고분자 도장한 알루미늄의 시멘트에 의한 부식

이광학,김흥식 울산대학교 2001 공학연구논문집 Vol.32 No.2

본 연구에서는 아파트 공사현장에서 거푸집으로 사용중인 고분자도장 알루미늄 판재의 시료를 채취하여 광학현미경, SEM/EDS 및 EPMA/EDS로 전착도막의 파괴단계 및 부식생성물을 분석하여 도장층의 박리현상을 실험적으로 규명하므로서 도장층의 내구성을 향상시키는 연구를 수행하였다. 알루미늄 표면과 도장막 사이에 적절한 접합이 이루어지지 아니하였고, 도장층이 국부적으로 파손된 곳에서 알루미늄과 시멘트가 반응하여 알루미늄 표면에 부식생성물 A12O3-CaO 또는 A12O3-CaO-SiO2 화합물이 생성되었다. 따라서, 도장층의 내식성을 향상시킬 수 있는 방안으로 도장층과 알루미늄 사이에 희생양극 역할을 하는 인산아연처리를 실용화하여 내식성이 우수한 고분자도장 알루미늄 거푸집을 생산할 수 있도록 하였다. A research for enhansing corrosion resistance of polymer coated aluminium plate in cement consolidating environment has been conducted. Examination of specimen polymer coated aluminium using SEM/EDS, EPMA and optical microscopes revealed the causes of polymer film rupture from the aluminium surface to be cathodic disbonding. Corrosion products, such as A12O3-CaO, A12O3-CaO-SiO2 compounds formed by the reaction of aluminium surface with cement have been observed at the locally degraded polymer film. Therefore, zincphosphating process has been developed and applied on the surface of aluminium for the zinc sacrificial cathodic protection of aluminium from carbonaceous corrosion environment in the cement consolidating process.

수소 gas에 의한 산화철의 환원속도에 관한 첨가물의 영향

이광학 울산대학교 1982 연구논문집 Vol.13 No.1

본 실험에서는 산화철의 환원시 rate-determining step이 되는 Wustite의 환원을 900℃이상의 온도에서 수소 gas분위기 하에서 실시하였다. promoter로서는 Li₂O, MgO, CaO를 각각 첨가하였고 Wustite의 환원속도에 미치는 영향을 고찰하였다. 실험결과 불순물 함량이 1.2wt% 일때가 환원속도가 최대로 나타났다. 순수한 Wustite의 환원속도보다 promoter가 첨가되었을 때의 환원속도가 약 1.5~2배 정도 크게 나타났다. 수소 gas의 유속이 일정할 때는 환원온도가 높을수록 환원속도는 증가하고 일정한 반응온도에서는 수소gas의 유속이 클수록 환원속도가 증가하였다. 이러한 현상은 적절한 수소gas를 흘러 보냄으로서 H₂ gas의 starvation을 피할 수 있는 것으로 생각할 수 있다. 실험결과에서 관찰된 모든 현상들은 lattice defect의 이론보다는 Vol'kenshtein의 lattice disturbance이론으로 잘 설명될 수 있었다. Doping effect on the reduction rate of wustite by H₂gas wustite reduction which is the rate-determining step of iron oxide reduction, was studied in H₂ gas atmosphere at temperatures above 900℃. Promoters such as Li₂O, MgO and CaO were added respectively to observe their effects on reduction of wustite. The results showed that the reduction rate maximum at 1.2wt% regardless of promoters. When promoters were added, the reduction rates were increased at a degree of about 1.5 to 2 times in comparison with that of no addition. At constant H₂gas flow rate the reduction rate increased as the reaction temperature increased. Similarly, at constant reaction temperature the reduction rate increased as the H₂gas flow rate increased. This may be due to advoiding hydrogen gas starvation. Those could be well explained by the Vol'kenshtein's lattice disturbance theory rather than the lattice defect theory.

황동광의 환원배소에 관한 속도론적 연구

이광학,양병일 대한금속재료학회 1989 대한금속재료학회 학술대회 개요집 Vol.1989 No.1

CaO 존재하에서 황동광의 환원배소에 관한 연구

이광학,양병일 대한금속재료학회(대한금속학회) 1990 대한금속·재료학회지 Vol.28 No.2

The reduction roasting behavior of chalcopyrite concentrate was investigated using various combination of a desulfurizing agent, such as CaO, Na₂CO₃, BaO and MgO under Hz and CO atomsphere. The laboratory reduction experiments were carried using thermogravimetric analysis(TGA), and the degrees of metallization were determined by both weight loss and chemical analysis methods. The rate of reduction was increased by increasing the temperature and the amount of desulfurizing agents. The effect of desulfurizing agents was in the order of Na₂CO₃, CaO, BaO and MgO. Using these combinations, the sulfur was removed from the mineral as CaS or Na₂S etc.. The apparent activation energy(ΔEa) for the reduction roasting of chalcopyrite is about 4.28 ㎉/㏖. Based on this magnitude of the activation energy, it is suggested that a diffusion reaction is the rate limiting step for the temperature range(500-900℃) investigated.

혼합광으로 부터 황산-티오황산염을이용한 갈륨과 게르마늄의 추출에 관한 연구

이광학 대한금속재료학회(대한금속학회) 1989 대한금속·재료학회지 Vol.27 No.4

Extraction of gallium and germanium has been investigated from a complex ore with sulfuric acid-sodium thiosulfate leachants. The order of reaction as well as the overall reaction rate constant was with respect to sulfuric acid concentration, calculated. Furtheremore, the apparent activation energy and the frequency factor for gallium and germanium were calculated to be A= 1.08min^(-1)., ΔEa=4.5㎉/㏖ and A= 1.01min^(-1)., 5.2㎉/㏖, respectively. Stirring speed has no effect on the extraction rate, which suggested that this profess was chemically controlled. The influence of sodium thiosulfate on the extraction rate was found to be little significant. The rate of extraction increases with increasing temperature and decreases with increasing pulp density. Gallium and germanium extractions were realized approximately as high as 99%, and 70%, respectively.

소성 녹주석으로부터 베릴륨 추출에 관한 연구

이광학 대한금속재료학회(대한금속학회) 1988 대한금속·재료학회지 Vol.26 No.4

A compact naturally occurring α-beryl was decrepitated at 960℃ to a porous β-structure, from which, beryllium extraction was investigated by sulfuric acid leaching at atmospheric pressure. The order of reaction as well as the overall reaction rate constant were calculated. Furthermore the apparent activation energy and the frequency factor were determined. A Langmuir-type equation was developed for the effect of pulp density and total surface area on the rate of beryllium extraction. The maximum theoretically attainable rate of beryllium extraction and proportionality constant were assessed. The effect of particle size on beryllium leaching with sulfuric acid is described by an exponential form. Beryllium extractions were realized approximately as high as 90%.

폐기 동-스래그로부터 동의 회수에 관한 연구

이광학,이재운,문광호 대한금속재료학회(대한금속학회) 1991 대한금속·재료학회지 Vol.29 No.12

The recovery of copper was studied from industrial discard copper slags. In flash smelter and electric furnace slags, it was obtained the most Cu recovery when 5% carbon added to slags by carbothermic reduction, and 7% FeS added to 5% carbon by sulfide washing. Also, Cu recovery was very increased when 5% CaO added to 7% FeS with 5% carbon but, Cu recovery was lower Na₂CO₃ added to 7% FeS with 5% carbon than CaO added. These results were investigated with A.A, ICP, XRD, SEM-EDX, SEM-WDX and chemical analysis etc.. In this study we can get the most Cu recovery after 4 hours reaction in flash smelter and electric furnace slags.

스퀴즈병용 다이캐스팅법에 의해 제조한 ADC12 합금의 기계적성질 및 미세조직에 관한 연구

김용현,김흥식,이광학 울산대학교 1998 공학연구논문집 Vol.29 No.2

ADC12 합금의 금형주조시 스퀴즈병용 다이캐스팅법을 적용하여 응고중 부분적으로 소성변형 시킨 결과 변화되는 기계적 성질과 미세조직을 연구하였다. 일반 금형주조시 발생하는 주조품의 내부 결함으로 기공과 핀홀등이 스퀴즈병용 다이캐스팅법을 적용하므로서 모두 제거할 수 있었다. 수지상 초정과 알루미늄-규소 망상조직은 소성 변형되어 미세한 결정입자로서 소지금속에 균질하게 분포되었으며, 그결과로서 인장강도와 신율이 일반 금형 주조품보다 2.6배 증가하였다. A research has been conducted on the mechanical properties and microstructure of ADC12 alloy casted by partial squeeze die casting method. Internal defects normally developed in ordinary die casted ADC12 alloy such as blow holes and pipe holes were suppressed by partial squeeze die casting. primary aluminium dendrite and aluminium-silicone network structures were plastically deformed and distributed in matrix uniformly as a fine crystalline particles. As a result of plastic deformation of ADC12 alloy during sodification process, tensile properties of the alloy increased 2.6 times higher than that of typically die casted ADC12 alloy.

고로 slag의 탈황능력

김영홍,이광학 울산대학교 1982 연구논문집 Vol.13 No.2

CaO-MgO-SiO₂, CaO-Al₂O₃-SiO₂ 및 Cao-MgO-Al₂O₃-SiO₂계 slag의 탈황능력을 1500℃에서 CO, CO₂, SO₂ 및 Ar의 혼합가스를 이용하여 측정하였다. CaO-MgO-SiO₂계 slag에 MnO첨가시 slag의 탈황능력에 미치는 영향과 탄소포화철과 slag간의 탈황반응속도에 미치는 영향을 조사하였다. MnO를 첨가한 경우를 제외하고는 slag의 탈황능력은 slag의 조성비율, R= N??+N/2??/N??+N/3??(Bell식)에 밀접한 관계를 갖는다는 것이 확인되었다. 또한 slag에 MnO를 첨가하면 탈황능력은 첨가량에 비례하여 증가하며 slag에 의한 metal의 탈황반응속도 역시 반응초기에는 빨라진다. 그러나 탈황반응이 진행됨에 따라 MnO의 첨가량이 많을수록 탈황반응속도는 급속히 감소하고 slag/metal간의 S의 평형분배비율도 낮게 나타난다. Sulphide capacities, wt%S(Po₂/Ps₂)??, have been measured for the systems CaO-MgO-SiO₂, CaO-Al₂O₃-SiO₂ and Cao-MgO-Al₂O₃-SiO₂ at 1500℃, using gas mixture of CO, CO₂, SO₂ and Ar. and the effects of MnO addition to the slag Cao-MgO-SiO₂ on the sulphide capacity and the rate of desulphurization of C-saturated iron by the slag have also been studied. It is conformed that sulphide capacities of the slags except MnO addition are correlated closely with the composition ratio, R=N??+N/2??/N??+N/3?? (Bell's equation). The results show that MnO addition to the slag increase the sulphide capacity and the fast initial desulphurization rate of the iron by the slag proportionally with the amount of MnO added, but after the initial period of desulphurization the rate slows down more rapidly with a higher MnO addition, giving a much lower sulphur partition ratio at the end of reaction.

아연 용탕 내에서 불순물의 입자 크기 측정에 관한 연구

이광학,문광호,김영홍,최욱태 울산대학교 1995 공학연구논문집 Vol.26 No.2

LiMCA방법으로 아연 용탕내에 Pb를 첨가하여 불순물의 입자크기를 측정하였다. 아연 용탕내에 Pb의 첨가량이 증가할수록 불순물의 수는 증가하였으며 불순물의 입자 분포는 일정범위를 크게 벗어나지 않고 d=50㎛이하의 입자직경이 약90% 이상 존재하였다. 실험 후 시편을 분석한 결과, 시편내에 미량의 ZnO와 PbO가 존재함을 확인하였으며, 이는 아연용탕 내에서 제 2상의 거동을 예상하고 첨가한 Pb에 의해 형성된 PbO와 극소량의 ZnO등이 불순물로 거동한 것으로 사료된다. 본 실험은 약1분 정도의 짧은 시간으로 수행되었으며, 실험결과 사용된 장치의 감지 한계는 불순물의 입자직경이 d=29㎛이었다. The particle size of impurities was measured with addition to Pb in the molten Zinc by using LiMCA method. The number of impurities was increased with increasing Pb addition in the molten Zinc and particle size distribution of impurities was not deviated from the constant range therefore the particle size, d=50㎛ existed about 90% in this study. The experimental results of X-ray analysis, it was found that the small amount of PbO and ZnO which are formed with Pb addition to the molten Zinc, expecting the second particle role, behavior as impurities. This study was carried out about one minute and the detect limit of particle size of impurities using instrument was obtained d=29㎛.