Papers by Keyword: Scandium

Abstract: The combination of weldability, corrosion resistance and sufficient strength make it possible to use deformed semi-finished products from the Al-Mg system alloys for sheathing ships' hulls, in car, aircraft and rocket construction, as well as in other areas of industry. To increase the strength characteristics, it is promising to alloy them with small additives of metals such as titanium, zirconium, scandium, and others. In this paper, studies were carried out to obtain deformed semi-finished products (strips, rods and wires) from aluminum alloys in which the scandium content varied from 0.1 to 0.25%. For this purpose, various metal treatment conditions simulated in the laboratory of School of Non-Ferrous Metals and Material Science in Siberian federal university. For the preparation of sheet semi-finished products regimes of hot and cold rolling of a cast billet simulated from a thickness of 40 mm to a thickness of 3 mm. For the preparation of sheet semi-finished products, the modes of hot and cold rolling of the cast billet from a thickness of 40 mm to a thickness of 1-3 mm have been modeled. To produce a welding wire with a size of 2×2 mm, a combined casting and rolling-extruding (CCRE) process was simulated to produce a 9 mm billet and its further rolling in square gauges. Rods with a diameter of 9 mm were produced on a combined processing unit, and wire on a rolling mill with a roll diameter of 130 mm. In accordance with the research program, the mechanical properties of hot-deformed, cold-deformed and annealed sheet semi-finished products were measured. Then the semi-finished products were welded together with the obtained wire and the quality and properties of the welded joint and their corrosion resistance were evaluated. Research results are currently used to develop industrial technologies for the production of sheets and plates from experimental alloys of the Al-Mg system doped with scandium.

Abstract: The crystal structure of a new ternary aluminide of refined composition Sc₆Cu_24.1(2)Al_11.9(2) was solved by direct methods from X-ray powder diffraction data. It belongs to the cubic space group Im-3, Pearson symbol cI176-8, a = 13.5337(5) Å. The structure of Sc₆Cu_24.1Al_11.9 may be described as a packing of 16-vertex coordination polyhedra of the Sc atoms, which form icosahedral clusters around the origin and the center of the body-centered unit cell. The voids at the centers of the clusters are filled by Cu₄ tetrahedra, disordered between two possible orientations. The structure is closely related to the structure types Ru₃Be₁₇ and Ce₆Au_27.6Sn_6.8.

Abstract: In this project, the addition of scandium (Sc) into A356 aluminium alloy was studied for its effect on the mechanical properties after gravity die casting process. Scandium addition was administered at the weight percentages of 0.1, 0.2 and 0.3. The results obtained in this work revealed that scandium can significantly enhance the mechanical properties of A356 alloy in terms of tensile strength, hardness and charpy impact strength. In general, the addition of 0.2 wt% Sc in A356 alloy was found to be able to achieve the maximum tensile strength of 172.94MPa as compared to 136.03MPa for sample without Sc. No significant improvement in tensile strength was found when more than 0.3wt% added to the alloy. As for hardness, the sample with 0.3 wt% Sc attained the maximum Vicker’s hardness of 86.60 HV as compared to 76.48 HV for unmodified A356. Similarly, the addition of 0.3wt% Sc in A356 can achieve highest impact energy of 2.71J as compare to 1.09J for unmodified A356.

Abstract: The sorption properties of acid-modified Transcarpathian clinoptilolite towards Sc (III) under dynamic conditions have been studied. It was found that the most effective acid-modifier is 0.5M HCl solution. Maximal sorption capacity is observed in the previously heat-treated at 50 oC samples of H-clinoptilolite in low alkaline solutions (pH=8.5). At this conditions almost all of the Sc (III) ions are in the form of neutral hydroxo complex [Sc (OH)₃(H₂O)₃]. The sorption capacity of H-clinoptilolite towards Sc (III) ions under optimum conditions is 9.98 mg/g. The best desorbent of Sc (III) from acid-modified clinoptilolite is 6 M HCl solution. This desorbent removes 98% of sorbed Sc (III).

Abstract: Structural transformations and formation of chemical inhomogeneity in the weld and HAZ metal in fusion welding of complex alloy of V96 type were studied. It is shown that under the influence of welding heat, partial melting of the alloy phase components proceeds in the heat-affected zone with formation of structures of eutectic origin in the form of extended interlayers along the grain boundaries, causing metal embrittlement. Scandium addition to the alloy enables reducing the solidification processes and degree of segregation along the grain boundaries, as well as localizing partial melting of the grains without formation of coarse eutectic interlayers.

Abstract: Semiconductor-mediated photocatalytic oxidation is an interesting method for water decontamination and a specially modified TiO₂ is said to be a promising material. This study verified that the synthesis of 1wt%Ag modified-Sc_0.01Ti_0.99O_1.995 powder samples prepared by Polymeric Precursor Method is capable of forming a mixture of anatase-rutile phase with high photocatalytic performance. This kind of material is found to have a lower bandgap compared to the TiO₂-anatase commercial powders, which can be associated to an innovative hybrid modification. The simultaneous insertion of scandium in order to generate a p-type semiconductor and a metallic silver nanophase acting as an electron trapper demonstrated being capable of enhancing the degradation of rhodamine B compared to the commercial TiO₂. In spite of the different thermal treatments or phase amounts, the hybrid modified powder samples showed higher photocatalytic activity than the commercial ones.

Abstract: Al-Zn-Mg alloys are widely used construct material for wide range of application including automotive industry, building, and aviation. Scandium is rare earth metal, which modifies structure of semi-products and can lead to increasing of tensile and yield strength because of Al₃Sc intermetallics of nanoscale size. This paper describes results of influence of small addition of scandium (0,08 wt. %) on mechanical and corrosion properties of cold-rolled sheets of 1913 alloy. 1913 is Russian medium strength corrosion resistant weldable Al-Zn-Mg alloy with addition of Cu for improvement of stress corrosion resistance and Mn with Zr for structure improvement. It is shown that addition of Sc transforms kinetics of artificial aging and accelerates decomposition of solid solution, besides tensile strength increases up to 50 MPa in artificially aged tempers. Changes in microstructure and quench sensitivity are described; results of intergranural corrosion, exfoliation and stress corrosion tests are introduced after different heat treatment including peak strength aging and overaging tempers.

Abstract: Scandium has been introduced into the Al-B₄C composite to form Al₃Sc precipitates which offer a significant strengthening effect and a good thermal stability of the mechanical properties at elevated temperatures. In the present study, the grain structure and Al₃Sc precipitation of the hot-rolled Al-15 vol.% B₄C composite containing Sc were examined by optical and electron microscopes. The mechanical properties of the hot deformed composite were evaluated by means of Vickers microhardness measurements. The post heat treatment after hot rolling was conducted to obtain desirable mechanical properties. The hot-rolled Al-B₄C composite containing Sc can yield a considerable precipitation hardening under an appropriate post heat treatment. Results show that some Sc could be consumed during high temperature solution treatments, which remarkably reduced the precipitation hardening of Al₃Sc precipitates. The amount of Sc loss is associated with the deformation ratio and solution time.

Abstract: In this study, c-axis oriented AlN and Al1−xScxN films have been successfully grown on Si (100) and quartz glass by DC magnetron reactive sputtering method. The XRD patterns show that the crystal structure of the Al1−xScxN films is (002) orientation. The grain size and band gap energy (Eg) of the Al1−xScxN films decrease as the Sc concentration increases. The frequency of the E2 (high) mode observed in the Al1−xScxN films shows higher red shift compared to that observed in AlN film and the peak shifts to the low wave number with the increasing of Sc concentration.

Abstract: Some methods and application status for Recovery of scandium and extraction of high purity scandium oxide from materials containing scandium were summarized . some corresponding recovery methods and extraction processes were suggested.