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허태녕 대한금속재료학회(대한금속학회) 1990 대한금속·재료학회지 Vol.28 No.3
A Zn/KOH fluidized bed electrode was mathematically modelled to investigate the performance and characteristics of the electrode in the case of recharging period for the possible use of energy storage. The model is based on electrodeposition reactions between particulate bed and electrolytes flooded the bed. The potential distribution through the bed was studied and it was found that the shape of the distribution was affected both by the exchange current density of the secondary reaction and the effective resistivity ratio of particulate bed and electrolytes.
허태녕,차상윤,장민수 대한금속재료학회(대한금속학회) 1990 대한금속·재료학회지 Vol.28 No.11
The phase transformation of mixture of Y₂O₃, BaCO₃ and CuO powders with mole ratio of 1/2 : 2 : 3 and that of the superconducting Y₁Ba₂Cu₃Oy single phase were investigated by thermal gravimetric and differential thermal analysis between the temperature ranges of 20℃ and 1300℃. Above 1010℃, partial melting and phase decomposition of Y₁Ba₂Cu₃Oy single phase was detected and it was found that the new phases were (Y₂BaCuO_5) and BaCuO₂by SEM -EDX. By considering the change of the thermal expansion coefficient of the superconductor bar with temperature, it was concluded that superconducting Y₁Ba₂Cu₃Oy undergoes phase transformation at 400℃ and 700℃.
CaO 좌재하에서 수소에 의한 황화동의 환원에 관한 연구
윤종규,허태녕 대한금속재료학회(대한금속학회) 1980 대한금속·재료학회지 Vol.18 No.6
黃化銅 (Cuprous Sulfide ; Cu₂S)의 수소에 의한 還元實驗이 500℃에서 1,000℃의 온도범위에서 行하여졌다. 수소의 流速을 一定하게 유지시키며 等溫條件下에서 實驗한 結果를 濕式黃分析法으로 구한 脫黃率과 反應時間과의 關係로 나타내었다. 脫黃率은 反應溫度의 上昇에 따라 증가하며 反應生戒物인 H₂S의 제거제로 CaO를 存在시킨 경우에는 더욱 증가됨을 알 수 있었다. 또 모든 경우에 還元反應은 初期에 급격히 일어나며 反應時間이 길어질수록 反應速度의 증가 정도가 점차 둔화됨을 알 수 있었으며 初期의 급격한 反應에 의해 同一條件下에서 可能한 全體反應量의 약 80% 정도가 이루어졌다. 또한 첨가제로 Na₂CO₃와 NaF를 가한 경우에는 初期反應速度가 급격히 증가하였으나 그 機構에 대해서는 더욱 硏究가 있어야 하겠다. 수소를 還元劑로 사용하고 CaO를 H₂S 제거제로써 存在시킨경우 이 還元反應系의 初期反應速度常數 K=80.31 exp (-4440/RT)이며 活性化에너지는 약 4.44Kcal/mole 이었다. A study on the direct reduction of Cuprous Sulfide by Hydrogen gas in the presence of CaO was investigated in the temperature range of the 500℃ to 1,000℃. Under the constant velocity of hydrogen gas, experiments were carried out isothermally and Sulfur Elimination Percent was determined by quantitative sulfur analysis. The effects of reaction temperature, time, and ratio of CaO/Cu₂S were studied. In all cases reduction reactions were carried rapidly in the initial stage and after that reaction rates were decreased gradually. The effects of additives-Na₂O₃ and NaF-were explained by the rapid increasing of the initial reaction rates but the mechanism of that will be studied more. The activation energy of reduction process of the system was found to be 4.44Kcal/mole and the rate constant could be expressed by the following equation K=80.31 exp (-4440/RT).
가스분무 및 분무성형법에 의한 Al-Pb 베아링 제조에 관한 연구 (1)
양영석,성장현,박신성,정철민,허태녕,정은 대한금속재료학회(대한금속학회) 1990 대한금속·재료학회지 Vol.28 No.9
Spray Forming technology has been developed at the Department of Materials Science and Engineering, Univ. of Ulsan, for the fabrication of tube, billet and plate of Al-12%Pb alloys. Spray Forming Process involves atomizing a stream of molten metals and collecting the droplets on a substrate before they have solidified, The effects of geometry(orifice diameter and tip design) and position of the metal delivery orifice in atomization device on the pressure characteristics at the tip of orifice have been studied. Mathematical model has been developed to predict the velocity and temperature profiles of the droplets as a function of their flight distances. Microstructural characteristics of Al-12%Pb hyper-monotectic alloys by spray forming process were examined. Dense (~99. 4%) material with fine-grained equiaxed microstructure was spray-formed using nitrogen as the atomizing gas. It was found that lead(Pb) particles existing in the microstructure were homogeneously distributed in the aluminium matrix and along the grain boundaries. The shape of lead particle were approximately spherical and the mean particle size was about 3-4㎛.