• Title/Summary/Keyword: cementation

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Recent Trend of Esthetic All-Ceramic Materials and Guidelines for Correct Cementation (올세라믹 심미 수복재료의 최신 동향과 적합한 시멘트 선택 및 사용)

  • Park, Yeong-Joon
    • The Journal of the Korean dental association
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    • v.58 no.7
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    • pp.413-434
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    • 2020
  • Recently, there are much improvement in optical and mechanical properties of dental ceramic materials coupled with improved fabrication techniques, which have caused a considerable shift in the preference of the dentists to ceramic restorations. Because the chemical composition and microstructure of all-ceramic materials are different by the type, correct choice of cement type and surface treatment procedure, and cementation strategy is essential for the success of ceramic restorations with adequate retention and decreased incidence of complications. This manuscript reviews on the most often prescribed and some newly developed ceramic materials, and the selection criteria and usage guidelines of cement materials that are used in conjunction with various ceramic materials. This manuscript emphasizes that continuous updating the information of newly developed ceramic and cement materials and application techniques by the dentists and dental staffs are demanding in response to the constantly improving ceramic and cement materials and corresponding application protocol changes.

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Recovery of Gallium and Indium from Zinc Residues by Acid Leaching (산침출에 의한 아연제련잔사로부터 갈륨 및 인디움의 회수)

  • 이화영;김성규;오종기
    • Resources Recycling
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    • v.2 no.2
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    • pp.22-26
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    • 1993
  • The flowsheet for the recovery of gallium and indium from zinc residues has been established based on the sulfuric acid treatment. In comparison with the alkali treatment, the method proposed in this work allowed the recovery of indium together with gallium. The majority of iron contained in leach liquor could be removed through the two-stage neutrallization under oxidative or reductive atmosphere. Crude gallium and indium could be obtained through the alkali and/or acid leaching of the products generated from the above treatment. In addition, cementation of indium with zinc powders could also be used for the concentration of it from weak acid solutions.

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Luting between Resin Cement and Dental Prosthetic Materials (레진시멘트와 보철재료와의 접착)

  • Kim, Kwang-Mahn
    • The Journal of the Korean dental association
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    • v.53 no.3
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    • pp.195-200
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    • 2015
  • Cementation is the last procedure and an important factor to access successful fixed prosthodontic treatment. Even though there are many kinds of luting materials in dental field, the resin cements are popularly used in now. Metals, polymers and ceramics are used as a material of fixed dental prosthesis. The bonding mechanisms between teeth and fixed restorations are composed of mechanical and chemical mechanism. In dentistry, we are relying on mechanical bonding, but we tried to get chemical bonding and many ways are introduced. So, we have to approach luting procedure differently by the materials of prosthesis for clinical success. In this article, let us think the proper cementation ways according to each prosthesis material.

Computer simulation of aluminide coating by pack cementation (팩 세멘테이션에 의한 알루미나이드 코팅의 컴퓨터 시뮬레이션)

  • Kim, M.I.;Sohn, H.S.;Lee, I.W.
    • Journal of the Korean Society for Heat Treatment
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    • v.8 no.1
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    • pp.3-11
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    • 1995
  • A theoretical model which combines gaseous transport and solid state diffusion was used to study aluminide coating process by pack cementation. The aluminide coatings were applied in the high activity pack containing $NH_4Cl$ activator with Ni substrate under argon atmosphere. On the basis of the process conditions, the suggested model allows the surface composition, the growth rate of coating layers and the aluminium concentration profiles in coatings to be calculated. In the case of $NH_4Cl$ activator, careful consideration was required in the analysis, because activator contains nitrogen and hydrogen as well as halogen element to activate the pack. A good agreement is obtained between the theoretical predictions and the experimental results.

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Change of pore structure and uniaxial compressive strength of sandstone under electrochemical coupling

  • Chai, Zhaoyun;Bai, Jinbo;Sun, Yaohui
    • Geomechanics and Engineering
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    • v.17 no.2
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    • pp.157-164
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    • 2019
  • The effect of electrochemical modification of the physical and mechanical properties of sandstone from Paleozoic coal measure strata was investigated by means of liquid nitrogen physical adsorption, X-ray diffraction and uniaxial compressive strength (UCS) tests using purified water, 1 mol/L NaCl, 1 mol/L $CaCl_2$ and 1 mol/L $AlCl_3$ aqueous solution as electrolytes. Electrochemical corrosion of electrodes and wire leads occurred mainly in the anodic zone. After electrochemical modification, pore morphology showed little change in distribution, decrease in total pore specific surface area and volume, and increased average pore diameter. The total pore specific surface area in the anodic zone was greater than in the cathodic zone, but total pore volume was less. Mineralogical composition was unchanged by the modification. Changes in UCS were caused by a number of factors, including corrosion, weakening by aqueous solutions, and electrochemical cementation, and electrochemical cementation stronger than corrosion and weakening by aqueous solutions.