Hydrogen Absorption and Release Behavior in Hydrogen Decrepitation Process of Nd-Fe-B Alloys

The behavior of hydrogen absorption and release in hydrogen decrepitation (HD) process of Nd Fe B alloys were investigated. The results reveal that the reactivity and the amount of hydrogen absorption in HD process are related to the surface activity of the alloy so that the fresh and active surface has a higher efficiency. The presence of Nd rich phase at the grain boundary is an essential factor of the HD activity of the alloy at room temperature. On degassing, hydrogen is released from the HD powder continuously with increasing temperature. And the residual hydrogen is as low as 0 0015% at 1073 K, which shows that the hydrogen is almost exhaused. It is feasible to remove the hydrogen from the HD powder by heating treatment at the temperature of 523～723 K for 1 h prior to the magnetic field forming in order to decrease the harmful effect of hydrogen on the easy axis alignment of HD magnet.

MSSBAUER STUDIES ON THE HYDROGEN DECREPITATION AND DESORPTION OF Nd_(16)Fe_(76)B_8 MAGNET

Hydrogen decrepitation and desorption of the Nd16Fe76B8 magnet are studied by X-ray diffraction analysis and Fe Mossbauer spectroscopy. The results of the as-cast alloy samples treated under various hydrogen gas pressures at various temperatures are reported. A special hydrogenation- dehydrogenation treatment of the Nd- Fe- B cast alloy can produce excellent isotropic magnet powders and the treated sample has passed a hydrogenation- disproportion- recombination process. The effect of the presence of α- Fe in magnet powders is discussed.

Hydrogen Decrepitation of a Sm_2Fe_(17)Alloy

1.IntroductionThe rhombohedral compoundSmFeN(x=1～3)is currently attractinginterest due to its promise as a new perma-nent magnet material.Its magnetic proper-ties have been investigated in details.TheSm-Fe-N materials with quite good mag-

NdFeB铸块在HD工艺中的吸氢行为研究

采用真空感应炉熔炼合金 ,用不锈钢压力罐充入H2 进行HD实验 ,对NdFeB铸块在HD工艺中的吸氢行为进行了研究。研究发现 ,Nd FeB铸块在氢爆过程中明显存在孕育期 ,其吸氢过程分为 3个阶段 :慢速吸氢阶段、快速吸氢阶段和缓慢吸氢阶段 ;随氢气压力 (1～ 4× 10 5Pa)的升高 ,孕育时间缩短 ,吸氢更快 ,当压力达到了 2～ 3× 10 5Pa时 ,获得较好的HD效果 ;随铸块粒度的减小 ,孕育时间缩短 ,吸氢越彻底。研究同时发现 ,随温度的升高 ,NdFeB铸块吸氢越迅速 ,当温度升至一定程度时 ,孕育期消失 ,3 5 3K时吸氢效果最佳。

HD工艺在烧结NdFeB中的应用

综述了近 2 0年来氢爆工艺在烧结NdFeB中的研究及应用状况 ,叙述了氢爆工艺的原理和优点 ,以及NdFeB合金在吸氢过程中的断裂方式、主相磁性参数的变化情况、吸氢量和烧结过程中的脱氢规律 ,分析了合金表面状态、温度与压力、氢气量及扩散速度、α-Fe对HD工艺的影响 ,并就氢爆工艺的改进进行了展望。

异核氢分子离子HD^+在磁场中的哈密顿量

考虑原子核的运动,通过球极坐标和直角坐标向椭球坐标的变换,采用特殊的变换方法,对平行磁场中的异核氢分子离子HD+的哈密顿量进行推导,同时构造出绝热厄密共轭哈密顿算符.

氢分子离子HD^+的薛定谔方程的求解方法

从实验室坐标系下的氢分子离子HD+的哈密顿算符出发,考虑到原子核的运动以及电子与原子核之间的相互作用,讨论异核和同核氢分子离子HD+的薛定谔方程的Born-Oppenheimer近似求解方法和绝热近似求解方法,同时展示四种展开波函数的方法,其中包括B-splines技术的应用.

氢爆碎(HD)工艺对Nd-Fe-B磁体的制备、微结构和磁性能的影响

选用40HP和40SHP牌号合金铸锭分别采用氢爆碎和传统制粉工艺制备了烧结磁体,研究了氢爆碎工艺及烧结温度对磁体的微观组织和磁性能的影响。结果表明,HD工艺能明显提高NdFeB磁体的磁性能。

稀土永磁材料的HD工艺研究及应用

综述了HD工艺在稀土永磁材料中的研究及应用现状。阐述了HD工艺的原理、特点、优点以及稀土永磁材料氢化过程中的吸氢机理、断裂方式、吸氢量的变化规律。并对HD工艺的应用前景进行了展望。

Hydrogen Absorption of Nd-Fe-B Alloys

The technical parameters of HD process were studied, including the effects of temperature and neodymium contents on the incubation period of hydrogen absorption, hydrogen concentration and the rate of hydrogen absorbed. The results show that the incubation period is shortened and the rate of hydrogen absorbed is accelerated with rising temperature and surface area. These are attributed to the rising rate of hydrogen diffusion at higher temperature. The change of the incubation period and the rate of hydrogen absorbed have the similar trend resulted from the increasing content of the Nd-rich phase owing to the rising temperature. Moreover, the percent of the Nd-rich phase in the ingot can be calculated according to the total hydrogen weight gain.

Effect of HD Process on Microstructure and Hard Magnetic Properties of NdFeAlB Magnet

The effect of Hydrogen Decrepitation (HD) process on the magnetic properties and microstructure of sintered NdFeAlB magnet (HD magnet) was investigated. The results show that the coercivity of HD magnet is higher than that of traditional ball milling (BM) magnet, while the remanence and the maximum energy product of HD magnet are lower. Microstructure analysis shows that some fine un sintered powders are distributed at the grain boundaries of HD magnet. X ray diffraction (XRD) analysis reveals that the degree of easy axis alignment of HD magnet is lower. Some ideas to improve the current HD process were proposed.

HD Processes in the Production of SmCo_5 Permanent Magnets

The application of ‘extreme’ hydrogen-decrepitation (HD) process using high-pressure disproportionation was extended to Sm-Co5-type-alloy. The alloy with nominal composition of Sm36Co64 was treated under 1.0～2.0 MPa H2 pressure for several hours at room temperature for decrepitation. After disproportionation were high hydrogen pressures, the bulk alloys were disproportionated into particles with a size of 200. Investigations by powder X-ray diffractometer (XRD) showed, the after HD sample crystallized in the hexagonal CaCu5-type structure. The temperature dependence of pressure analysis (TPA) curve of the SmCo5 alloy showed that the hydrogen absorption temperature was about 150 ℃. Cylindrical sintered magnets of composition Sm36Co64 were prepared using HD ball milled, isostatic pressing, vacuum sintering and subsequent heat treatment. The demagnetization curves showed that the HD processes could improve the magnetic properties and squareness factor of the SmCo5 sintered magnet.

过氧化氢催化活化体系对HD消毒性能的研究

传统含氯消毒剂消毒效率高,但往往腐蚀性较强,对环境和人类健康有一定影响;含氧消毒剂尤其是过氧化物作为绿色消毒剂成为研究的热点。基于过氧化氢与胍类活化剂和金属盐催化剂反应生成更高活性物质的原理,以30% H2O2为主剂,考察有机活化剂氨基胍硫酸盐、金属盐催化剂钼酸钠以及表面活性剂等助剂对该体系消毒HD效果的影响,优化获得最佳消毒条件;在室温涡旋震荡条件下,消毒剂溶液与HD液滴体积比50:1,消毒反应15 min消毒率达到99.9%以上。

氢爆工艺对NdFeAlB磁体的微结构和永磁性能的影响

研究了氢爆工艺 (HD)对烧结NdFeAlB的微观结构与永磁性能的影响。用HD工艺制备的NdFeAlB烧结磁体 (HD磁体 )的矫顽力比传统球磨 (BM)工艺的高 ,但剩磁及磁能积较低 ;微观分析发现HD磁体的晶粒边界上存在有未烧结完全的磁粉 ;X射线衍射测试表明HD磁体易磁化轴的取向度较低。

高性能烧结NdFeB磁体的制备技术

采用鳞片铸锭、氢爆加气流磨制粉、脉冲场振动取向加橡皮模等静压成型等改进的技术在工业生产线上成功制造了N52高性能烧结NdFeB磁体.用X射线衍射仪、光学金相显微镜、透射电镜和扫描电镜研究了磁体的结构;用磁强自动记录仪测量了磁体的退磁曲线.实验结果表明,Nd29·0Pr0·5Ga0·2Fe69·1Nb0·2B1·0磁体室温磁性能达到Br=1·457T,Hci=1097kA·m-1,(BH)max=409kJ·m-3,且磁体的均匀性和一致性较好.

NdFeB合金选择氢爆的研究

对NdFeB合金的选择氢爆进行了研究。研究表明,在较低的环境温度和氢气压力下,通过事先对合金中富Nd相的吸氢量进行理论计算并对放入容器内的NdFeB合金量进行定量控制,NdFeB合金在吸氢过程中完全可以实现良好的选择氢爆。SEM观察表明,选择氢爆时其碎裂的方式均为沿晶断裂,爆裂后粉末中的主相晶粒均是单晶粒子,Nd2Fe14B主相晶粒内均无裂纹形成。与完全氢爆相比,选择氢爆后的晶粒较粗大,且较均匀,但细小晶粒较少。

不同工艺制备烧结NdFeB磁体的显微组织和磁性能研究

研究了利用速凝(SC)工艺以及速凝工艺结合氢破碎(HD)工艺制备NdFeB磁体的性能和微观结构。结果发现,单独引入SC工艺虽然保证了母合金α-Fe不析出,其成分不发生偏析,但是由于其特殊的微观组织结构,利用机械破碎的方法制粉容易使粉末多以多晶的状态出现,这不仅使磁体取向度降低,并使烧结磁体主相晶粒内分布有大量富钕相,这种现象必然影响到磁体的矫顽力。把SC工艺和HD工艺结合起来,可以有效地解决这个问题。

利用混合稀土制备稀土永磁体的工艺研究

用富含La,Se的混合稀土代替部分PrNd合金作为原料,按(NdPr)18.2(MM)13.6Fe66.22B1.08Cu0.2Al0.7(质量分数)进行配料,以甩带熔炼方式形成薄带状合金,合金经氢破碎后,用气流磨制成粉末,最后经压制、烧结得到一种廉价稀土永磁体。用磁性测量仪测量了样品的磁性能;用定氧仪考察了防氧化剂对粉体氧含量的影响,用SEM观察了烧结样品的组织形貌。该永磁体的剩余磁感应强度为1.16～1.2T,内禀矫顽力为960～1000kA/m,磁能积为248～264kJ/m3。该磁体性能与N33,N35钕铁硼磁体性能相当。

NdFeB合金吸氢过程的研究

氢破碎工艺作为烧结钕铁硼永磁体制作过程中铸锭粗破碎的新工艺,具有使主相破碎成单晶的独特优点。为了优化氢破碎工艺,主要研究了铸锭表面积、温度和钕含量对钕铁硼铸锭发生破碎的吸氢孕育期、平均吸氢量和吸氢速度的影响。结果发现,表面积增大,吸氢孕育期缩短。温度提高,孕育期缩短,吸氢速度加快,平均吸氢量稍有变化,这主要是因为温度的提高,增加氢扩散速度所致。而提高钕含量,孕育期同样缩短,吸氢速度加快,平均吸氢量增大,这与富钕相的增多有关。并且,可以通过吸氢量来计算铸锭中富钕相的含量。

蒽油两段加氢生产清洁燃料油技术

蒽油高氮、氧及芳烃含量给加氢技术提出了很多新的问题,为了解决这些制约蒽油工业化生产清洁燃料油的问题,本文提出中国石油化工股份公司抚顺石油化工研究院采用两段加氢工艺,在适宜的催化剂作用下,将蒽油转化为分子较小的芳烃和环烷烃,蒽油两段加氢总液收大于99.9%,其中汽油馏分收率约26.5%,柴油馏分收率约73.5%。实现了蒽油完全转化为清洁燃料油的目的,具备了工业长周期运转的可能。