A novel accelerated corrosion test method enhancing oxygen supply to simulate the corrosion of reinforcing steel in concrete has been proposed in this study. Oxygen reduction current density measured by means of potentiodynamic polarization test for a Fe sample embedded in cement paste or mortar in a saturated Ca(OH)₂ solution under ambient air decreased with an increase of the cover thickness and the current density was inversely proportional to the cover thickness from 1 mm to 10 mm, suggesting that diffusion limited oxygen reduction can be accelerated by making the reducing thickness below 10 mm. The novel strategy to enhance oxygen supply in the proposed method is to apply pressurized oxygen instead of ambient air using a newly developed hyperbaric oxygen accelerated chamber. In 0.5 MPa of oxygen Fe samples covered with 5 mm of mortar or cement paste showed oxygen reduction current density almost 25 times as high as that under the ambient air. The thickness of rust layer formed during 30-day corrosion test of Fe samples covered with 5 mm of mortal or cement paste containing chloride ion in a saline solution under 0.5 MPa of oxygen was in good agreement with the increased oxygen reduction current density, indicative of acceleration of corrosion proportional to applied oxygen partial pressure. Furthermore, the characteristics of the rust formed under the pressured oxygen were similar to that of the rust formed under a practical service environment. Thus, the hyperbaric oxygen is beneficial and effective to validly accelerate the corrosion of reinforcing steel in concrete.

The recovery of copper (Cu) from secondary sources has received much attention because of its scarcity of natural resources. In this work, we estimated the input, in-use stock and discard of copper and copper alloy during 1950-2015 in global scale, and forecast them until 2050. In addition, we estimated the potential of scrap recovery for copper/copper alloys. It was estimated that the total amount of in-use stock of copper and copper alloy were 177,000 kt and 44,200 kt in 2015, respectively. The in-use stock, discard and input of copper in 2050 will reach 381,000-588,000 kt, 15,400-22,200 kt and 18,990-33,000 kt, respectively, whereas those for copper alloy will reach 77, 500-134,000 kt, 3,020-4,680 kt and 3,760-7,200 kt, respectively. The copper content in recoverable scraps of copper and copper alloy will reach 15,100-27,300 kt, and this accounts for 55.1-79.0% of copper content in annual input of copper and copper alloy in 2050. The range in forecast was caused by the difference in the saturation amount of in-use stock per capita and recovering rates of scraps.

A magnesium matrix composite made of Mg-1mass%Ca and 10 vol% hydroxyapatite (HAp) particles was synthesized. The alloy powder was processed by pulverization of the small blocks of the alloy ingot using a high-speed blade grinder. Unreacted composite was successfully produced by extruding the two component powders at a temperature of 538 K. In the extruded composites, the grains of the magnesium matrix were equiaxed and the matrix grain size was 3.9 μm. As for the HAp particles, both thin clustering and severe agglomeration with the size of ~30 μm were observed. The Young’s modulus, tensile yield strength and tensile strength of the extruded composite were 39 GPa, 101 MPa and 153 MPa, respectively. The damping capacity of the composite was higher than that of extruded magnesium. The composite also showed good forgeability at a temperature of 523 K. However, quite high impurity contents of Fe (0.130 mass%) and Ni (0.010 mass%) were introduced in the magnesium matrix of the composite, probably as a result of contamination that accumulates during the processing (pulverization) of the alloy powder.

In this study, high-pressure sliding is combined with incremental feeding so that a severely deformed area is enlarged without increasing the machine capacity. With this combined process (called the incremental feeding high-pressure sliding: IF-HPS), a sheet sample is lateraly fed every after sliding under high pressure. The IF-HPS process was applied to a Ni-based superalloy (Inconel 718) and a Ti-6Al-7Nb alloy (F1295) for grain refinement. The applicability of the IF-HPS process is examined with the advent of superplasticity through the grain refinement. Vickers microhardness measurement shows that the hardness is higher in the area of the second pass than the first pass for both Inconel 718 and F1295 but the hardness increase is more prominent in the area where the second passes is superimposed on the first passparticularly for the Inconel 718. After tensile testing, superplastic elongation more than 400% appears in the superimposed areas of both Inconel 718 and F1295. For the F1295 alloy, the area of the second pass also exhibits a suplerplastic elongation of 400%. Analysis by finte element method (FEM) reveals that strain introduced by outwardflow from the severely deformed area is sensitive to friction coefficient between the sample and anvil outside of the flat contact area. The strain due to this outwardflow conributes to the grain refinement in the second pass for the F1295 alloy but insufficient for the Inconel 718.