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To reduce the core loss of the non-oriented electrical steel sheet containing 3.1wt% of Si, Sn was added and its effect has been analyzed. The core loss of the specimen monotonically decreases with the increase of Sn up to 0.22wt%. Major reason for the reduction is found to be due to fact that the addition of Sn enhances the development of (110) crystallographic plane parallel to the rolling plane at the expense of (111) plane. The average grain sizes of the specimens, another important factor on the core loss, remain between 40㎛ and 53㎛ and do not show any significant variation due to the Sn content.

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Superconducting thick film of Bi-Pb-Sr-Ca-Cu-O system with the (001) texture of 2212 phase was prepared by the melt texture growth method(Tc=77-80K). The superconducting thick film was formed by the screen printing method on the silver substrate, and the growth of the (001) texture with respect to the condition of heat treatments was investigated. In the melt texture growth, all step of the heat treatment-melting, slow cooling and post annealing were essential for the (001) texture growth. Especially during the post annealing degree of (001) texture growth was conspicuous. Thus prepared thick films showed higher critical current density than the sintered bulk superconductor. The post annealed samples (845℃, 50hrs) showed the critical density of 2100 A/㎠, which was considerbly higher than the sintered bulk superconductor(∼10² A/㎠). (001) texture developed during the post annealing was thought to be responsible for such high value of current density in this thick film.

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Thermo-viscoplastic responses and densification behaviors of porous alloy steel preforms under hot upsetting are investigated. By using the relationship between Rockwell hardness and relative density for sintered porous alloy steel, density distributions of upsetted specimen are investigated.

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Densifications behavior of metal powders during hot compaction is investigated. Experimental data for both copper and tin powders support the mathematical model proposed by Kim and Suh. Linear equations are used to describe the pressure-densification measure relations at the instantaneous and equilibrium responses. The slopes of these equations are represented by a function of temperature to correlate hot compaction data with the micromechanical model analysis. A power law creep response for time dependent densification agrees well with experimental data at various pressures and temperatures.

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This is the first paper of a series of papers on adiabatic shear band formed in an HY-100 steel under dynamic torsional loading. In the present study, the formation process of adiabatic shear band in an HY-100 steel was observed by means of a high speed photography in conjunction with the stress-strain behavior. A torsional Kolsky bar was employed to impose dynamic torsional loading, a strain rate of about 1500/s, in a thin walled tubular specimen. The results show three consecutive stages of plastic deformation process in the HY-100 steel. The first stage starts immediately after initial yield and consists of homogeneous deformation. This is followed by the second stage which the strain becomes to localize into a rather broad band. As deformation continued, at the final stage, the region of high local strain narrows to form a shear band. The adiabatic shear band leads to final failure resulting from the loss of load carrying capacity of the material. Microscopic study shows that fracture process involves formation and coalescence of voids and microcracks initiated at MnS and carbide particles. A preliminary TEM study reveals development of fine dislocation cell structure within the shear band.

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This study is to develop a process for the recovery of lithium and boron from the bittern, which is a by-product in manufacturing table salt from seawater and to prepare their compounds. Borate and lithium ions in the bittern were separated and recovered by the ion exchange method. Commercial anion exchange resin, Amberlite IRA-743, was used for the recovery of boron. Inorganic adsorbent, SnSbA, was synthesized at a Sb/Sn ratio of 1.75 for the lithium recovery. Boric acid was made through the acidification of the boron eluate and lithium carbonate was made from the lithium eluate through several treatments such as carbonation. The continuous ion exchange column equipment was scaled up four times as large for boron and seven and a half times for lithium as the batch column and the scale-up test results showed good agreements to the batch results.

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