球磨工艺对细颗粒钨粉质量及硬质合金晶粒夹粗的影响

利用球磨机对细颗粒钨粉进行分散处理，研究球磨过程不同转速、不同时间对细颗粒钨粉粒度及团聚颗粒的影响。将球磨后的钨粉制备成碳化钨粉和硬质合金，通过合金金相组织的对比分析找到细颗粒钨粉球磨工艺与合金晶粒夹粗的关联性，为合金晶粒夹粗问题提供新的解决思路。结果表明：选用21 r/min、80 min的球磨工艺分散处理的钨粉团聚颗粒最少，制备的碳化钨粉生产的硬质合金WC晶粒大小均匀、无夹粗出现。     

球形钨粉的制备及粉末特性研究

以团聚严重、不规则形状的还原钨粉为原料,经过球磨处理后,采用射频等离子体球化技术制备球形钨粉。在射频等离子体球化过程中,研究原料粉末形态对球化结果的影响。采用扫描电子显微镜、激光粒度分析仪和BT-100粉体综合特性测试仪对球磨和球化处理前后粉末的形貌、粒度、松装密度和振实密度进行测试和分析。结果表明:球磨处理后,钨粉颗粒分散状态良好,粒径明显降低,粒度分布明显变窄;经过球化处理后,钨粉颗粒呈规则球形,表面光滑,松装密度和振实密度得到明显提高。     

球磨时间对钨粉粒度分布及形貌影响

通过改变球磨时间,获得不同粒度分布的钨粉颗粒,分析球磨时间对钨粉粒度分布和形貌特征的影响,提高粒度分布在目标区间（5～11 μm）的钨粉颗粒体积分数。结果表明,球磨的前2 h对原料中大颗粒钨粉的影响较大,钨粉颗粒最大粒径由134 μm迅速下降到20 μm左右。随着球磨时间的增加,钨粉粒度分布指标减缓下降,除粒径变小外,颗粒形貌基本无变化,但是在球磨10 h后开始出现团聚现象。综合分析可知,球磨时间的改变对钨粉粒度分布指标影响较大,球磨时间为8 h时,可获得粒度分布最窄的钨粉颗粒,在目标区间的钨粉颗粒体积分数达到75%。     

蓝钨还原钨粉过程相成分探讨

利用电子探针扫描仪分析了蓝钨(TBO)在770℃～900℃内还原钨粉过程中相成分的变化情况。在此过程中研究了蓝钨的颗粒形貌，以及蓝钨还原为γ-氧化钨(WO2.72)、γ-氧化钨(WO2.72)还原为二氧化钨(WO2)和二氧化钨还原为钨粉的相变情况。研究表明：γ-氧化钨到二氧化钨的还原过程是控制钨粉颗粒形貌的关键过程，如果控制好工艺条件，有利于制取亚细或超细钨粉，而从二氧化钨到钨粉的还原过程不是控制钨粉颗粒形貌的关键过程。     

纳米钨粉形貌结构对碳化钨粉末性能的影响

采用球磨破碎分级的氧化钨为原料,氢还原制备出平均粒度为30 nm的纳米钨粉,并分别以干磨搅拌和添加适量分散剂的湿式球磨的方式配碳,然后置于通氢钼丝碳化炉中在1180℃长时间碳化,得到了粒度分别为109和148 nm的碳化钨粉末,继而于低压真空烧结炉中,在1360℃的温度下烧结制备出WC-7%Co(质量分数)烧结体,研究了纳米钨粉形貌结构对纳米碳化钨粉末及其超细晶硬质合金性能的影响。通过比表面测定仪和费氏粒度仪测定了粉体的比表面和粒度,采用X射线衍射(XRD)分析了碳化产物的相成分,用扫描电镜(SEM)观察了粉末的形貌和烧结体的显微组织结构,按硬质合金性能测试标准对WC-Co烧结体的物理和力学性能进行了测定。结果表明,湿磨配碳强制破坏了纳米钨颗粒,呈其氧化钨前驱体的团聚状的形貌结构,可以改善纳米钨粉和碳粉弥散分布的均匀性,更有利于获得颗粒细小、均匀,分散性好的优质纳米碳化钨粉,其所制备的超细晶WC-7%Co硬质合金,显微组织均匀,综合性能优,硬度和抗弯强度分别为HRA 93.7和4450 MPa。     

Ni、Fe含量对制备钨纳米晶须的影响

以钨粉、硝酸镍、硝酸铁为原料,通过氧化还原法,制备出了定向生长在钨粉表面的纳米晶须。采用XRD、SEM、EDS等分析手段初步研究了Ni、Fe含量对制备钨纳米晶须的影响。结果表明,以硝酸盐形式加入Ni、Fe可使钨粉形貌发生变化,表面催化定向生长出钨纳米晶须;在实验选定成分范围内,制备钨纳米晶须的最佳质量配比为W∶Ni∶Fe=90∶5∶5。     

溶胶凝胶纳米WO3的还原特征

利用溶胶凝胶法制备的纳米WO3粉，研究了一段还原工艺和两段还原工艺下，制备纳米W粉的基本特征；分别用XRD、TEM、FESEM、BET和SAXS（X射线小角度散射法）等手段研究了制备过程中各步骤的产物及最终产物物相组成、颗粒形貌和粒度组成。试验结果表明：一段还原工艺中，可以在700℃、90min的条件下将纳米WO3粉还原为纳米W粉，W粉平均粒度〈50nm；两段还原工艺中，在600℃、40min可将纳米WO3粉还原为纳米WO2粉，WO2粉在700℃、90min还原为W粉，W粉平均粒度〈38nm；两阶段还原工艺优于一阶段还原工艺，可获得稳定且粒径更小的纳米W粉。     

溶胶-凝胶法制备稀土CeO2掺杂纳米钨粉的研究

以偏钨酸铵(AMT)、柠檬酸和硝酸铈为原料,用溶胶-凝胶法(sol-gel)制备稀土CeO2掺杂纳米钨粉。通过热重-差热(TG-DSC)、X射线衍射(XRD)、扫描电子显微镜(SEM)、比表面积法(BET)等测试手段对复合粉体的合成工艺、物相、颗粒形貌和粒径进行了分析。结果表明:当pH值为1时,还原后的粉体颗粒呈准球形,无团聚,稀土元素以CeO2形式存在且均匀地分布在钨粉中,平均颗粒粒径为80nm左右,满足制备高性能掺杂稀土氧化物亚微米结构浸渍阴极的要求。     

纳米钨粉生产工艺研究

探讨以APT为原料生产纳米钨粉的工艺流程及生产工艺．以APT为原料在高温、湿氢、弱还原的条件下制取优质紫钨;紫钨经还原炉在工艺条件：还原温度650-750℃、装舟量0．25-0．50kg、推舟速度10-20min／舟、氢气流量为40-60m3／h、氢气露点-70--60℃下可制备BET平均粒径为0．03-0．06μm的纳米级超细钨粉,并对影响紫钨还原的各种工艺参数进行了分析．结果表明：在合适的工艺条件下传统工艺也可以制备出纳米级超细颗粒钨粉．     

不规则形貌钨粉的形成机理

采用偏钨酸铵(Ammonium Metatungstate,or AMT)为原料直接氢还原制备钨粉。研究了偏钨酸铵在还原过程中的相转变和颗粒形貌的演变过程,解释了不规则形状钨颗粒形成的机理。采用XRD研究了还原过程中粉末的相变化过程,扫描电镜对钨粉的形貌进行了表征。实验结果表明:在还原的过程中,钨经历了WO3→WO2.90→WO2→W的相转变过程。由于"局部反应"机理的主导作用,偏钨酸铵在750℃直接氢还原,制备出的钨粉颗粒形状不规则,粉末颗粒存在松散的聚集。当还原温度升高时",挥发-沉积"作用显著,还原的钨粉颗粒形状逐渐规则化。     

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.     

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。     

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.