No abstract available

[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.)

No abstract available

[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] Highlights: • Zr-doped BFO exhibited best multiferroic properties. • The microstructural defects were studied by positron annihilation lifetime spectrum. • Cation vacancy has intimate correlation with the multiferroic properties of BFO. • The electric and magnetic properties of BFO can be improved by Ce/Zr doping. The polycrystalline samples of undoped BiFeO₃, Ce doped BiFeO₃ (Bi_0.9Ce_0.1FeO₃) and Zr dpoped BiFeO₃ (BiFe_0.9Zr_0.1O₃) were prepared by rapid liquid phase sintering technique. The effects of A-site substitution with Ce and B-site substitution with Zr on the structure, defects and multiferroic properties of BiFeO₃ ceramics were comparative investigated. Undoped and doped BiFeO₃ samples are well crystallized in perovskite structure, whilst Ce and Zr doping results in slight distortion in the lattice structure. With Ce and Zr doping, the average grain sizes decrease. Positron annihilation lifetime measurements reveal that there are vacancy-type defects in the three samples, and Bi_0.9Ce_0.1FeO₃ sample has the maximum open volume and concentration of the vacancy defect among those three samples. Both Ce and Zr doping can improve the leakage current, ferroelectric and magnetic properties, whereas Zr doping exhibited better ability. The better electric properties in BiFe_0.9Zr_0.1O₃ may be due to the effective reduction of oxygen vacancies, Fe²⁺ and impurity phases by Zr doping. The cause for better magnetic properties in BiFe_0.9Zr_0.1O₃ sample may be that the insertion of Fe vacancies and nonmagnetically active Zr⁴⁺ ions in antiferromagnetic Fe sublattice can effectively suppress the spiral spin modulation structure.

[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

[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