Microstructure and hardness of two-phase Ni₃Al and Ni₃V intermetallic alloy layers reinforced with VC, NbC and WC particles, which were clad by laser metal deposition on SUS304 steel, were studied, focusing on the effect of the charged carbide species. In VC and NbC composite layers, premature microstructure composed of Ni solid solution and Ni₃Al phase was developed in as-clad layers while stable microstructure composed of the Ni₃Al and Ni₃V phases was developed in annealed one. Hardness level in the both composite layers was increased by annealing. In WC composite layer, microstructure composed of the Ni₃Al and Ni₃V phases was developed in as-clad layer while microstructure composed of Ni solid solution and Ni₃Al phase was developed in annealed one. Hardness level in the WC composite layer was conversely decreased by annealing. The VC and NbC particles were relatively stable during cladding as well as annealing, resulting in unaffected matrix composition. The WC particles were unstable, resulting in degenerated matrix composition. The present work reveals that reinforcement of VC and NbC particles into the two-phase Ni₃Al and Ni₃V intermetallic alloy is favorable as cladding layer from the point of microstructural stability as well as mechanical property.

A novel method to produce palladium micrometer-sized particles is presented. This method consists of the leaching of palladium using dimethyl sulfoxide (DMSO) solution containing CuCl₂ and NaCl followed by the precipitation with citric acid aqueous solution. Precisely, palladium was dissolved in a DMSO solution containing 0.1-0.2 M of CuCl₂ and 0-0.2 M of NaCl at 343 K. The dissolved palladium was precipitated by the addition of a citric acid aqueous solution, and the dried precipitates were imaged using standard SEM. We obtained micrometer-sized particles: angular particles were formed by the addition of 0.1-0.5 M citric acid aqueous solution while spherical particles by 1.0-2.0 M citric acid solution. The maximum recovery efficiency of palladium was 76.1% and purity of palladium was 92.5 mass%. To investigate the mechanism of particle formation, in-situ monitoring of the formations of palladium particles in the liquid phase was conducted using atmospheric scanning electron microscopy (ASEM). The monitoring revealed that palladium particles form coral-like branching strings in the liquid phase. Comparison with dried spherical particles suggests that the stings were changed into spherical shapes during drying.

We have developed a novel process for recycling gold (Au) from secondary sources: the leaching of gold using Organic Aqua Regius, e.g. dimethyl sulfoxide (DMSO) or propylene carbonate (PC) solutions containing copper bromide (CuBr₂) and potassium bromide (KBr), which could offer a number of advantages, including eco-friendliness and ease of operation. In this study, we applied PC solution to recover Au from Waste Electric and Electronic Equipment (WEEE). First, the WEEE samples (memory card, mobile phone board and small appliances) were coarsely grinded and finely grinded. Then, thermal activation of semiconductors (TASC) technology using TiO₂ was applied to decompose the polymers and oxidize base metals containing in WEEEs. Next, the leaching of Au from the oxidized samples were conducted in a PC solution with 0.2 M of CuBr₂ and 0.2 M of KBr, at 353-373 K, followed by biphasic separation with sulfuric acid. The dissolved Au in the PC phase was recovered by reduction of ascorbic acid. The recovery ratio of Au was 56.0%, 67.2% and 65.7% from memory card, mobile phone board and small appliances, respectively.

Magnetic properties and mechanical properties of high purity Fe-3 mass%Si alloy by cold crucible levitation melting was investigated. The raw material of the alloy made from electrolytic iron and pure silicon with a purity of 99.99 mass% and 99.999 mass% in amount of impurities excluding Fe and Si were suppressed to 90 ppm or less. In the magnetic property, the iron loss of the alloy was reduced to a third of 35H210, a silicon steel sheet of the same Si composition commercially. This reduction shows the effect of high purity. In the magnetic domain observation, the equal behavior as magnetic properties was observed. In mechanical property, it proved that the high purity Fe-3 mass%Si alloy was easy to draw because the elongation of the alloy was higher than the commercially available silicon steel sheet.

In this study, a stainless steel mesh was used as a mold for fabricating aluminum foam with a complex shape during the foaming of a precursor by employing optical heating. From the foaming of the precursor in stainless steel mesh molds with the shapes of an airplane and vehicle, it was shown that aluminum foam with similar shapes to the stainless steel mesh mold can be obtained. No protrusion of the aluminum foam through the mesh openings was observed. A mesh pattern was transferred to the surface of the aluminum foam when a rough mesh was used. In contrast, aluminum foam with a smooth surface was obtained when a fine mesh was used.