• Title/Summary/Keyword: Acidic and Alkaline Solution

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Weibull Statistical Analysis on the Mechanical Properties of SiC by Immersion in Acidic and Alkaline Solutions (산 및 알칼리 용액에 부식된 SiC의 기계적 특성에 대한 와이블 통계 해석)

  • Ahn, Seok-Hwan;Jeong, Sang-Cheol;Nam, Ki-Woo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.9
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    • pp.767-773
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    • 2016
  • A Weibull statistical analysis of the mechanical properties of SiC ceramics was carried out by immersion in acidic and alkaline solutions. The heat treatment was carried out at 1373 K. The corrosion of SiC was carried out in acidic and alkaline solutions under KSL1607. The bending strength of corroded crack-healed specimens decreased 47% and 70% compared to those of uncorroded specimens in acidic and alkaline solutions, respectively. The corrosion of SiC ceramics is faster in alkaline solution than in acid solution. The scale and shape parameters were evaluated for the as-received and corroded materials, respectively. The shape parameter of the as-received material corroded in acidic and alkaline solutions was significantly more apparent in the acidic solution. Further, the heat-treated material was large in acidic solution but small in alkaline solution. The shape parameters of the as-received and heat-treated materials were smaller in both acidic and alkaline solutions.

Manufacturing Process and Component Analysis of Seawater Salt Using Seaweeds (해조류를 이용한 해수소금 제조기법 및 성분분석)

  • Lee, Seung-Won;Kim, Hyeon-Ju;Moon, Deok-Soo;Jung, Dong-Ho;Choi, Hark-Sun
    • Journal of Ocean Engineering and Technology
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    • v.21 no.4
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    • pp.61-65
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    • 2007
  • In this research, we have developed a manufacturing process for seawater salt by horizontal spray drying technique using the deep ocean water and seaweed(sea tangle). Deep ocean water, strong acidic electrolyzed water and strong alkaline electrolyzed water were used as extraction solvent of seaweed. Sodium content in seaweed extract solution by strong alkaline electrolyzed water was 1.63(mg/g), which was 3.5 times lower than of seaweed extract by strong acidic electrolyzed water. Major mineral content(Na, K, Ca) in seawater salt by deep ocean water were higher than strong acidic electrolyzed water and strong alkaline electrolyzed water. On the contrary, Mg contents in seawater salt by deep ocean water were lower than strong acidic electrolyzed water and strong alkaline electrolyzed water. Based on the results of seawater salt production using seaweed, it is possible to make law-salt efficiently.

Comparison of Acidic and Alkaline Bath in Electroless Nickel Plating on Porous Carbon Substrate (다공성 탄소전극상 무전해 니켈도금의 산성과 알칼리용액 비교 연구)

  • Chun, So-Young;Kang, In-Seok;Rhym, Young-Mok;Kim, Doo-Hyun;Lee, Jae-Ho
    • Journal of the Korean institute of surface engineering
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    • v.43 no.2
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    • pp.105-110
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    • 2010
  • Electroless nickel plating on porous carbon substrate for the application of MCFC electrodes was investigated. Acidic and alkaline bath were used for the electroless nickel plating. The pore sizes of carbon substrates were 16-20 ${\mu}m$ and over 20 ${\mu}m$. The carbon surface was changed from hydrophobic to hydrophilic after immersing the substrate in an ammonia solution for 40 min at $60^{\circ}C$. The contact angle of water was decreased from $85^{\circ}C$ to less than $20^{\circ}$ after ammonia pretreatment. The deposition rate in the alkaline bath was higher than that in the acidic bath. The deposition rate was increased with increasing pH in both acidic and alkaline bath. The content of phosphorous in nickel deposit was decreased with increasing pH in both acidic and alkaline bath. The contents of phosphorous is low in alkaline bath. The minimum concentration of $PdCl_2$ for the electroless nickel plating was 10 ppm in alkaline bath and 5 ppm in acidic bath. The thickness of nickel was not affected by the concentration of $PdCl_2$.

Mechanical properties and immersion characteristics of sensitinized STS310S, STS316L and STS347H in the range of 480~720℃ (480~720℃에서 예민화한 STS310S, STS316L 및 STS347H의 기계적 성질 및 침지 특성)

  • Kim, Young-Soo;Lee, So-Young;Do, Jae-Yoon;Ahn, Seok-Hwan;Nam, Ki-Woo
    • Journal of Power System Engineering
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    • v.20 no.3
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    • pp.43-50
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    • 2016
  • The current study was carried to understand the immersion characteristics and mechanical properties of heat treated stainless steels. Stainless steels (STS310S, STS316L and STS347H) were thermally treated at temperature ranges from 480 to $720^{\circ}C$. Nominal stress was determined to be slightly different depending on the heat treatment temperature. The Cr concentration in STS310S was increased at the temperatures of 600 and $660^{\circ}C$, whereas the Cr concentration in STS316L and STS347H were almost constant regardless of heat treatment temperatures. Vickers hardness was found larger as a thermal treatment temperature was increased. Immersion tests of the stainless steels were also carried out in acidic solution and alkaline solution for 240 hours. Among three different stainless steels, the pitting was detected in the acidic solution, not in the alkaline solution. The pitting of STS347H was occurred more than STS310S and STS316L.

Surface Texturing and Anti-Reflection Coating of Multi-crystalline Silicon Solar Cell (다결정 실리콘 태양전지의 표면 텍스쳐링 및 반사방지막의 영향)

  • Jun, Seong-Uk;Lim, Kyung-Muk;Choi, Sock-Hwan;Hong, Yung-Myung;Cho, Kyung-Mox
    • Journal of the Korean institute of surface engineering
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    • v.40 no.3
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    • pp.138-143
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    • 2007
  • The effects of texturing and anti-reflection coating on the reflection properties of multi-crystalline silicon solar cell have been investigated. The chemical solutions of alkaline and acidic etching solutions were used for texturing at the surface of multi-crystalline Si wafer. Experiments were performed with various temperature and time conditions in order to determine the optimized etching condition. Alkaline etching solution was found inadequate to the texturing of multi-crystalline Si due to its high reflectance of about 25%. The reflectance of Si wafer texturing with acidic etching solution showed a very low reflectance about 10%, which was attributed to the formation of homogeneous. Also, deposition of ITO anti-reflection coating reduced the reflectance of multi-crystalline si etched with acidic solution($HF+HNO_3$) to 2.6%.

The Adhesion of Abrasive Particle during Poly-Si, TEOS and SiN CMP (Poly-Si, TEOS, SiN 막질의 CMP 공정 중의 연마입자 오염 특성 평가.)

  • Kim, Jin-Young;Hong, Yi-Kwan;Park, Jin-Goo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.06a
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    • pp.561-562
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    • 2006
  • The purpose of this study was to investigate the root cause of adhesion of silica and ceria particles during Poly-Si, TEOS, and SiN CMP process, respectively. The zeta-potentials of abrasive particles and wafers were observed negative surface charges in the alkaline solutions. SAC and STI patterned wafers have intermediate values of their composition surface's zeta potentials. The theoretical interaction force and adhesion force of silica and ceria particle were calculated in solution with acidic, neutral and alkaline pH. A stronger attractive force was calculated for silica and ceria particles on wafers in acidic solutions than in alkaline solutions. The theoretical interaction forces of the SAC and STI patterned wafers have intermediate values of their constitution wafer's values. The adhesion forces is observed lower values in alkaline solutions than in acidic solutions. And the ceria particle has lower adhesion than that of the silica particle.

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The Degradation of Indomethacin in Aqueous Solution (수용액에 있어서의 Indomethacin 분해)

  • 전인구;이민화;우종학
    • YAKHAK HOEJI
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    • v.20 no.1
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    • pp.76-82
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    • 1976
  • The base-catalyzed hydrolysis of indomethacin over a range of pH 8,2 to 10.0 was investigated, according to the first order kinetic equation. The energy of activation for the reaction was calculated 20, 18 kcal/mole from the Arrhenius plot. And the optimal pH of indomethacin in aqueous solution was estimated as pH 4.93 by the extrapolation of the log k-pH profiles in strong acidic and alkaline regions. And the influences of alkaline earth metals, heavy metals and some other compounds on the degradation of indomethacin were observed with no effect.

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Antimicrobial and Other Properties of a New Stabilized Alkaline Glutaraldehyde Disinfectant/Sterilizer (병원에서 사용하는 수술도구 살균제, glutaraldehyde 용액의 살균 효과에 관하여)

  • 궁리환
    • YAKHAK HOEJI
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    • v.31 no.4
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    • pp.236-251
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    • 1987
  • The chemistry, antimicrobial properties, organic soil resistance, toxicity, corrosivity and chemical stability of stabilized alkaline 2%, glutaraldehyde solution(SGS) are discussed. SGS retains the maximum antimicrobial activity of alkaline glutaraldehyde solutions and the chemical stability here to fore observed only with acidic glutaraldehyde solutions. These improvements, along with the inherent resistance of glutaradehyde to neutralization by organic soil, allow SGS to be continuously used for 14 days in situations of high dilution, or 28 days in situations of low dilution.

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Determination of the Frumkin and Temkin Adsorption Isotherms of Hydrogen at Nickel/Acidic and Alkaline Aqueous Solution Interfaces Using the Phase-Shift Method and Correlation Constants

  • Chun, Jang-H.
    • Journal of the Korean Electrochemical Society
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    • v.15 no.1
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    • pp.54-66
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    • 2012
  • The phase-shift method and correlation constants, which are unique electrochemical impedance spectroscopy techniques for studying the linear relationship between the phase shift ($90^{\circ}{\geq}-{\varphi}{\geq}0^{\circ}$) vs. potential (E) behavior for the optimum intermediate frequency ($f_o$) and the fractional surface coverage ($0{\leq}{\theta}{\leq}1$) vs. E behavior, are proposed and verified to determine the Frumkin, Langmuir, and Temkin adsorption isotherms and the related electrode kinetic and thermodynamic parameters. At Ni/0.5 M $H_2SO_4$ and 0.1M LiOH aqueous solution interfaces, the Frumkin and Temkin adsorption isotherms (${\theta}$ vs. E) of H for the cathodic hydrogen ($H_2$) evolution, interaction parameters (g), equilibrium constants (K), standard Gibbs energies (${\Delta}G^0_{\theta}$) of H adsorption, and rates of change (r) of ${\Delta}G^0_{\theta}$ with ${\theta}$ have been determined using the phase-shift method and correlation constants. A lateral repulsive interaction (g>0) between the adsorbed H species appears. The value of K in the alkaline aqueous solution is much greater than that in the acidic aqueous solution.

Preparation of Surface-anionized Poly(vinyl alcohol-co-methacrylic acid) Hydrogel Beads (표면에 음이온이 도입된 폴리(비닐 알코올-co-메타아크릴산) 하이드로젤 입자의 제조)

  • 윤주표;박연흠;이세근;박기홍;이철주
    • Polymer(Korea)
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    • v.27 no.2
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    • pp.159-166
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    • 2003
  • For the purpose of obtaining surface-anionized poly(vinyl alcohol) (PVA) hydrogel beads, vinyl acetate(VAc) and methacrylic acid(MMA) were copolymerized by the suspension polymerization technique and followed by the saponification. It was confirmed by $^1$H-NMR that the copolymerized microspheres contained carboxylic acid groups in their surface. poly(VAc-co-MAA) microspheres were completely saponified in the heterogeneous system. The saponification reaction was laster than that of PVAc microspheres. We observed the swelling property of saponified PVA microspheres treated in the acidic solution and in the alkaline solution successively. Saponified microspheres shrank in acidic solution and swelled in alkaline solution respectively, which was reversible. from the result, saponified microspheres were highly water-absorbing hydrogel beads and were certified -COOH group at their surface by $^1$H-NMR and FT-IR.