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排序方式: 共有336条查询结果,搜索用时 11 毫秒
21.
Teplenko Marina A. Podchernyaeva Irina A. Panasyuk Alla D. 《Powder Metallurgy and Metal Ceramics》2002,41(3-4):154-161
We have studied the process of electrospark alloying of titanium alloy VT6 and steels with a composite material based on AlN ZrB2 with ZrSi2 additive. We have established that Al2SiO5 and ZrSiO4 forming in the coating directly during its formation play the role of a solid lubricant. Under optimal conditions for electrospark alloying of the titanium alloy, the coefficient of friction is 0.13, the wear is 6 m/km for a sliding velocity of 14 m/sec and a load of 2.56 MPa. Ceramics based on AlN ZrB2 can be recommended for use as wear-resistant and corrosion-resistant coatings. 相似文献
22.
Lavrenko Vladimir A. Panasyuk Alla D. Firstov Sergei A. 《Powder Metallurgy and Metal Ceramics》2003,42(5-6):291-296
Potentiodynamic polarization, XRD, Auger electron spectroscopy, and scanning electron microscopy have been applied to determine the mechanisms of electrolytic corrosion of the intermetallides TiAl, TiAl3, and 2Ti3Al in 3% NaCl solution with the addition of MgSO4 in comparison with the corrosion of the pure metals (Al and Ti). There is comparatively high corrosion resistance in TiAl and Ti3Al because of the protective action from thin films of rutile TiO2. Evidence is obtained for the differences between these intermetallides from the appearance of pure titanium on deep anodic polarization (above +0.15 V for TiAl and +0.7 V for Ti3Al): the aluminum and titanium enter the solution in the forms of Al3+ and TiO2+ and intermetallides dissolve rapidly. The final solid-state products from anodic oxidation in that case are rutile, magnesium aluminate, and also magnesium and sodium titanates. In addition to pure titanium, TiAl and 2Ti3Al as constructional materials may be recommended for use in sea water. 相似文献
23.
Oleg N. Grigoriev Boris A. Galanov Vladimir A. Lavrenko Alla D. Panasyuk Sergey M. Ivanov Alexandr V. Koroteev Klaus G. Nickel 《Journal of the European Ceramic Society》2010,30(11):2397-2405
The oxidation of ZrB2–SiC and ZrB2–SiC–ZrSi2 ceramics of different composition has been studied experimentally at 1500 °C in pure oxygen for up to 50 h. ZrB2–SiC–ZrSi2 ceramics proved to be the most oxidation-resistant at ZrSi2 contents of less then 4 wt%. These ceramics were more oxidation-resistant than ZrB2–SiC ceramics. An analytical model of growth kinetics for a multilayered scale based on an oxidation–diffusion balance was developed and tested. 相似文献
24.
Podchernyaeva Irina A. Panasyuk Alla D. 《Powder Metallurgy and Metal Ceramics》2000,39(11-12):554-559
Studies have been done on how various concentrated energy forms (spark discharge and laser beam) affect the formation, composition, and structure of coatings made from the new composite material TiB2 ― AlN (1:1). The working surfaces have been examined by x-ray phase analysis, microprobe, and metallography. It is found that the composition and structure of a spark coating differ from those of the depositing electrode. The TiB2 ― AlN material is recommended for hardening low-carbon steels. 相似文献
25.
26.
O. V. Baum L. A. Popov V. I. Voloshin O. D. Kochetkova 《Measurement Techniques》1997,40(10):1011-1016
The problem of synthesizing Frank orthogonal lead system signals from those recorded by the standard lead system is considered, to answer the important practical question: can the synthesized EKG signals be used in practice for their diagnostic classification in terms of the Washington Code? 相似文献
27.
Anton A. Kovalchuk Vitaliy G. Shevchenko Alexander N. Shchegolikhin Polina M. Nedorezova Alla N. Klyamkina Alexander M. Aladyshev 《Journal of Materials Science》2008,43(22):7132-7140
Isotactic polypropylene (iPP) and syndiotactic polypropylene (sPP) nanocomposites containing 0.1–3.5 wt.% multi-wall carbon
nanotubes (MWCNTs) have been synthesized via in situ polymerization method with the use of C2- and Cs- symmetry zirconocenes activated by methylaluminoxane (MAO) in liquid propylene medium. Fracture morphology studies by SEM
reveal different MWCNT dispersion efficiency in various polymer matrices, which arises from the catalytic peculiarities of
the composite synthesis. Considerable Young’s modulus enhancement of iPP and sPP (25–66%) takes place even at low MWCNT loadings
(below 0.5 wt.%). The obtained nanocomposites can find use as efficient electromagnetic shielding materials and microwave
absorbing filters due to relatively low permittivity values and considerable dielectric losses in microwave range. Calorimetry
data demonstrate that MWCNTs exert evident influence as nucleating agents causing the rise of iPP and sPP crystallization
temperature. Considerable retardation effect on iPP thermal oxidative degradation has been observed: the temperature of maximal
weight loss rate rises by ~52 °C upon incorporating only 1.4 wt.% MWCNTs. 相似文献
28.
Abdelilah Alla 《Polymer》2005,46(9):2854-2861
A series of polyamides 6,4 were prepared from 1,6-hexanediamine and active esters of 2,3-di-O-acylated l-tartaric acid by polycondensation in solution. Both O-alkoyl and O-benzoyl esters were used as hydroxyl protecting groups. The resulting acylated polytartaramides were found to be semicrystalline polymers with Tm between 100 and 200 °C and Tg slightly above 100 °C. Controlled hydrolysis of the ester side group led to the preparation of poly(hexamethylene l-tartaramide)s with different content in free hydroxyl groups. These polyamides continue being crystalline but their properties largely differ from those displayed by their parent acylated polymers. 相似文献
29.
Susan Masten Brent Simpson Susan Hengemuehle Paramjeet Pati Alla Alpatova Boubacar Dembele 《臭氧:科学与工程》2015,37(1):29-35
Jatropha curcas is a well-known source of non-edible vegetable oil that is being promoted as an energy source and high quality feedstock in biodiesel production, especially in developing countries. The potential that the resulting seedcake by-product from jatropha oil extraction (?70% by volume) could also be used as a component in animal feed raises the prospect that a commercially viable jatropha-based industry could be developed. To date, however, the use of jatropha seedcake in livestock feed formulation has been constrained by the presence of phorbol esters (PE), which are known promutagenic and toxic compounds, and by the inability to eliminate PE by cost-effective means. Using seedcake by-product collected from a commercial facility in West Africa that processes jatropha biodiesel, this study demonstrates cost-effective measures of eliminating PE from jatropha seedcake using a combination of solar irradiation and ozonation. 相似文献
30.
Mayka Bautista Antxon Martínez de Ilarduya Abdelilah Alla Sebastin Muoz‐Guerra 《Polymer Composites》2016,37(9):2603-2610
A series of low‐molecular‐weight poly(butylene succinate‐co‐glutarate‐co−2‐trimethylammonium chloride glutarate) terpolyester ionomers containing 35% mol of total glutarate units but varying in the content of charged units were synthesized by polycondensation at mild temperatures using a scandium catalyst. The terpolyester ionomers started to decompose at the temperatures of >175°C and all of them were semicrystalline and have glass transition temperature similar to poly(butylene succinate) (PBS). These terpolyesters were used to compatibilize the nanocomposites made of PBS‐cloisite (CL) prepared by melt extrusion. X‐ray diffraction revealed that an intercalated structure was present in these nanocomposites. The thermal properties of the three‐component mixtures did not differ substantially from those of PBS–CL but the mechanical properties were significantly improved by the addition of the ionomer, in particular tenacity. The beneficial effect afforded by the terpolyester ionomer was attributed to its ability for strengthening the binding between the PBS and the nanoclay. POLYM. COMPOS., 37:2603–2610, 2016. © 2015 Society of Plastics Engineers 相似文献