Results 1 - 10 of 1176
Results 1 - 10 of 1176. Search took: 0.023 seconds
|Sort by: date | relevance|
[en] Five borosilicate glasses containing up to 20% zirconium oxide and 10% non-radioactive fission products or lanthanum oxide (which simulates the behaviour of the actinides) were leached in stagnant distilled water at 200 C for 2 years. The leaching rates of Na, La, Mn, Cs and Mo varied with time and the chemical composition of the glass from 0.7 to 12, 0.006 to 0.14, 0.8 to 1.2, 0.4 to 0.8 and 8 to 25 mg/m2/d respectively. The glasses which showed the best short-term resistance do not have the best long-term resistance. (orig.)
[en] The neutron powder diffraction and Transmission Electron Microscopy(TEM) were employed to study about the substitutional site of the Zr atom in the Zr-added LiCoO2. From the neutron diffraction study, it was concluded that the Zr atom is hardly incorporated in the LiCoO2 system and it exists in the form of ZrO2. Transmission electron microscopy observations also show that ZrO2(50∼100nm) is well distributed in the LiCoO2 system. The origin of the improvement of the cycling property and the rate capability are considered as the existence of the ZrO2 - LiCoO2
[en] The electronic and geometric structure of non stoichiometric pure and doped -Zr Yttria has been studied by means of photoemission and X-ray absorption. Main results show the influence of the doping atom on the level of non stoichiometry as well as on the induced disorder and on the change of the partial ionic character of the Y-O bond
[fr]La structure electronique et geometrique de l'oxyde d'Yttrium pur et dope avec Zr est etudiee par photoemission et absorption X. Les resultats montrent l'influence de l'atome dopant au niveau de la non stoechiometrie ainsi que sur le desordre induit et sur le changement du caractere ionique partiel de la liaison Y-0
[en] Aluminum and its alloys are the second most commonly used metal for a variety of engineering applications. They solidify in columnar structure with large grain size which normally affects their mechanical behavior and surface quality. It is now becoming customary in aluminum foundry to grain refine their structure by adding either titanium or titanium + boron to their melt before solidification. In this paper, the effect of addition of Ti on the mechanical properties, ductility and wear resistance of commercially pure aluminum is investigated. Titanium was added at a level of 0.15 % wt. This ratio corresponds to the peritectic limit on the Al-Ti phase diagram and is normally used for grain refining of aluminum. It was found that addition of Ti at this level resulted in grain refinement of aluminum structure whereas addition of Zr alone resulted in grain coarsening of Al structure while it resulted in grain refinement when it is added in the presence of Ti. Regarding the effect of Zr on the wear resistance of aluminum it was found that at small loads and speeds addition of Ti or Zr or both together resulted in deterioration of its wear resistance whereas at higher loads and speeds resulted in pronounced improvement of its wear resistance. (author)
[en] The evolution behaviors of MnS inclusions during 1473 K heating have been systematically investigated for EH36 shipbuilding steel with Zr addition. It is revealed that heating promotes MnS precipitation on the surfaces of ZrO2 inclusions. Further, quantified results by confocal scanning laser microscopy indicate that the area fraction of MnS first increases, reaches a maximum value, and undergoes a sharp decrease, which corresponds to the three unambiguously defined stages, namely, coarsening, Ostwald ripening, and crushing.
[en] Aluminum and its alloys solidify in large grains columnar structure which tends to reduce their mechanical behaviour and surface quality. Therefore, they are industrially grain refined by titanium or titanium + boron. Furthermore, aluminum oxidizes in ordinary atmosphere which makes its weldability difficult and weak. Therefore, it is anticipated that the effect of addition of zirconium at a weight percentages of 0.1% (which proved to be an effective grain refiner on the weldability of aluminum grain refined by Ti) is worthwhile investigating. This formed the objective of this research work. In this paper, the effect of zirconium addition at a weight percentage of 0.1%, which corresponds to the peritctic limit on the aluminum-zirconium phase diagram, on the weldability of aluminum grain refined by Ti is investigated. Rolled sheets of commercially pure aluminum, Al grain refined Ti of 3 mm thickness were welded together using Gas Tungsten Arc Welding method (GTAW), formerly known as TIG. A constant air gap was maintained at a constant current level, 30 ampere AC, was used because it removes the oxides of the welding process under the same process parameters. Metallographic examination of weldments of the different combinations of aluminum and its microalloys at the heat affected zone, HAZ, and base metal was carried out and examined for width, porosity, cracks and microhardness. It was found that grain refining of commercially pure aluminum by Ti resulted in enhancement of its weldability. Similarly, addition of zirconium to Al grain refined by Ti resulted in further enhancement of the weldment. Photomicrographs of the HAZ regions are presented and discussed. (author)
[en] A photometric determination of zirconium in low-alloyed steels (zirconium content is 0.02-1%) is developed. The method is based on the measurement of the colouring intensity of Zr(4) complex with arsenazo 3, formed in 2-10 n HCl solution. Lambdalsub(max) of the complex is 665 nm, molar coefficient of quenching in 2 n HCl solution is 1.2x105. Optimum concentration is 20-150 μg per 100 ml of the solution, the lower determination limit constitutes 0.05 μg/ml. Al, Cu, Mg, Mn, Ti do not interfere with Zr determination. Fe(3) is reduced with ascorbic acid
[en] Research highlights: → Adding 0.41-1.18 wt.%Zr can refine the grains of Mg-3Sn-2Ca alloy. → Adding 0.41-1.18 wt.%Zr can modify the primary CaMgSn phase of Mg-3Sn-2Ca alloy. → Adding 0.41-0.76 wt.%Zr can improve the mechanical properties of Mg-3Sn-2Ca alloy. -- Abstract: At present, the mechanical properties of the Mg-3Sn-2Ca magnesium alloy are not satisfying and further enhance needs to be considered via further alloying/microalloying additions. The effects of Zr addition on the as-cast microstructure and mechanical properties of the alloy were investigated by using optical and electron microscopies, differential scanning calorimetry (DSC) analysis, and tensile and creep tests. The results indicate that adding 0.41, 0.76 or 1.18 wt.% Zr can refine the grains of the alloy, and the primary CaMgSn phases in the Zr-containing alloys are changed from coarse needle-like net to relatively fine short block and/or particle-like shapes. As a result, the tensile and/or creep properties of the Zr-containing alloys are improved. Among the Zr-containing alloys, the alloy with the addition of 0.76 wt.% Zr exhibits the relatively optimum mechanical properties.