ZA27铸造合金的凝固特性

研究了ZA27铸造合金中的常见微量元素以及铸件厚度、浇注温度、变质处理对ZA27合金凝固特性的影响。实验结果表明,铸件厚度是影响ZA27合金凝固特性的最主要因素,适量的Ti可以改善ZA27合金的凝固特性,浇注温度及变质处理对ZA27合金的凝固特性也有不同程度的影响。根据实验结果,推荐了较佳工艺参数。     

复合变质处理对ZG85Cr12MoNi组织和性能的影响

ZG85Cr12MoNi是一种耐磨性能优良的合金钢,但组织中共品碳化物量较多,脆性较大,应用于承受冲击的工况下身发生断裂,为提哀其抗断裂能力,研究了钾、钠稀土和钛复合变质处理对其组织和性能的影响。结果表明,ZG85Cr12MoNi经钾、钠、稀土和钛复合变质处理后,组织细化,共晶碳化物由条块状变成团球状,分布趋平均匀,冲击韧性和断裂韧性大幅度提高,热疲劳性能也明显改善,用作轧机导卫板使用安全,寿命比高铬铸铁和高镍铬合金分别提高300％和35．6％。     

铸造ZA27合金固态组织转变特征的研究

ZA27合金固态转变非常复杂,而固态转变对其合金的性能有直接影响。ZA27合金的固态转变主要包括共析转变和脱溶,脱溶过程又有调幅转变和时效过程中过饱和析出。用TEM、STEM对ZA27合金铸态微观组织转变,成分分布等进行测试和分析研究,提出了一些新见解。这对控制组织提高性能提供了依据。     

Fe元素对ZA27合金显微组织和力学性能的影响

在ZA27合金中添加0.5%~2%的Fe元素,利用金相、扫描电镜(SEM)、能谱分析(EDS)、X射线扫描(XRD)、拉伸实验等测试手段,研究Fe含量对ZA27合金显微组织和力学性能的影响。结果表明:不同Fe含量的ZA27合金基体组织均由富铝的α相和富锌的η相组成。Fe元素以FeAl3金属间化合物的形式分布于基体中。随Fe含量增加,FeAl3的含量增多、尺寸增大。FeAl3能阻碍晶界迁移,起到细化枝晶的作用。研究还发现,室温下,随Fe含量增加,ZA27的强度和伸长率均降低;150℃高温下,Fe含量为1.5%左右的ZA27合金抗拉强度达192.75MPa,比未加Fe元素的ZA27合金提高约54.4%,伸长率达15.65%,从而获得兼具高强度和高塑性的高温ZA27合金。     

高强高阻尼Mg-Zr系合金的研究(Ⅰ)——Ca/Y变质处理Mg-O.6Zr合金阻尼行为的研究

采用动态机械热分析(DMA)技术研究了Ca/Y变质处理对Mg-0.6Zr合金阻尼行为的影响,分析了合金随应变振幅和温度阻尼变化的机制.结果表明,添加0.3%Ca和0.3%Ca+0.1%Y(质量分数,下同)变质处理后的细晶强化和固溶强化作用提高了合金的拉伸强度和延伸率,同时由于Ca/Y元素的加入及晶界数量增多对位错运动的进一步阻碍作用降低了合金的应变振幅效应,从而降低了其阻尼性能;研究还发现Mg-0.6Zr合金在温度为75 ℃处出现一个明显的阻尼峰,而添加0.3%Ca+0.1%Y变质处理后,并未出现阻尼峰.分析认为,试验合金的阻尼机制可按G-L位错钉扎模型和晶界面软化及粘性滑动机制解释.     

SiCP/ZA22复合材料组织及性能

对采用半固态搅拌法制备的SiC_P/ZA22复合材料的组织和常温、高温力学性能进行了研究,并和ZA22基体合金作了对比.研究发现:SiC颗粒大多分布于晶界,部分SiC颗粒和基体界面上有反应物生成,SiC可以充当合金初生相形核衬底,分布于晶内并细化枝晶.力学性能与颗粒分布均匀性、界面结合强度密切相关.和ZA22合金相比,该复合材料弹性模量上升,冲击韧性下降,高温条件下表现出较好的力学稳定性.     

稀土对ICDP轧辊组织及抗热疲劳性能影响的研究

用稀土在熔炼后期对铁液进行变质处理,并通过金相、热疲劳试验来研究不同稀土含量对轧辊组织及其热疲劳性能的影响.试验表明,稀土含量不超过0.1％时,能有效控制轧辊基体组织中碳化物与石墨的形态、分布,进而改善轧辊的抗热疲劳性能.但稀土含量超过0.1％后轧辊基体组织中的碳化物形态与分布变化不大,石墨变得粗大,引起其抗热疲劳性能恶化.     

高韧性锌基合金的成分、性能及耐磨性

在ZA27合金的基础上,研究了Al、Cu及微量元素B、Ti对锌基合金力学性能的影响,确定了高强韧锌基耐磨合金-ZA30的成分为：w（Al）=29％-31％,w（Cu）=2．0％-2．5％,w（Mg）=0．01％-0．02％,Zn：余量,B、Ti微量．进行了与ZA27在46#工业齿轮油润滑条件下的耐磨性能的对比试验,并对合金耐磨机理及各元素对合金性能影响的机理进行了探讨．研究结果表明：与ZA27相比,ZA30在强度略有提高的基础上,延伸率从3％-6％提高到12．1％-17．3％：ZA30的耐磨性优于ZA27．     

RE复合变质处理对高铬合金铸铁组织及性能的影响

采用光学显微镜、扫描电镜和力学性能检测设备等研究了RE复合变质处理对高铬合金铸铁显微组织和力学性能的影响。试验结果表明,变质处理可以细化基体组织,消除柱状树枝晶,改善碳化物形态和分布,使碳化物棱角得到钝化,碳化物更加细小,从而使高铬合金铸铁力学性能得到提高,与未变质高铬合金铸铁相比,变质高铬合金铸铁的硬度和冲击韧度分别提高了1.74%和27.27%,达到了HRC64.0和4.2 J/cm2。     

M951合金的热疲劳行为

测试了3种镍基合金和1种定向钴基高温合金矩形缺口试样的热疲劳行为.试样缺口处萌生裂纹的扩展长度作为热循环次数的函数.实验结果表明新型镍基导向叶片材料M951合金的热疲劳裂纹萌生速率和裂纹扩展速率最低.M951合金的热疲劳裂纹主要沿晶内枝晶间扩展,主裂纹生长以裂纹尖端连续开裂的形式进行.     

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。     

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.     

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。     

Effect of antibiotics of chemotaxis of human leukocytes

The effect of 20 different antibiotics on chemotaxis by human neutrophils was studied. Human leukocytes incubated with chloramphenicol, rifampin, sodium fusidate, and tetracyclines in vitro showed markedly depressed migration. The mechanisms by which these antibiotics affect leukotaxis are discussed.