인공(人工) Molybenite 합성(合成)

황용길 ( Yong Kil Hwang ),성장현 ( Jang Hyun Sung ),정중희 ( Jyoung Hee Jung ),이상화 ( Sang Hwa Lee ) 東亞大學校附設 石堂傳統文化硏究院 1979 石堂論叢 Vol.3 No.-

For the purpose of puroducing synthetic molybdenum disulphide and investigating the mechanism by which the synthetic molybdenum disulphide formed, the sodium molybdate and sulphur with a given ratio were sufficiently mixed and reacted at a given temperature. The thermal analysis for various samples and the structual analysis of molybdenum disulphide were performed by means of thermal balance and X-ray diffractor-meter. From the above experiments, the following results could be drawn. 1) The suitable reaction temperature for the production of the synthetic molybdenum disulphide with sodium molybdate and sulphur was found to be in the range 500° to 600℃. 2) The recovery of the synthetic molybdenum disulphide was decreased by increasing the mixing ratio of sulphur to sodium molybdate and the highest value for the yield of molybdenum disulphide was obtained when the theoretical value for the mixing ratio of sulphur to sodium molybdate was used. 3) The particle size of molybdenum, disulphide thus produced was shown to be -325 mesh. It was also shown that the roasting temperature range of naturally formed molybdenite was 400° to 600℃, while the roasting temperature range of synthetic molybdenum disulphide was 300° to 500℃. 4) The X-ray diffraction analysis showed that the crystal structure of naturally formed molybdenite and the synthetic molybdenum disulphide were hexagonal and rombohedral lattice, respectively.

전해법에 의한 Mn-ferrite 생성

김유상(Yu-Sang Kim),황용길(Yong-kil Hwang) 한국표면공학회 1992 한국표면공학회지 Vol.25 No.1

알루미늄 기관의 무전해 니켈-구리-인 합금도금에 관한 연구(Ⅰ)

오이식(Lee-Sich Oh),황용길(Yong-Kil Hwang) 한국표면공학회 1991 한국표면공학회지 Vol.24 No.2

무전해 니켈-구리-인 도금의 도금속도와 열처리에 따른 경도 및 내식성 변화

오이식(Lee-Sick Oh),황용길(Yong-Kil Hwang) 한국표면공학회 1990 한국표면공학회지 Vol.23 No.4

PC강선의 지연파괴에 관하여

오응환,황용길 東亞大學校 海洋資源硏究所 1988 硏究論文集 Vol.1 No.1

Investigation of the PC steel rods were performed by using the induction heat treatment at various conditions, corrosion test in 20%NH₄SCN aqueous solution. It was summarized as below; 1) The samples before heat treating were not well corrosed than the samples after heat treating, and the more increasing heat treatment temperature up to 960℃, the more increasing amount of corrosion, and PH value increased in the bulk both heat treated sample and original sample in aqueous solution from PH 4.6 to Ph 7.5 and decreased about PH 6.7 through passing time. 2) Produced oxides through corrosion were became mainly to FeOOH and ε-Fe₂O₃. 3) Fracture time velocity(B) sample involved T₁, B elements were quick over seven times. 4) Hardness of (B) sample involved T₁, B is over about H??450, (A) Sample is below about H??450. 5) When the delayed fracture were performed by FIP method, the reduction area were nearly occured. It is considered that the sample was broken by expanded pressure of H₂ gas in steel from Fe₃C cathode surface as the results equilibrium was broken, so that was produced.

石炭石과 無煙炭에 의한 밀·스케일의 還元

黃龍吉,李成龍,朴載奉 동아대학교 공과대학 부설 한국자원개발연구소 1986 硏究報告 Vol.10 No.1

Some coked anthracite and Mill Scale pellet was packed in a tube furnace. And then, the heating samples was reacted with CO₂ gas made from wasting acid. The results of the experiment of reduction and gasification were as follows. 1) When waste acid was neutralized by some lime stone, vields of CO₂ gas was attained 80%. 2) The amount of CO gas producted at 1100℃ was 1.37times the amount of CO₂ gas made from wasting acid, and 1.5 times the amount at 1300℃. 3) During 5 houre for experiment the rate of reduction was 78% at 100℃ and 97.2% at 1300℃. 4) When Mill Scale pellet was reducted into CO gas, the value of activation energy was 3154.2 ㎈/g-㏖. The following can be resulted from what mentioned above: The neutralization of waste acid by lime stone can be a preventive of water pollution. And we can product not only fuel gas by the gasification of the anthracite reacting with CO₂ gas, but also sponge iron by the reduction of Mill Scale. The above four results can serve as a base source for the production of those materials.

無電解 Ni-Cu-P 鍍金速度에 미치는 浴組成과 條件의 影響

吳伊植,黃龍吉 東亞大學校 1990 東亞論叢 Vol.27 No.1

In the eletroless nickel-copper-phosphorus alloy plating bath which contained nickel sulphate, copper sulphate, sodium hypophosphite, sodium citrate, etylenediamine, inhibitor(thiourea) ad accelerater (NaF), effect of their concentration on the rate of deposition was tested by gravimetric method. The results obtained from this experiment are summarized as follows; 1. The optimum composition of the electroless nickel-copper-phosphorus bath was estimated 0.1 mole of nickel sulphate, 0.01 mole of copper sulphate, 0.2 mole of sodium hypophosphite, 0.18mole of sodium citrate and 0.04 mole of etypenediamine at pH 9∼10, 80∼85℃ and 30 minutes. 2. The activation energies for 75∼85℃ have been calculated to be 66.7 KJ/mole. 3. The deposition rate from the bath which contained neither NaF(accelerator) nor thiourea(stabilizer) was about 44.799(mg/10cm²·30min) at pH 9.0, 80℃. whereas plating rate increased further(34%) to 60.030(mg/10cm²·30min) with addition of 200 ppm of NaF and 0.8 ppm of thiourea to the bath.

精密機械 및 機能性材料用 鐵粉末의 還元機構

黃龍吉 東亞大學校 大學院 1989 大學院論文集 Vol.14 No.-

Ferrous chlorides (FeCl₂) have been neutralized by Ammonium hydroxide(NH₄, OH), then Iron hydroxides(Fe(OH)₂) are obtained by air oxidation. After filtration, washing and drying, chemical and physical properties have been investigated. This Iron hydroxides have been charged into the tube type reduction furnace and reduced in 3 ℓ/min hydrogen gas flow. As the result, it was summarized as below. 1) Sample is yellowish acicular β·FeOOH which are less smaller then 1μ. 2) When β·FeOOH were calcinated, there are 10% weight loss about 200-300℃ range, they are decomposed to 0.2-0.5μ γ-Fe₂O₃. at 600℃. 3) After hydrogen reducing below 330℃, Fe( )O( ) have been produced. When this magnetite was oxidized about 250-300℃, Coercivity force(Hc) have been 250 Oe and particle size of α-Fe₂O₃ are 0.3-0.5μ. 4) As the result hydrogen reducing at 550℃, 0.3-0.5μ spheroidal Iron particles have been produced.

炭素鋼線의 鋼種別 高周波誘導加熱에 따른 機械的 性質에 관한 硏究

吳應煥,黃龍吉 東亞大學校 大學院 1988 大學院論文集 Vol.13 No.-

This study has been carried out to investigate into the characteristic changes of mechanical properties of carbon steel wires with high frequency induction heat treatment. The results obtained from the experiments are as folows: 1.Yield Point(or yield ratio) was inceased with the increasing of carbon content and relaxation resistance above 0.3% C was improved remarkably. 2.The change of delayed fracture resistance scarcely showed anything by carbon content, but known effet of delayed fracture resistance wiht restraint effect of grain growth of Ti. 3.Spot weldability was dropped excessively above 0.4%C equivalent, but showed the most excellent in 0.28%C steel (AISI10B30) contained Ti.

Ni鹽 溶液에서의 Ni 이온의 還元擧動

黃龍吉,金炳哲 東亞大學校 1987 東亞論叢 Vol.24 No.1

Electroless Nickel Plating was performed to investigate into the effect of change in deposite rate of nickelion, corrosion resistance of deposites layer and changes in hardness by heat treatment. The results obtained from this study are summarized as follows, The main factors controlling the deposite rate were NA₃C??. H??O??, 2H₂O and Pb(NO₃)₂. The highest hardness value obtained by heat treatment of deposite plating layer appeared to be H??975 at the temperature of 350。C for 1hour. The improvement of hardness value by heat treatment was caused by the formation of Ni₃P crystal from amorphous plating layer. The corrosion resistance of deposite layer was increased with increasing phosphorous content. The phosphorous content was related with PH of bath solution. Among the three specimens obtained by PH 4.1, 5 and 6, The highest corrosion resistance appeared for the specimen of PH 4.1 under the condition of immersion of the specimen in IN-HNO₃