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ALSI4140鋼의 超音波減度와 機械的 性質의 相互關係에 關한 硏究
朴宗賢,郭慶眞,朴大英,宋振泰 韓國非破壞檢査學會 1985 한국비파괴검사학회지 Vol.4 No.2
A study has been made on the correlation between ultrasonic attenuation and mechanical properties with different prior austenite grain size. It was found that ultrasonic attenuation is increased with increasing grain size, decreasing yield strength and increasing charpy impact energy value for ALSI 4140 steel.
Fe80 B12 Si8 비정질 합금에 Cr 첨가가 자기적 성질에 미치는 영향
신찬수,송진태 대한금속재료학회(대한금속학회) 1986 대한금속·재료학회지 Vol.24 No.11
The effect of Cr element and heat treatment on the physical and magnetic properties of Fe_(80)B_(12)Si_8 (at.%) amorphous alloy which has a high saturation magnetization and a low core loss was investigated in this study. The (Fe_(1-x)Cr_x)_(80)B_(12)Si_8 (x= 0-0.10) amorphous allay ribbons were fabricated by single roller method and annealed for 20 minutes at various temperatures below the crystallization temperature in Ar gas atmosphere. With increasing Cr contents, it was found that crystallization temperature increased from 472℃ to 490℃ and soft magnetic properties were improved. The coercive force decreased and the maximum permeability increased with increasing Cr contents. These improvements may be attributed to the decreasing of magnetostriction by Cr addition to Fe_(80)B_(12)Si_8 alloy. The annealing treatment improved the soft magnetic properties of Fe_(1-x)Cr_x)_(80)B_(12)Si_8 amorphous alloys and the optimum annealing temperature was 60℃ lower than the crystallization temperature. Coercive force and high frequency magnetic properties of (Fe_(0.96)Cr_(0.04))_(80)B_(12)Si_8 amorphous alloy that was annealed at 425℃ for 20 minutes were comparable to a zero magnetostrictive Co-based alloy.
Fe 기 비정실 합금의 자기특성과 자구에 미치는 Nb 첨가와 열처리 효과
최진학,송진태 대한금속재료학회(대한금속학회) 1987 대한금속·재료학회지 Vol.25 No.2
The effect of Nb element and annealing condition on the magnetic domain properties were investigated in Fe_(80)B_(16)Si₄(at %) amorphous alloy which has high saturation magnetization and low core loss. With increasing Nb contents in (Fe_(1-x)Nb_x)(80)B_(16)Si₄(x=0-0.10) amorphous alloy ribbons, the crystallization temperature increased from 448℃ to 542℃ and soft magnetic properties were improved by decreasing coercive force and increasing maximum permeability. These improvements were attributed to the decreasing of magnetostriction and the reduction of domain width by Nb addition. The annealing treatment also improved the soft magnetic properties of (Fe_(1-x)Nb_x)_(80)B_(16)Si₄ amorphous alloys and the optimum annealing temperature was 425℃-450℃. (Fe_(0.92)Nb_(0.08))_(80)B_(16)Si₄. and (Fe_(0.90)Nb_(0.10))_(80)B_(16)Si₄, amorphous alloys which were annealed at these temperatures had low coercive force and high maximum magnetic permeability. It could be thought that these improvements were attributed to the relaxation of internal stress and were related to the disappearance of maze domain and the for mation of 180˚ domain.
윤승열,이수완,송진태 한국부식학회 1981 Corrosion Science and Technology Vol.10 No.1
Dezincification phenomenon of 70% Cu-30% Zn brass containing small amounts of Sn (<1.7%) has been studied in 0.5M acidic chloride solutions. All the specimens used were prepared originally from electrolytic upper and zinc and chemical grade tin. Recording of potentiodynamic polarization curves and examination of the tnicrostracture for toe specimens in various conditions were main expeimetal techniques. Poteniodynamic polarization curves thus obtained revealed that 7/3 brags could initilly be dezincified either by selective dissolution of zinc or by copper redeposition mechanism depending on the electrode potential. Experimental results showed that addition of small amount of tin (from 0.74% up to 1.76%) to 7/3 brass could inhibit dezincification in case the copper reaeposition mechanism holds. This was found to be possible through that the added tin promotes hydrogen evolution reaction on the brass and this h.e.r. competes with copper redeposition retarding the latter. In other words. dezincification in 7/3 brass is replaced to general corrosion by the eddition of small amounts of tin. Microscopic examinations for the specimens which had been subjected to potentiostatic polarization at given potentials showed that the well-defined dezincfied layer could only be developed at elevated temperature (90℃), and in case the dezincified copper layer had already formed on the electrode surface. It was found through the microscopic examination of the dezincified dezincified specimen that the dezincification front occured in 7/3 brass was protruding along the grainboundaries in the brass matrix, indicating the latter was serving a a diffusion channel for the outgoing zinc aton to the electrode/solution interface.