Isopolytungstate 음이온의 성장과정에 관한 연구

김봉걸 한국화학공학회 1972 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.10 No.4

Much works have been done on isopolytungstate ion formation processes by acidifying sodium tungstate solutions. Concerning this field of research which are closely related to improving quality of the refined final tungsten products in the metallic form, there have been reports by investigators such as Kepert, Jander, Souchay, Aveston, and others. However these studies were done by potentiometric, conductometric, polarographic and ultracentrifugal methods, and the results were found to be mutually inconsistent. The cryoscopic method, however, has not been fully investigated in spite of the accuracy of this method at neutral range in contrast to the potentiometric method which have often been tried for the study of isopolytungstates. Therefore, cryoscopic method was adopted in this work, and the following results were obtained for the condensation of isopolytungstates in various pH ranges, by mean of the pH measurement, U. V. spectrophotometric method, and cryoscopic method. A. By cryoscopic method: 1. Initially, HWO₄^- ions were found in dilute Na₂WO₄ solutions acidified with HClO₄. 2. The W₃O_(11)^(4-) ions appeared when the mole ratio of H^+/WO₄^(2-) was made to 1.05, and H₂W_(12)O_(40)^(6-) to 1.55. 3. And, similarly, W₂O_7^(2-) ions appeared at the mole ratios of the following values, 1.15, 1.25, 1.30, and 1.35. B. By pH measurement: 1. The HWO₄^- ion appeared in the solutions whose pH values were maintained from 3.7 to 6.5. 2. And W₂O_7^(2-) ions formed at the pH values ranging from 3.8 to 6.3, W₃O_(11)^(4-) ions at 6.35 and H₃W_(6)O_(21)^(3-) or H₂W_(12)O_(40)^(6-) ions at 3.2. C. By U. V. spectrophotometric method: The U. V. absorption band due to HWO₄^- ions observed to range from 335 to 430 mμ in wave length, W₂O_7^(2-) isons from 345 to 435 mμ, W₃O_(11)^(4-) ions from 350 to 440 mμ, and H₂W_(12)O_(40)^(6-) ions from 368 to 457 mμ.

濕式法에 依한 γ-MnO_2 製造에 關한 硏究(第2報) : Purification of Manganes Oxides by Acid Treatment

金鳳杰,姜泰範,韓正洙 慶熙大學校 1982 論文集 Vol.11 No.-

Studies on the effect of reaction temperature, reaction time and concentration of acid on the purification of manganese oxides was conducted to manufacture γ-MnO₂ available as dry cell depolarizer by wet process. The results obtained were follows: 1.When oxidized the precipitates of OH￣/Mn^++ mole ratio 2.2 by aeration at 13℃ for 6 hours, MnO₂content obtained 89.99%, which was identified as crystalline γ-MnO₂by X-ray diffraction analysis. 2. When manganese oxides was treated at 70℃ for 2hrs with 30% H₂SO₄and 30% HNO₃, the highest content, of MnO₂was obtained as 96.90% and 96.60%, respectively, which was identified as crystalline γ-MnO₂by X-ray diffraction analysis and different thermal analysis.

濕式法에 依한 γ-MnO_2 製造에 關한 硏究

金鳳杰,姜泰範 慶熙大學校 1979 論文集 Vol.9 No.-

In order to make γ-MnO_2 substance for a dry cell which is considered as higher oxidation grade through the chemical process, 0.lM-MnSO_4 solution is added by the NaOH solution of varied concentration. Three difference substance which are of consequently obtained from the above experiment, are oxidized with air. An analysis has been made for the product which is preparated to the mole ratio from the above method through the measurement with X-Ray differactometer. The consequences of the applied experiment in this research are as follows: 1. Mn_3O_4-MnSO_4-nH_2O was obtained when oxidized by air the suspension solution of 2MnSO_4-Mn(OH)_2, for two hours, which formed at mole ratio 1 of OH^-/Mn^(++). 2. γ-MnOOH·MnSO_4 -nH_2O was obtained by airation the suspension solution of 2MnSO_4-Mn(OH)_2, for 24 hours, which formed at mole ratio 1. 3. γ-MnO_2 was obtained by airation the suspension solution of Mn(OH)_2, for 24 hours, which was formed at mole ratio 3. 4. γ-Mn_2O_3 was obtained by airation the suspension solution of NaHMnO_2, for 24 hours, which was formed at mole ratio 5.

졸-겔법을 이용한 알루미나 코오팅막의 제조 및 특성에 관한 연구

金鳳杰,權昶吾,崔在鎬 慶熙大學校 1991 論文集 Vol.20 No.-

The purpose of this study is to investigate preparation and the physical properties of alumina coating film by sol―gel method according to the various ratio of acid. In other to prove the crystalline phase transfer, pore size, surface area, pore distribution and coating thickness, XRD, BET and SEM analysis were examined. 1. Particle size of sols were the most small when acid added to 0.07㏖. Drying of sols were long as adding DCCA and as incresing the acid content. The more boehmite weight percent were incresed, the more viscosity of sols were strikingly incresing in pure sols but were gradually incresing in DCCA sols. The more acid content were incresed, the more viscosity of sols were incredsed. 2. Preparation of coating film without crack were possible at low boehmite weight percent and viscosity of sols were less than 3cps in pure sols and 5cps in DCCA sols. Weight and thickness of coating film according to the repetition coating, were linera incresed by repetition coating. By seven times coating, thickness of coating film was 8 μm. 3. Surface area, average pore size and pore volume were decresed as incresing the acid content. In pore distribution, the most pore existed range of 20∼70Å. 4. Phase transition of alumina according to the thermal treatment temperature appeared γ―Al_2O_3 at 600℃, δ―Al_2O_3 and θ―Al_2O_3 at 600∼1000℃ and α―Al_2O_3 at 1200℃.

TiN 超硬薄膜의 被覆에 關한 硏究

金鳳杰,金昌煜,金宗範 慶熙大學校 材料科學技術硏究所 1989 材料科學技術硏究論集 Vol.2 No.-

The TiN film was coated by normal pressure chemical vapor deposition method on the Al_(2)O_(3) plate using TiCl_(4). N_(2) and H_(2) obtained from NH_(3) gas. The effect of the deposition time, temperature, N_(2)/H_(2) ratio, TiCl_(4) (g) flew rate and total flow rate of reactant gas on deposition were investigated. The results were as follows. 1. The thickness of TiN thin film was increased linealy with increase of deposition time and TiCl_(4)(g) flow rate. 2. The microhardness of TiN thin film was high (1,950 ㎏_(f)/㎟) when the crystal plane was oriented preferably along (220) plane, and such orientation was prevalent in N_(2)/H_(2) ratio 0.352 and TiCl_(4)(g) flow rate more than 28㎖/min respectively. 3. The rate determining step of the deposition rate was mass transport of reactant gas and apparent activation energy was 9.3㎉/㏖.

이소폴리 텅스텐酸 및 그의 鹽에 關한 硏究

김봉걸,Bong-Kul Kim 대한화학회 1969 대한화학회지 Vol.13 No.4

Isopolytungstic acid and it's salts, which are formed in sodium tungstate solutions, when acidified with perchloric acid, have been investigated by cryoscopic method. The results obtained are summarized as follows; It was not possible to measure the molecular weight of sodium isopolytungstates which are salthydrates, by means of cryoscopic method. Regardless of the concentration of solution, paratungstate and acid hexatungstate are formed at $H^+/WO_4^{2-}$ ratio of 1.15 and 1.50. It has been shown that isopolytungstic acid and it's salts are also formed at $H^+/WO_4^{2-}$ ratio of 1.30 and 1.90 and in highly concentrated solutions at 1.40 and 1.65.

Ceramic Capacitor 제조용 재료의 개발에 關한 硏究

金鳳杰,金昌煜 慶熙大學校 1979 論文集 Vol.9 No.-

This essay is concerened upon BaTiO_3-SnO_2 ceramic capacitors which were made from pure barium titanate. In datails, The contents are as follows. 1. Pure barium titanate is made of decomposition of barium titanyl oxalate. 2. BaTiO_3-SnO_2 Ceramic capacitors, 15% tin oxide addition to pure barium titanate, have good dielectric effects to variable temperature. 3. In comparation to the dielectric effect variable temperature BaTiO_3-SnO_2 Ceramic capacitor was better than national products.

封着유리의 製造에 關한 硏究

金鳳杰,金宗範,權昶吾,朴慶煥 慶熙大學校 1988 論文集 Vol.17 No.-

The purpose of these studies are to prepare low melting devitrifiable solder glass for high termal expansion seal and to find out solder glass which is the optimum condition in terms of thermal properties among others. Then five kinds of frits were prepared by quenching after melting of solder glass in the Pt-crucible at 1,100℃, which contained 2wt% of ZrO₂ as a neucleation agent with being control led by the concentration of mother glass of PbO-ZnO-B₂O₃-SiO₂ system. For probing the characteristics of the solder glass, DTA, X-ray powder diffraction, thermal, expansion, sealability, fluidity and activation energy were examined. The results are as follows: 1. It was possible in sealing of low temperature that the sealability & crystallization temperature was lowered and the fludity was good owing to an increase in PbO wt% but it was inadquate in sealing of color TV tube for 80.5wt% PbO and over because thermal expansion was increased. 2. The optimum holding time was 60 minutes. 3. In the sample contained 80.5wt% PbO, the thermal expansion coefficient was 101.8×10^-7/℃, the crystallization temperature was 443℃, flow button diameter was 27.7㎜, the sealability was 25.15㎏f/㎠, It is better than the existing solder glass. 4. The crystals proved in process of melting and crystallization were Pb_8Zn(Si₂O_7)₃, PbZrO, Zn₂SiO₁ etc. 5. The activation energy needed for crystallization was 87.13kJ/mol.

酸化리튬의 置換에 따른 硼硅酸유리의 分相에 關한 硏究

金鳳杰,梁重植 慶熙大學校 1980 論文集 Vol.10 No.-

The phase separation of low-alkali borosilicate glass with the composition of 6.25 Na_2O·18.75 B_2O_3· 75.00 SiO_2 (mole%) substituting Li_2O for Na_2O was studied. The phase separation in the temperature range of transformation was examined with various heating temperatures and soaking times. Durability to water, thermal expansion, specifie density and visible light transmittance of the specimen were investigated and the microstructure of the separated phase was also observed by transmission electron micrograph techniques. The maximum alkali extraction result with he best phase separation effect was obtained when Na_2O of the base glass was replaced with 1.88 Li_2O (mole %) and electron micrograph of carbon film replica of 1.88 Li_2O·4.37 Na_2O·18.75 B_2O_3·75.00 SiO_2 (mole %) glass showed that glass consisted of homogeneous two phases. The minimum specific density was shown with the specimen treated at 570℃ and it was also shown that the longer the treating time the lower the specific density. The apparent activation energies of approximately 45 Kcal/mole by the alkali extraction and 43Kcal/mole by the thermal expansion method were derived from the Arrhenius plots, respectively.

SOL-GEL法에 依한 LAS系 結晶化유리의 製造에 있어서 租成比유리의 特性에 미치는 影響

김봉걸,양중식,조훈성,권창오,박경호 慶熙大學校 材料科學技術硏究所 1990 材料科學技術硏究論集 Vol.3 No.-

The purpose of this study is to investigate into the physical properties of Li₂O-Al₂O₃-nSiO₂ (LAnS) system of crystallized glass prepared by sol-gel method according to the composition ratio of LAnS. In order to find the crystallization temperature as well as the state of crystalline, differential thermal analysis and X-ray diffraction analysis were examined. The results obtained are as follows : 1. Gelling time became longer as increasing the composition ratio of SiO₂ and also found that it became faster as increasing the additive amount of water. Also, additive amount of water required for the gellation was above four times of the theoretical amount of water required hydrolysis. 2. Surface area and mean pore size became larger as increasing the composition ratio of SiO₂ and for LA4S dried gel, surface area was 331.1m^(2)/g, mean pore size distributed about 5nm and 30-50nm. 3. The crystallization temperature is high as increasing the composition ratio of SiO₂ and for LA4S, crystallization temperature is 800℃. Also, LA4S formed at 800℃ for the crystalline phase of β-eucryptite and at 900℃ for crystalline phase of β-spodumene.