V85Ti10Y5和V85Ti10Cu5氢分离合金组织与性能研究

利用高真空非自耗电弧熔炼炉制备了V85Ti10Y5和V85Ti10Cu5氢分离合金。通过SEM、TEM、XRD、氢渗透实验、PCT吸氢实验、恒压缓冷实验,研究了Y、Cu元素的加入对合金氢渗透性能、氢溶解性能及抗氢脆性能的影响。结果表明:铸态V85Ti10Y5和V85Ti10Cu5合金组织均由V-基体和第二相组成,但前者第二相是弥散分布的富Y颗粒,而后者为既在晶内析出又沿晶界连续分布的铜钛金属间化合物。V85Ti10Y5合金中Y2O3的生成及V85Ti10Cu5合金中部分固溶Cu的斥氢作用和Cu2Ti形成使V中Ti的固溶量减少,进而降低合金中的氢浓度,减小氢固溶产生的内应力,提高抗氢脆性能。V85Ti10Y5和V85Ti10Cu5合金在缓冷过程中均未发生氢脆现象,表现出优异的抗氢脆性能,而且在673 K时的氢渗透率分别为0.139×10-6 mol H2 m-1 s-1 Pa0.5和0.174×10-6 mol H2 m-1 s-1 Pa0.5,是Pd77Ag23氢渗透率的5.5和6.9倍,与商用钯合金相比均展现出较高的渗透率。     

Particle loss: An initial investigation into size effects and stress-dilatancy

Drained triaxial tests have been performed to explore the effect of particle loss on shearing behaviour and critical states in granular mixtures. The mixtures comprise Leighton Buzzard sand (d₅₀ = 0.8 mm), to which was added 15% by mass of salt particles of different nominal sizes: 0.063 mm, 0.25 mm and 0.5 mm. Shearing behaviours before and after particle loss (by dissolution) were compared. A good fit is observed between the test data and a stress-dilatancy relationship for the post-dissolution tests, highlighting the ability of the stress-dilatancy analysis as a means to interpret the effects of particle loss on shearing. It was noted that critical state strength parameter M is determined by the post-dissolution grading regardless of size of removed particle. However, the duration of contractant volumetric strain increased with the larger removed particles (0.25 mm & 0.5 mm) even when initial specific volumes were virtually identical. It is suggested that a loose volumetric state is reached if the sand particle network is initially disrupted by the amount and/or size of salt particles, which following dissolution results in structural or fabric phenomena that are not reflected in scalar volumetric measures such as specific volume.     

45钢与QT450-10的表面耐腐蚀处理工艺及性能研究

针对注塑机零件中常用的材料45钢和QT450-10,采用未经热处理的模拟试样,分别进行两组不同工艺参数的软氮化及磷化（发黑）和浸涂防锈油等处理方式。最后使用中性盐雾腐蚀试验评估各试样获得的耐腐蚀性能。研究表面：采用相同的表面处理工艺,45钢的耐腐蚀性能优于QT450-10;QT450-10未经磷化（发黑）处理,无论是否浸涂防锈油,表面耐腐蚀性均很差。     

06Cr13换热钢管与06Cr19Ni10管板焊材选择试验研究

使用ER316L、ER309L及ERNiCr-3焊丝对06Cr13换热钢管与06Cr19Ni10管板进行平缝GTAW管头自动焊接,通过PT、Leica显微镜和维氏硬度等方法检测,06Cr13换热钢管与06Cr19Ni10管板使用ER316L焊丝进行焊接时,焊缝没有裂纹,组织性能最优,说明试验所选焊接工艺参数是合理的,ERNiCr-3焊丝焊后试件存在裂纹,试验不合格。     

MPT-AES法测定抚顺市采暖期PM_(2.5)和PM_(10)中的重金属

用微波等离子体炬(MPT)为激发光源,氩气为等离子体工作气体,用气动雾化迚样,研究了微波等离子体炬原子发射光谱法(MPT-AES)测定抚顺环境样品中的重金属元素Pb,Cd,Cr,Cu,Mn的方法。考察了各微量元素的分析谱线,载气流量,工作气流量和微波向前功率对元素Pb,Cd,Cr,Cu,Mn的发射强度的影响,分析了酸浓度及共存离子对其测定的影响,得到了测量不同金属离子的最佳工作条件,在最佳条件下测量元素Pb,Cd,Cr,Cu,Mn的检出限分别为22.9,5.7,30.7,3.6,6.0 ng·mL-1,精密度分别为5.97%,4.92%,1.24%,1.54%,1.87%,加标回收率在84.6%-104.0%之间。     

激光熔化沉积AlSi10Mg成形特性及力学性能

目的研究激光熔化沉积Al Si10Mg铝合金的成形特性及力学性能。方法以颗粒度45～105μm的Al Si10Mg粉末为材料,6061铝合金为基板,利用光纤激光器在充氩舱内分别进行单层单道、竖直薄壁单墙体与倾斜薄壁墙体的成形试验。测试单墙体的抗拉强度与延伸率,并通过扫描电子显微镜和光学显微镜对微观组织形貌进行分析。结果单层单道沉积层高度与激光扫描速度负相关,与送粉速度成线性正相关;而沉积层宽度与扫描速度负相关,与激光功率正相关。沉积单墙体时,沉积前10层最不稳定,墙体厚度低于后续层的厚度。为了使沉积过程稳定,墙体不塌陷,通过激光功率在前20层左右逐层递减,成功制备出250层(高10cm)以上的单墙体。工艺选取合适时,AlSi10Mg具有良好的成形能力,激光头角度保持竖直不变,墙体倾角60°以下可以稳定沉积。制备沉积态Al Si10Mg气孔率约3%,抗拉强度250MPa左右,延伸率5%以上,抗拉强度高于成分相似的ZL104铸件25%。微观组织内Al-Si共晶细小,没有针片状共晶组织,并且组织沿沉积方向呈现周期性变化。结论 Al Si10Mg在激光熔化沉积时具有良好的成形能力,沉积态的组织强度高于铸态组织强度。优化后的工艺可以稳定沉积制备下圆上方的变截面薄壁样件。     

Geographically and technologically mediated knowledge spillovers between European regions

This paper aims at investigating inter-regional knowledge spillovers across European sub-national regions. The basic questions that we wish to answer may be formulated in the following way: do regional geographical and technological proximities matter for the creation of new knowledge within the European regional landscape? After a review of the related literature, we consider a regional knowledge production function that allows for extra regional innovation-generating inputs. Accounting for regional specific social capability, this knowledge production function is applied to an extended sample of 153 European sub-national regions over the period 1989–1996. Interregional knowledge spillovers are shown to exist between geographically close regions and between regions displaying similar technological profiles. However, technological proximity and geographical proximity coincides to a certain extent. Knowledge spillovers are mainly driven by the private business sector. If knowledge spillovers occur within a given country, the national border turns out to seriously hamper interregional spillovers on the European scale. The author wishes to thank Eckhardt Bode, Henri Capron, Raymond J.G.M. Florax, Charlie Karlsson, Roger Stough and Roger Vickerman for their useful comments and suggestions. An earlier version of this paper was presented at the 41st Annual Meeting of the Western Regional Science Association in February 2002, Monterey, California.     

Extracting dust from soil: a simple solution to a tricky task

Air quality is commonly assessed by the ambient concentration of airborne particles sized smaller than 10 microm (PM10). However, in addition to concentration, particle shape as well as the type and bioaccessibility of elements adsorbed to this particulate fraction are likely to be related to subsequent respiratory health effects. In order to investigate this relationship, a relatively large mass of the relevant size fraction is needed since sample preparation is necessary prior to analysis. Most existing methods for sampling dust have been developed for analysing the dust directly, without prior handling or digestion. In order to provide sufficient material to be used for subsequent bioaccessibility analysis, these methods require repetitive and time consuming sampling as well as special equipment and procedures which are high in both cost and maintenance. This paper describes an inexpensive and relatively simple procedure for extracting the PM10 fraction from soil to be used for lung bioaccessibility studies. The method described involves dry and wet sieving in order to exclude larger size fractions as far as possible. Vacuum filtering of the wet-sieved soil solution through a 10 microm mesh was then employed to extract the required fraction. In order to avoid frequent blocking of the mesh, Stokes's law was applied in the construction of a tube which enables separation of the solution holding the smallest fraction.     

Interpretation of the variability of levels of regional background aerosols in the Western Mediterranean

Results on interpretation of the variability of regional background PM levels in the Western Mediterranean basin (WMB) are presented. Mean PM levels recorded at Montseny, MSY (North-Eastern Spain) in the 2002-2007 period reached 17, 13 and 11 µg/m³ of PM₁₀, PM_2.5 and PM₁, respectively.The daily evolution of PM levels is regulated by the breeze circulation (mountain and sea breezes). PM levels are lower at the rural sites at night owing to the nocturnal drainage flows and to the lowering of the mixing layer height below the MSY high. These nocturnal low levels allowed us to estimate the continental background PM levels. At midday, the atmospheric pollutants accumulated in the pre-coastal depression are transported upwards by the breeze, increasing PM levels.Maximum PM₁₀ levels were recorded in summer, and February-March and November, and minimum values in the rest of the year coinciding with the highest frequency of Atlantic advection. PM peak episodes attributed to Saharan dust outbreaks were recorded in summer and February-March. In addition, anticyclonic situations (February-March and November) may impact in elevated rural areas by increasing hourly levels of PM₁ up to 75 µg/m³. This scenario induces the stagnation of pollutants in the pre-coastal depression. Solar radiation activates mountain winds, transporting polluted air masses from the valleys to elevated areas resulting in an increase of fine PM levels in areas outside the boundary layer.A significant decrease in PM annual means (40% and 34% for the entire monitoring period, 7 µgPM₁₀/m³ and 5 µgPM_2.5/m³) was recorded at MSY between 2002 and 2007. There appears to be no single cause behind these trends. This could partially be ascribed to the varying frequency and intensity of Saharan dust episodes, but also to large-scale meteorological processes or cycles, and/or to local or meso-scale processes such as nearby anthropogenic emission sources.     

Spatial competition and regulatory change in the grain handling and transportation system in western Canada

The grain handling and transportation system (GHTS) has been a defining component of the western Canadian economy since the early part of the last century. Only two major railways serve the grain handling industry, so the potential for the exercise of market power in transportation appears to be significant. In fact, spatially oriented regulations applicable to railways exist in Canada to mitigate this, but to date they have not often been used by shippers. While the reasons for this are not completely clear, we suggest that the regulations are now inadequate for the current state of the GHTS. Using a unique data set from the year 2000, we assess the effect on the grain handling industry of modifications to these regulations, and find that significant gains for shippers from these modifications are possible. These gains are computed to be on the order of C$10–15 million per year for grain shippers alone. We would like to thank conference and presentation participants (Transportation Research Board, Canadian Agricultural Economics Society, University of British Columbia, University of Leeds and California State University, Long Beach) as well as the anonymous reviewers who commented on the earlier versions of this paper. We would also like to acknowledge support from the Saskatchewan Department of Highways.