439M铁素体不锈钢点蚀诱发机理

 439M铁素体不锈钢广泛应用于汽车排气系统消声器中,其主要失效形式是点蚀破坏。采用点腐蚀试验、去钝化起始pH值试验、微区电化学试验,并结合扫描电镜及能谱分析,观察分析了点腐蚀和夹杂物的形貌,研究了点蚀诱发时夹杂物的变化情况。研究结果表明,439M不锈钢的点蚀主要在复合氧化物夹杂处诱发,而TiN夹杂物未诱发点蚀;夹杂物诱发点蚀时,复合氧化物夹杂的CaO优先溶解。最后,建立了在氯离子环境下439M不锈钢中复合氧化物夹杂诱发点蚀的模型。     

Mn对2205双相不锈钢耐点蚀性能的影响

研究锰元素对2205双相不锈钢耐点蚀性能的影响, 锰质量分数的变化范围为0. 93%~1. 26%.分别采用化学腐蚀法、动电位极化法研究双相不锈钢2205的耐腐蚀性能, 采用夹杂物自动分析技术研究锰对钢中夹杂物种类及数量的影响, 通过扫描电镜、能谱及夹杂物原位分析法观察化学腐蚀及电化学腐蚀前后钢中夹杂物及其周围钢基体的变化情况.采用电感耦合等离子体发光光谱测定腐蚀产物的成分.研究结果表明, 不同类型的夹杂物对耐腐蚀性能的影响不同, (Mn、Si) 氧化物以及(Mn、Si、Cr) 氧硫化物在腐蚀液中更易溶解进而促进腐蚀, 而(Cr、Mn、Al) 氧化物却很稳定.锰的加入会促进钢中(Cr、Mn、Al) 夹杂的析出, 此类夹杂物不仅自身很容易被含Cl离子的溶液腐蚀, 而且作为点蚀的起始点, 促进了点蚀坑的形成, 加快了基体腐蚀, 最终导致不锈钢耐点蚀性能的下降.      

碳钢中夹杂物诱发点蚀的规律和特性研究

海洋环境对于金属的腐蚀具有明显的加速作用,尤其在高铁海底隧道环境中,金属比正常的服役时间变短,这种腐蚀情况下会影响高铁的安全和准点运行。基于以上背景,通过夹杂物自动扫描、钢的加速腐蚀及电化学测试对钢中的夹杂物诱发腐蚀行为进行系统分析,重点分析了高铁轨旁信号设备连接金属件（Q235）中夹杂物在盐雾环境下的腐蚀行为。结果表明：钢中主要夹杂物为氧化物、硫化物或者其复合夹杂,而这两类夹杂物对于诱发钢基体点蚀的原因不同。其中数量最多、尺寸小于5 μm类型的夹杂物为硫化物夹杂和氧硫复合类型夹杂物;数量少、尺寸大于5 μm的夹杂物为氧化物夹杂。在服役过程中,钢中硫化物夹杂易溶解脱落形成点蚀坑,而氧化物夹杂周围基体会先溶解引起夹杂物脱落形成点蚀坑,复合类夹杂物也是诱发钢发生腐蚀的因素,不同复合类型的夹杂物腐蚀方式不同,硫化物夹杂和氧硫复合夹杂对碳钢影响较大。电化学测试表明自腐蚀电位约为为−0.1 V,Q235钢本身抗腐蚀能力不强。夹杂物在腐蚀过程中参与了腐蚀,引起阳极极化曲线的波动,加快了Q235钢的腐蚀情况。研究结果对于认识和改善钢的耐腐蚀性能有指导意义。     

Mn对2205双相不锈钢耐点蚀性能的影响

研究锰元素对2205双相不锈钢耐点蚀性能的影响,锰质量分数的变化范围为0. 93%～1. 26%.分别采用化学腐蚀法、动电位极化法研究双相不锈钢2205的耐腐蚀性能,采用夹杂物自动分析技术研究锰对钢中夹杂物种类及数量的影响,通过扫描电镜、能谱及夹杂物原位分析法观察化学腐蚀及电化学腐蚀前后钢中夹杂物及其周围钢基体的变化情况.采用电感耦合等离子体发光光谱测定腐蚀产物的成分.研究结果表明,不同类型的夹杂物对耐腐蚀性能的影响不同,(Mn、Si)氧化物以及(Mn、Si、Cr)氧硫化物在腐蚀液中更易溶解进而促进腐蚀,而(Cr、Mn、Al)氧化物却很稳定.锰的加入会促进钢中(Cr、Mn、Al)夹杂的析出,此类夹杂物不仅自身很容易被含Cl离子的溶液腐蚀,而且作为点蚀的起始点,促进了点蚀坑的形成,加快了基体腐蚀,最终导致不锈钢耐点蚀性能的下降.     

碳钢及低合金钢在氯离子溶液中夹杂物诱发点蚀位置显微腐蚀实验探讨

选择3种冶金因素有代表性的碳钢及低合金钢, 通过极化实验方法确定点蚀诱发初期及点蚀期的电位值, 利用显微腐蚀实验方法和电子探针分析了不同夹杂物在诱发点蚀过程中的特征, 并在利用琼脂涂封的条件下, 考察及分析了点蚀诱发时夹杂物溶解析出情况。结果表明:夹杂物是钢中主要点蚀诱发源, 钢基体与夹杂物交界处的钝化膜保护作用最弱, 点蚀均从该处诱发;点蚀诱发初期, 钢基体与夹杂物交界处的钝化膜破裂时, 对硫化物夹杂, 优先析出的是铁离子, 而不是硫离子;夹杂物的成分及形态的不同都会影响到产物的溢出位置。     

不同脱氧程度锰钢耐点蚀性能比较

选择四种不同脱氧程度的锰钢,在pH10的3%(质量分数)NaCl溶液中进行动电位极化实验,比较钢的点蚀诱发敏感性;在3%(质量分数)海盐水中进行室内间浸挂片实验,评价钢的点蚀扩展速度;利用扫描电镜(SEM)和电子探针(EPMA)分析了钢中夹杂物组成和腐蚀形貌.结果表明,随着脱氧程度的加强,钢中的硫化物夹杂由短棒状变为长条状.脱氧程度越差,钢基体热力学稳定性越强,钢的点蚀诱发敏感性也越弱.室内间浸挂片实验结果表明,脱氧程度较强的锰钢表现出更强的点蚀扩展能力.     

夹杂物对低合金钢点蚀诱发敏感性的影响

为了进一步提高低合金钢的抗点蚀性能,采用Ti/Al脱氧及Ca处理工艺熔炼并轧制制备了试验钢。利用场发射扫描电镜及能谱仪(SEM-EDS)、电化学极化试验及浸蚀前、后夹杂物的原位观测,研究了不同脱氧工艺钢中夹杂物在模拟海水介质中诱导点蚀的行为。结果表明:与Al脱氧钢相比,Ti脱氧钢中形成了富含Ti Ox、数量更多、尺寸更细小的夹杂物,有利于Mn S的局部分散析出,降低其诱发点蚀的危害,采用Ti脱氧工艺有助于提高钢的抗点蚀性能;Mn S诱发点蚀的能力强于氧化物夹杂,点蚀优先在Mn S夹杂与基体的界面处及夹杂物曲率半径小的区域萌生;降低夹杂物的腐蚀活性应该以调控夹杂物的组成为基础,其次优化夹杂物的形貌(球形化),在微米级范围内,夹杂物尺寸对点蚀诱发的影响最小。     

碳钢在NaCl溶液中初始腐蚀行为的探讨

采用电化学极化与金相显微镜原位观察相结合的方法,对Q235钢在3%NaCl溶液中腐蚀的初始行为进行了研究。借助原子力显微镜对初始腐蚀的试样观察分析,发现试样在-900 mV(vs SCE)就出现了点蚀,点蚀优先在晶界附近的铁素体上生成。蚀坑长大后,优先沿轧制方向发展,而形成腐蚀沟槽。钢中夹杂没有发生活性溶解,导电性夹杂物作为阴极仅对腐蚀过程起促进作用。     

夹杂物对Cr-Ni系高强度钢耐蚀性能的影响

对比研究了2种Cr-Ni系高强度钢在人造海水条件下耐蚀性能差异,采用ASPEX自动扫描电镜分析了钢中夹杂物种类、数量和分布,利用金相显微镜对夹杂物引发腐蚀的过程开展了原位分析,并利用扫描电镜(SEM),观察了腐蚀后样品的微观形貌。全浸腐蚀实验结果表明,A钢虽然合金含量较高,但其腐蚀速率要大于B钢;夹杂物分析及其原位腐蚀实验研究表明,B钢通过Ca处理获得了良好的夹杂物改性效果,将钢中对耐蚀性提高不利的MnS夹杂物改性为CaS复合夹杂物,降低了B钢的点蚀敏感性,提高了B钢的耐蚀性能。     

稀土耐候钢中的夹杂物及耐点蚀性能研究

利用电子探针、扫描电镜及能谱仪、图像分析仪对含稀土和不含稀土耐候钢中夹杂物的成分、形貌、尺寸等进行了研究。钢中加入稀土后,小球状的稀土硫化物和稀土氧硫化物夹杂取代了钢中原有的有害的长条硫化锰夹杂。对于低硫低氧(S:～0.004%,O:～0.002%)的耐候钢,0.0065%～0.016%的稀土含量保证了钢中夹杂物的良好变质效果,变质后的夹杂弥散分布而且85%以上的稀土夹杂物都小于2μm。通过干湿周期浸润实验室加速腐蚀试验研究了Cu-P-RE耐候钢和对比Q235钢的耐蚀性能。通过电化学极化试验和扫描电镜分析研究了稀土耐候钢中的夹杂物诱发点蚀行为。结果表明,微米级弥散分布的稀土夹杂取代了易腐蚀的长条硫化锰夹杂,减弱了钢中的微区域电化学腐蚀,从而抑制了钢中点腐蚀的发生和扩展。并可以诱发耐候钢表面发生均匀的全面腐蚀,促进均匀致密保护性锈层的生成。Cu-P耐候钢中加入适量稀土提高了钢的点蚀电位和耐点蚀能力,降低了耐候钢的腐蚀速率,提高了其耐蚀能力。     

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.