球磨工艺对Al2O3/Mo复合材料组织的影响

针对原位自生Al2O3增强钼基复合材料晶粒较大的问题,采用溶胶-凝胶与高能球磨相结合的方法细化复合材料晶粒,并利用SEM、XRD对不同球磨工艺所制备Al2O3/Mo复合粉末及复合材料的组织进行了观察和分析。结果表明:随着球磨时间的延长,Al2O3/Mo复合粉末颗粒由球状变为层片状再成为细小的球状,颗粒大小由约1.5μm细化为约500nm,其中的钼晶粒不断细化;高球料比所得粉末的分散性和破碎细化程度较好;转速提高使得粉末颗粒的尺寸均匀程度降低,且伴有结块现象,不利于粉末的细化。在球料比5∶1、转速300r/min、球磨时间60h条件下获得的复合粉末,经压坯烧结可制备出Al2O3颗粒为纳米级的钼基复合材料。     

Al_2O_3掺杂钼合金粉末的形貌变化

采用水热合成法结合低温煅烧及两次还原工艺制备了Al2O3质量分数分别为0、0.25%、0.5%、0.75%、1.0%的钼合金粉末。通过SEM观察了混合钼合金粉末的形貌,采用XRD分析了钼合金粉末的相组成,研究了不同制备阶段Al2O3掺杂量对钼合金粉末的影响。结果表明:Al2O3掺杂量对钼合金粉末的均匀性、颗粒分布、粒径大小有一定影响,Al2O3掺杂量的增加对钼合金粉末的团聚有分散作用。经两次氢气还原,片状的MoO3颗粒完全被还原为球状的Mo颗粒,混合粉末主要由Mo和α-Al2O3相组成,不含其他相。α-Al2O3能细化还原后的Mo颗粒,且Al2O3掺杂量越大,Mo颗粒的细化效果越显著。     

球磨时间对Al2O3/Mo复合材料组织与性能的影响

采用溶胶-凝胶法制备Al2O3/Mo混合粉体,利用高能球磨法细化Al2O3/Mo复合材料中氧化铝和钼的晶粒尺寸,研究了球磨时间对Al2O3/Mo复合材料组织与性能的影响,利用XRD和扫描电镜对复合粉末形貌和复合材料进行了物相和形貌分析。研究表明:随着球磨时间的延长,复合粉末的形貌经历了球状到层片状再到球状的变化,粉末粒度逐渐减小,经粉末冶金烧结后的复合材料中,氧化铝和钼的粒径逐渐减小,经过60h的球磨,氧化铝颗粒的尺寸达到500nm左右;复合材料的密度呈现先增加后减小的趋势,显微硬度则逐渐上升至403.2HV。     

MA制备ODS钴基高温合金粉末的研究

为开发高性能的ODS钴基高温合金,通过机械合金化制备了Co-Cr-Ni-W-Y2O3的复合粉末,探讨了机械合金化对粉末颗粒大小,晶粒以及晶格畸变的影响,研究了加入过程控制剂对球磨粉末状态的影响。结果表明,随着球磨时间的延长,粉末粒度和晶粒都减小,晶格畸变增大;球磨8 h以上,粒度、晶格畸变变化趋势变缓,但球磨时间的进一步延长有利于元素更加均匀的分布;加入酒精球磨的粉末分散度明显比未加入酒精的粉末好,粒度更小。     

高能球磨制备Al2O3/Cu复合材料

采用高能球磨法制备Al2O3/Cu复合粉末,通过X射线衍射仪(XRD)和扫描电镜(SEM)研究高能球磨时间对复合粉末的物相、晶粒尺寸和表面形貌的影响。结果表明,随球磨时间的增加,基体Cu的晶粒不断被细化,在球磨初期,晶粒尺寸减小很快,当晶粒尺寸小于20 nm时,细化速率变缓而趋于稳定;Cu颗粒形貌由树枝状变为层状,并向椭球体转变;纳米Al2O3颗粒逐渐嵌入Cu颗粒体内,且分散均匀,从而获得纳米Al2O3颗粒弥散分布的Cu基复合粉末。并探讨了高能球磨对放电等离子体烧结Al2O3/Cu复合材料导电性能和力学性能的影响,研究认为高能球磨可以促进基体的晶界强化和弥散强化,而晶界的增加并不会导致电阻率的显著增大,影响电阻率的主要因素为Al2O3的体积分数、孔隙和杂质的固溶。     

高能球磨法制备超细Al2O3粉末

采用高能球磨法制备超细Al2O3粉末,研究了球磨时间、球磨转速及工艺控制剂等工艺参数对Al2O3粉末粒度和形貌的影响。结果表明:在一定范围内,延长球磨时间,提高球磨转速均能有效地减小颗粒尺寸;在球磨过程中加入工艺控制剂,能有效地防止粉末粘附在磨球和磨罐上,并改善粉末颗粒的均匀性。在本文试验条件下,加入工艺控制剂乙醇,球磨转速为400r/min,球磨时间为30h等条件下,获得Al2O3粉末的D50为0.82μm,Al2O3粉末粒径分布在0.12～6.37μm范围内。     

机械合金化制备Al2O3/Mo5Si3粉末研究

以MoO3粉、Mo粉、Si粉和Al粉为原料,利用机械合金化制备了具有纳米晶组成的Al2O3/Mo5Si3复合粉体,利用X射线衍射(XRD)、激光粒度分析仪(LPS)和扫描电子显微镜(SEM)对Al2O3/Mo5Si3复合粉体的形成以及在球磨过程中的粉体演变进行分析和表征.结果表明:球磨10h后,原料粉末发生反应生成了A...     

球磨速度和过程控制剂对Ti-Cr合金机械合金化的影响

研究了球磨速度变化(125～225r/min)和过程控制剂种类(酒精、硬脂酸和二者的混合物)及其加入量(0～4.5％)对Ti-Cr合金机械合金化(MA)的影响。研究结果表明,球磨速度的高低对所获得的MA粉末的粒度有显著影响。在其他条件相同的情况下,球磨速度越高,MA的效率越高,粉末的粒度越小。在Ti-Cr合金的MA过程中,使用酒精作为过程控制剂,能够有效地降低球磨带入的杂质量,但是粉末的细化速度将减慢;酒精的加入量以不超过1.5％或者在4.5％以上为宜。硬脂酸不适合用做Ti-Cr合金MA过程的过程控制剂。通过调整球磨速度和合理选用过程控制剂,可以实现对球磨杂质来源的调控。     

过程控制剂对机械合金化过程与粉末特征的影响

在纳米粉末制备中 ,机械合金化 (MA)是制备纳米晶结构复合粉末的最简单、最经济及应用最广泛的一种方法。但是在MA过程中 ,粉末存在严重的团聚结块和粘壁现象 ,大大阻碍了MA的发展。为此 ,作者在MA过程中添加了不同的过程控制剂 (PCA) ,以研究各种PCA对粉末的MA过程及粉末的晶粒尺寸和晶格畸变、粒度与粒度组成、密度、比表面、粉末团聚和粘壁等粉末特性的影响     

真空原位氧化工艺参数对析出Al2O3显微形貌的影响

采用一种新型的真空原位氧化工艺制备了Al2O3/Cu复合材料。本文主要讨论新工艺参数对原位氧化析出的Al2O3颗粒的数量、分布、粒度的影响。结果表明：在真空环境下，原位氧化工艺更易于控制，析出的Al2O3颗粒为椭球形，粒径、颗粒间距均小于1μm，均匀、弥散分布在基体上。升温速率、反应温度、原始粉末中Al的含量均对Al2O3颗粒的析出及分布有显著的影响。由于Al氧化的强放热效应，三者必须合理匹配，才能制备出组织性能优越的复合材料。     

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)     

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.     

Quality of life of relatives of mental patients

Usage of quality of life of psychiatric patients' relatives as the parameter of estimation of the quality of psychiatric care is considered. By means of standard questionnaire elaborated by the authors as well as by means of both individual and group conversations the quality of life was analyzed in 40 relatives which lived together with psychiatric patients. Different spheres of their life and difficulties (financial, social-psychologic, production) were examined in families with such patients. The defects of psychiatric care that had direct influence on the quality of life of the psychiatric patients' relatives are outlined.