간행물
한국재료학회지 KCI 등재 SCOPUS Korean Journal of Materials Research
- 발행기관 한국재료학회
- 자료유형 학술지
- 간기 월간
- ISSN 2799-8525 (Print)2799-8681 (Online)
- 수록기간 1991 ~ 2024
- 주제분류 공학 > 재료공학 공학 분류의 다른 간행물
- 십진분류KDC 530DDC 620
권호리스트/논문검색
제17권 제12호 (2007년 12월) 10건
1.
2007.12
구독 인증기관 무료, 개인회원 유료
This study examined the effect of growth temperature on the electrical and optical properties ofhydrogenated Al-doped zinc oxide (AZO:H) thin films deposited by rf magnetron sputtering using a ceramictarget (98wt.% ZnO, 2wt.% Al2O3). Various AZO films on glass were prepared by changing the substratetemperature from room temperature to 200oC. It was shown that intentionally incorporated hydrogen plays animportant role on the electrical properties of AZO:H films by increasing free carrier concentration. As a result,in the 2% H2 addition at the growth temperature of 150oC, resistivity of 3.21×10-4Ω·cm, mobility of 21.9cm2/V−s, electric charge carrier concentration of 9.35×1020cm-3 was obtained. The AZO:H films show a hexagonalwurtzite structure preferentially oriented in the (002) crystallographic direction.
4,000원
2.
2007.12
구독 인증기관 무료, 개인회원 유료
The texture and microstructure in Cu/Nb added ultra low carbon steels through the different thickness layer were studied after hot rolling. It was found that the two ultra low carbon steels all show the inhomogeneity of hot rolling texture and the Cu-added ultra low carbon steel was far more inhomogeneous than Nb-added one. In the center layer, the strong α fibre, γ fibre textures and the shear textures including 001<110>, 111<112> were founded. Near the surface, the α fibre texture and the orientation texture caused by a typical plane-strain deformation condition of bcc metals were observed.
3,000원
3.
2007.12
구독 인증기관 무료, 개인회원 유료
The total energy and strength of Mg alloy doped with Al, Ca and Zn, were calculated using thedensity functional theory. The calculations was performed by two programs; the discrete variational Xα (DV-Xα) method, which is a sort of molecular orbital full potential method; Vienna Ab-initio Simulation Package(VASP), which is a sort of pseudo potential method. The fundamental mixed orbital structure in each energylevel near the Fermi level was investigated with simple model using DV-Xα. The optimized crystal structurescalculated by VASP were compared to the measured structure. The density of state and the energy levels ofdopant elements was discussed in association with properties. When the lattice parameter obtained from thisstudy was compared, it was slightly different from the theoretical value but it was similar to Mk, and weobtained the reliability of data. A parameter Mk obtained by the DV-Xα method was proportional toelectronegativity and inversely proportional to ionic radii. We can predict the mechanical properties becauseis proportional to hardness.
4,000원
4.
2007.12
구독 인증기관 무료, 개인회원 유료
We investigated dry etching of acrylic (PMMA) in O2/N2 plasmas using a multi-layers electrode reactive ion etching (RIE) system. The multi-layers electrode RIE system had an electrode (or a chuck) consisted of 4 individual layers in a series. The diameter of the electrodes was 150 mm. The etch process parameters we studied were both applied RIE chuck power on the electrodes and % O2 composition in the N2/O2 plasma mixtures. In details, the RIE chuck power was changed from 75 to 200 W.% O2 in the plasmas was varied from 0 to 100% at the fixed total gas flow rates of 20 sccm. The etch results of acrylic in the multilayers electrode RIE system were characterized in terms of negatively induced dc bias on the electrode, etch rates and RMS surface roughness. Etch rate of acrylic was increased more than twice from about 0.2μm/min to over 0.4μm/min when RIE chuck power was changed from 75 to 200 W. 1 sigma uniformity of etch rate variation of acrylic on the 4 layers electrode was slightly increased from 2.3 to 3.2% when RIE chuck power was changed from 75 to 200 W at the fixed etch condition of 16 sccm O2/4 sccm N2 gas flow and 100 mTorr chamber pressure. Surface morphology was also investigated using both a surface profilometry and scanning electron microscopy (SEM). The RMS roughness of etched acrylic surface was strongly affected by % O2 composition in the O2/N2 plasmas. However, RIE chuck power changes hardly affected the roughness results in the range of 75-200 W. During etching experiment, Optical Emission Spectroscopy (OES) data was taken and we found both N2 peak (354.27 nm) and O2 peak (777.54 nm). The preliminarily overall results showed that the multi-layers electrode concept could be successfully utilized for high volume reactive ion etching of acrylic in the future.
4,000원
5.
2007.12
구독 인증기관 무료, 개인회원 유료
Plasma electrolytic oxidation (PEO) treatment was performed on cast Mg-6 wt%Al alloy solution-treated at 693K for 16h and aged at 498K. The surface roughness, thickness, micro-hardness, wear and corrosion properties of coatings on solution-treated and aged Mg-6 wt%Al alloy were investigated. The coatings on aged Mg-6 wt%Al alloy had thinner layer and lower micro-hardness and wear resistance than the solution-treated Mg-6 wt%Al alloy. As the aging time increased, the thickness of coatings decreased while the surface roughness was almost no changed. In addition, the micro-hardness and wear property of coatings decreased with increasing the aging time unlike the uncoated Mg-6 wt%Al alloy showing the peak micro-hardness and the best wear property after aging for 16 h. However, the coatings on Mg-6 wt%Al alloy peak-aged for 16h revealed the best corrosion resistance in 3.5% NaCl solution, which was explained based on the microstructural characteristics.
4,000원
6.
2007.12
구독 인증기관 무료, 개인회원 유료
Austenite precipitation behavior was studied with solidification rates and alloying contents, N and Cr, in duplex stainless steels by directional solidification. Directional solidification experiments were carried out with solidification rates, 1~100mm/s, and N and Cr contents, 0~0.27wt.%, 25~28wt.% respectively, in a duplex stainless steel, CD4MCU. As the solidification rate increases, the dendrite spacing reduced and the austenite phase in the ferrite matrix became finer. The volume fraction of austenite phase increased and its shape went to be round with increasing nitrogen contents in duplex stainless alloys. The Cr alloying element, even though it is a ferrite former, showed to enhance the nitrogen solubility in the alloy and caused the austenite round and finer. Also, Cr was supposed to decrease the austenite volume fraction, but it increased the austenite slightly due to increasing nitrogen solubility during solidification.
4,000원
7.
2007.12
구독 인증기관 무료, 개인회원 유료
Piezoelectric energy harvesting from our surrounding vibration has been studied for driving the wireless sensor node. To change the vibration energy into the electric-energy efficiently, the natural frequency of cantilever needs to be adjusted to that of a vibration source. When adding 6.80g mass on the end of the fabricated cantilever, a natural frequency shifts from 136 Hz into 49.5 Hz. In addition, electro-mechanical coupling factor increased from 10.20% to 11.90% and resulted in the 1.18 times increase of maximum output power.
3,000원
8.
2007.12
구독 인증기관 무료, 개인회원 유료
The magnetron sputtering was used to deposit Ni buffer layers on the polyimide surfaces to increase the adhesion strength between Cu thin films and polyimide as well as to prevent Cu diffusion into the polyimide. The Ni layer thickness was varied from 100 to 400Å. The adhesion strength increased rather significantly up to 200Å of Ni thickness, however, there was no significant increase in strength over 200Å. The XPS analysis revealed that Ni thin films could increase the adhesion strength by reacting with the polar C=O bonds on the polyimide surface and also it could prevent Cu diffusion into the polyimide. The Cu/Ni/ polyimide multilayer thin films showed a high stability even at the high heating temperature of 200˚C, however, at the temperature of 300˚C, Cu diffused through the Ni buffer layer into polyimide, resulting in the drastic decrease in adhesion strength.
4,000원
9.
2007.12
구독 인증기관 무료, 개인회원 유료
Hydroxyapatite (HAp) and biphasic calcium phosphate (BCP) nano powders were synthesized using the microwave-assisted synthesis process dependent on pH and microwave irradiation time. The average size of a powder was less than 100 nm in diameter. Through in-vitro cytotoxicity tests by an extract dilution method, the HAp and BCP nano powders have shown to be cytocompatible for L-929 fibroblast cells, osteoblastlike MG-63 cells and osteoclast-like Raw 264.7 cells. The activation of osteoblast was estimated by alkaline phosphatase (ALP) activity. When the HAp and BCP were treated to MG-63 cells, alkaline phosphatase activities increased on day 3, compared with those of the untreated cells. Also, the collagen fibers increased when the HAp and BCP powders suspension were treated to MG-63 cells, compared to those of the untreated cells. Quantitative alizarin red S mineralization assays showed a trend toward increasing mineralization in osteoblast cultured with powder suspension. In conclusion, hydroxyapatite and biphasic calcium phosphate appeared to be a bone graft substitute material with optimal biocompatibility and could be further applied to clinical use as an artificial bone graft substitute.
4,000원
10.
2007.12
구독 인증기관 무료, 개인회원 유료
According to progress rapidly digitalization, networked and mobilization of electronics industry, there are demands for being smaller, thinner, more light, and more efficient complex functions of electronic devices which are wireless devices, semi-conductors, packages and mobile devices. Therefore, the solder resist on a printed circuit board have been required with the high resolution and the eco-friendly materials in the surface treatments such as high heating process and coating process with electrolysis. In this study, the photoinitiator initiator and monomers of the solder resist were prepared with their contents for reducing the occurrence of the under-cut. We investigated the sample surface by UV/VIS spectrometer, FT-IR, OM after HASL and ENIG process. From our results, it is possible to get a high adhesion of resist with optimal contents between the photoinitiator initiator and monomers after surface treatments.
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