발간논문

Home > KJMM 논문 > 발간논문

Co/Pd artificial superlattices with a bi-layer and a quadri-layer structure combined with reactively sputtered AlN were fabricated by RF magnetron sputtering and the magnetic and magnetooptical properties were investigated. Kerr rotation angle of Co/Pd multilayer without any dielectric layers was 0.15˚ at 780㎚, but the optimized quadri-layer structure Co/Pd multilayer combined with AlN anti-reflection layer, phase-layer and Al reflector showed 1.9˚ so FOM(Figure Of Merit) was 9 times larger than that of bare Co/Pd film. It turned out that the coercivity of Co/Pd multilayer increased as AIN underlayer thickness increased, which is due to an enhancement of the perpendicular magnetic anisotropy energy of Co/Pd artificial superlattices in case of increasing AIN underlayer thickness.

keyword :

The interface morphologies of silicon thin films in recrystallization were observed indirectly by imposing pulses to scan speed and the relations between interface morphologies and corresponding defect morphologies were investigated. In cellular interface of large amplitude to primary spacing ratio (A/λ₁) small tip radius and low defect density were observed. In this interface the main defects were isolated threading disolcations running parallel to scan direction. As cell amplitude decreased, tip radius and defect density increased and continuous subgrainboundaries were observed. These results were analyzed by simple diffusion model. At large cell amplitude dendritic interfaces were observed especially in large thermal gradient region. The interface growing direction was $lt;100$gt; and the films showed (100) texture.

keyword :

Crystallographic texture and microstructure characteristics of electrogalvanized zinc on carbon steel in zinc sulfate solution was studied in terms of chloride concentration in the electrolyte and the current density. The chloride addition strengthened the basal texture of the electroplated layer by increasing the conductivity of electrolyte and lowering the cathod overvoltage. On the other hand, increasing the current density weakened the basal texture by increasing the cathode overvoltage. Chloride addition also promoted a ridge type surface topographical feature parallel to the substrate surface, and a granular cross-sectional grain size decreased with the chloride content. Increasing the current density resulted in a ridge type structure inclined to the substrate surface and a columnar cross-sectional microstructure. Increased current density also reduced the cross-sectional grain size due to accelerated nucleation rate. Hardness of the electrogalvanized layer increased with the reduced grain size or adsorbed chloride.

keyword :

The gangue silicates in the prereduction of chrome ore by carbon were studied to understand the mechanism of the enhanced reduction effect. Mixed powder batches of chrome ore and carbon were isothermally held for 120 minutes in the temperature range from 1100 to 1400℃. Samples were investigated using X-ray diffractometer, polarizing and reflective microscopes and wavelength dispersive spectroscope. The results were as follows : The gangue silicates such as forsterite retarded the reduction rate of chromite spinets at the temperatures below 1280℃ but accelerated it at higher temperatures. SiO, reduced from the SiO₂ in the chrome ore, acted as an extra reluctant in addition to C, CO and Mg, to enhance the reduction rate. Si0 was further reduced by carbon in the reduction product (Cr, Fe)_7 C₃ and dissolved in it, and thus making the metal a Si-bearing carbide. The reduction rate might have been enhanced further by the reformation of forsterite as a result of simultaneous reduction of chromite spinet by SiO and Mg. The reformed forsterite was found to be euhedral which is characteristic of forsterite.

keyword :

A study has been made of the fabrication condition for obtaining the cube texture of high purity aluminum foils and of electrochemical etching of the aluminum foil. The cube texture of high purity aluminum foils of 110㎛ in thickness was obtained by cold rolling, followed by annealing above 400℃ for 1 hour under vacuum. The microstructures of the cold rolled and heat treated aluminum foils were studied. The effects of current density and chloride ion concentration on the etch pit morphology and capacitance were studied. The etch tunnel size decreases and the etch tunnel density increases with increasing current density and chloride ion concentration.

keyword :