Feasibility of a renewable sorbent for phosphorus was determined by testing the anion-exchange ability of hydrotalcite, which holds formate ions in its interlayer. The formate hydrotalcite, successfully prepared by reacting raw hydrotalcite with a formic acid/1-propanol solution, exhibited high performance for phosphorus removal and collection based on a stoichiometric anion-exchange principle. It was estimated that the collected orthophosphate ions existed as poly-anion forms of HPO 4 2-and PO 4 3-with a ratio of 67.6:32.4 in the interlayer after the sorption. The formate hydrotalcite is also able to revert to the starting hydrotalcite after the sorption, when treated with Na 2 CO 3 aqueous solution, demonstrating that it can be an attractive alternative to the conventional chloride or nitrate hydrotalcite as an anion exchanger.

The hot deformation behavior of a Mg14Li6Al1Ca alloy was studied using the hot compression true stressstrain curves corresponding to the temperature range of 473673 K at strain rates of 1 © 10 ¹1 1 © 10 ¹3 s ¹1 . The true stressstrain curves indicated dynamic softening under the test conditions. The peak stress during deformation could be correlated with the temperature and strain rate using a hyperbolic-sine equation. The activation energy of the Mg14Li6Al1Ca alloy was determined to be 193 kJ mol ¹1 . The Zener-Hollomon parameter (Z) for the Mg14Li 6Al1Ca alloy was determined. The tendency for dynamic recrystallization increases at low strain rates and high temperatures, corresponding to low Z values. The hot deformation behavior of the Mg14Li6Al1Ca alloy was modelled by a suitable constitutive equation. Furthermore, the size of the equiaxed grains in the hot-deformed and quenched specimens was estimated from the Z value.

Austenitic stainless steels including type SUS304 of the Japanese Industrial Standard (JIS), which is similar to ASME Type 304 SS, are candidate materials for the various facilities of high-pressure gaseous hydrogen, such as a hydrogen station containers and piping. To prevent the hydrogen penetration into SUS304, we developed the passivation films mainly composed of chromium oxide and investigated the hydrogen barrier properties using the gas permeability test and the slow strain rate tensile (SSRT) test. The passivation films with a maximum thickness of 300 nm was formed on the surface of hot-rolled SUS304 (Ni equivalent 22.4) by a series of wet processing steps such as electro-polishing, chemical oxidation, cathode precipitation of chromium and passivation immersion. Cross-sectional views of TEM observation suggested that the film was amorphous like structure including many independent voids with a size of 10 to 20 nm. The hydrogen gas permeability test was performed in a hydrogen gas pressure of 400 kPa at 573 K, 673 K, and 773 K. The estimated hydrogen transmittance of SUS304 substrate with passivation coating was 2.8 × 10−13 mol / (m · s · Pa) at 773 K, while that without passivation coating was 2.2 × 10−11 mol / (m · s · Pa) at 773 K. SSRT test was performed in 110 MPa hydrogen and nitrogen gas atmosphere at room temperature, and strain rate was 4.17 × 10−5 s−1. The fracture surface of the specimen without passivation coating showed brittle like and relative reduction rate (RRA) was 0.61. On the other hand, the fracture surface of the specimen with passivation coating showed typical ductile like dimple structure and RRA was 0.88. As the passivation films did not peel, adhesion between passivation film and SUS304 surface seems to be well. From these considerations, we anticipate the developed passivation film can inhibit hydrogen embrittlement of SUS304.

In this study, porous Mg-Zn composites with designed relative density were manufactured by spacer method. The effects of porosity and Zn addition rate on the compression properties were investigated. The relative density of the manufactured porous Mg-Zn composites were a little lower than the design value, but it was almost controllable. The compressive stress-strain curves of porous Mg-Zn showed the peak value of stress in the initial stage of deformation followed by a long plateau and the steeply rise in stress by densification. The compression properties showed relative density dependence, and the higher the relative density, the higher the Young s modulus, plateau stress, and initial peak stress. Young s modulus increased as the amount of Zn added increased, but the plateau stress and initial peak stress were higher when Zn was added at 5 mass% than when 10 mass% was added.