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171.
Bronk Detlev W.; Carmichael Leonard; Dollard John; Hilgard Ernest R.; Whitehorn John C. 《Canadian Metallurgical Quarterly》1970,25(5):411
This article offers a collection of retrospective comments by members of the original Harvard Commission. Each member provides his own comment and discusses his experiences in life and work. Comments are provided by: Detlev W. Bronk, Leonard Carmichael, John Dollard, Ernest R. Hilgard and John C. Whitehorn. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
172.
Detlev Thierig 《国际钢铁研究》1970,41(9):895-897
Die photometrische Bestimmung von Aluminium im Stahl mit Chromazurol S unter Zusatz von Polyvinylalkohol als Schutzkolloid wurde untersucht. Der Aluminium-Komplex wird bei pH 6 gebildet, die Extinktion bei 620 nm gemessen. Störende Elemente werden durch eine Natronlaugefällung in Gegenwart von Zinkchlorid und Borsäure entfernt. Die Nachweisgrenze des Verfahrens liegt bei 0,0008% Al. Die Standardabweichung bei der Bestimmung von 0,0032% Al beträgt 0,00028% Al. Der Extinktionskoeffizient liegt bei 73 400 l/Mol · cm. 相似文献
173.
White crystallites were visually observed on fractured or polished surfaces of SiC samples (grain sizes below ∼500 nm) during exposure to air at room temperature for several days. Characterization of the crystallites by scanning electron microscopy, secondary ion mass spectroscopy, and X-ray diffraction identified B(OH)3 crystals with a strong (002) texture. The rate of boric acid formation was determined by a gravimetric experiment. The rate of weight gain increased significantly after an incubation period of 1 week. Nucleation is initially the rate-limiting process. Subsequently small B(OH)3 crystals form on the surface, whose growth rate is determined by grain boundary diffusion of boron to the SiC surface. An estimated grain boundary diffusion coefficient of boron in SiC was many orders of magnitude higher than extrapolated literature values. 相似文献
174.
K. Kaspar K. Fritsch K. Habicht B. Willenberg H. Hillebrecht 《Journal of Electronic Materials》2017,46(1):92-100
In this study we show a preparation method for nanostructured Bi0.85Sb0.15 powders via a chemical reduction route in a polyol medium, yielding material with particle sizes of 20–150 nm in scalable amounts. The powders were consolidated by spark plasma sintering (SPS) in order to maintain the nanostructure. To investigate influence of the sinter process, the powders were characterized by x-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDX), and scanning electron microscopy (SEM) measurements before and after SPS. Transport properties, Seebeck effect, and thermal conductivity were determined in the low temperature range below 300 K. The samples showed excellent thermal conductivity of 2.3–2.6 W/m × K at 300 K and Seebeck coefficients from ?97 μV/K to ?107 μV/K at 300 K with a maximum of ?141 μV/K at 110 K, thus leading to ZT values of up to 0.31 at room temperature. The results show that Bi-Sb-alloys are promising materials for low-temperature applications. Our wet chemical approach gives access to scalable amounts of nano-material with increased homogeneity and good thermoelectric properties after SPS. 相似文献
175.
Carbon Nanotubes: An All‐Solution‐Based Hybrid CMOS‐Like Quantum Dot/Carbon Nanotube Inverter (Adv. Mater. 35/2017) 下载免费PDF全文
176.
C. W. Fritsch V. E. Weiss R. H. Anderson 《Journal of the American Oil Chemists' Society》1971,48(8):392-393
The active oxygen method (AOM) stability of refined coconut oil is generally 250 hr; however, samples with as low a stability
as 30 hr have been obtained. The addition of BHA, BHT and citrate increased the AOM stability to about 350 hr even though
the initial stability was 30 or 250 hr. Refined coconut oil samples which hydrolyzed from 2 to 10 times as rapidly as normal
oils have been encountered. Such samples are undesirable for food production as soapy off-flavors may be produced. The rate
of hydrolysis of coconut oil samples was evaluated by a simple laboratory test. Coconut oil free fatty acids produced a soapy
off-flavor at a lower level in sweet foods than in salty ones. Soapy off-flavors were produced in a low moisture food containing
coconut oil by the lipase activity of cinnamon. 相似文献
177.
Mathew R. Opitz Knuth Albertsen James J. Beeson Detlev F. Hennings Jules L. Routbort Clive A. Randall 《Journal of the American Ceramic Society》2003,86(11):1879-1884
Base metal technology, mainly using Ni electrodes in multilayer ceramic capacitors (MLCCs), is now well established. This technology requires a so-called reoxidation treatment after sintering the MLCCs in a reducing atmosphere to guarantee a sufficient electrical reliability. Large numbers of electrodes, and production of physically larger components for high-voltage components, are two technological trends that make the control of the reoxidation process rather difficult. The reoxidation process has been studied to determine oxygen diffusion pathways into commercial MLCCs, using 18 O tracer diffusion and finite element calculations. In MLCCs oxygen diffusion mainly occurs along the Ni electrodes. Furthermore, the reoxidation process is mostly controlled by the thermodynamic potential of the Ni/NiO equilibrium in the interior of the capacitor, but it is the short circuit diffusion along the interface of the electrode that controls the kinetics of the oxygen transport into the interior of the capacitor device. 相似文献
178.
Hydroxyl Defect Effect on Reoxidation of Sc‐Doped (Ba,Ca)(Ti,Zr)O3 Fired in Reducing Atmospheres 下载免费PDF全文
Yu‐Ju Kao Che‐Yi Su Christian Pithan Detlev F. Hennings Chi‐Yuen Huang Rainer Waser 《Journal of the American Ceramic Society》2016,99(4):1311-1317
The behavior of grain and grain‐boundary conductivity of acceptor (Sc)‐doped (Ba,Ca)(Ti,Zr)O3 ceramics sintered in moist reducing atmosphere and subsequently reoxidized in dry and moist atmosphere was investigated by means of impedance spectroscopy (IS). In moist firing atmosphere, water vapor was found to react with oxygen vacancies, forming positively charged hydroxyl defects on regular oxygen sites in the crystal lattice. Proton hopping is considered to raise the ionic conductivity significantly. Therefore, hydroxyl defects in turn influence the grain conduction. Hydroxyl defects are also considered to be responsible for alternations of the dielectric maximum at the Curie point. 相似文献
179.
Georg Mauer José-Luis Marqués-López Robert Vaßen Detlev Stöver 《Journal of Thermal Spray Technology》2007,16(5-6):933-939
Wear at the electrode surfaces of a one-cathode plasma torch changes the characteristic fluctuation pattern of the plasma
jet. This affects the trajectory of the particles injected into the plasma jet in a non-controllable way, which degrades the
reproducibility of the process. Time-based voltage measurements and Fourier analysis were carried out on a one-cathode F4
torch at different wear conditions to determine the evolution of wear dependant characteristics. A significant correlation
is observed between increasing torch wear and decreasing voltage roughness and high frequency noise. Furthermore, by means
of particle diagnostic systems, the change in the particle velocity and temperature has been measured. The variations of the
particle characteristics are significant and thus an influence on the sprayed coating microstructure is to be expected.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
180.
Robert Vaßen Franziska Traeger Detlev Stöver 《Journal of Thermal Spray Technology》2004,13(3):396-404
It is generally known that the porosity of thermal barrier coatings is essential to guarantee a sufficiently high strain tolerance
of the coating during thermal cycling. However, much less is known about the influence of the specific morphology of porosity,
such as microcracks and typically larger pores, on the performance of the coatings. Both features are usually formed during
plasma spraying of yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBCs). In this investigation, the influence
of microcracks on the thermal cycling behavior was studied. The amount of microcracks within YSZ thermal barrier coatings
was changed by changing the powder-feeding rate. Only small changes of the total porosity were observed. Mercury porosimetry
served as a tool to investigate both the amount of microcracks and pores in the coating. Additionally, microcrack densities
were determined from metallographical investigations. A linear dependence between the amount of fine pores determined by Hg
porosimetry and the crack density was obtained for one set of coatings. Thermal cycling TBC specimens with different microcrack
densities were produced and tested in a gas burner test facility. At high surface temperatures (above 1300 °C), failure occurred
in the ceramic close to the surface. Under these conditions, the samples with increased horizontal microcrack densities showed
a significant increase of thermal cycling life. 相似文献