• Corrosion Science and Technology
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• v.5 no.3
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• pp.99-105
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• 2006

This paper is to investigate feasibility on quantitative aging state of epoxy coating on concrete wall in containment structure under operation of nuclear power plants. For evaluating the physical characteristics of the epoxy coating, adhesion strengths of two kinds of degraded epoxy coating systems on both steel surfaces and concrete surfaces were measured via accelerated aging. Comparatively impedance data taken by ultrasonic test were also taken to relate with adhesion data. After aging, in case of concrete, from half of specimens, aging of epoxy coating was developed. As for steel, on $4^{th}$ inspection day, adhesion force was failed. To improve reliability on quality degradation of epoxy, relationship between adhesion and impedance was analyzed. By tracing to co-respond to these data, it was possible to Fig. out physical state of as-built epoxy coating. The possibility to develop new methodology of time - dependent aging state on epoxy coating was found and discussed.

• Composites Research
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• v.22 no.6
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• pp.39-44
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• 2009

The effect of exposure times on the aging characteristics of carbon fiber/epoxy composite ring specimen was evaluated using an accelerating aging tester. Combined exposure conditions, such as temperature, moisture, and ultraviolet, were applied up to 3000 hours. Tensile properties and flexural properties including the effect of curvature were evaluated on the specimens subject to various exposure times through a material testing system. Their aging surfaces were observed through a scanning electron microscope. According to the results, tensile modulus was little affected by the exposure times. However, tensile strength, at the early stage of the exposure times, increased due to physical aging and curing reaction, but tensile strength slightly decreased due to degradation as the exposure times increased. The flexural modulus and flexural strength increased at the early stage of the exposure times, but slightly decreased as the exposure times increased. Aging surfaces of the specimens examined using the scanning electron microscope revealed a different morphology in various exposure times and provided useful information for identifying the degradation in mechanical properties of the composite subject to various exposure times.

• Analytical Science and Technology
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• v.15 no.3
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• pp.229-235
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• 2002

Plasma source ion implantation (PSII) technique was utilized to improve the wettability of polystyrene surfaces. It is well known that treated surfaces undergo aging, leading to hydrophobic recovery with time. We investigated the aging effect of polystyrene thin film on the various molecular weights. Polystyrenes with several molecular weights ($M_w$ = 760, 2430, 31600, 115700, 280000, 903600) were treated in different experimental conditions including gas species and pulse energy, and their hydrophilicity was measured by contact angle goniometer. To study wettability decay as a function of the molecular weight, PSII-treated samples were aged at different temperatures. Hydrophobic recovery of high molecular weight polystyrene was much slower than that of low molecular weight, even at high temperatures. The methods used to characterize treated surfaces were water contact angle measurement, TOF-SIMS, XPS, SEM and AFM.

• Macromolecular Research
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• v.12 no.6
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• pp.608-614
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• 2004

Isotactic polypropylene (PP) surfaces were modified with argon and oxygen plasmas using a radio­frequency (RF) glow discharge at 240 mTorr and 40 W. The changes in topography and surface structure were investigated by atomic force microscopy (AFM) in conjunction with specular reflectance of infrared (IR) microspectroscopy. Under our operating conditions, the AFM image analysis revealed that longer plasma treatment resulted in significant ablation on the PP surface, regardless of the kind of plasma employed, but the topography was dependent on the nature of the gases. Specular reflectance IR spectroscopic analysis indicated that the constant removal of surface material was an important ablative aspect when using either plasma, but the nature of the ablative behavior and the resultant aging effects were clearly dependent on the choice of plasma. The use of argon plasma resulted in a negligible aging effect; in contrast, the use of oxygen plasma caused a noticeable aging effect, which was due to reactions of trapped or isolated radicals with oxygen in air, and was partly responsible for the increased surface area caused by ablation. The use of oxygen plasma is believed to be an advantageous approach to modifying polymeric materials with functionalized surfaces, e.g., for surface grafting of unsaturated monomers and incorporating oxygen-containing groups onto PP.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.86-94
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• 1997

Quick aging of catalysts has done with IAE(Institute for advanced engineering) AGING MODE suggested by IAE. To estimate the effects of number of aging cycle, temperature and $H_2O$, characteristics of surfaces, mechanical properties and weibull modulus were estimated. Also, the conversion efficiency of aged catalysts was evaluated with model gas bench test. The area of surface and pore volume were decreased according to the number of aging cycle. The precious metal which is well dispersed in fresh state was sintered and agglomerated with aging. The mechanical of deactivation and sintering of catalysts are discussed on the basis of mechanical tests. The conversion efficiency was decreased with the repeats of aging. Especially, the existence of $H_2O$ in supply gas had a main role in catalyst deactivation withy high temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.50-56
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• 1994

Partial discharge on organic insulation surfaces are an important sauce of aging. Furthermore the modern PD measurement technigues are rapid developed as quality control and diagnostic tests to determine the fitness for use of HV equipment employing sol id electrical insulation. This paper deals with theory of conventional PD measurement and new tendency of technical development on PD measurements und evaluations. Finally the Measuring system used for diagnosing the surface aging on the organic insulation at High Voltage Laboratory of Technical University of Darmstadt in Germany is presented.

• Journal of the Korean Society for Railway
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• v.8 no.2
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• pp.188-194
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• 2005

Aging characteristics of glass fabric/phenolic composites for tilting train subjected to combined environmental aging factors were investigated. A 2.5KW accelerated aging tester with a xenon-arc lamp was used to provide environmental aging factors such as temperature, moisture, and ultraviolet. A series of aging tests were conducted up to 3000 hours and several types of specimens were prepared along the warp direction and the fill direction. Mechanical degradations for tensile, flexural, and shear properties were evaluated as a function of exposure times through a material testing system. Thermal analysis properties such as storage shear modulus, loss shear modulus, and tan 3 were measured through a dynamic mechanical analyzer. Finally exposed surfaces of the composites were examined using a scanning electron microscope. According to the experimental results, mechanical properties and thermal analysis properties of glass fabric/phenolic composites were found to be slightly degraded as a function of exposure times due to combined environmental effects.

• Fashion & Textile Research Journal
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• v.16 no.3
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• pp.456-461
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• 2014

The objective of this study is to give PP(polypropylene) fabric a good affinity for water. Oxygen plasma was treated to PP fabrics in a commercial glow discharge reactor with different RF power, discharge pressure, and reaction time. The PP fiber surfaces were characterized by the measurement of contact angle and ESCA. A JEOL scanning electron microscope was used to observe the surface morphology of fibers. The spontaneous water uptake amount of PP fabrics was determined by the demand wettability test. To determine the effect of aging on the surface properties of $O_2$ plasma treated PP, all the above measurements of the samples were carried out after 1, 7, 30, 60, and 150 days. The results are as follows. The PP fiber surfaces treated by $O_2$ plasma treatment have a chemical composition that consisted of various oxygen containing polar groups. Consequently, the contact angles of the treated PP fibers decreased, which improved the water uptake rate of PP fabrics. Surface roughness of the treated PP affected the fabric wettabiity as well. Wettability of the treated PP decreased and leveled off with aging. The $O_2$ plasma treatment is a simple and effective method to increase the water uptake rate of PP fabrics.

• Journal of the Korean Ceramic Society
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• v.36 no.12
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• pp.1390-1395
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• 1999

Zr(Y,Ce)O2 TZP ceramics were prepared by sintering compacts of 3 mol% Y2O3-TZP(3Y-TZP) powders with different amount of 12 mol% CeO2-TZP(12Ce-TZP) in air at 140$0^{\circ}C$ for 2 h. The phase changes microstructure and mechanical properties of Zr(Y. Ce)O2 TZP after hydrothermal aging(20$0^{\circ}C$ 5h) were investigated. Although an addition of 12Ce-TZP accelerated the grain growth of Zr(Y, Ce)O2 TZP it restrained the transformation of tetragonal to the monoclinic phase during aging. The degradation in mechanical properties of sintered bodies was governed by the formed monoclinic phase and chemical composition. Induced Vickers indentation crack was propagated intergranually. From SEM observation of the fracture surfaces the pull-out of individual grain was confirmed.

• Journal of Korea Foundry Society
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• v.12 no.5
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• pp.397-402
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• 1992

The effect of the solution & aging treatment on the tensile strength, yield strength, elongation, reduction of area, hardness was studied in the 17-4 PH stainless steel. SEM pictures were also taken in order to examine the fracture surfaces and precipitated particles. X-ray diffraction patterns for the heat treated samples were also observed. Mechanical properties of the heat treated samples were superior to those of as cast samples. Tensile strength, yield strength, hardeness decreased with the increase of aging temperature. On the other hand, elongation and reduction of area increased as the aging temperature increased.