• Title/Summary/Keyword: Dissolution temperature

Search Result 416, Processing Time 0.024 seconds

Dissolution Behaviors of Sericin in Cocoon Shell on the Fluorescence Colors (누에고치층의 형광색에 따른 Sericin의 용해성)

  • 손승종;남중희
    • Journal of Sericultural and Entomological Science
    • /
    • v.30 no.1
    • /
    • pp.33-39
    • /
    • 1988
  • In the case of white cocoon, the fluorescence colors are classified as a yellowish fluorescence cocoon(Y.F.C.) and a violet fluorescence cocoon(V.F.C.) by exposing to ultra-violet ray. Accordingly, experiments were carried out to investigate the difference of sericin behaviors between Y.F.C. and V.F.C. by measuring the sericin solubility, surface tension and viscosity of the sericin solution. Also, the reelability of two different type of cocoons was investigated in the silk reeling process. The results were summarized as follows; 1. The sericin solubility of Y.F.C. shell is higher than that of V.F.C. shell with the dissolution temperature and time. It is shown that the sericin solubility curves of Y.F.c. and V.F.C. are similar in shape, but the difference of sericin solubility between Y.F.C. and V.F.C. is more significant at higher bath temperature. 2. The initial sericin dissolution curves of Y.F.C. and V.F.C. cocoon shell can be divided by four parts within the range of dissolving time from 5 minutes to 60 minutes. The initial dissolution velocity of Y.F.C. shell is faster than that of V.F.C. but the velocity difference is negligible after 30 minutes of dissolving time. 3. The gelation of V.F.C. sericin solution is faster than that of Y.F.C. at early stage(in the range of 15 minutes to 60 minutes). 4. In the silk reeling process, the reelability of Y.F.C. is better than that of V.F.C. with about 11%. This is mainly due to the higher sericin solubility in Y.F.C. followed by the fast dissolution velocity.

  • PDF

Effect of Soaking Temperature on the Bake Hardnability of Ti-Nb Stabilized Steel Sheets (Ti-Nb 복합 첨가강의 BH특성에 미치는 균열온도의 영향)

  • Hur, Bo-Young;Um, Yong-Su;Kim, Sang-Youl;Cho, Sang-Hun;Nam, Tae-Woon
    • Journal of Korea Foundry Society
    • /
    • v.24 no.4
    • /
    • pp.231-237
    • /
    • 2004
  • Bake hardenable steel utilizes the phenomenon of strain aging to provide an increase in the yield strength of formed components. An increase of the carbon content will improve the bake hardening response: more solutes are available to pin mobile dislocations and to form the clusters more rapidly. But aging resistance decrease as increasing solute carbon. In order to under-stand the compatibility between bake hardenability and aging resistance. The optimum solute carbon control methods during manufacture should be determined. In this paper, the effect of continuous heat cycle conditions such as soaking temperature, rapid cooling start temperature, cooling rate on BH(Bake Hardenability), AI(Aging Index), YP-El(Yield Point Elongation) and other mechanical properties have been investigated. and following results were obtained. In the case of soaking temperature, BH increases with higher soaking temperature because of NbC $dissolution(830^{\circ}C)$, Therefore the solute carbon and BH at $850^{\circ}C$ and $870^{\circ}C$ are higher than these at $810^{\circ}C$. But BH at $870^{\circ}C$ is a little lower than that at $850^{\circ}C$ owing to the ferrite grain size. The measurement of amount of dissolution C using IFT(Internal Friction Test) can explain the relation of solute carbon and BH.

Synthesis of High Purity Tungsten Oxide with Tungsten Chloride from the Chlorination of Scheelite (회중석의 염소화 생성물로부터 고순도 WO3의 합성)

  • Um, Myeong-Heon;Park, Young-Seong;Lee, Chul-Tae
    • Applied Chemistry for Engineering
    • /
    • v.4 no.4
    • /
    • pp.798-806
    • /
    • 1993
  • In this study we developed the synthesis of high purity tungsten oxide from tungsten chlorides obtained by the chlorination of scheelite in a fluidized bed reactor. Within a minute of dissolution time, tungsten chlorides were almost dissolved in $H_2O_2$ solution. The proper dissolution conditions for the tungsten chlorides were as follows : $H_2O_2$ concentration 0.5%, dissolution temperature $15^{\circ}C$ and $H_2O_2$ amount to 0.5g tungsten chlorides 30ml. Under above conditions, the tungsten oxide prepared from dissolved product was identified as $WO_3$ and the purity of $WO_3$ was 99.53%.

  • PDF

A study on the effect of alumina coating on NiO dissolution in molten carbonate fuel cell (용융탄산염형 연료전지의 NiO 공기극의 용해거동에 미치는 알루미나 코팅효과에 대한 연구)

  • Ryu B. H.;Yoon S. P.;Han J;Nam S. W.;lim T.-H.;Hong S.-A.
    • New & Renewable Energy
    • /
    • v.1 no.1 s.1
    • /
    • pp.64-71
    • /
    • 2005
  • The stability of alumina-coated NiO cathodes was studied in $Li_{0.62}/K_{0.38}$ molten carbonate electrolyte. Alumina was effectively coated on the porous Ni plate using galvanostatic pulse plating method. The deposition mechanism of alumina was governed by the concentration of hydroixde ions near the working electrode, which was controlled by the temperature of bath solution. Alumina-coated NiO cathodes were formed to $A1_2O_3-NiO$ solid solution by the oxidation process and their Ni solubilities were were than that of NiO up to the immersion time of 100h. However, their Ni solubilities increased and were similar to that of the bare NiO cathode after 100h. It was because aluminum into the solid solution was segregated to $\alpha-LiAlO_2$ on the NiO and its Product did not Play a role of the Physical barrier against NiO dissolution.

  • PDF

Recovery of Sn from Copper Alloy Dross by a Selective Dissolution and Its Heat-treatment for the Synthesis of SnO2 (선택적 용해에 의한 동합금 부산물에서의 Sn 회수 및 열처리에 의한 SnO2 합성)

  • Ryu, Jeong Ho;Kong, Man-Sik;Lee, Jung-Il
    • Journal of the Korean Society for Heat Treatment
    • /
    • v.26 no.4
    • /
    • pp.173-177
    • /
    • 2013
  • Separation and recovery of valuable metals such as zinc, nickel or tin from copper alloy dross has recently attracted from the viewpoints of environmental protection and resource recycling. In this report, preliminary study on concentration and separation of tin from copper alloy dross using selective dissolution method was performed. The tin in the copper alloy dross did not dissolve in the nitric acid solution which could allow the concentration and separation of the tin from the copper alloy dross. Precipitation of tin as $H_2SnO_3$ (metastannic acid) occurred in the solution and transformed to tin dioxide ($SnO_2$) after drying process. The dried sample was heat-treated at low temperature and its phase characteristics, surface morphology and chemical composition were investigated.

Austenite Grain Growth Prediction Modeling of C-Mn-Mo-Ni Steel HAZ Considering Precipitates (C-Mn-Mo-Ni강 용접열영향부의 석출물을 고려한 오스테나이트 결정립 성장 거동 예측)

  • 서영대;엄상호;이창희;김주학;홍준화
    • Journal of Welding and Joining
    • /
    • v.20 no.5
    • /
    • pp.78-86
    • /
    • 2002
  • A metallurgical model for the prediction of prior austenite grain size considering the dissolution kinetics of M$_3$C precipitates at the heat affected zone of SA508-cl.3 was proposed. The isothermal kinetics of grain growth and dissolution were respectively described by well-known equation, $dD/dT=M({\Delta}F_{eff})^M$ and Whelan's analytical model. The isothermal grain growth experiments were carried out for measure the kinetic parameters of grain growth. The precipitates of the base metal and the specimens exposed to thermal cycle were examined by TEM-carbon extraction replica method. The model was assessed by the comparison of BUE simulation experiments and showed good consistencies. However, there was no difference between the model considering and ignoring $M_3C$ precipitates. It seems considered that pinning force exerted by $M_3C$ Precipitates was lower than driving force for grain growth due to large size and small fraction of precipitates, and mobility of grain boundary was low in the lower temperature range.

Evaluation of dissolution characteristics of magnetite in an inorganic acidic solution for the PHWR system decontamination

  • Ayantika Banerjee ;Wangkyu Choi ;Byung-Seon Choi ;Sangyoon Park;Seon-Byeong Kim
    • Nuclear Engineering and Technology
    • /
    • v.55 no.5
    • /
    • pp.1892-1900
    • /
    • 2023
  • A protective oxide layer forms on the material surfaces of a Nuclear Power Plant during operation due to high temperature. These oxides can host radionuclides, the activated corrosion products of fission products, resulting in decommissioning workers' exposure. These deposited oxides are iron oxides such as Fe3O4, Fe2O3 and mixed ferrites such as nickel ferrites, chromium ferrites, and cobalt ferrites. Developing a new chemical decontamination technology for domestic CANDU-type reactors is challenging due to variations in oxide compositions from different structural materials in a Pressurized Water Reactor (PWR) system. The Korea Atomic Energy Research Institute (KAERI) has already developed a chemical decontamination process for PWRs called 'HyBRID' (Hydrazine-Based Reductive metal Ion Decontamination) that does not use organic acids or organic chelating agents at all. As the first step to developing a new chemical decontamination technology for the Pressurized Heavy Water Reactor (PHWR) system, we investigated magnetite dissolution behaviors in various HyBRID inorganic acidic solutions to assess their applicability to the PHWR reactor system, which forms a thicker oxide film.

Geochemical Characteristics of Groundwater in Korea with Different Aquifer Geology and Temperature -Comparative Study with Granitic Groundwater (대수층 지질 및 온도에 따른 국내 지하수의 지구화학적 특징 -화강암질암내 지하수와의 비교연구)

  • 이종운;전효택;전용원
    • Journal of the Korean Society of Groundwater Environment
    • /
    • v.4 no.4
    • /
    • pp.212-222
    • /
    • 1997
  • Geochemistry of metasedimentary groundwaters and spar waters has been studied in comparison with that of granitic groundwaters in Korea. Metasedimentary groundwaters show $Ca^{2+]$-${HCO_3}^-$ type at depth and low sodium concentrations compared with granitic groundwaters, which is due to the lack of plagioclase in their aquifer mineralogy and, therefore, the predominant reaction of calcite dissolution. According to factor analysis, metasedimentary groundwaters at 100~300 m depth are represented by 1) the dissolution of calcite and Mg-carbonates, 2) transformation of kaolinite to illite, and 3) the presence of sodium as not the product of plagioclase dissolution but a artificial pollutant. Discriminant function between the granitic and metasedimentary groundwaters shows a good discriminating ability with 81.8%, and groundwaters of volcanic aquifer, which has abundant plagioclase, are included in the granitic group by this function. Spa water samples show the result of active water-rock interaction due to high temperature.

  • PDF

The Effect on Iron Dissolution from Iron Cookware by Acid Condiment (산성조미료가 철냄비의 철 용출에 미치는 영향)

  • 김명선;한재숙;남출륭구
    • Journal of the East Asian Society of Dietary Life
    • /
    • v.9 no.4
    • /
    • pp.483-488
    • /
    • 1999
  • Effect on iron dissolution from iron sauce pans treated with the acetic, malic, citric acid and concentration(0. 0.02. 0.04. 0.1, 0.2, 0.4. 1.0, 2.0, 4.0%) of acidity, boiling times(0, 10. 20, 30, 40, 50, 60mins.) and temperature(5, 20, 40. 60, 80, 10$0^{\circ}C$) of acidity solution and in new and used sauce pans was investigated. As acetic acid concentration increases, iron content has increased. Iron dissolution concentration from iron sauce pan for boiling in malic acid increased more than that of acetic acid and citric acid. At above 6$0^{\circ}C$, as temperature increases, concentration of iron dissolved from iron sauce pan has increased. As boiling time increases, concentration of iron dissolved from iron sauce pan has also increased. Concentration of iron by repeated use has increased. And iron concentration has dissolved in large amount from new pan rather than used pan. Concentration of iron with distilled water by repeated use has increased only slightly. But 1% acetic acid has dissolved in large quantities.

  • PDF

Effects of Ag and Cu Additions on the Electrochemical Migration Susceptibility of Pb-free Solders in Na2SO4 Solution

  • Yoo, Y.R.;Nam, H.S.;Jung, J.Y.;Lee, S.B.;Park, Y.B.;Joo, Y.C.;Kim, Y.S.
    • Corrosion Science and Technology
    • /
    • v.6 no.2
    • /
    • pp.50-55
    • /
    • 2007
  • The smaller size and higher integration of advanced electronic package systems result in severe electrochemical reliability issues in microelectronic packaging due to higher electric field under high temperature and humidity conditions. Under these harsh conditions, electronic components respond to applied voltages by electrochemical ionization of metal and the formation of a filament, which leads to short-circuit failure of an electronic component, which is termed electrochemical migration. This work aims to evaluate electrochemical migration susceptibility of the pure Sn, Sn-3.5Ag, Sn-3.0Ag-0.5Cu solder alloys in $Na_{2}SO_{4}$. The water drop test was performed to understand the failure mechanism in a pad patterned solder alloy. The polarization test and anodic dissolution test were performed, and ionic species and concentration were analyzed. Ag and Cu additions increased the time to failure of Pb-free solder in 0.001 wt% $Na_{2}SO_{4}$ solution at room temperature and the dendrite was mainly composed of Sn regardless of the solders. In the case of SnAg solders, when Ag and Cu added to the solders, Ag and Cu improved the passivation behavior and pitting corrosion resistance and formed inert intermetallic compounds and thus the dissolution of Ag and Cu was suppressed; only Sn was dissolved. If ionic species is mainly Sn ion, dissolution content than cathodic deposition efficiency will affect the composition of the dendrite. Therefore, Ag and Cu additions improve the electrochemical migration resistance of SnAg and SnAgCu solders.