• Title/Summary/Keyword: Co-base alloy

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TECHNIQUES FOR INTERGRANULAR CRACK FORMATION AND ASSESSMENT IN ALLOY 600 BASE AND ALLOY 182 WELD METALS

  • LEE, TAE HYUN;HWANG, IL SOON;KIM, HONG DEOK;KIM, JI HYUN
    • Nuclear Engineering and Technology
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    • v.47 no.1
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    • pp.102-114
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    • 2015
  • Background: A technique developed to produce artificial intergranular stress corrosion cracks in structural components was applied to thick, forged alloy 600 base and alloy 182 weld metals for use in the qualification of nondestructive examination techniques for welded components in nuclear power plants. Methods: An externally controlled procedure was demonstrated to produce intergranular stress corrosion cracks that are comparable to service-induced cracks in both the base and weld metals. During the process of crack generation, an online direct current potential drop method using array probes was used to measure and monitor the sizes and shapes of the cracks. Results: A microstructural characterization of the produced cracks revealed realistic conformation of the crack faces unlike those in machined notches produced by an electrodischarge machine or simple fatigue loading using a universal testing machine. Conclusion: A comparison with a destructive metallographic examination showed that the characteristics, orientations, and sizes of the intergranular cracks produced in this study are highly reproducible.

An Experimental Study on The Cytotoxicity of Dental Base Metal Alleys by Extraction Method (용출법을 이용한 치과용 base metal alloy의 세포독성에 관한 실험적 연구)

  • Yoon, Min-Eui;Jin, Tai-Ho;Dong, Jin-Keun
    • The Journal of Korean Academy of Prosthodontics
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    • v.27 no.2
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    • pp.123-130
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    • 1989
  • In order to investigate the biocompatibility of base metal alloys in dental prosthesis, the 3 types of Ni-Cr alloys and the 3 types of Co-Cr alloys were collected and each alloy was extracted in the culture medium. L-cells derived from the subcutaneous tissue of mouse and extracted medium were cultivated. The relative growth rate of L-cells in the tissue culture was calculated with N-R assay. The obtained results were as follows: 1. In the case of the Co-Cr alloys tested, its cytotoxicity proved weak. 2. In the case of the Ni-Cr alloys tested, there was no significant degree of cytotoxicity, especially 25% Victory was proved noncytotoxicity.

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Fabrication and Mechanical Properties of Ni-based Amorphous Bulk Alloys (Ni기 비정질 벌크합금의 제조와 기계적 성질)

  • Kim, Sung-Gyoo
    • Journal of Korea Foundry Society
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    • v.22 no.6
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    • pp.288-292
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    • 2002
  • Ni-base amorphous alloys were manufactured using melt-spinning and Cu-mold die casting methods. Amorphous formability, the supercooled liquid region before crystallization and mechanical properties were examined. The reduced glass transition temperature and the supercooled liquid region of $Ni_{51} Nb_{20} Zr_9 Ti_9 Co_8 Cu_3$alloy were 0.621 and 46 K respectively. $Ni_{51} Nb_{20} Zr_9 Ti_9 Co_8 Cu_3$ alloy was produced in the rod shape 3mm diameter using the Cu-mold die casting. Hardness, compression strength, elongation and elastic modulus of the alloy were 850 DPN, 2.75 GPa, 1.8% and 150 GPa respectively. Moreover, compression strength of 2.75 GPa was the highest value in the amorphous bulk alloy produced up to now.

Microstructrue and Mechanical Properties of A3003 Aluminium Alloy Welds by Heat-treatment (열처리된 A3003 알루미늄합금 용접부의 미세조직 및 기계적 특성)

  • Lee, Il-Cheon;Song, Yeong-Jong;Gook, Jin-Seon;Yoon, Dong-Joo;Kim, Byung-Il
    • Journal of Welding and Joining
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    • v.25 no.5
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    • pp.51-57
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    • 2007
  • The present work was aimed to examine the variation of microstructure and mechanical properties by annealing($100{\sim}620^{\circ}C$, $2{\sim}8hr$) in A3003 Al alloy welded pipes. The A3003 Al alloy pipes with 34 mm in external diameter and 1.3 mm in thickness were manufactured by high frequency induction welding with the V shaped convergence angle $6.7^{\circ}$ and power input 50 kW. The tensile and yield strength decreased with increasing the annealing temperature remarkably, but elongation increased remarkably. Vickers hardness in welds decreased with increasing the annealing temperature remarkably. The primary intermetallic compound of $Al_{12}(Fe,\;Mn)_2Si$ was precipitated in welds as the same base metal. In a certain experimental condition, the welds line in A3003 alloys disappeared at $450^{\circ}C$ for 2 hr because of the same mechanical property and structure between welds and base metal.

Effect Boron and Silicon on Various Properties of Dental Cobalt-Chromium Alloys (치과용 Co-Cr 합금의 제성질에 미치는 Boron과 Silicon의 영향)

  • Jung, Jong-Hyun
    • Journal of Technologic Dentistry
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    • v.14 no.1
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    • pp.119-132
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    • 1992
  • This paper aims to investigate the effect of B and Si upon the mechanical properties, microstructure and corrosion resistance of Co-Cr base alloy. Ten groups of alloy ingot ingot with various contents of B and Si were remelted by high frequency electrical induction furnace and cast into tensile specimen of ADA Specification No. 14 Tensile and hardness test were carried out by Amsler and Rockwell hardness tester(R-30N), respectively. The microstructures of specimen were observed by SEM. The results obtained are summarized as follows : 1. As B content is increased, tensile strength, yield strength and Rockwell hardness number(R-30N) are also increased significantly, while the elongation is decreased significantly. 2. As Si contect os increased, no significant chang in tensile strength is noticed, yield strength is slightly decreased, but Rockwell hardness number(R-30N) is moderately in creased, Elongation marks maxium value with 1% Si content while with more than 1% Si it is decreased. 3. As B content is increased corrosion resistance is decreased and is at best with 1.5% B content. Corrosion resistance is increased with the increase of Si content and the alloys with Si over 3.0% showed corrosion resistance. 4. As B content increased, precipitates are increased in number at grain boundaries. The grain size tends to become coarse with the increase of Si content. 5. Co rich-Cr alloy is present through matrix whereas at the grain boundaries Cr base precipitates are primarily formed.

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Influence of Carbon Content on the Mechanical Properties of the Ni-Co Alloy (Ni-Co 합금강의 기계적 특성에 대한 탄소함량의 영향)

  • Choi, Byung-Ky;Jang, Kyeung-Cheun;Choi, Byung-Hui;Lee, Kee-Ahn
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.15 no.5
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    • pp.7-13
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    • 2006
  • This study was to evaluate the effect of carbon content on metallic change and fatigue characteristics with Fe-29%Ni-17%Co, low heat expansion alloy, widely using electronic components, precision machines, and sealing with glass and metal etc. The steels were fabricated with variation of carbon content, 0, 0.03, 0.06, 0.1, and 0.20% with VIM and tensile test and fatigue test were performed to achieve the above purpose. The more carbon content, the higher hardness value and yield strength. But elongation of 0.03%C, 0.06%C, and 0.10%C specimen decreased about 2.2%, 1.5% and 0.8% respectively more than that of the base metal. Especially the strength and elongation of 0.20%C specimen increased simultaneously about 14.4% and 7.5%. Fatigue life of 0.03%C specimen decreased but the more carbon content, the higher fatigue life over 0.06% carbon content more than that of base metal.

A STUDY ON THE FLEXURAL BOND STRENGTH OF THE GOLD AND THE Co-Cr ALLOY TO THE DENTURE BASE RESINS (금 합금 및 비 귀금속 합금에 대한 의치상 레진의 결합강도에 관한 연구)

  • Park, Hyun-Joo;Kim, Chang-Whe;Kim, Yung-Soo
    • The Journal of Korean Academy of Prosthodontics
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    • v.38 no.4
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    • pp.500-509
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    • 2000
  • In general, the three major oral functions of edentulous patients-mastication, phonation, esthetics-can be rehabilitated by the complete dentures, and both the resin based complete denture and the metal based complete denture are commonly used by many clinicians today. For the sake of many advantages such as the excellent thermal conductivity, low volumetric change, high strength, low risk of fracture and the better patient's adaptation, the metal based complete dentures are indicated to the several cases. But, there are common failures of these type of dentures mainly by the fracture or the debonding between the resin structures and the metal frameworks which is caused by the discrepancies of the flexural strength and the coefficient of thermal expansion. This is aggravated by the water contamination of the interface when exposed to the oral environment and results in the failure of complete denture treatment. So, the purpose of this study is to compare the bond strength and the fracture patterns of the gold alloy based and the Co-Cr alloy based complete dentures using the PMMA resins and the 4-META adhesive resins. The results of this study were as follows. 1. Both to the PMMA resin and the 4-META resin, the flexural bond strength of gold alloy is lower than that of Co-Cr alloy(P<0.05) 2. To the Co-Cr alloy, the bond strength of the 4-META resin is significantly higher than that of PMMA resin(P<0.05). 3. The flexural strength of the group with the mechanical retention form is significantly higher than that of the group without retention form(P<0.05). 4. Comparing with the other groups, the fracture patterns of the group 3 are quite different from the group 1,2,5.

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Effect of Substrate on Electroless Co-Base Deposited Films (무전해 코발트계 석출막에 미치는 기판의 영향)

  • Han, Chang-Suk;Chun, Chang-Hwan;Han, Seung-Oh
    • Korean Journal of Materials Research
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    • v.19 no.6
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    • pp.319-324
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    • 2009
  • The deposition behavior and structural and magnetic properties of electroless Co-B and Co-Fe-B deposits, as well as the amorphous ribbon substrates, were investigated. These Co-based alloy deposits exhibited characteristic polycrystalline structures and surface morphology and magnetic properties that were dependent on the type of amorphous substrates. The catalytic activity sequence of the amorphous ribbon electrodes for anodic oxidation of DMAB was estimated from the current density-potential curve in the anodic partial electrolytic bath that did not contain the metal ions. Both the deposition rate and potential in the initial region were obtained in order of the catalytic activity, depending on the alloy compositions of the substrates. The deposition rate linearly varied against the deposition time. The initial deposition potential may have also determined the structural and magnetic properties of the deposit based on the thickness of ${\mu}m$ order. Furthermore, a basic study of the electroless deposition processes on an amorphous ribbon substrate has been carried out in connection with the structural and magnetic properties of the deposits.

EFFECTS OF METAL SURFACE TREATMENTS ON THE SHEAR BOND STRENGTH BETWEEN NI-CR DENTURE BASE AND RELINE RESINS (금속 표면처리방법이 니켈-크롬 합금 의치상과 첨상레진간의 결합강도에 미치는 영향)

  • Kim Young-Il;Jeong Chang-Mo;Jeon Young-Chan
    • The Journal of Korean Academy of Prosthodontics
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    • v.40 no.4
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    • pp.396-405
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    • 2002
  • The purpose of this study was to evaluate the effects of four metal surface treatments on the shear bond strength of reline resin to Ni-Cr alloy. The denture base metal used in this study was Ni-Cr alloy(Ticonium Premium 100. Ticonium Co., U.S.A.). 120 specimens were divided into five metal surface treatments: sandblasting only, MR. BOND(Tokuyama Corp.. Japan), Cesead Opaque Primer(Kuraray Co., Japan), METALPRIMER II(GC Corp., Japan) and Super-Bond C&B(Sun Medical Co., Japan) after sandblasting. They were bonded with one of three reline resins Mild Rebaron(GC Corp., Japan), Mild Rebaron LC(GC Corp., Japan) and Meta Base M(Sun Medical Co., Japan). Then they were thermocycled 1,000 times at temperature of $4^{\circ}C$ and $60^{\circ}C$. The shear bond strengths were measured using the universal testing machine(Instron, Model 4301, England) with a cross-head speed of 2 mm/min. The results were as follows : 1. All metal primers and adhesive cement significantly improved the bond strength of reline resin to Ni-Cr alloy compared with sandblasted specimens. 2. In Mild Rebaron and Mild Rebaron LC. Cesead Opaque Primer showed the highest bond strength, but the differences among Cesead Opaque Primer, MR. BOND and METALPRIMER II were not significant. The bond strength of Cesead Opaque Primer was significantly different with that of Super-Bond C&B. 3. In Meta Base M, Super-Bond C&B showed the highest bond strength, but there was no difference between Super-Bond C&B and three metal primers. 4. There was no difference in the bond strength between Mild Rebaron and Mild Rebaron LC when metal surface was treated with the same method. 5. The bond strengths of Mild Rebaron and Mild Rebaron LC treated with Cesead Opaque Primer were higher than that of Meta Base M. The bond strengths of Mild Rebaron treated with MR. BOND and METALPRIMER II was higher than that of Meta Base M, However, there was no difference among three reline resins treated with Super-Bond C&B.