轧制温度和变形量对Mo85-Cu复合材料组织和物理性能的影响

采用熔渗法制备Mo85-Cu复合材料,通过SEM、DSC和热导仪研究轧制温度和轧制变形量对其微观组织和物理性能的影响。实验结果表明:该轧制工艺适宜于钼铜合金的工业化生产,一定范围内轧制变形量的增大有利于提高钼铜材料的致密度,改善钼铜合金的物理性能;经600℃轧制比350℃轧制的Mo85-Cu复合材料综合性能优异,与350℃轧制相比,600℃轧制的Mo85-Cu的热导率由164.1 W·m 1·K 1提高到173.7 W·m 1·K 1,气密性由5.4×10 9Pa·m3·s 1提高到3.4×10 9Pa·m3·s 1,整体密度由9.76 g/cm3提高到9.86 g/cm3,各项性能指标均满足电子封装材料产品要求。     

冷等静压法制备Mo-30Cu合金的组织与轧制性能

采用冷等静压法(cool isostatic pressing,CIP)制得大尺寸钼骨架,对骨架进行渗铜制备Mo-30Cu合金,并在350℃进行温轧,研究CIP压力及熔渗温度和熔渗时间对合金致密度的影响以及合金的轧制性能。结果表明:采用冷等静压法在120~180 MPa压力下可制备孔隙分布均匀,无分层等缺陷的钼骨架,熔渗后坯料的线收缩率随CIP压力增加而逐渐降低,最佳CIP压力为160 MPa;在一定范围内升高熔渗温度与延长保温时间均有助于提高合金致密度;冷等静压–溶渗法制备的高致密Mo-30Cu合金具有较好的温轧性能,有效提高了大尺寸试样的加工性能。CIP压力为160 MPa压制的骨架在1 350℃渗铜6 h后相对密度达到99%以上,合金的温轧变形量可达到65%。     

多孔金刚石坯体熔渗铜工艺

金刚石/Cu具有优异的热物理性能,采用熔渗法可以实现金刚石/Cu的近净成形,本文对多孔金刚石坯体熔渗铜的相关工艺及影响因素进行了较深入的研究。研究结果表明,在多孔坯体上下方都放置铜块时对熔渗过程比较有利;熔渗温度达到1 200℃、压力为20 MPa、保温30 min时复合材料致密度达到99.8%,接近全致密,热导率可以达到587 W/(m.K),进一步提高熔渗温度和延长保温时间时,该复合材料的致密度没有显著变化,热导率下降,这主要与界面结构变化引起的界面热阻变化有关。熔渗过程存在孕育期,熔渗温度低于1 200℃或压力低于20 MPa时,复合材料的致密度较低,甚至不能完成熔渗。     

微波快速熔渗制备钼铜复合材料

通过微波快速熔渗制备钼铜复合材料,探究预烧结骨架、熔渗起始位置及熔渗温度对熔渗效果的影响.结果表明,100 MPa压制生坯在1 400 ℃下常规烧结1.5 h具有理想孔隙率.当有氢氩气氛保护的情况下,底部渗铜可以使铜相分布更加均匀.在1 250 ℃下保温1 h微波熔渗后的钼铜复合材料即具有较优良的综合性能,和较均匀的显微结构.微波熔渗极大地缩短熔渗时间,可以节约生产能源和成本,是一种很好的加工方式.      

洁净燃料发动机粉末冶金阀座熔渗烧结工艺研究

采用正交试验优化了洁净燃料发动机粉末冶金阀座熔渗烧结工艺参数,分析了熔渗烧结工艺参数对阀座密度和上下面硬度等性能的影响。结果表明:随着渗铜量的增加,阀座材料密度迅速增加,上下表面硬度差距缩小。熔渗烧结温度对阀座材料密度影响不大。当熔渗烧结温度从1130℃升高到1165℃,材料硬度逐渐提高;当温度达到1200℃后,Co–Cr–Mo硬质颗粒中合金元素向基体中发生明显扩散,导致阀座硬度下降。熔渗烧结时间对材料密度影响不大,缩短时间有利于缩小上下面硬度差距。当渗铜质量分数达到20%,渗铜温度1165℃,渗铜时间40 min,阀座力学性能最佳。熔渗烧结后密度为8.15 g·cm~(-3),上下表面硬度分别为HRC 30.4和HRC 30.1,基体材料与Fe–Mo、Co–Cr–Mo硬质颗粒均有一定的冶金结合。     

冷轧高强集装箱板轧制稳定性控制技术

 冷轧高强集装箱板由于其屈服强度、成形性能及尺寸精度的要求,对冷轧轧制稳定性和板形控制提出极大挑战。针对某钢厂薄规格冷轧高强集装箱板生产过程存在的肋浪和边裂情况进行分析,采用试验方法研究了热轧带钢库区冷却过程对钢卷温度及性能均匀性的影响,利用数值模拟的方法研究了该钢种在UCM机型冷轧轧制过程中带材变形特征,揭示了带材浪形和边裂的并发机理,同时分析了不同工艺对带钢变形均匀性的影响规律。结合理论及仿真分析,提出了针对热卷性能均匀性及酸轧轧制稳定性的优化方案,改进后冷轧板形质量明显提高,带材边裂缺陷完全消除,冷轧高强集装箱板的轧制稳定性及产品质量均得到大幅提升。     

00Cr17TiMo铁素体不锈钢热轧边裂分析

通过边裂缺陷分析、采用模拟轧制试验的方法研究加热温度对边裂的影响、以及连铸坯晶粒粗化试验等三方面对00Cr17Ti Mo铁素体不锈钢热轧边裂的原因进行逐渐深入的分析和研究。最终得出以下结论:当加热温度达到1 150℃时,晶粒开始长大,当加热温度达到1 200℃时,出现明显混晶现象。混晶导致在轧制过程中出现不均匀变形,经过精轧后出现边部层状结构以及边裂等缺陷。     

Ti诱导无压反应熔渗制备Fe-TiC金属基复合材料的研究

研究了一种Ti诱导无压反应熔渗制备金属基复合材料的方法:通过凝胶注模成形工艺,以蔗糖为造孔剂制备了孔隙率高达80％的多孔Ti-TiC陶瓷骨架预置体,真空状态下,在1380℃,分别以Fe-Cr-C和Fe-Cr-Ti-C两种合金熔体熔渗该多孔骨架预置体,制备了Fe-TiC金属基复合材料.并利用扫描电子显微镜、X射线衍射对复合材料的组织结构,元素组成和相组成进行了测试和分析.结果表明:在熔渗过程中骨架中的Ti元素的溶解析出和与C元素的原位反应促进了熔渗过程的进行,随着熔渗保温时间的增加,基体中的增强相TiC分布趋于均匀化,并且TiC晶粒逐渐长大,1380℃保温3h时,晶粒长大到30 μm;用Fe-Cr-Ti-C合金熔渗该多孔骨架1380℃保温1h即可制备出TiC晶粒细小、分布均匀的Fe-TiC金属基复合材料,并且该材料具有优异的抗磨粒磨损性能.     

预加铜粉对85W-Cu板材性能的影响

钨铜是一种理想的电子封装基板或热沉材料.采用纯钨粉压坯、2%(质量分数)铜粉和钨粉混合压坯为熔渗对象制备85W-Cu材料,通过比较试样的致密度、显微硬度、显微结构等性能,研究了预加铜粉对熔渗烧结85W-Cu性能影响.实验结果表明预加铜粉能够有效降低钨颗粒的固相烧结,改善板材的冷轧塑性变形能力.但是,预加铜粉对材料的致密化不利,制备的材料致密度较低,且提高熔渗烧结温度不能有效提高致密度.     

冷轧复合材料的复合工艺实验

 进行了钢 铜、钢 铝冷轧复合实验,即表面处理+复合轧制+轧后热处理。结果表明,复合轧制前,必须对基材和复合材料进行表面清洗,基材钢需进行表面毛化处理,要求表面粗糙度为Rz=81~101 μm,较薄的复合材料如铜、铝可不经毛化处理直接复合轧制。钢 铝无张力复合轧制所需总相对压下量为40%≤ε≤60%,钢 铜无张力复合轧制所需的总相对压下量为ε≥70%。应严格控制热处理的退火温度和保温时间,保温时间过长,会削弱复合面的强度;钢 铝退火温度控制在320 ℃左右,保温时间约1 h;钢 铜退火温度在550~600 ℃范围内,保温时间约15 h。研究认为复合轧制过程中,带材之间的相对跑偏、厚度比控制是亟待解决的问题。     

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.