Materials Literature
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The use of ozone depleting, so-called hard CFCs as blowing agents for rigid PU foams is presently experiencing considerable political and legislative pressure, to such an extent that a complete ban of these substances is expected within the foreseeable future. Consequently, there exists an urgent need for new thermal…
The dc electrical conductivity of the ternary glasses [81 mol, TeO2-19 mol P2O5]0.95 [RnOm]0.05 (R=La, Ce, Pr, Nd, Sm, and Yb) have been measured in the temperature range 50–300 °C. The electrical conductivity data have been examined and discussed on the basis of small polaron hopping conduction theory for the purpose…
In the present article, we review the recent neutron scattering studies on the anomalous behaviours found in the premartensitic bcc-based metals and alloys, i.e. alkali metals, group-IV metals, β-phase alloys, Ni-base alloys and others such as T1 and group-III metals. Lattice dynamical anomalies appearing on the [110]…
At high temperatures Sr 2 MnO 4-y crystallizes in the K 2 NiF 4 structure with anion defects. X -ray structure determination in space group I 4/m m m (No. 139) with a = 380.58(3), c = 1253.19(11) pm reveals the composition Sr 2 MnO 3.84±0.05 for a single crystal prepared under argon at 1510 °C. The oxygen deficiency i…
The ionic conductivities, σi, of La0.6Sr0.4Co1–yNiyO3(y= 0, 0.02) have been measured by the a.c. four-probe method with electron-blocking electrodes, and compared with diffusivity of oxygen from the oxygen isotopic-exchange reaction. The ionic conductivities estimated from both methods are similar. σi; values for the…
Unfinished wood siding was exposed outdoors for 1 to 16 weeks. Following this preweathering, the specimens were finished with a variety of film-forming finishes (paints or solid-color stains) and placed outdoors again (weathered) for several years. The finished specimens were evaluated annually to determine the effect…
Mechanical properties of α Ti are strongly influenced by texture and oxygen content. The effect of texture and oxygen content on the deformation behavior was investigated using three kinds of textured Ti sheets containing 0.05, 0.1, 0.2 and 0.4 mass%O. Especially, we paid attention to deformation twinning and 〈c+a〉 sl…
espanolSe ha preparado aluminato monocalcico por la via sol-gel y por el metodo Pechini. Siguiendo este ultimo metodo se obtuvo CaO AI2O3 (CA) ortorrombico a 900**C sin formacion de fases intermedias, mientras que la fase ortorrombica de CA cristalizo junto a otras fases cuando el gel se calcino a l.OOO^'C. Cuando los…
The authors point out that aerospace electronic and power systems demand increasing levels of safety, efficiency and power delivery because of the severe effects from long term operation in the space environment, often without any manned operation or maintenance. Consequently, the design requirements place more emphas…
A study has been made of the feasibility of applying optical fibre sensing technology to acoustic monitoring of partial discharges within gas insulated substations (GIS). A test rig has been constructed to simulate a section of GIS in which acoustic sources could be placed. This has been used to test the optical syste…
One of the problems with which we meet when we use the commercially available rare earth metals is the presence of interstitial impurity elements, particularly oxygen. Its amount often exceeds a thousand mass ppm. According to the thermodynamical values for the rare earth-oxygen system, some of the rare earth metals s…
Radiation damage in lithium orthosilicate (Li4SiO4) and Al-doped Li4SiO4 (Li3.7Al0.1SiO4) irradiated with oxygen ions was studied with ionic conductivity measurements, Raman spectroscopy, Fourier transform infrared photo-acoustic spectroscopy (FT-IR PAS) and transmission electron microscopy. It was seen from the ionic…
We have measured the dielectric constants of 6CHBT. The results from studies of various alignments and thicknesses measured under different electric and magnetic fields are presented. We discuss how the dielectric properties depend on boundary conditions, sample thickness and the magnitudes of electric and magnetic fi…
Low temperature (T = 10 K) luminescence decay curves of A2SeCl6 (A = Rb, Cs) are recorded which follow optical excitation at λexc = 458 nm applying different pulse lengths between 90 ns and 100 μs. For short excitation pulses a biexponential decay is observed, for pulse widths t exc > 10 μs a single exponential decay…
A TEM observation and an EDX analysis were carried out on interfaces between Ag-Cu-2wt% Ti alloy and three types of SiC containing B and C, BeO or Al2O3 as additives. They were brazed at temperatures of 850° or 950°C for 30 min. Interfacial structures of the specimens joined at 850°C were SiC (containing B+C)/TiC/Ti5S…
Pyrochlore type Na0.39Bi3.47O7 containing Bi5+ was prepared by low temperature hydrothermal reaction using hydrated sodium bismuth oxide, NaBiO3⋅nH2O, as a starting material. The mean valence of Bi in the pyrochlore is 3.94. The X-ray powder pattern for the pyrochlore was indexed in the cubic system with a=10.943(8)Å.…
Article Influence of the Cyclic Hydriding-Dehydriding Treatment on Pressure-Composition-Temperature Relations of the LaNi5 — H System* was published on January 1, 1993 in the journal Zeitschrift für Physikalische Chemie (volume 179, issue 1-2).
Composite alumina ceramics with a mullite whisker content of up to 30vol% were fabricated by hot-pressing at 1400 to 1600°C under 30MPa for 30min. The bending strength, hardness, elastic modulus and fracture toughness of the hot-pressed bodies were investigated. Considerably dense alumina-mullite whisker composite cer…
Abstract This paper discusses a generalized method to measure with the electron probe microanalyzer (EPMA) the oxygen in a material containing a surface oxide layer. The continuum background is the most difficult to measure, particularly for materials in which oxygen‐free samples cannot be produced. The method depends…
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