• Title/Summary/Keyword: 비귀금속

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EFFECT OF SURFACE TREATMENT OF NONPRECIOUS METAL FOR PORCELAIN IN THE SHEAR BOND STRENDTH BETWEEN METAL AND PORCELAIN (도재소부용 비귀금속 합금의 표면처리가 금속과 도재간의 전단결합강도에 미치는 영향)

  • Lee, Cheong-Hee;Cho, Sung-Am
    • The Journal of Korean Academy of Prosthodontics
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    • v.34 no.3
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    • pp.533-538
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    • 1996

  • A study of shear bond strength between porcelain and alloy pretreated with sandblasting, sputter etching, and sputter etching after sandblasting was established by Instron universal testing machine. 1. Sputter etched group after sandblasted(group IV) and sandblasted group(group II) were stronger than control group(group I) (P<0.05). 2. Sputter etched group(group III) and control group(group I) were not different(P>0.05).

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The Effect of a Au Based Bonding Agent Coating on Non-Precious Metals-Ceramic Bond Strength (비귀금속 합금에 적용한 Au Based Bonding Agent가 금속-도재 결합에 미치는 영향)

  • Lee, Jung-Hwan;Ahn, Jae-Seok
    • Journal of dental hygiene science
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    • v.9 no.4
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    • pp.405-412
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    • 2009

  • The purpose of this study investigated the effect of Au coating on adhesion between porcelain matrix and metal substructure interface. Titanium, Ni-Cr alloy and Co-Cr alloy are well known as proper metal for the dental restorations. The success of a porcelain fused to metal (PFM) restoration depends upon the quality of the porcelain-metal bond. However, adhesion between dental alloys and porcelain is related to diffusion of oxygen during ceramic firing. The excessive oxidized layers make hard adhesion between dental alloy and ceramic. Ni-Cr and Co-Cr specimens were divided into test and a control group and Titanium specimens were divided into three test groups and a control group. Each group had 20 specimens. The adhesion characteristics of porcelain and metal with Au coating layer and without Au coating layer were observed with scanning electron microscopy(SEM). The adhesion was evaluated by a biaxial flexure test and volume fraction of adherent porcelain was determined by SEM/EDS analysis. Result of this study suggest that Au coating layer is effective barrier to diffuse oxide layer completely protect non-precious alloys from oxidation during the porcelain firing. The SEM photomicrographs of cross-section specimens showed a smooth interface between Au coating layer and metals and porcelain which suggested proper chemical bonding, and no gap, porosity were observed. The mode of failure was mainly adhesive for Ti tested specimens, but mixed failures with adhesive and cohesive were observed in Ni-Cr and Co-Cr specimens. The adhesion between non-precious metals and porcelain would not be improved by Au coating agent. However, It is suggested that the continuous study is required further investigation and development.

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Research on Co- and Mo-Based Catalysts for the Oxygen Evolution Reaction in Electrochemical Water Splitting System (전기화학적 물 분해 시스템에서 산소발생반응을 위한 Co와 Mo 기반 촉매의 최근 연구 동향)

  • Junseong Park;Won Suk Jung;Jong Chan Bu
    • Journal of the Korean Electrochemical Society
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    • v.26 no.4
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    • pp.64-70
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    • 2023

  • Global warming is getting worse since a dramatic increase in greenhouse gas emissions recently. As a result, the necessity and implementation of carbon neutrality is required more urgently. To do this, among various new and renewable energies, attention in hydrogen arises. Hydrogen as a carbon-free power source is an abundant resource on Earth and is eco-friendly. Eventually, perfectly eco-friendly hydrogen can be obtained through electrolysis of water. However, the catalyst used in the oxygen evolution reaction is rare and expensive, and has a durability issue. Consequently, the development of a non-precious metal catalyst is necessary. In this review paper, we summarize and introduce Co- and Mo- based catalysts among recently announced oxygen evolution catalysts. This will help understand the design of catalyst to increase the activity and durability of non-precious metal catalysts.

  • https://doi.org/10.5229/JKES.2023.26.4.64 인용 PDF

Surface roughness changes caused by the galvanic corrosion between a titanium abutment and base metal alloy (티타늄 지대주와 비귀금속 합금사이의 갈바닉 부식에 의한 표면 거칠기 변화 평가)

  • Lee, Jung-Jin;Song, Kwang-Yeob;Ahn, Seung-Keun;Park, Ju-Mi
    • The Journal of Korean Academy of Prosthodontics
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    • v.49 no.1
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    • pp.65-72
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    • 2011

  • Purpose: The purpose of this study was to evaluate the level of electro-chemical corrosion and surface roughness change for the cases of Ti abutment connected to restoration made of base metal alloys. Materials and methods: It was hypothesized that Ni-Cr alloys in different compositions possess different corrosion resistances, and thus the specimens ($13{\times}13{\times}1.5\;mm$) in this study were fabricated with 3 different types of metal alloys, commonly used for metal ceramic restorations. The electrochemical characteristics were evaluated with potentiostat (Parstat 2273A) and the level of surface roughness change was observed with surface roughness tester. Paired t-test was used to compare mean average surface roughness (Ra) changes of each specimen group. Results: All specimens made of nickel-chromium based alloys, average surface roughness was increased significantly (P < .05). Among them, the Ni-Cr-Be alloy ($0.016{\pm}.007\;{\mu}m$) had the largest change of roughness followed by Ni-Cr ($0.012{\pm}.003\;{\mu}m$) and Ni-Cr-Ti ($0.012{\pm}.002\;{\mu}m$) alloy. There was no significant changes in surface roughness between each metal alloys after corrosion. Conclusion: In the case of galvanic couples of Ti in contact with all specimens made of nickel-chromium based alloys, average surface roughness was increased.

  • https://doi.org/10.4047/jkap.2011.49.1.65 인용 PDF KSCI