질화철의 잔류응력에 관한 연구

장충근,김기원,권혁무 충남대학교 자연과학연구소 1979 學術硏究誌 Vol.6 No.2

Studies on the X-ray stress measurement have been made in various kinds of nitrided iron specimens. The relation between the hardness measured mechanically and the stress measured by X-rays is Considered. The main results observed are: (1) Nitrided pure iron has the tendency of increaing residual stress with, the increasing time duration of nitriding, (2) Carbon steel has the tendency of decreasing residual stress with the increasing time duration of nitriding treatment. (3) Both of the above cases showed the same results that the hardness increases with the time duration of nitriding treatment.

질화철의 경도에 미치는 탄소와 규소의 영향

장충근,권혁무 충남대학교 자연과학연구소 1979 學術硏究誌 Vol.6 No.2

The effect of carbon and silicon on the hardness of nitrided iron at the temperature range of 650℃- 850℃ was investigated, In the case of carbon added iron, the peak hardnesses and surface hardness were increased but the thickness of nitrided layer was decresed than the nitrided pure iron, In the case of silicon added iron, the internal hardness and surface hardness were decreased than the carbon added iron.

철-탄소 합금에서 r'- phase의 성장에 미치는 탄소의 영향

장충근,오헌진,오희필 충남대학교 자연과학연구소 1979 學術硏究誌 Vol.6 No.2

To obtain the diffusion coefficient of nitrogen in Fe-C alloys, the 0-3% C-Fe alloy was nitrided by the liquid drop nitriding method in the temperature range of 650 C- 850 C. The main results observed are: (1) The frequency factor Do of nitrogen in 0-3%C-Fe alloy; Do(mC) = 1.17 exp[-1.08(mC)]㎠/sec (2) The activation energy Q of nitrogen in the alloy; Q(mC)= 27.2 exp [30.7(mC)]Kcal/mole (3) And finally, the diffusion coefficient of nitrogen in 0-3%C-Fe alloy is D_(N)= Do(mC) exp[-Q(mC)/RT] ㎠/sec

炭素鋼中의 크롬擴散과 空孔機構

張忠根,金基元,千光鉉 충남대학교 자연과학연구소 1974 學術硏究誌 Vol.1 No.1

Chromium diffusion into the carburized iron is measured over the temperature range 800℃-1. 200℃. The diffusion coefficient is obtained by the calculation from the diffused time and depth. Chromium diffusion into the carburized iron appears notably over the temperature 900℃, and the diffusion coefficient of chromium decreases with an increase of the cardon concentration ironin. The above experimental results have shown that a major penetration mechanism is jumping into the vacancy which has been made in the transition from BCC iron structure to FCC type. The relationships of the depth of penetration and diffusion coefficient with the Carbon concentration under the constant temperature is given by the equation X_(p)=50(1-0.96C). D=0. 028X_(p)^(2)

球狀黑鉛鑄鐵의 鹽浴窒化

張忠根,金水泳,李相益 충남대학교 자연과학연구소 1977 學術硏究誌 Vol.4 No.1

Liquid nitriding is being is used for machine parts to improve fatigue strength and resistance to wear and seizure in spheroidal graphite cist iron. The difference in matrixes with as cast, pesrlite or ferritic structure in the iron has an important effect on nitriding. in the present work, spheroidal graphite cast irons with different matrixes nitrided by the tufftride process at 570 C for 1-6 hrs for a bask study on the nitriding of spheroids1 graphite castiron. The relationship between maximun hardness and nitriding time can be obtained as follows. In ferritic matris, hardness of matrix increased from 250Hv for 6hrs of nitriding time. In pearlite matrix, hardness of matrix increased from 390Hv to 560Hv. for 6 hrs of nitrding time.

CdTe 감마선 검출소자의 표면거칠기가 Au/CdTe Schottky Barrier의 전기적 특성에 미치는 영향

장충근,송재용,최철규,오희필,황선태 충남대학교 기초과학연구소 1990 연구논문집 Vol.10 No.-

The effects of the surface roughness of CdTe gamma­ray detector chips on the electrical characteristics of Au/n-CdTe Schottky barrier have been investigated using the Schottky diode prepared with he surface roughness in the range of 0.1∼0.5㎛. Measured for the diode are the electrical resistance characteristics, the potential barrier height and the electrical noise. The dynamic resistance is observed to decrease exponentially as R_d=370exp(-9.94ㆍRa)with the surface roughness(Ra) of the CdTe wafers. The potential barrier hight shows an exponential decay like ∮_B=0.88exp(-0.75ㆍRa) with the increase in roughness while the electrical noise shows a linear growth.

刑狀記憶合金의 擬彈性 機構에 關한 硏究

張忠根,崔哲圭,琴彩 충남대학교 기초과학연구소 1982 연구논문집 Vol.3 No.-

The pseudo-elasticity in the ternary alloy (Cu_74 Zn_20)Al_6 is investigated experimentally and the results are interpreted in terms of the continual mechanical twinning. Measured are the effects of temperature on such as stress-strain curve, critical shearing stress, twinning stress and load concentration. Also the relation between shearing stress and strain rate, and cyclic strain-stress curve are obtained experimentally. The experimental results of the present study are in good agreement with the Bolling-Richman theory which is a model-independent description of mechanical twinning. The transformation temperature of (Cu_74 Zn_20)Al_6 alloy are M_f : 333°K, Ms : 358°K, As : 353°K, and A_f : 393°K. The stress-strain curve shows clearly the pseudo-elasticity which is related with the mechanical twinning generated in the sample. The critical shear stress has the positive temperature-dependence indicating that the dominant process in the sample is a deformation by mechanical twinning rather than the deform by slip. Also, the temperature effects on work hardening, the relation between twinning stress and load concentration, and other measurements all indicate that the continual mechanical twinning is the main cause of the pseudo-elasticity in the Cu-based memory alloy (Cu_74, Zn_20)Al_6.

Al-Si 合金의 吸振特性에 미치는 硅素의 影響

張忠根,崔勝平,權赫茂 충남대학교 1985 忠南科學硏究誌 Vol.12 No.1

Binary alloys containing up from 0% to 18% silicon at intervals of 3% we have been produced by casting. Each specimen was lathed, and had a dimension of 46㎜ length, 16㎜ diameter. Effect of silicon on the vibration damping of Al-Si alloys have been investigated using an impluse method which an iron ball, 1.95gr weight, 4.0㎜ diameter, was fallen from a height 150㎜ freely, and gave an impulse to middle of a specimen. The relation of frequencies-intensity (dB) from which its maximum natural frequency can be obtained was measured by both the condenser microphone(B & K #4165) and the digital frequency analyser(B & K # 2131C). A decrease in quantity of the relative logarithmic decrement δ_Re concerning to each percentage silicon increase in Al-Si alloys was 5.4×10 gm^-1 sec. The effect of vibration damping relying on the Si contents in the Al-Si alloys was negligible.

Tantalum Pentoxide 박막의 전기적 특성에 관한 연구

장충근,송재용,이기선,강준길,김수용 충남대학교 1990 忠南科學硏究誌 Vol.17 No.2

Thin tantalum pentoxide(Ta_2O_5) films were deposited by oxygenassisted pyrolysis of tantalum methoxide using LPCVD method and their UV-absorption characteristics, X-ray diffraction, surface structure and I - V characteristics were investigated. Ta_2O_5 films as grown were originally amorphous and became polycrystalline hexagonal δ-Ta_2O_5 after annealing at 800℃ in the nitrogen gas atmosphere for 4 hours. The structures of the si_3N_4 films deposited by LPCVD were basically amorphous but mixed micro crystallites were observed in the films. For the Ta_2O_5 films of about 1000Å thick, the leakage current density through the films was 10 exp (-7) A/㎠ at 5 MV/㎝. The leakage current density was high and breakdown voltage was low with respect to Si_3N_4, Ta_2O_5 films could make them attractive in multiplayer dielectric thin films for memory devices.

Cu-Al 合金의 形狀記憶效果

張忠根,琴彩,徐日煥,尹和重,吳熙弼 충남대학교 자연과학연구소 1981 忠南科學硏究誌 Vol.8 No.1

The shape recovery process and the percentage recovery of Cu-Al alloys have been measured as a function of temperature in the range of 450-750℃ at the composition range from 10.8 to 15.0 wt pct aluminum. These alloys show one way memory effect and approximately 40% recoveries at parent phase finish point.