不同氮气压力烧结对WC-TiC-NbC-Co硬质合金表面结构和性能的影响

采用不同氮气压力烧结制备WC-TiC-NbC-Co合金,再使用CVD方法进行涂层.通过扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射分析仪(XRD)、表面粗糙度仪和划痕测试仪对烧结后及涂层后的样品表面形貌、成分、物相、粗糙度及涂层结合力进行表征与测量.结果表明,与真空烧结相比,在氮气氛中烧结的WC-TiC-NbC-Co硬质合金样品的表面形成了以TiC相为主的梯度层,梯度层厚度随着氮气压力的升高而增大.当氮气压力为15 kPa时,梯度层厚度达到了10μm,当氮气压力为10 kPa时,样品与CVD涂层具有最好的结合力.说明适当的氮气压力可以在合金表面形成一定厚度梯度层,并有助于提高涂层结合力.     

不同氮气压力烧结对WC-TiC-NbC-Co硬质合金表面结构和性能的影响

采用不同氮气压力烧结制备WC-TiC-NbC-Co合金,再使用CVD方法进行涂层.通过扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射分析仪(XRD)、表面粗糙度仪和划痕测试仪对烧结后及涂层后的样品表面形貌、成分、物相、粗糙度及涂层结合力进行表征与测量.结果表明,与真空烧结相比,在氮气氛中烧结的WC-TiC-NbC-Co硬质合金样品的表面形成了以TiC相为主的梯度层,梯度层厚度随着氮气压力的升高而增大.当氮气压力为15 kPa时,梯度层厚度达到了10μm,当氮气压力为10 kPa时,样品与CVD涂层具有最好的结合力.说明适当的氮气压力可以在合金表面形成一定厚度梯度层,并有助于提高涂层结合力.     

不同氮气压力烧结对WC-TiC-NbC-Co硬质合金表面结构和性能的影响

采用不同氮气压力烧结制备WC-TiC-NbC-Co合金,再使用CVD方法进行涂层.通过扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射分析仪(XRD)、表面粗糙度仪和划痕测试仪对烧结后及涂层后的样品表面形貌、成分、物相、粗糙度及涂层结合力进行表征与测量.结果表明,与真空烧结相比,在氮气氛中烧结的WC-TiC-NbC-Co硬质合金样品的表面形成了以TiC相为主的梯度层,梯度层厚度随着氮气压力的升高而增大.当氮气压力为15 kPa时,梯度层厚度达到了10μm,当氮气压力为10 kPa时,样品与CVD涂层具有最好的结合力.说明适当的氮气压力可以在合金表面形成一定厚度梯度层,并有助于提高涂层结合力.     

渗氮烧结的YT15梯度硬质合金微观组织

采用渗氮烧结工艺制备YT15梯度硬质合金,利用扫描电镜、能谱仪、X射线衍射等手段,研究该合金的表面微观组织,并对其表面梯度层的形成进行热力学分析.结果表明Ti元素与N元素之间较强的结合力驱动Ti元素向外和Co元素向内定向迁移,在合金表面形成厚度为10 μm的富含Ti(C,N)相的梯度层.实验结果与热力学分析均表明氮气氛...     

TiN添加量对WC-TiC-TaNbC-10Co硬质合金组织结构及性能的影响

采用一步烧结法, 通过改变原材料中TiN的添加量研究其对硬质合金组织结构及性能的影响。采用扫描电子显微镜、X射线能谱分析仪、X射线衍射分析仪、粗糙度测量仪、划痕测试仪等, 探究TiN添加量对WC-TiC-TaNbC-10Co硬质合金物理力学性能、微观组织结构、物相组成、表面形貌以及与涂层的结合力等性能的影响。结果表明: TiN添加量在0~1.6%范围内, 随着TiN添加量的增加, 合金的相对磁饱和强度和密度减小, 矫顽磁力增大、硬度和抗弯强度增大, 合金的脱β层厚度增加, 表面粗糙度先减小后增加, 与CVD涂层的结合力先增加后减小; 当TiN添加量为0.8%时, 合金与CVD涂层的结合力最好。      

烧结温度对不含氮原料制备的脱β层梯度硬质合金的影响

采用不含氮硬质合金原料,通过在梯度烧结工艺之前添加一步微压氮化烧结工艺制备脱β层梯度硬质合金;采用SEM观察合金表层的组织结构,图像分析工具测量脱β层的厚度。结果表明:在添加微压(氮气分压为0.5kPa)氮化烧结工艺的情况下,编号Co-8梯度硬质合金在1 420、1 450、1 480℃,1h的烧结工艺下形成脱β层的厚度分别为8、13、24μm;而编号Co-6梯度硬质合金在1 420℃时所形成的脱β层的厚度接近于零,在其他两种烧结温度下,所形成的脱β层的厚度也明显低于编号Co-8梯度硬质合金。与添加Ti(C,N)的原料相比,在相同的烧结工艺下,本文所采用的不含氮原料制备梯度硬质合金的脱β层厚度也明显降低。     

烧结碳气氛对CVD涂层刀片基体脱β层厚度的影响

为了研究烧结气氛对硬质合金脱β层厚度的影响，本研究以WC、Co、Ti(C,N)、(Ti,W)C和(Ta,Nb)C粉末为原料，通过脱氮气氛烧结制备了WC-(Ti,W)C-Ti(C,N)-(Ta,Nb)C-Co梯度硬质合金，并分析了Ti(C,N)含量和烧结碳气氛对合金微观组织与性能的影响规律。结果表明，添加Ti(C,N)将促进立方相向合金内部扩散，钴往外的扩散驱动力增强，在合金表面形成岛状或层状覆钴现象。烧结气氛主要是通过合金表面的碳含量来影响液相和立方相的迁移来影响脱β层的形成，随烧结炉碳气氛升高，脱β层厚度减少，添加0.9%Ti(C,N)制备的梯度硬质合金在低、中、高3种碳浓度气氛中脱β层厚度分别为20.2μm、10.7μm、0μm，因此，碳浓度气氛是影响脱β层厚度的一个重要因素。     

表层富立方相WC-TiC-Co功能梯度硬质合金

采用粉末冶金技术制备WC-15%TiC-6%Co硬质合金(质量分数), 通过控制氮气压力、固相烧结温度和烧结时间对合金进行渗氮烧结, 得到表层富立方相WC-TiC-Co功能梯度硬质合金。利用扫描电子显微镜、X射线衍射仪和能谱仪研究硬质合金梯度区域的微观组织、物相组成及元素分布。结果表明: 制备的WC-TiC-Co硬质合金梯度层厚度大于20 μm, 并且表层富含Ti元素和N元素, 其组成形式为Ti(C_0.7, N_0.3)。     

烧结气氛对表面无立方相硬质合金组织和性能的影响

分别在氩气和氮气烧结气氛下制备了表面无立方相硬质合金,借助电子背散射衍射（EBSD）分析了表面无立方相层（Cubic-phaseFreeLayer,CFL）及相邻含立方相侧的组织特征,并对比了两种合金的切削性能。结果表明：在氮气气氛中烧结时,合金的液相维持时间更长,WC晶粒较氩气气氛烧结更为粗大。同时,氮气气氛下立方相的溶解析出被抑制,形成的CFL厚度较薄,立方相晶粒的聚集程度低于氩气气氛烧结,分布更加均匀。氮气气氛烧结的合金刀片在切削过程中可长时间维持刀尖形状,不发生软化变形,切削性能优于氩气气氛烧结的刀片。     

磷酸盐体系正向电压对ZrH_(1.8)表面阻氢陶瓷层的影响

磷酸盐电解液体系下,以CeO_2作为电解液添加剂,采用恒压模式对氢化锆(ZrH_(1.8))表面进行微弧氧化(MAO)处理,研究正向电压对陶瓷层厚度、相结构、形貌,结合力以及阻氢渗透性能的影响。利用扫描电镜(SEM)、 X射线衍射仪(XRD)、涂层测厚仪、涂层划痕仪,分别分析了陶瓷层的表面和截面形貌、相结构、陶瓷层厚度以及膜层与基体的结合力,通过真空脱氢实验评价陶瓷层的阻氢性能。结果表明:随着正向电压的增加,氢化锆表面微弧氧化陶瓷层的厚度逐渐增加,当正向电压为375 V时陶瓷层的阻氢性能较好,氢渗透降低因子PRF值可达到14.2;正向电压的改变对陶瓷层的相结构没有明显影响,膜层主要由单斜相氧化锆(m-ZrO_2)、四方相氧化锆(t-ZrO_2)和立方相氧化铈(c-CeO_2)组成,且以单斜相氧化锆(m-ZrO_2)为主。     

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.     

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.