• Analytical Science and Technology
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• v.16 no.2
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• pp.117-124
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• 2003

Oxygen to metal ratio has been measured by wet and dry chemical analysis to study the properties of sintered $UO_2$ pellets and $U_3O_8$ in the lithium reduction process of spent pressurized water reactor fuels. Uranium dioxide pellets simulated for the spent PWR fuels with burnup values of 20,000~60,000 MWd/MtU were prepared by mixing $UO_2$ powder and oxides of fission product elements, pelleting the powder mixture and sintering it at $1,700^{\circ}C$ under a hydrogen atmosphere. For wet chemical analysis, the simulated spent fuels were dissolved with mixed acid (10 M HCl : 8 M $HNO_3$, 2.5 : 1, v/v) using acid digestion bomb technique. The total amount of uranium and fission products added in the simulated spent fuels were measured using inductively coupled plasma atomic emission spectrometry. Weight change of the simulated fuel during its oxydation was measured by thermogravimetry and then the O/M ratio result was compared to that obtained by wet chemical analysis. Influence of $Mo_{0.4}-Ru_{0.4}-Rh_{0.1}-Pd_{0.1}$, quaternary alloy, on the determination of O/M ratio was investigated.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.3
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• pp.378-395
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• 1994

The purpose of this study was to investigate the effect of various metal surface treatments and adhesive systems on the flexural bond strength of composite resin to Au-Ag-Cu-Pd alloy. The specimens were divided into nine groups by the combinations of surface treatment methods and adhesive systems. The types of surface treatment in this study were alumina blasting only, alumina blasting-Sn plating, alumina blasting-heating and three kinds of adhesive system used in this study were Silicoater system(Heraeus Kulzer GmbH,Germany), Superbond C & B(Sun Medical Co.,Ltd.,Japan) and Cesead opaque primer(Kurary Co.,Ltd.,Japan). After surface treatments and adhesive systems were applied, each specimen was built up with Dentacolor composite resin (Heraeus Kulzer GmbH,Germany). Four-point flexural bond strength was measured by Instron universal testing machine (Model 4301,U.S.A.) and modes of failure were observed by SEM(JEOL,SSM-840A,Japan). The obtained results were as follows: 1. The group that was bonded with Superbond C & B after alumina blasting-heating shelved the highest bond strength with significant difference among the groups, except the group with Cesead opaque primer after alumina blasting-Sn plating(P<0.05). 2. In the groups bonded with Cesead opaque primer, there was significant difference only in the bond strength between the alumina blasting-Sn plating group and alumina blasting group, where the former showed a higher bond strength(P<0.05). 3. In the groups bonded with Silicoater system, there were no significant differences in bond strength regardless of the surface treatment method(P<0.05). 4. In SEM evaluation, the groups of high bond strength, especially bonded with Superbond C & B after alumina blasting-heating and Cesead opaque primer after alumina blasting-Sn plating, revealed mainly cohesive-adhesive failure, whereas the others showed the tendency of adhesive failure.

• Journal of the Korean Society for Heat Treatment
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• v.3 no.4
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• pp.23-40
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• 1990

This study has been carried out to investigate into some effects of Mn content with varying amounts and austenite grain size on hardenability in boron-added Fe-C-Cr-Mo alloy systems. (1) Austenite grains have been found to hardly grow in the temperature range of $900^{\circ}C$ to $950^{\circ}C$, whereas they grow rapidly in the temperature range of $975^{\circ}C$ to $1100^{\circ}C$. (2) Austenite grain growth is considerably small with increasing holding time at a given austenitizing temperature and is, in particular, hardly found to occur at a temperature of $900^{\circ}C$. (3) The hardenability improves ramarkably as Mn content is increased at three different austenitizing temperatures $900^{\circ}C$, $1000^{\circ}C$ and $1100^{\circ}C$. (4) The maximum hardenability is obtained from steels A, B and C austenitized at the $900^{\circ}C$, although Mn content is varied in each specimen.

• 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.

• Korean Journal of Metals and Materials
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• v.49 no.12
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• pp.937-944
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• 2011

Studies have been carried out in order to reduce fuel-cladding chemical interaction (FCCI) behavior of metallic fuel in sodium-cooled fast reactors (SFR) using an electroplating technique. A $20{\mu}m$ thick Cr layer has been plated by the electrochemical method in the Sargent bath over the HT9 (12Cr-1Mo) clad material and diffusion couple tests of the U-10Zr metallic fuel as well as the rare earth alloy (70Ce-29La) have been conducted. The results show that the Cr plating can prevent FCCI behavior along the fuel-clad interface. However, cracks developed through the thickness during plating, which resulted in the migration of some fuel constituents. Variation of bath temperature, application of pulse current, and post heat treatment have been conducted to control such cracks. We found out that some conditions like the pulse current and the post heat treatment enhanced the layer property by reducing the internal cracks and improving the diffusion couple test.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2000.05a
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• pp.1-1
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• 2000

The results of the modification of metal materials treated by high temperature pulst:d plasma fluxes (HTlPPF) with a specific power of incident flux changing in the $(3...100)10^5{]\;}W/cm^2$ range and a pulse duration lying from 15 to $50{\;}\mu\textrm{s}$ have been presented. The results of HTPPF action were studied on the stainless steels of 18Cr-l0Ni, 16Cr- 15Ni, 13Cr-2Mo types; on the structural carbon steels of (13...35)Cr, St. 3, St. 20, St. 45 types; on the tool steels of U8, 65G, ShHI5 types, and others; on nickel and high nickel alloy of 20Cr-45Ni type; on zirconium- and vanadium-base alloys and other materials. The microstructure and properties (mechanical, tribological, erosion, and other properties) of modified materials and surface alloying of metals exposed to HTPPF action have been investigated. It was found that the modification of materials by HTPPF resulted in a simultaneous increase of several properties of the treated articles: microhardness of the surface and layers of 40...60 $\mu\textrm{m}$ in depth, tribological characteristics (friction coefficient, wear resistance), mechanical properties ({\sigma_y}, {\;}{\sigma_{0.2}}.{\;}{\sigma_r}) on retention of the initial plasticity ($\delta$), corrosion resistance, radistanation erosion under ion irradiation, and others. The determining factor of the changes observed is the structural-phase modification of the near-surface layers, in particular, the formation of the fine cellular structure in the near-surface layers at a depth of $20{\;}{\mu\textrm{m}}$ with dimension of cells changing in the range from 0.1 to $1., 5{\;}\mu\textrm{m}$, depending on the kind of material, its preliminary treatment, and the parameters of plasma fluxes. The remits obtained have shown the possibility of purposeful surface alloying of metals exposed to HTPPF action over a depth up to 20...45 $\mu\textrm{m}$ and the concentration of alloying element (Ni, Cr, V) up to 20 wt.%. Possible industrial brunches for using the treatment have been also considered, as well as some results on modifying the serial industrial articles by HTPPF.