Ce对Al4.5Cu合金流动性和热裂倾向的影响

研究加入稀土Ce对Al4.5Cu合金流动性、凝固收缩、微观组织和热裂倾向的影响。结果表明,适量稀土Ce的加入,降低金属液的黏度,提高合金流动性,减少金属在凝固过程中的收缩,抑制合金枝晶化的趋势,改善铸造合金的微观组织,净化合金,提高合金的导热率,明显地减少合金的热裂倾向。稀土Ce加入量为4%时,Al4.5Cu合金流动性最佳、凝固收缩量最小、合金晶粒组织细化圆整,同时其热裂倾向最小。     

混合稀土变质对Al—4.5%Cu合金热裂的影响

用对比的方法，研究了混合稀土变质处理对Ａｌ－４．５％Ｃｕ合金热裂倾向的影响。试验结果表明：混合稀土变质处理缩小Ａｌ－４．５％Ｃｕ合金有效结晶区间，减小合金的线收缩、净化合金、提高合金的导热率，从而有效地降低Ａｌ－４．５％Ｃｕ合金的热裂倾向，混合稀土加入量为０．２％时，裂纹的最大宽度和裂纹的总长度都出现最小值，合金的热裂倾向最小。     

铸造铝合金的流动性、热裂倾向性和收缩率研究

本研究采用单螺旋模具、约束棒模具和锥形模具对A356铝合金（简称：A356）和低硅铸造铝合金（Al3.5Si0.5Mg0.4Cu,简称：低硅铝合金）的流动性、热裂倾向性和体收缩率进行了评估与分析。研究结果发现：在相同的浇注工艺下,低硅铝合金的流动长度小于A356,热裂倾向性大于A356,且收缩率较大;当提高浇注温度至770℃时,低硅铝合金的流动性增加了28.8%,热裂敏感系数增大至76,收缩性增大4.6%。造成两种铝合金铸造性能差异的主要原因是二者元素含量不同,低硅铝合金由于Si含量的降低,其凝固范围较宽,凝固模式趋向于“糊状凝固”,且在“脆性温度区间”停留时间较长,故展现出了比A356较差的流动性和更大的热裂倾向性,收缩率也较大。     

Sn对Mg-Al-Ca系合金热裂敏感性的影响

为了研究Sn对Mg-Al-Ca系合金热裂敏感性的影响,通过Clyne-Davies模型对MgAl_7Ca_1Sn_x(x=0,0.5,1,2)系合金的热裂敏感性进行预测。采用"T"型热裂模具,对MgAl_7Ca_1Sn_x系合金凝固过程中的温度、收缩应力信号数据进行采集,研究热裂纹萌生和扩展的相关信息。利用X射线衍射(XRD)和扫描电子显微镜(SEM)分别对MgAl_7Ca_1Sn_x系合金显微组织和热裂断口区域形貌进行观察。揭示合金的凝固最后阶段剩余液相分数,脆弱区域的凝固温度变化,第二相种类等因素对Mg Al_7Ca_1Sn_x系合金热裂倾向的影响;合金热裂倾向从大到小顺序为MgAl_7Ca_1Sn_1MgAl_7Ca_1Sn_2MgAl_7Ca_1Sn_(0.5)MgAl_7Ca_1。其中,由于Mg Al7Ca1Sn1合金凝固温度区间最宽,脆弱区域的凝固温度变化最大,凝固最后阶段形成液膜最少,枝晶干涉点后析出的第二相阻碍枝晶间的补缩等多种原因使之热裂倾向最大。     

稀土处理铬镍钼铸钢在上海通过鉴定

随着现代工业的发展,铸造低合金钢的用量正与日俱增,但由于该钢存在合金元素偏析大、导热性较低,从而使该材料铸件裂纹倾向较为严重.上海工程技术大学接受了上海市稀土办布置的“稀土对低合金高强度铸钢热裂倾向性和机械性能影响的研究”课题,该校进行了近二年的试验,表明:1.钢中添加0.04～0.1%混合稀土金属可显著提高钢的抗热裂性.2.微量稀土的加入,对低硫钢高温回火状态的韧塑性产生有利影响.经上海大隆机器厂大炉试验,用稀土处理铬镍钼钢不仅提高抗热裂倾向,并增加钢液流动性,提高铸件焊接性能.     

Er和Ce对铸造ZL101A铝合金组织与力学性能的作用对比研究

在ZL101A铝合金中分别加入稀土元素Er和Ce,比较加入两种稀土后合金的组织和力学性能方面的差异。结果表明：在α-Al和共晶Si方面,Er的细化作用明显优于Ce,加入Er可在ZL101A铝合金中形成更加细小和弥散分布的稀土化合物相,使合金的力学性能有较大程度的提高,其ZL101A (Er)合金的抗拉强度达到188 MPa,伸长率是6.7%,高于ZL101A (Ce)合金。     

稀土La对(Ag-Cu8)-25Sn-xLa合金微观结构及凝固机制的影响

研究了稀土La对(Ag-cu28)-25SnxLa合金微观结构的影响,并探讨了稀土La含量的变化在其凝固过程中的作用.采用高频感应加热熔炼,经水淬制得(Ag-Cu28) -25Sn-xLa合金.通过XRD,SEM,EDS等分析手段,研究了合金的物相组成、凝固组织及元素分布情况.研究结果表明:微量的稀土La足以改变(Ag-Cu28) -25Sn合金的凝固过程；La含量不大于0.5％时,合金的物相组成为Ag3Sn,Cu3Sn和Cu6Sn5相；当La含量不小于1.0％(质量分数)时,合金的物相组成为Ag3Sn和Cu3Sn；同时,随La含量的增加合金的凝固组织不断细化,且有利于Ag(Sn)固溶体初生相的析出.     

锌基热镀合金的流动性能分析

采用金属型螺旋线试样测量纯锌及锌基热镀合金的流动性,以10℃为一个温度梯度,测量了420-510℃之间的流线长度数值。分析了液态金属流动性的影响因素,在锌液中加入0．3％（质量分数）的稀土合金,探讨了合金成分对流动性的影响。研究发现加入0．3％的稀土合金后,在相同温度下,合金的流动性比纯锌有明显提高。     

稀土在铝及铝合金中的应用现状与展望

稀土（RE）是十分活泼的金属。稀土元素作为微量元素加入铝合金中，可以净化合金熔体、减少夹杂．细化、变质微观组织；作为合金元素加入适量稀土可显著提高铝合金的综合性能。本文讨论了稀土在铝及铝合金中的作用机理，论述了稀土在铝及铝合金中的开发应用现状．展望了稀土铝合金的发展前景。     

7xxx系铝合金凝固过程中收缩行为的测定

应用自主设计的测量装置对7xxx系铝合金凝固过程中的收缩行为进行了系统的测量。主要研究了3种7xxx系铝合金的收缩行为和微观组织对热裂敏感性的影响。研究发现,在凝固过程中,3种7xxx系铝合金表现出了非常不同的收缩行为。7050和7075铝合金的热膨胀系数曲线从收缩起始点(固相率fs分别为0.69和0.73)开始陡然增加至峰值,之后随着温度的降低减小至一个常数值;7022铝合金的热膨胀系数曲线与以上两种不同,从收缩起始点(固相率为0.8)开始先出现一个波动上升,其后随着温度降低数值单调递增。微观组织显示,收缩过程的起始点是枝晶搭接的开始点。凝固过程中,7050合金的热膨胀系数大于7022合金,可以认为凝固过程的收缩行为能作为热裂敏感性的一种判断准则。     

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。     

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.     

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。     

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.     

参与式农业基地建设行动方案设计

为了编制实用性强的基地建设行动方案,首先,确定参与式发展的主体,搭建一个"决策框架";其次,针对行动目标,提出不同参与主体,如管理者、农民、消费者等团队与个人的目标及行动内容;最后,工作应向重塑伙伴式合作关系,挖掘农民自我发展潜力,完成三大角色的转换,打造农业基地文化等方向推进.