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91.
Alan A. Luo Robert C. Kubic John M. Tartaglia 《Metallurgical and Materials Transactions A》2003,34(11):2549-2557
This study investigated the microstructure and fatigue properties of hydroformed sections of the 5754 and 6063 aluminum alloys.
The second-phase particles in 6063-T7 are identified as a mixture of Al12Fe3Si and Al9Fe2Si2, with a slightly higher fraction of the former. The constituent particles in the 5754 alloy are Al4Mn-type hexagonal compounds, where Mn is partially substituted by various other elements, resulting in Al4(Fe,Mn,Si,Cr). The results show that despite its lower yield strength, the hydroformed 5754 alloy has higher ultimate tensile
strength, ductility, and, more importantly, higher fatigue resistance than the 6063 material. Both crystallographic stage
I and noncrystallographic stage II cracking are found in the 6063-T7 samples, but only stage II cracking is observed in the
5754 alloy. This implies that the low fatigue strength of 6063-T7 is related to its relatively large grain size, resulting
in rapid stage I crack propagation. The higher fatigue lives of the 5754 alloy compared to the 6063 alloy in both the low-
and high-cycle life regimes are due to the increased fatigue-crack-initiation and propagation resistance of the 5754 alloy
and its probable cyclic strain-hardening behavior. 相似文献
92.
《Materials Letters》2007,61(8-9):1881-1884
Organic ultraviolet (UV) ray absorbents, cinnamic acid (CA) and p-methoxycinnamic acid (PMOCA) were intercalated into Zn2Al layered double hydroxides (Zn2Al-LDHs) by co-precipitation reaction. The organic–inorganic nanocomposites, Zn2Al-LDH/CA and Zn2Al-LDH/PMOCA were obtained. The samples showed excellent UV ray absorption ability and their catalytic activity for the air oxidation of castor oil greatly decreased when the organic UV ray absorbents were intercalated in the layers of the Zn2Al-LDHs. The studies suggested that Zn2Al-LDH/organic UV absorbent nanocomposites might be used as safe sunscreen materials. 相似文献
93.
Phase behavior in liquid crystallization was studied for a series of liquid crystalline (LC) diblock copolymers consisting of rubbery amorphous and side-chain liquid crystalline components, poly(n-butyl acrylate) (PBA) and poly[11-(4′-cyanophenyl-4″-phenoxy)undecyl acrylate] (PLC), respectively, using a time-resolved small-angle X-ray scattering (SAXS) techniques, DSC and polarized optical microscopy (POM). The block copolymers used had three kinds of copolymer compositions, 44, 20 and 15 wt% of PLC compositions (BLC44, BLC20 and BLC15, respectively). BLC44 showed a smectic liquid crystalline structure. In the process of liquid crystallization for BLC44, the SAXS peak due to the microphase separation structure existing before liquid crystallization was changed continuously to be at a smaller angular side, and at almost the same time, a new peak appeared at a further smaller angular side and developed. The former peak disappeared with the development of liquid crystallization. The behavior of these SAXS peaks suggests that the microphase separation structure was changed discretely at the transition from isotropic to smectic and that two phases coexist in the early stage of the liquid crystallization. The coexistence of two peaks in the early stage of the liquid crystallization corresponded to the POM observation. In the isotropization process, coexistence of two phases was not observed. For BLC20 exhibiting a cylindrical structure in both isotropic and liquid crystalline states, the liquid crystalline structure was not smectic but probably nematic, and the spacing was changed continuously in liquid crystallization. No liquid crystallization was observed in SAXS, POM and DSC for BLC15. The orientation of smectic layers within lamellar domains was investigated using 2D-SAXS images. The smectic layer was aligned perpendicularly to the lamellar interface. 相似文献
94.
95.
《Energy Policy》2005,33(13):1677-1689
There exists a political goal in Sweden and elsewhere to increase the use of renewable energy and wind power seems to be a favourable choice from an environmental perspective. However, although the public generally expresses a positive attitude towards wind power, the experience often shows that specific wind power projects face resistance from the local population. This paper analyses the attitudes towards wind power among the electricity consumers as well as the foundations of these attitudes. Results are based on a postal survey that was sent out to 1000 Swedish house owners. According to the results, the public is generally positive towards wind power. The probability of finding an average individual in support of wind power decreases with age and income. People with an interest in environmental issues are, however, more likely to be positive towards wind power than the average respondent and the results do not support the NIMBY-hypothesis. In addition, people that are more inclined to express public preferences are also more likely to be positive towards wind electricity than people who are less inclined to do so. These results imply, for instance, that the potential of markets for “green” electricity may be limited, other support schemes is thus required if the politically stated goal to increase wind power capacity is to be fulfilled. 相似文献
96.
A. P. Vasil’ev V. P. Vasyukhno M. E. Netecha V. L. Vysotskii R. I. Kalinin A. A. Sarkisov A. Yu. Kazennov Yu. V. Sivintsev A. M. Chernyaev 《Atomic Energy》2006,101(1):506-511
The radioecological conditions which developed on the territory over the long operating time of the object of the naval fleet
in Guba Andreev are described. The results of an analysis of the sources of the real and potential danger and measures to
prevent dangerous effects for the environment and the workers at the time remediation work is performed are discussed.
__________
Translated from Atomnaya énergiya, Vol. 101, No. 1, pp. 49–55, July, 2006. 相似文献
97.
98.
99.
Garey A. Fox John W. Fuchs Victor F. Medina Kaumudi Atapattu 《Canadian Metallurgical Quarterly》2007,133(3):255-262
Recent research has proposed the use of asphalt and tall-oil-pitch emulsions for stabilizing radioactive contamination deposited on surfaces in urban areas. The objective of this project was to investigate whether surface applied emulsions could capture airborne radioactive particulate. Laboratory experiments included wind-blown particulate capture studies using an acrylic column and particulate retainment experiments using a wind box capable of producing wind speeds of 96?km/h. A probe methodology was developed to relate particulate retainment to a tack force on the emulsion surface. Experiments were also performed to determine the potential for such emulsions to absorb particulate matter into their emulsion matrix. Tall-oil-pitch emulsions outperformed asphalt emulsions in terms of particulate retention, tack force, and the ability to absorb magnesium silicate. Both tall-oil-pitch and asphalt emulsions were capable of extracting 22–24?g?m?2 of powder from particulate-laden airflow. Tall-oil-pitch emulsions were capable of retaining as much as 5–10% of magnesium silicate powder applied (i.e., retainment densities of 10–20?g?m?2) even after seven?days of curing and after applying 96.5?km/h (60?mph) wind. Tall-oil-pitch emulsions were able to absorb surface-applied magnesium silicate (approximately 0.1–0.2?g of magnesium silicate per 1.0?g of emulsion within three?days) into their emulsion matrix, preventing the magnesium silicate from being exposed to the external environment. Initial results with these five different emulsion formulations suggested particulate capture was feasible. Future emulsion formulations (i.e., longer curing times with greater acid concentrations) should be tested to optimize this postdetonation response strategy. 相似文献
100.
《Diamond and Related Materials》2005,14(2):226-231
It is well known that hard disk drive media with high orientation ratio (OR) has higher SNR and better thermal stability, which is desirable for higher density recording. The oriented media requires a mechanical texturing process on NiP-plated Al-substrates. Mechanical texturing process is a process to generate circumferential texture patterns (grooves) on the NiP surface using tape with diamond slurry rotating the disk while contacting of the tape and slurry. In this study, we compare the texture parameter δ/λ, where δ is the average depth of the texture line and λ is the average distance between two texture lines, line density (LD), orientation ratio (OR), and recording performances of disks prepared by three types of diamond slurries, namely mono-crystalline diamond (MD), poly-crystalline diamond (PD), and poly-mono-crystalline diamond (Hybrid). Mono-crystalline diamond slurry is a single crystallite, which has sharper edges and fewer facets. Poly-crystalline diamond slurry contains many single crystallites, which has more rounded edges and facets. Hybrid-crystalline diamond is formed from milled (and rounded) mono-crystalline diamond, using atmospheric and temperature changes to micro fracture the surface of the mono-crystallite structure, producing a harder nucleus and more and sharper cutting facets as compared to poly-crystalline diamond. Experimental results show that the substrates textured with hybrid-crystalline diamond slurry can create disk surface with the highest line density and δ/λ, which results in the highest OR, the lowest intergranular exchange coupling energy, the lowest DC erase noise, and the highest SNR, than the substrates textured with mono-crystalline and poly-crystalline diamond slurries. With increasing the texture parameter δ/λ from 0.034 to 0.058, an OR increases from 1.48 to 1.82 and the SNR increases from 19.10 to 19.66. There are very well correlations among δ/λ, OR, and SNR. 相似文献