Time filter

Source Type

Kaloshkin S.,Moscow State University | Romankov S.,Institute of Multidisciplinary Research for Advanced Materials | Komarov S.,Nippon Light Metal Company | Kaevitser E.,Moscow State University
Frontiers in Mechanochemistry and Mechanical Alloying | Year: 2011

The technique of mechanical alloying (MA) was used to coat the metal substrate with other metals. The Al-Ti and Al-Ni binary systems were investigated, at that, all the elements were used both as substrates and as coating powders. Thickness and quality of coating depending on the MA treatment parameters, such as intensity and duration of milling, amount of loaded powder, were investigated. As-synthesized coatings showed structures with high apparent density and free of porosity. However, the surface morphology of the MA-coatings was very rough. Annealing treatment led to the leveling of surface microstructure and formation of different aluminide phases in the coatings. MA allows to produce thick coatings for a relatively short time with good adherence. © CSIR-National Metallurgical Laboratory, Jamshedpur-831007, India, 2011. Source

Yabe T.,Tohoku University | Enoki M.,Institute of Multidisciplinary Research for Advanced Materials | Ohtani H.,Institute of Multidisciplinary Research for Advanced Materials
Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals | Year: 2016

A thermodynamic analysis of the Al-Cu binary system has been performed to consider the metastable phase equilibria of the face-centered cubic (fcc) phase. The total energies of the ordered structures were obtained using first-principles calculations based on the fcc lattice. The cluster expansion method was applied to the results, and the free energies were calculated for the solid solution at finite temperatures. The results were analyzed together with some experimental data, and the equilibrium phase diagram of the Al-Cu binary system was calculated based on the CALPHAD (Calculation of Phase Diagrams) method. The results suggested a metastable two-phase separation of the fcc phase in the Al-rich region. The coherent spinodal line was calculated according to Cahn's treatment and revealed that the critical temperature decreased by about 100 K because of the coherency of the separated phases in the fcc matrix. In consideration of both Cahn's treatment and the effect of vacancies, it was suggested that the initial formation step of the Guinier-Preston zone might be relevant to the metastable coherent spinodal decomposition in the fcc solid solution. © 2016 The Japan Institute of Metals and Materials. Source

News Article
Site: http://phys.org/chemistry-news/

A research group—consisting of Masahiro Goto, distinguished chief researcher, Center for Green Research on Energy and Environmental Materials, NIMS; Michiko Sasaki, postdoctoral researcher, Center for Materials Research by Information Integration, NIMS; Masahiro Tosa, group leader, Research Center for Structural Materials, NIMS; Kazue Kurihara, professor, and Motohiro Kasuya, assistant professor, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University—developed a coating technique using a zinc oxide (ZnO) material, an environment-friendly, low-friction material developed exclusively by NIMS. When bearing balls were coated with the ZnO material, the material's low frictional characteristics were maintained and the friction coefficient of the bearing was reduced by approximately one-third. Moreover, the research group and Fox Corporation jointly developed a small jet engine generator for emergency use. By integrating the ZnO-coated bearings into the generator, its fuel consumption was reduced by 1%. In consideration of worsening global environment/energy issues, it is important to reduce friction occurring in drive mechanisms including engines in terms of energy saving. However, because the mechanically driven part in an engine becomes extremely hot, friction reduction technology applied in such an environment must be heat resistant. We focused on ZnO, capable of both reducing friction and resisting heat, and identified its friction reduction mechanism at the nano level. Then, we developed a basic technique to apply a low-friction ZnO coating by controlling the crystal orientation of ZnO. In efforts to put the developed basic technique to practical use, we applied the technique to reduce the friction level of commercially-available, high-performance bearings to an even further extent. We developed the technique for applying ZnO coating to bearing balls while controlling the crystal orientation of the ZnO material by rotating bearing balls in cage-shaped sample holders. As a result, we succeeded in reducing the friction coefficient of the bearings by approximately one-third. In addition, we integrated the resulting bearings into a small jet engine, evaluated its performance, and observed a 1% reduction in fuel consumption. Furthermore, we worked to miniaturize generators to be used in times of emergency when procurement of fuel is difficult. In this effort, we succeeded in developing a small jet engine generator equipped with ZnO-coated bearings. It weighs only about 40 kg, and can be carried by two adults. This compact generator, however, can produce 8,000 W of power, which can approximately cover the amount of power consumed by two households, and will be made available for emergency use. The newly developed low-friction ZnO coating is expected to be applicable not only to bearings but also to any mechanically driven parts that require friction reduction, given that the coating is usable in a wide range of conditions: from room temperature to high temperature, in oil, in vacuum and in atmosphere. By applying this coating technology to different types of mechanically driven parts in systems such as automobiles, it may be possible to save energy in these systems. This study was conducted in line with the university-led green innovation project "Green Network of Excellence (GRENE)" sponsored by the Ministry of Education, Culture, Sports, Science and Technology. More specifically, this study was carried out in accordance with the "Green Tribology Innovation Network" project (Principal investigator: Professor Kazue Kurihara, Tohoku University) within a GRENE category, the "Advanced Environmental Materials." We will give a presentation on this study on August 5, 2016, during the PRICM9 meetings to be held in Kyoto.

Murao R.,Tohoku University | Sugiyama K.,Tohoku University | Kashiwagi Y.,Institute of Multidisciplinary Research for Advanced Materials | Kameoka S.,Institute of Multidisciplinary Research for Advanced Materials | Tsai A.P.,Institute of Multidisciplinary Research for Advanced Materials
Philosophical Magazine | Year: 2011

Raney Pd and Rh fine particles were prepared from decagonal Al75Pd25 and Al9Rh2 with an Al9Co2-type structure, respectively, by leaching with NaOH aqueous solution. The atomic pair distribution functions (PDFs) for the Raney Pd and Rh fine particles indicate structural features similar to an fcc structure, suggesting atomic rearrangement toward the closest packing of constituents during the leaching process. Transmission electron micrographs indicate that Raney Pd and Rh are aggregates of fcc-structured nano-crystallites with a diameter of 5-6 nm. © 2011 Taylor & Francis. Source

Arita T.,Institute of Multidisciplinary Research for Advanced Materials | Ueda Y.,Institute of Multidisciplinary Research for Advanced Materials | Minami K.,Tohoku University | Naka T.,Institute of Multidisciplinary Research for Advanced Materials | Adschiri T.,Tohoku University
Industrial and Engineering Chemistry Research | Year: 2010

Ceria (CeO2) nanocyrstals which could be transparently dispersed in several organic solvents were synthesized by organic-ligand-assisted hydrothermal synthesis. We have studied the dispersity of the nanocrystals into typical organic solvents using dynamic light scattering (DLS) measurement. The mean diameter of the dispersant (the nanocrystals' cluster) varied with changing the solvent species. When the solubility parameter (SP) values of the solvent and the modifier were comparable to each other, the nanocrystals tended to disperse in the solvent with the initial particle size. One of the three-dimensional SPs, i.e., the Hansen solubility parameters, brought more detailed understanding of the mechanism of the dispersion of the surface modified nanocrystals. Because of the dense modifier layer on the surface of the ceria nanocrystals, the hydrogen bonding ability of the solvent was not the dominant factor to determine dispersion of the surface modified nanocrystals. The dispersion and polar factors of the Hansen SPs could describe the ideal condition of perfect dispersion of the surface modified CeO2 nanocrystals. © 2010 American Chemical Society. Source

Discover hidden collaborations