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Cu-Mn-Al 합금에서 Al 이 Mn 원자의 확산에 미치는 영향
김동의 대한금속재료학회(대한금속학회) 1980 대한금속·재료학회지 Vol.18 No.6
Cu-Mn-Al 삼원계합금의 FCC-γ 상영역에서, 기체-고체접촉방법에 의하여 Mn의 상호확산계수 D~_(Mn)을 Mn과 Al의 함수로 구하였다. Mn의 확산 계수는 Mn 함량이 증가하면 증가하고, 불순물로서 Al이 증가하면 오히려 감소하는 경향을 보였다. 즉, Cu-Mn의 2원계 합금에서, 10a/o Mn일 경우 D~_(Mn)은 0.50×10^(-9) ㎠/sec, 20a/o Mn에서는 0.93×10^(-9) ㎠/sec 이였으나, 0.5a/o Al이 첨가되므로서, 10a/o Mn일 경우 D~_(Mn)은 0.43×10^(-9) ㎠/sec, 20a/o Mn에서는 0.82×10^(-9) ㎠/sec로 감소하였다. Interdiffusion coefficients of manganese D~_(Mn) were investigated as the functions of solute atoms of manganese and impurity atoms of aluminum in FCC-γ phase of Cu-Mn-Al ternary alloy at 800℃ by using the vapor-solid couple method. Diffusivity of manganese are gradually increased by the addition of manganese, but decreased by the addition of aluminum. D~_(Mn) in Cu-Mn binary alloy is 0.50×10^(-9) ㎠/sec at 10a/o Mn, 0.93×10 D~_(Mn) ㎠/sec at 20a/o Mn, but it is decreased by the addition of 0.5a/o Al to 0.43×10^(-9) ㎠/sec at 10a/o Mn, 0.82×10^(-9) ㎠/sec at 20a/o Mn.
Hematite의 還元速度에 미치는 Al₂O₃, CaO, SiO₂의 影響
金東義,尹秉河,朴漢赫 경북대학교 공과대학 1985 工大硏究誌 Vol.14 No.-
Reduction of hematite by H_2 and CO-CO_2 gas was performed at 800℃, 900℃, 1000℃ after the addition of Al_2O_3, CaO and SiO_2 as an impurity substances. The reduction rate was appeared maximum by CaO and minimum by Al_2O_3 addition, when their amounts were equal at any temperatures, and regardless of the kinds of foreign oxides, the effects on the reduction rate revealed maximum, when the amount was about 1.0wt%. The reduction rate by the mixed control rate equation was showed straight lines by adopting the values of De and Kr from those experimental data. As the results, effects on the reduction rate when hematite contains foreign oxides, such as Al_2O_3, CaO and SiO_2, at high temperature, it was controlled by chemical reaction, and at low temperature it was controlled by interparticle pore diffusion.
金東義 慶北大學校 1980 論文集 Vol.30 No.-
Interdiffusion coefficients of manganese in FCC-γ phase of Cr-Mn alloy in the concentration range from 2 to 28 at. pct Mn at 800℃ have been studied with vapor-solid couple. The experiment was carried out with vapor-solid diffusion couples which were constructed with manganese vapor atoms diffusing onto surface of the matrix Cu plates. In three series of the experiment a few grams of MnCl_2 was added to the manganese powder in order to increase the mobility of manganese vapor atoms. Manganese interdiffusion coefficients werre calculated by Boltzmann-Matano equation, that were 0.20∼0.50×10 exp(-9)㎠/sec up to 10 at pct Mn, 0.50∼0.93×10 exp(-9)㎠/sec up to 20 at pct Mn and 0.99∼1.11×10 exp(-9)㎠/sec up to 28 at pct Mn content.
김동의,정권표,조용환 대한금속재료학회(대한금속학회) 1988 대한금속·재료학회지 Vol.26 No.1
Reduction of molten iron oxide with Ar-H₂ plasma was studied using a DC 15KW power sourse. 50g of sample was melted by Ar plasma and reduced in a stream of Ar-H₂ gas, the flow rate of which was 17ℓ/min. Degree of reduction (R) was reached as much as 95% within 12 min by Ar-H₂(14%) plasma, and it was linearly propotional to both the reduction time and the partial pressure of hydrogen. Additives such as CaO, MaO, SiO₂ and A1₂O₃charged in the range of 1-20% showed only trivial effects, however in case of charging serpentine which contained same ratio of acid and basic components, there was a tendence to increase in the reduction degree Kch. Reduction rate constant was calculated, as a function of hydrogen concentration in the Ar-H₂Plasma, the 0.512. Reduction rate and gas utilization % were increased with the increase in plasma temperature, dissociation of H₂and gas ionization such as H→H^+ + e.
酸化鐵의 CO/CO_2가스 還元速度에 미치는 不純物의 影響
金東義,裵錫煥 경북대학교 1985 論文集 Vol.40 No.-
The quantitative reaction of pure hematite and CO/CO_2 (80/20) gas mixture was studied at 900℃. Impurities such as CaO, SiO_2, and Al_2O_3 were added respectively to observe their effect on reduction of hematite. The micro-structure of reduced phases was observed by optical microscope and S. E. M. to investigate the depth of each phase. The results revealed that the change of reduction rate of pure hematite and added impurities increased rapidly to 30% and 39-50% respectively in the initial stage and then the reduction rate decreased, because the formation of dense iron layers by sintering and recrystalization surrounded partial reduced wu¨stite reflics, and this hindered the reducing gas diffusion. The reduction rate which impurities were added always is increased than that of pure hematite, was the maximum at 1.2wt.% regardless of its kinds of impurities. Each promoters is increased the reaction rate by the role of active center when the reduction is proceeding. The increased of reduction rate was proportional to ionic radius (r) and ionic charge (ε) of added impurities.