Recent developments in metal foams, especially aluminum, have produced a new class of lightweight materials at the side of the traditional ones such as polymers, ceramics or glass. The combination of a metallic character together with a cellular structure gives an interesting potential for a wide application of this material, particularly for high volume markets such as the automotive industry. Increased demands concerning cost economy, passenger safety in automobiles and materials recycling all bring constructors now to use metal foams. Hereby it provides the additional environmental benefits from a potentially improved fuel economy and lower CO2 emissions. Then, short review of metallic foam was done in the present paper. The possibility of carbonate and hydroxide as foaming agent for Al-Si-Cu alloy by powder metallurgy route is studied, after preparation processes of metallic foams were briefly reviewed in the present paper. It was done by measuring thermal decomposition behavior of foaming agents and evaluating cell structure of those aluminum foams. To obtain fine and homogenous cell structure in powder metallurgy route by using safer carbonate as foaming agent, it has made clear that importance of selecting foaming agent starting decomposition after melting of matrix. It is clearly different from TiH2-foam to grow coarse-rounded cell structure. From this point of view, MgCO3 and CaMg(CO3)2 is suitable for matrix of Al-Si-Cu alloy. CaMg(CO3)2-foam could expand to 1.19 in specific gravity, and keep homogeneous, fine and spherical cell structure.
It has been estimated that as much as 29 million m3 of contaminated soil and fallen leaves should be removed and stored in interim storage facilities as a result of the Fukushima nuclear crisis that followed the earthquake in 2011. In this research, a soil remediation method was investigated in order to reduce the intermediate storage. In other words, screening and washing of cesium (Cs) contaminated soil, as well as Cs adsorption onto various clay minerals have been tested. It was found that screening and washing were effective in reducing radioactivity; clay minerals such as zeolite, biotite, montmorillonite and muscovite adsorbed Cs well. In addition, flotation can be applied to these minerals, so they can be removed from soil, which would lead in further reduction of radioactivity. If the radioactivity of contaminated soil can be reduced sufficiently, the soil can return to the nature.
Several metallic materials have been developed for many purposes by alloying and controlling microstructure. From the viewpoint of materials recycling, several properties should be controlled by the latter in simple alloys. Then, observation and evaluation of lattice defects such as vacancy, dislocation and grain boundary are very important for understanding microstructure development during thermo-mechanical treatments. The purpose of this study was to establish a method for estimating density of lattice defects in cold rolled and annealed Ti by a precise measurement of electrical resistivity. Pure Ti plates were cold rolled at room temperature. Bar shaped specimens were cut from the plates. Electrical resistivities at 77 K (liquid nitrogen) and 300 K were measured by a direct current four-point method with a constant current of 100 mA. The accuracy of temperature control at 300 K was 0.1 K in silicone oil. Basically the electrical resistivities gradually increased with increasing a reduction of thickness. The density of dislocation was determined to be 2–8 × 1014 m−2 in the 15–80% CR specimens
Conversion of carbon dioxide to useful chemicals or fuels has become an active area of research. However, most methods used in these studies need expensive or precious reagents, such as hydrogen or rare metals. The objective of this study is the reduction of carbon dioxide to organic compounds using a cyclic Fenton reaction that uses only inexpensive reagents. We achieved carbon dioxide reduction to methanol and ethanol using this reaction at ambient temperatures and pressures. The Fenton reaction was promoted by the repetitive addition of H2O2 and Fe(II) salts, resulting in the synthesis of methanol/ethanol and formic/acetic acids from carbon dioxide saturated water. In addition, it was found that H2O2 and Fe(II) in a molar ratio of 1 or 2 is optimal for the reaction as this increase the generation of ·OH. The catalytic effects of magnetite, pyrite, sodium hypophosphite and copper sulfate were also investigated in the reduction of carbon dioxide to acetic acid. All reagents acted as a catalyst, and the concentration of TOC and acetic acid was increased. The highest concentration of acetic acid was achieved with the addition of copper sulfate. This enhanced the generation of H· or H− as Cu(II) forms more stable complexes with oxalic acid than Fe(II)/Fe(III), meaning more free Fe(II)/Fe(III) ions were present in the solution.
Spent automobile catalyst is an important secondary resource of PGMs but the present recycling technologies require high energy-consumption. It is of much important to enrich the PGMs with some energy saving physical separation methods. This catalyst is usually composed of cordierite lattice which is covered by PGMs bearing coat layer. We adopted heating-quenching process as a pre-treatment of subsequent selective grinding and compositional concentration. It was found that micro-cracks were generated in the coat layer and the interface of the two phases and that some part of the coat layer was detached from the cordierite substrate. This paper analyzes the mechanism of these phenomena by using mathematical calculation and FEM simulation.
The authors introduce novel research results on material synthesis and recycling by grinding. The research is focused at first mechanical activation of fine particles of solid material caused by grinding, and this leads to synthesize functional material from two starting materials without heating. One of the examples is to show the formation of complex oxides such as CaTiO3 from CaO and TiO2. Another one is dechlorination of PVC by its grinding with CaO to form CaOHCl and hydrocarbon. This means that it is possible to separate chlorine from PVC by its washing with water. Grinding operation enables us to reduce indium (In) by from indium oxide (In2O3) and ITO in the presence of Li3N under NH3/N2 gaseous environment. The reaction can be given by: In2O3 + Li3N + NH3→2In + 3LiOH + N2. The purity of In and its recover are quite high over 90%. Further example of the mechanical activation followed by heating up to about 400°C is to generate hydrogen (H2) from biomass such as wood and straw. The biomass is milled with inorganic substance such as CaO, followed by heating at non-oxidative environment. The generation of H2 in high concentration can be attained during heating, due to adsorption of CO2 and CO by CaO to form CaCO3. This implies that the grinding plays a big role to bring out many possible applications for material synthesis, material and waste processing.
Demand for magnesium alloy parts is expected to increase because of its low density and high specific strength. However, recycling technique for post-consumer magnesium alloy scraps has not been established yet. In particular, low-cost processing for the removal of organic impurities used for painting is needed. In this study, super-heated steam (SHS) treatment was examined as a new technique to remove paint impurities from post-consumer magnesium alloy scraps. As the result, it was found that most of the impurities were easily removed after SHS treatment of 400~410°C and simple mechanical friction.