The energy conservation achievements realized by the Japanese steel industry since the first oil crisis (1973) were reported. In addition, the outline of the self action plan on environmental conservation announced by the Japan Iron and Steel Federation in December 1996, the new energy-saving technologies containing next generation iron- and steel-making technologies and the development problems it should tackle toward the realization of a sustainable society were clarified in this paper.
Dust recycling technology by the rotary hearth furnace has been applied at Nippon Steel′s Kimitsu Works since 2000. The dust and sludge with iron oxide and carbon are agglomerated into shaped articles and the iron oxide is reduced in a high temperature atmosphere. Zinc and other impurities in the dust and sludge are expelled and exhausted into off gas. The DRI pellets made from the dust and sludge have 70% metallization and are strong enough for being recycled to the blast furnaces. No.1 plant, which was constructed in May 2000 and has an agglomeration method of pelletizing, recycles mainly dry dusts. No.2 plant, which was constructed in December 2002 and has an agglomeration method of extrusion, recycles mainly sludge. The combination of the two plants is a solution for recycling various kinds of dusts and sludge emitted in a large scale steel works as Kimitsu Works
Since a large amount of blast furnace (BF) slag is generated, its new recycling processes for the production of valuable materials have been required. Development of reusing method for waste glasses is also strongly demanded. The authors have tried to fabricate porous materials from those two materials by using the hydrothermal treatment. In the present work, hydrothermal hot pressing technique was conducted at 250-350°C. From BF slag, a heat-insulating material was obtained, possessing the low thermal conductivity of 0.25 W / m K. SiO2-Na2O-B2O3 glass was converted into glass containing water which exhibits the foaming as low as 200°C and becomes porous glass material.
The SrZr1-xYxO3-α of proton conductor was prepared by normal sintering and SPS (spark plasma sintering) methods in order to separate pure hydrogen gas from H2-containing mixed gases in high temperature range. The SrZr1-xYxO3-α has high proton conductivity under H2 gas atmosphere from 973 K to 1273 K. In this hydrogen separation system, hydrogen is oxidized to proton at the anode, and proton is reduced to hydrogen at the cathode using proton conductor by electrochemical method. Proton conductors SrZr0.9Y0.1O3-α obtained by normal sintering at 1580°C for 10 h and SPS at 1500°C for 3 min were found to be single phase of perovskite structure. Furthermore, the crystal structure of SrZr0.9Y0.1O3-α was chemically stable under H2 and CO2 gases atmosphere. Relative densities of SrZr0.9Y0.1O3-α obtained by SPS at 1400 and 1500°C were over 95 %. Furthermore, the relative density increased with sintering temperature and time of SPS. The proton conductivity of SrZr0.9Y0.1O3-α of SPS increased with sintering temperature, and was higher than one of normal sintering under wet 10 % H2 and Ar gases atmosphere. From the measurement of EMF (electromotive force) of hydrogen concentration cell at 800°C, the ionic transport number of SrZr0.9Y0.1O3-α of SPS at 1400°C for 5 min was about 1, and the electron conductivity was considerably low.
BaMgAl10O17:Eu2+ is a promising blue phosphor for lump, CRT and PDP. Conventionally, the BAM phosphors synthesize by the solid-state reaction from the mixture of oxide or carbonate starting materials. The solid-state reaction needs high temperature to get well-crystallized single phase. However, the control of particle morphology and size distribution is difficult for such a high temperature synthesis. In this study, we reported new synthetic technique using flash creation method derived nanopowder precursor. In the new technique, well-crystallized single phase phosphors were obtained at 1400°C for 6h. Although the powders were grown into the plate-like particles, the BAM powders retain the nano-size morphology after annealing. The emission intensity under UV excitation of Ba0.9Eu0.1MgAl10O17 from the FCM-derived nanopowder was 110% compared with phosphors prepared by the conventional solid-state reaction. The excitation intensity under VUV (146nm) of the FCM derived nanopowder was 159% of the conventional solid-state reaction.
Diamond films were synthesized on a Mo substrate using combustion flame. Most diamond films delaminated, during the cooling process. In our previous work it has been shown that a three stepwise combustion flame method was possible to prevent a delamination. But it was not perfect. In this study, effect of a distance of the flame inner cone from the substrate (the inner cone distance) of each step of the three stepwise method and substrate surface profiles after scratching treatment were remarked as most important factor to prevent the delamination. In order to improve the bonding strength, the inner cone distance of each step of the three stepwise method and surface profile were changed. The first step of the three stepwise method was set to the distance d=1.0mm, the second step was set to the distance d=2.0mm and the third step was set to the distance d=3.0mm, respectively, with each the scratching treatment of #180, 400, 800 and 1500 on the substrate surface. The results showed that the change of the distance of the three stepwise method was effective much in the delamination prevention. Especially, no delamination was observed at the scratching treatment of #400 and no abnormal growth of diamond crystal was also observed by the changing distances. The result of SEM observation and XRD analysis showed that high quality diamond crystal at the synthesized film for the scratching treatment of #400 was obtained by the changing distances. It was concluded that high delamination resistance diamond film could be realized by changing the distances.