Sealing treatment is a post-surface treatment of the plasma spray coating process to improve the corrosion resistance of the coating material. In this study, the effect of the sealing on the corrosion resistance and adhesive strength of the plasma spray-coated alumina coatings was analyzed. For sealing, an epoxy resin was applied to the surface of the coated specimen using a brush. The coated specimen was subjected to a salt spray test for up to 48 hours and microstructural analysis revealed that corrosion in the coating layer/base material interface was suppressed due to the resin sealing. Measurement of the adhesive strength of the specimens subjected to the salt spray test indicated that the adhesive strength of the sealed specimens remained higher than that of the unsealed specimens. In conclusion, the resin sealing treatment for the plasma spray-coated alumina coatings is an effective method for suppressing corrosion in the coating layer/base material interface and maintaining high adhesive strength.

This study is aimed at preparing and evaluating the plasma resistance of YAS (Y2O3-Al2O3-SiO2) coating layer with crystalline YAG phase contents. For this purpose, YAS frits with controlled phase contents are prepared and melt-coated on sintered Al2O3 ceramics. Then, the results of phase analysis of crystalline YAS coating layer are compared to that of YAS frits, and discussed with regard to the plasma resistance of the YAS coating layer. The phase contents of the YAS frit change in a manner different from that of the prepared YAS coating layer, presumably owing to the composition change of YAS frit during the melt-coating process. The plasma resistance of the YAS coating layer is shown to increase with the YAG phase contents in the coating layer. Comparing the weight loss of YAS coating layer with those of commercial Y2O3, Al2O3, and quartz ceramics, the plasma resistance of the prepared YAS coating layer is 8 times higher than that of quartz and 3 times higher than that of Al2O3; this layer shows 70 % of the resistance of Y2O3.

The objective of this experiment was to assess the relationship between electrical resistance of the vaginal mucosa and plasma progesterone for optimal mating time in the bitch. Eight mature beagle bitches were examined, and we observed eight times of estrus. Vaginal electric resistance was recorded weekly using a Draminski ovulation detector in anestrus, and daily in estrus. Plasma progesterone concentration was estimated by radioimmunoassay. In the bitch, incline in vaginal electric resistance (376.20 ± 105.63 units) showed a closely association with the onset of proestrus. Ovulation day was determined as the first day when plasma progesterone concentration increased above 5.0 ng/ml (Day 0). On Day 0, vaginal mucous electric resistance was 438 ± 132 units. Vaginal mucous electric resistance showed a slight decrease or was maintained until Day 0. However, it showed an explosive increase, and peaked on Day 1~3, which was above 600 units. Two of eight cases peaked on Day 1, three of eight cases were revealed on Day 2, and others were revealed on Day 3. After Day 4, resistance showed a rapid drop to below 600 units and reached 200 units on Day 8. The optimal mating time was determined when vaginal mucous electric resistance was above 600 units.

현재 지구온난화 등의 환경문제로 인해 각종 산업분야에서 정량화에 대한 요구가 증대되어 해양산업에도 그 수요가 증가하고 있는 실정이다. 따라서 본 연구에서는 차세대 경량화 재료인 마그네슘이 활용되기 위해서 반드시 극복해야할 가장 중요한 특성인 내식특성에 대하여 고찰하고, 그 내식특성 향상을 위한 마그네슘 박막의 Morphology나 결정배향성의 영향을 해명하고자 하였다. 실험결과로부터 제작한 Mg 박막의 전기화학적 내식특성은 Ar 가스압이 높은 조건에서 제작한 막일수록 내식특성이 우수하였다. 이러한 경향은 표면 및 단면의 Morphology와 결정배향성과의 상관관계를 통하여 설명 가능하였다.

In this study, the plasma sprayed and coatings have been investigated for applications of microelectronic components. The plasma sprayed coatings had a well-defined splatted lamellae microstructure, intersplat pores and a higher amount of microcracks within the splats. The plasma sprayed coating had a relatively lower hardness of 300-400Hv, compared to 650-800Hv for coating, and would be readily damaged by mechanical attacks such as erosion, wear and friction. For a reactive ion etching against F-containing plasmas, however, the coating had a much higher resistance than the coating because of the reduced erosion rate of by-products.

In this work, the effects of atmospheric oxygen plasma treatment of carbon fibers on mechanical interfacial properties of carbon fibers-reinforced epoxy matrix composites was studied. The surface properties of the carbon fibers were determined by acid/base values, Fourier-transform infrared spectrometer (FT-IR), and X-ray photoelectron spectroscopy (XPS) analyses. Also, the crack resistance properties of the composites were investigated in critical stress intensity factor (KIC), and critical strain energy release rate mode II (GIIC) measurements. As experimental results, FT-IR of the carbon fibers showed that the carboxyl/ester groups (C=O) at 1632 cm-1 and hydroxyl group (O-H) at 3450 cm-1 were observed for the plasma treated carbon fibers, and the treated carbon fibers had the higher O-H peak intensity than that of the untreated ones. The XPS results also indicated that the O1S/C1S ratio of the carbon fiber surfaces treated by the oxygen plasma led to development of oxygen-containing functional groups. The mechanical interfacial properties of the composites, including KIC (critical stress intensity factor) and GIIC (critical strain energy release rate mode II), were also improved for the oxygen plasma-treated carbon fibersreinforced composites. These results could be explained that the oxygen plasma treatment played an important role to increase interfacial adhesions between carbon fibers and epoxy matrix resins in our composite system.