fe 14B phase in cast ingots,but also has bad influence on the latter powder-making and shaping process,especially disserves the performance of sintered Nd-Fe-B magnets severitily which expressed specificly in the departments that the remnant magnetism and magnetic energy product don’t increase as the result of the decrease of the rare-earth content,and the intrinsic coercive force is also influenced.Therefore,adopting the manner of vacuum high temperature annealing can cancel α-Fe in cast ingots.By using the cast ingots after annealing to make sintered magnets directly ,the remnant magnetism and magnetic energy product increase significantly,but intrinsic coercive force is relatively low.
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