• Title/Summary/Keyword: Metal Dissolution

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Dissolution Phenomenon of the Base Metal during TLP Bonding Using the Modified Base Metal Powder and Ni Base Filler Metal Powder (유사 조성의 모재분말과 Ni기 삽입금속 혼합분말을 사용한 천이액상확산 접합 시 모재의 용해현상)

  • Song, Woo-Young;Ye, Chang-Ho;Kang, Chung-Yun
    • Journal of Welding and Joining
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    • v.25 no.3
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    • pp.64-71
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    • 2007
  • The dissolution phenomenon of the solid phase powder and base metal by liquid phase insert metal during Transient Liquid Phase bonding using the mixed powder composed of the modified GTD111(base metal) powder and the GNi3 (Ni-l4Cr-9.5Co-3.5Al-2.5B) powder was investigated. In case of the mixed powder contains modified GTD111 powder 50wt%, all of the powder was melted by liquid phase at 1423K. At the temperature between solidus and liquidus of GNi3, liquid phase penetrated into the boundary of the modified GTD111 powder and solid particle separated from powder was melted easily because area of reaction was increased. With increasing mixing ratio of the modified GTD111, it needed the higher temperature to melt all of the modified GTD111 powder. During Transient Liquid Phase bonding using the mixed powder composed of the modified GTD111 50wt% and GNi3 50wt% as insert metal, width of the bonded interlayer was increased with increasing bonding temperature by reaction of the base metal and liquid phase in insert metal. Dissolution of the base metal and modified powder by liquid phase progressed all together and after all of the powder was melted nearly, the dissolution of the base metal occurred quickly.

Factors Affecting the Dissolution Behavior of Metals from Binary Alloys

  • Han, Kenneth N.
    • Resources Recycling
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    • v.10 no.1
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    • pp.49-55
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    • 2001
  • The strategy of recovering metals from scrap is in general much different from primary sources. One of the main differences between the treatment of scrap and that of primary sources lies with the fact that metals are frequently associated with other met-als to form alloys in scrap, while metals occur in primary sources as oxides or sulfides. In this paper, factors affecting the dis-solution behavior of metals from various alloy systems have been reviewed and discussed. Specific examples have been drawn from Au/Ag, Au/cu and Ag/cu systems. Results of the dissolution behavior of various metals from these alloys have been reviewed and compared to the dissolution behavior of single metal systems in various lixiviants such as acids, cyanide and ammonia. It has been observed that the presence of other metals in alloys would significantly affect the dissolution rate of the metal in question. The leaching behavior of metals from homogeneous alloys relies on the chemical interaction between atoms in the lattice of the alloys, while that from heterogeneous alloys is affected by galvanic interaction established in the solution The manner in which the dissolution of a certain metal is influenced by surrounding metals has been discussed in terms of pas-sive and noble nature of the metal in relation to the neighboring metals. The role of the standard electrochemical Potential of these metals on the selective dissolution for a given lixiviant has also been discussed.

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Effect of Chemical Passivation Treatment and Flow on the Corrosion of 304 Stainless Steel in Hydrochloric Acid Solution

  • Zhao, Jie;Cheng, Cong Qian;Cao, Tie Shan
    • Corrosion Science and Technology
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    • v.14 no.6
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    • pp.273-279
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    • 2015
  • Effects of passive film quality by chemical passivation and solution flow on the corrosion behavior of 304 stainless steel in HCl solution were investigated using a coloration indicator, and by corrosion weight loss, electrochemical polarization and element dissolution measurements. A high redness degree suggests a low passive-film integrity for 304 stainless steel following air exposure, while the minimum redness degree for the samples after chemical passivation suggests a high passive-film integrity. In the static condition, samples subjected to air exposure exhibited a high corrosion rate and preferential dissolution of Fe. Chemical passivation inhibited the corrosion rate due to the intrinsically high structural integrity of the passive film and high concentrations of Cr-rich oxides and hydroxide. Solution flow accelerated corrosion by promoting both the anodic dissolution reaction and the cathodic reaction. Solution flow also altered the preferential dissolution to fast uniform dissolution of metal elements.

Mitigating Metal-dissolution in a High-voltage 15 wt% Si-Graphite‖Li-rich Layered Oxide Full-Cell Utilizing Fluorinated Dual-Additives

  • Kim, Jaeram;Kwak, Sehyun;Pham, Hieu Quang;Jo, Hyuntak;Jeon, Do-Man;Yang, A-Reum;Song, Seung-Wan
    • Journal of Electrochemical Science and Technology
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    • v.13 no.2
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    • pp.269-278
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    • 2022
  • Utilization of high-voltage electrolyte additive(s) at a small fraction is a cost-effective strategy for a good solid electrolyte interphase (SEI) formation and performance improvement of a lithium-rich layered oxide-based high-energy lithium-ion cell by avoiding the occurrence of metal-dissolution that is one of the failure modes. To mitigate metal-dissolution, we explored fluorinated dual-additives of fluoroethylene carbonate (FEC) and di(2,2,2-trifluoroethyl)carbonate (DFDEC) for building-up of a good SEI in a 4.7 V full-cell that consists of high-capacity silicon-graphite composite (15 wt% Si/C/CF/C-graphite) anode and Li1.13Mn0.463Ni0.203Co0.203O2 (LMNC) cathode. The full-cell including optimum fractions of dual-additives shows increased capacity to 228 mAhg-1 at 0.2C and improved performance from the one in the base electrolyte. Surface analysis results find that the SEI stabilization of LMNC cathode induced by dual-additives leads to a suppression of soluble Mn2+-O formation at cathode surface, mitigating metal-dissolution event and crack formation as well as structural degradation. The SEI and structure of Si/C/CF/C-graphite anode is also stabilized by the effects of dual-additives, contributing to performance improvement. The data give insight into a basic understanding of cathode-electrolyte and anode-electrolyte interfacial processes and cathode-anode interaction that are critical factors affecting full-cell performance.

Analysis of Wafer Cleaning Solution Characteristics and Metal Dissolution Behavior according to the Addition of Chelating Agent (착화제 첨가에 따른 웨이퍼 세정 용액 특성 분석 및 금속 용해 거동)

  • Kim, Myungsuk;Ryu, Keunhyuk;Lee, Kun-Jae
    • Journal of Powder Materials
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    • v.28 no.1
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    • pp.25-30
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    • 2021
  • The surface of silicon dummy wafers is contaminated with metallic impurities owing to the reaction with and adhesion of chemicals during the oxidation process. These metallic impurities negatively affect the device performance, reliability, and yield. To solve this problem, a wafer-cleaning process that removes metallic impurities is essential. RCA (Radio Corporation of America) cleaning is commonly used, but there are problems such as increased surface roughness and formation of metal hydroxides. Herein, we attempt to use a chelating agent (EDTA) to reduce the surface roughness, improve the stability of cleaning solutions, and prevent the re-adsorption of impurities. The bonding between the cleaning solution and metal powder is analyzed by referring to the Pourbaix diagram. The changes in the ionic conductivity, H2O2 decomposition behavior, and degree of dissolution are checked with a conductivity meter, and the changes in the absorbance and particle size before and after the reaction are confirmed by ultraviolet-visible spectroscopy (UV-vis) and dynamic light scattering (DLS) analyses. Thus, the addition of a chelating agent prevents the decomposition of H2O2 and improves the life of the silicon wafer cleaning solution, allowing it to react smoothly with metallic impurities.

Preparation and Characterization of Water-Soluble Glass through Melting Process (I) : Dissolution Characteristics, Bactericidal Effects and Cytotoxicity (용융법에 의한 수용성 유리의 제조 및 특성 (I) : 용해 특성, 살균 효과 및 세포 독성)

  • 조종호;이용근;최세영;신철수;김경남
    • Journal of the Korean Ceramic Society
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    • v.32 no.10
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    • pp.1093-1102
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    • 1995
  • Water-soluble phosphate glasses containing Ag or Cu ion were prepared through melting process. Then the powdered glass samples were dissolved in D.I. water at room temperature with changing the dissolution time. In terms with the glass composition, dissolution characteristics, bactericidal effects and cytotoxicities were investigated. Dissolved amounts increased uniformly with dissolution time, and the dissolution rate was higher for ternary glass than for binary glass and with less metal oxide amount. And the dissolution rate of the glass with Ag ion was higher than that with Cu ion, and the bactericidal effect of the glass with Ag ion was also greater. Solution with more than 25 ppm of Ag was observed to have strong cytotoxicity to L929, and solutions of lower Ag concentration or with Cu seemed to have little cytotoxicity.

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WITNESSING DISSOLUTION OF A STAR CLUSTER IN THE SEXTANS DWARF GALAXY

  • Kim, Hak-Sub;Han, Sang-Il;Joo, Seok-Joo;Yoon, Suk-Jin
    • The Bulletin of The Korean Astronomical Society
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    • v.43 no.1
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    • pp.32.3-32.3
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    • 2018
  • We report a possible discovery of a relic of a dissolved star cluster in the Sextans dwarf spheroidal galaxy. Using the hk index (${\equiv}$(Ca-b)-(b-y)) as a photometric metallicity indicator, we have successfully discriminated the metal-poor and metal-rich stars in the galaxy and found an unexpected number density peak of metal-poor stars near the galaxy center. The analysis of color-magnitude diagrams reveals that they appear to be originated from an old, metal-poor globular cluster which might be slightly farther than the bulk of field stars in the galaxy. This supports the presence of the star cluster remnants in the galaxy which have been suggested by previous studies. If confirmed, dissolution of a star cluster provides a piece of evidence of a cored dark-matter halo profile for the Sextans dwarf galaxy.

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Characteristics of roadside soils and effects of pH and Time on their reaching behaviors of Pb, Zn, Cd and Mn (도로변 토양의 오염 특성과 Pb, Zn, Cd 및 Mn의 침출거동에 미치는 pH와 반응시간의 영향)

  • 이평구
    • Economic and Environmental Geology
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    • v.32 no.1
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    • pp.53-62
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    • 1999
  • The possibility of heavy metal pollution by contaminated roadside soils was studied under controlled conditions. The soil samples from roadside and those from a retention pond consisting of settling particles were characterized by the XRD analyses and the sequential extraction experiments. Characterization by sequential extraction, for roadside soil indicates elevate total concentrations of heavy metals. The leaching behavior of the samples under different pH and time conditions were also studied. Differences between both types of samples result mainly from the buffering effect of carbonates, present in roadside soils and lacking from settling particles. Acid leaching of the settling particles is equivalent to the sum of FI+FII+FIII, while the amounts leached from roadside soil are lower probably from kinetic reasons. The buffering effects of carbonates were found to greatly delay the onset of the leaching reactions and the extent of dissolution in most metals except for Ca and Mn. The study of leaching kinetics at pH of 6.5 and 5 showed that Cd and Zn reached the maximum possible concentration within 3 days, while Pb did not show any sign of dissolution at both ph values. The absolute amounts of dissolved Cd and Zn increased by 7 to 9 times by decreasing the pH from 6.5 to 5, indicating slightly acidified rain may result in significant metal dissolution. As deduced from both sequential extraction and leaching experiments, the relative mobility of heavy metals is found to be : Mn=Cd>Zn>>Pb>Fe, in spite of large differences in heavy metal contents and localizations.

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Dissolution Characteristics of Magnesite Ore in Hydrochloric Acid Solution and Removal of Impurity (마그네사이트 광석(鑛石)의 염산용해(鹽酸熔解) 특성(特性) 및 불순물(不純物) 제거)

  • Eom, Hyoung-Choon;Park, Hyung-Kyu;Kim, Chul-Joo;Kim, Sung-Don;Yoon, Ho-Sung
    • Resources Recycling
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    • v.18 no.6
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    • pp.38-45
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    • 2009
  • Dissolution characteristics of magnesite ore in hydrochloric acid solution and removal of impurity were investigated. The dissolution yield increased with increasing temperature and with decreasing particle size. The optimum conditions for dissolution were found to be reaction period of 120 min, reaction temperature of $80^{\circ}C$ and mean particle size of 100. Under optimal dissolution condition the extraction of Mg was 98%. It was found that most of Si and Al exist in the residue, and they can be removed by filtering. Dissolved impurity ions were precipitated as metal hydroxides by pH adjustment. Polymers were used as coagulants for metal hydroxides and the suitable coagulant dosage was 1mg/100ml of non-ionic polymer.

A Study on the Micro-machining Technique for Fabrication of Micro Grooves (미세 홈 형성을 위한 마이크로 가공기술에 관한 연구)

  • 박정우;이은상;문영훈
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.918-921
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    • 2000
  • Micro-machining, one of the non-traditional machining techniques, can achieve a wanted shape of the surface using metal dissolution with electrochemical reaction and can be applied to the metal such as high tension, heat resistance and hardened steel. The workpiece dissolves when it is positioned close to the tool electrode in electrolyte and the current is applied. Traditional machining has been used in the industries such as cutting, deburring, drilling and shaping. The aim of this work is to develop Micro-machining techniques for micro shape by establishing appropriate machining parameters of micro-machining

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