稀土在硬质合金球形粉末烧结体表面富集现象的观察

采用合金粉末烧结体表面观察法研究了稀土在WC-Co硬质合金中的作用机理。合金中的稀土分别以混合稀土(以La和Ce为主体成分)-Co预合金粉(简称RE-Co预合金粉)形式和La(NO3)3的丙酮溶液形式在湿磨时直接加入。用扫描电镜和能谱仪对平均粒径小于200μm的2种球形稀土硬质合金粉末(简称合金粉末)烧结体表面进行观察与分析,发现:以RE-Co预合金粉形式加入稀土时,在烧结过程中,合金中的稀土La和Ce以及杂质元素在合金粉末烧结体表面产生了明显的富集,形成了含La,Ce,S,Ca,W,C和O的复杂形式的化合物,在稀土富集物中没有检测到Co。以La(NO3)3形式加入稀土,在合金粉末烧结体表面没有检测到La。说明在合金粉末烧结体表面不存在La的富集或聚集。稀土的添加形式同时也影响合金粉末烧结体表面硬质相WC与粘结相的比例,以RE-Co预合金粉末形式加入稀土,合金粉末烧结体表面粘结相含量较少,因此,稀土的添加形式影响其在硬质合金中的作用机理。以RBCo预合金粉形式加入稀土,合金中的稀土不但具有较好的富集合金中杂质元素的作用,而且还可以阻止烧结体表面富粘结相结构的形成。     

稀土电解厂的设计及实践

前言Preface 混合稀土金属（RE）是由两个以上稀土元素组成的合金。如有的RE中含有La、Ce、Pr和Nd，有的RE中含有La、Ce、Pr。由于这两种混合稀土合金均有良好的特性，故在工业生产中得到了广泛应用。如用RE作为钢的净化剂（制成稀土钢）；在有色金属生产中用作添加剂（制成RE-Al，RE-Cu等合金）；RE与Fe可以生成稀土发火合金（用于制造打火石）；     

ICP-AES法测定钢中稀土夹杂物La,Ce,Pr,Nd,Sm含量

采用ICP-AES测定钢中稀土夹杂物La,Ce,Pr,Nd,Sm含量.确定了电解制度、优化了仪器工作条件、选择了元素最佳分析谱线.方法准确、快速、简便.     

富稀土合金添加对烧结(MM,PrNd)-Fe-B微观组织和磁性能的影响北大核心

本文采用粉末冶金工艺制备了含有混合稀土的烧结(MM,PrNd)-Fe-B磁体,并研究了富稀土合金添加对磁体微观组织和磁性能的影响。未添加富稀土合金的MM_(7)(PrNd)_(24)Fe_(74.99)B_(1.01)磁体晶界相中存在La、Ce元素聚集现象,添加6%的(PrNd)_(41)Fe_(57.99)B_(1.01)富稀土合金能够部分消除这种聚集现象,同时矫顽力从11.15 kOe提高至11.98 kOe。微观分析表明,添加富稀土合金后,磁体具有双主相结构。晶界中的La、Ce会置换(PrNd)(2)Fe_(14)B主相中Pr、Nd元素,同时Pr、Nd会置换(MM,PrNd)(2)Fe_(14)B主相中La、Ce元素。晶界中La、Ce元素的均匀分布和双主相结构有助于提升磁体的矫顽力。     

La0.65RE0.10Mg0.25Ni3.5Si0.15(RE=La,Ce,Pr,Nd,Sm)储氢合金的电化学性能及EIS分析

通过感应熔炼制备La0.65RE0.10Mg0.25Ni3.55i0.15(RE =La,Ce,Pr,Nd,Sm)合金.采用X射线衍射方法分析了合金的相结构,研究了其电化学性能,并采用电化学阻抗谱分析了合金电极的放氢动力学特性.研究结果表明,合金是以LaNi5、LaNi3为主相的多相结构,同时合金中少量的Si元素与Mg和Ni元素形成了少量的Mg2 Si相和Ni2Si相.Ce,Pr,Nd,Sm部分替代La以后,合金的放电容量下降,Ce的替代使合金容量大幅度降低.对于本系列合金,La被其他稀土元素部分替代后,合金经过100次循环后的容量保持率略有下降,但除了Pr元素以外,变化值均较小.合金电极的电化学阻抗谱分析表明,中低频区的容抗弧半径依次为Ce ＞La＞ Nd ＞Sm ＞Pr,这表明采用Nd、Sm、Pr替代La后合金电极在碱液中放电过程电荷传递电阻Rct减小,即合金表面活性增加,但Ce替代却导致Ret急剧增大,这可能与Ce在碱液中易形成氧化物降低了合金的表面活性有关.     

稀土电解厂的设计及生产实践

1、前言 混合稀土金属（RE）是由两个以上的稀土元素组成的合金。如RE中含有La、Ce、Pr和Nd，或RE中含有La、Ce和Pr。因这两者均具有良好的特性，故在工业应用中获得了较好的用途。如RE作为钢的净化剂（制成稀土处理钢）。在有色金属中为添加剂（如RE-Al，RE-Cu等合金）。RE-Fe生成稀土发火合金（大量用于制造打火石）。电热合金的加入物（如RE-Fe-Cr-Al合金用于电热丝）。     

掺杂稀土的高速钢预合金粉对WC基钢结硬质合金组织和性能影响

钢结硬质合金是一种性能介于硬质合金与高速合金钢的材料,可以取代部分传统硬质合金与工模具钢在模具和切削刀具领域的应用。本研究采用气雾化法制备稀土掺杂高速钢预合金粉作为钢结硬质合金的粘结相,制备了掺杂稀土的WC基钢结硬质合金,用扫描电子显微镜观察了样品的显微组织和断口形貌,并对合金的密度、硬度、抗弯强度和冲击韧性进行了检测。研究结果表明,在高速钢预合金粉中掺杂稀土元素能提高WC基钢结硬质合金的密度,改善其硬度、抗弯强度、冲击韧性等力学性能;添加Ce元素的效果好于Y元素;采用掺杂稀土元素Ce的高速钢预合金粉制备的WC基钢结硬质合金力学性能优于传统球磨混料法掺入稀土元素Ce制备的WC基钢结硬质合金。     

萃取流量参数对稀土槽分布的影响

以国内某稀土厂生产萃取线A的La/CePr/Nd萃取过程为研究对象,通过采集和分析萃取槽各级有机相和水相中稀土元素的含量,明确不同皂化有机相流量、料液流量、酸流量等条件对各级稀土元素含量分布和稀土总量的影响。适当提高皂化有机相流量、料液流量和酸流量,可使水相出口处La的含量较高,从而保证出口产品纯度,但会使55级有机相出口处有机相中Ce组分含量较高,Pr、Nd组分含量较低,增加下一系列分离Pr、Nd的压力。     

稀土掺杂NiCrSi高阻靶材制备及镀膜性能研究

采用真空热压烧结法制备稀土掺杂NiCrSi高阻合金靶材。利用X射线衍射仪、金相显微镜、扫描电镜、EDS能谱仪等表征手段测试分析靶材物相组成、显微组织及微区元素分布。同时将所制备靶材溅射沉积金属膜电阻器,研究稀土元素掺入种类对电阻器阻值稳定性的影响。结果表明,稀土掺杂NiCrSi高阻靶材由基体相CrSi_2和少量的CrSi、Ni_3Si相混合而成。靶材外观平整无裂纹,组织致密无孔隙,相对密度均在96%以上;晶粒尺寸约为20μm,大小分布均匀。掺入La、Ce、Pr、Nd后,靶材组织中Zr析出相减少,Zr元素偏聚分布得到显著改善。溅射沉积的金属膜电阻器电阻温度系数小于±25×10~(-6)/℃;与未添加稀土元素的NiCrSi电阻器相比,加入Pr后,电阻器电阻温度系数在高低温区差值降至22×10~(-6)/℃左右,变化幅度小,阻值稳定性高;加入Nd后,电阻温度系数差值变化幅度大,阻值稳定性较差。     

稀土尾矿库周边植物碱蓬对稀土元素的吸收与生物富集作用

为研究稀土尾矿库周边植物碱蓬对4种稀土元素(La、Ce、Pr、Nd)的吸收和富集特征,以广泛分布于稀土尾矿库周边的碱蓬及其根区土壤为研究对象,用ICP-MS法分析土壤中La、Ce、Pr、Nd、Sm、Gd的含量和碱蓬各器官中La、Ce、Pr、Nd的含量,并对土壤进行了污染评价。结果表明,土壤中6种稀土元素的平均含量顺序为:CeLaNdPrSmGd,其数值分别为7826.9 mg/kg、4117.8 mg/kg、2251.0 mg/kg、1393.3 mg/kg、240.1 mg/kg、217.0 mg/kg,且稀土尾矿库周边土壤受到了严重的稀土元素复合污染;碱蓬对La、Ce、Pr、Nd的吸收没有特别的选择性;碱蓬对La、Ce、Pr、Nd的转移能力和耐受力较强,且碱蓬植物体内积累了较多的稀土元素,所以碱蓬在一定意义上可用于该地区稀土元素污染土壤的修复;在采样点GW-1～GW-11中,碱蓬各器官中La、Ce、Pr、Nd的含量水平为根叶茎;在采样点GW-12～GW-18中,碱蓬各器官中La、Ce、Pr、Nd的含量水平为根茎叶,即La、Ce、Pr、Nd主要分布于碱蓬根部;相关性分析表明,碱蓬各器官中的稀土元素大部分来源于其根区土壤;在采样点GW-1～GW-18中,碱蓬对La、Ce、Pr、Nd转移系数的平均值分别为0.976、1.013、0.897、0.944,说明稀土尾矿库周边的碱蓬对稀土元素的转移能力顺序为:CeLaNdPr;碱蓬对La、Ce、Pr、Nd富集系数的平均值分别为0.117、0.153、0.108、0.149,说明稀土尾矿库周边的碱蓬对稀土元素富集能力顺序为:CeNdLaPr。     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of rates of infection of two methods of emergency ventricular drainage

The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies.     

浅析《野草》的版画特征

鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美".     

四辊破碎机车刀架的改造

针对四辊破碎机车刀架车削中存在的几个问题,详细介绍了电动车刀架的结构和工作原理,建立主要设计参数的数学表达式,并进行适当的分析。改造后,这种电动车刀架运行平稳、可靠、方便、省力,取得了预期的效果。     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

Results of treatment of cancer of the cardia

Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients.     

焦炭热性能指标意义浅析

通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。     

Comparison of the results of surgical and conservative treatment of fractures of the diaphysis of the tibia

In this paper is treated the fundamental problematic of the fracture of the diaphysis of the tibia and the therapeutic results after the conservative and operative treatment are confronted. Among 518 patients with 433 open fractures and 35 with closed fractures of the diaphysis of the tibia, successful treatment of more 2/3 was obtained in the period from 1968 to 1972. Following our casuistics and literature, whose results are similar, we find out that the average total treatment of the osteosynthesis of the fracture of the diaphysis was shortened for 2,5 months depending upon the type and the localisation of the fracture. Apolied methods of the operative and conservative and conservative treatment in relation to the velocity of the medical cure as well as to the extreme anatomical-functional results are analised. We noticed that osteosynthesis, made by the intermedullary nail and the extension of the canals or by a small AO table, by the achieved stability makes conditions of immediate motions and an early rehabilitation. Because of that it gives the best functional results.