발간논문

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The effect of Rotation of cathode on eccentricity, hardness and deposited quantities were investigated by rotating of cathode sample in the Sargent bath. And following results are obtained ; (1) The eccentricities were decreased below 5% of the deposited thickness by rotating of cathode. (2) The deposited quantities and uniformity of surface structure were increased at the linear velocity of 20×10^(-4) m/sec. (3) The deposited quantities were decreased when the linear velocity is elevated more than 20×10^(-4) m/sec and the pushed pattern was appeared on the cathode surface.

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The principal objective of this investigation was to examine precipitated phases during aging sequence and mechanical properties of high manganese heat resisting steels in which manganese was completely substituted for nickel. The influence of alloying elements on the aging hardenability, elevated temperature tensile strength, oxidation resistance and forgeability was investigated by adding elements such as niobium, molybdenum, tungsten, and boron to the steels containing various amounts of manganese and chromium and high content of nitrogen. It was found that the major hardening phase was M_(23)C_6 particles. The other phases identified were Nb(C, N), Cr₂N and σ phase.

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The texture and structure of the electrodeposit are associated with surface energies of deposit lattice planes and with cathode polarization. The copper deposit has the texture of {110} planes parallel to the deposit surface and the field oriented texture type structure, when sufficient copper ions exist near cathode as in the cases of the high bath temperature, agitated bath, high concentration solution and low current density. The deposit has the texture of [111] planes parallel to the deposit surface and the structure of growth lamellae parallel to surface, for the low ionic concentration adjacent to the cathode as in the cases of the low bath temperature, high current density, and low concentration solutions. The growth lamellar structure seems to be associated with stacking faults. For the electrolysis conditions between the above limited cases, textures different from [110] and [111] and structures different from the above ones can be obtained.

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The magnetic properties of Fe-30%Cr-25%Co alloys as a function of the additional rare earth metals were studied. A mumber of ingots for specimen containing 1 w/o to 2 w/o Y and Sm were prepared by arc melting under a protective atmosphere, resulting in a rapid freezing from the molten state. The samples were then annealed for various time at the temperature between 500℃ and 700℃. It was founded that the magnetic properties of Fe-Cr-Co-R(R: rare earth metals) alloys were superior to Fe-Cr-Co alloys, and the maximum energy product 2-3.5 MGOe were obtained by aging treatment with the aging time 16-32 hours and the aging temperature 500℃-600℃. It is concluded that a small amount of Y and Sm, especially Sm metals, remarkably increases the coercive force of Fe-Cr-Co magnet alloys, which may be attributed to the certain modification of their modulated structure or the precipitation of ferromagnetic phase such as RCo_5 and R₂Co_(17) in the matrix, due to rare earth metals.

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Equation for thermionic emission of metal-coated tungsten has been derived from Eyring`s absolute reaction rate theory, which can be used to evaluate the electron currant. The values of the electron currents for the systems, Zr-W, La-W, Ce-W, Sr-W, Cs-W and Ba-W were computed and found to he in good. agreement with the experimental results.

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The amenability of titaniferous magnetite from Soyonpyong-do to iron and titania slag was determined in a laboratory scale. The effects of grain size of the ore, amounts of sodium flux and carbon, and temperature on the smelting were studied. An attempt was also made to upgrade the titanic slag by leaching with sulfuric acid solution. Chlorination behaviours of titanic slag, titaniferous magnetite, and ilmenite were respectively investigated by a batch-boat technique. Optimum conditions for chlorination of titanic slag were compaired with those of other two titanium bearing substances.

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Recently, the study of die-design is actively developing with the reinforced cold forging dies. In this paper, the materials of the cold forging dies used spring steel in the reinforced-ring and die steel (SKD 11) in the insert. Yielding condition is based on Trasca`s solution (max. shear stress) and carried out numerical calculation for the cold forging dies. Effect of the reinforced-ring, dies dimension and thermal shrinkage allowance observed the influence of the strength of dies through the experimental results. It is found that if spring steels are proper treated, it could be available for cold forging reinforced-ring from obtained data.

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