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
제25권 제1호 (2015년 1월) 10건
1.
2015.01
구독 인증기관 무료, 개인회원 유료
This study suggested comprehensive structural characterization methods for the commercial blue light emitting diodes(LEDs). By using the Z-contrast intensity profile of Cs-corrected high-angle annular dark field scanning transmission electron microscope(HAADF-STEM) images from a commercial lateral GaN-based blue light emitting diode, we obtained important structural information on the epilayer structure of the LED, which would have beendifficult to obtain by conventional analysis. This method was simple but very powerful to obtain structural and chemical information on epi-structures in a nanometer-scale resolution. One of the examples was that we could determine whether the barrier in the multi-quantum well(MQW) was GaN or InGaN. Plan-view TEM observations were performed from the commercial blue LED to characterize the threading dislocations(TDs) and the related V-pit defects. Each TD observed in the region with the total LED epilayer structure including the MQW showed V-pit defects for almost of TDs independent of the TD types: edge-, screw-, mixed TDs. The total TD density from the region with the total LED epilayer structure including the MQW was about 3.6 × 108 cm−2 with a relative ratio of Edge- : Screw- :Mixed-TD portion as 80%: 7%: 13%. However, in the mesa etched region without the MQW total TD density was about 2.5 × 108 cm−2 with a relative ratio of Edge- : Screw- :Mixed TD portion of 86%: 5%: 9 %. The higher TD density in the total LED epilayer structure implied new generation of TDs mostly from the MQW region.
4,000원
2.
2015.01
구독 인증기관 무료, 개인회원 유료
The effect of retained and reversed austenite on the damping capacity in high manganese stainless steel with two phases of martensite and austenite was studied. The two phase structure of martensite and retained austenite was obtained by deformation for various degrees of deformation, and a two phase structure of martensite and reverse austenite was obtained by reverse annealing treatment for various temperatures after 70 % cold rolling. With the increase in the degree of deformation, the retained austenite and damping capacity rapidly decreased, with an increase in the reverse annealing temperature, the reversed austenite and damping capacity rapidly increased. With the volume fraction of the retained and reverse austenite, the damping capacity increased rapidly. At same volume of retained and reversed austenite, the damping capacity of the reversed austenite was higher than the retained austenite. Thus, the damping capacity was affected greatly by the reversed austenite.
4,000원
3.
2015.01
구독 인증기관 무료, 개인회원 유료
In this study, in order to improve the efficiency of n-type monocrystalline solar cells with an Alu cell structure, we investigate the effect of the amount of Al paste in thin n-type monocrystalline wafers with thicknesses of 120 μm, 130 μm, 140 μm. Formation of the Al doped p+ layer and wafer bowing occurred from the formation process of the Al back electrode was analyzed. Changing the amount of Al paste increased the thickness of the Al doped p+ layer, and sheet resistivity decreased; however, wafer bowing increased due to the thermal expansion coefficient between the Al paste and the c-Si wafer. With the application of 5.34 mg/cm2 of Al paste, wafer bowing in a thickness of 140 μm reached a maximum of 2.9 mm and wafer bowing in a thickness of 120 μm reached a maximum of 4 mm. The study’s results suggest that when considering uniformity and thickness of an Al doped p+ layer, sheet resistivity, and wafer bowing, the appropriate amount of Al paste for formation of the Al back electrode is 4.72 mg/cm2 in a wafer with a thickness of 120 μm.
4,000원
4.
2015.01
구독 인증기관 무료, 개인회원 유료
CMP(Chemical Mechanical Polishing) Processes have been used to improve the planarization of the wafers in the semiconductor manufacturing industry. Polishing performance of CMP Process is determined by the chemical reaction of the liquid sol containing abrasive, pressure of the head portion and rotational speed of the polishing pad. However, frictional heat generated during the CMP process causes agglomeration of the particles and the liquidity degradation, resulting in a non-uniform of surface roughness and surface scratch. To overcome this chronic problem, herein, we introduced NaCl salt as an additive into silica sol for elimination the generation of frictional heat. The added NaCl reduced the zata potential of silica sol and increased the contact surface of silica particles onto the sapphire wafer, resulting in increase of the removal rate up to 17 %. Additionally, it seems that the silica particles adsorbed on the polishing pad decreased the contact area between the sapphire water and polishing pad, which suppressed the generation of frictional heat.
4,000원
5.
2015.01
구독 인증기관 무료, 개인회원 유료
This paper proposes a novel way of fabricating aligned porous Sn by freeze-drying of camphene slurry with stannic oxide (SnO2) coated Sn powders. The SnO2 coated Sn powders were prepared by surface oxidation of the initial and ball-milled Sn powders, as well as heat treatment of tin chloride coated Cu powders. Camphene slurries with 10 vol% solid powders were prepared by mixing at 50 oC with a small amount of oligomeric polyester dispersant. Freezing the slurry was done in a Teflon cylinder attached to a copper bottom plate cooled at −25 oC. Improved dispersion stability of camphene slurry and the homogeneous frozen body was achieved using the oxidized Sn powder at 670 oC in air after ball milling. The porous Sn specimen, prepared by freeze-drying of the camphene slurry with oxidized Sn powder from the heat-treated Sn/tin chloride mixture and sintering at 1100 oC for 1 h in a hydrogen atmosphere, showed large pores of about 200 μm, which were aligned parallel to the camphene growth direction, and small pores in their internal walls. However, 100 μm spherical particles were observed in the bottom part of the specimen due to the melting of the Sn powder during sintering of the green compact.
4,000원
6.
2015.01
구독 인증기관 무료, 개인회원 유료
Hot rolling of Mg-6Zn-0.6Zr-0.4Ag-0.2Ca-(0, 8 wt%)Li powder was conducted at the temperature of 300 oC by putting the powder into the Cu pipe. The microstructure and mechanical properties of the samples were observed. Mg-6Zn- 0.6Zr-0.4Ag-0.2Ca without Li element was consisted of α phase and precipitates. The microstructure of the 8 wt%Li containing alloy consisted of two phases (α-Mg phase and β-Li phase). In addition, Mg2Zn3Li was formed in 8%Li added Mg-6Zn-0.6Zr- 0.4Ag-0.2Ca alloy. By addition of the Li element, the non-basal planes were expanded to the rolling direction, which was different from the based Mg alloy without Li. The tensile strength was gradually decreased from 357.1 MPa to 264 MPa with increasing Li addition from 0% to 8%Li. However, the elongation of the alloys was remarkably increased from 10 % to 21% by addition of the Li element to 8%. It is clearly considered that the non-basal texture and β phase contribute to the increase of elongation and formability.
4,000원
7.
2015.01
구독 인증기관 무료, 개인회원 유료
The effect of sintering temperature on the microstructure, electrical and dielectric properties of (V, Mn, Co, Dy, Bi)- codoped zinc oxide ceramics was investigated in this study. An increase in the sintering temperature increased the average grain size from 4.7 to 10.4 μm and decreased the sintered density from 5.47 to 5.37 g/cm3. As the sintering temperature increased, the breakdown field decreased greatly from 6027 to 1659 V/cm. The ceramics sintered at 900 oC were characterized by the highest nonlinear coefficient (36.2) and the lowest low leakage current density (36.4 μA/cm2). When the sintering temperature increased, the donor concentration of the semiconducting grain increased from 2.49 × 1017 to 6.16 × 1017/cm3, and the density of interface state increased from 1.34 × 1012 to 1.99 × 1012/cm2. The dielectric constant increased greatly from 412.3 to 1234.8 with increasing sintering temperature.
4,000원
8.
2015.01
구독 인증기관 무료, 개인회원 유료
Zn(BH4)2 was prepared by milling ZnCl2 and NaBH4 in a planetary ball mill in an Ar atmosphere, and XRD analysis, SEM observation, FT-IR analysis, DTA, and TGA were performed for synthesized Z (BH4)2 samples. 90 wt% MgH2+ 1.67 wt% Zn(BH4)2(+NaCl)+5 wt% Ni+1.67 wt% Ti+1.67 wt% Fe (named 90MgH2+1.67Zn(BH4) (+NaCl)+5Ni+1.67Ti+1.67Fe) samples were also prepared by milling in a planetary ball mill in an H2 atmosphere. The gas absorption and release properties of the Zn(BH4)2(+NaCl) and 90MgH2+1.67Zn(BH4)2(+NaCl)+5Ni+1.67Ti+1.67Fe samples were investigated. An FT-IR analysis showed that Zn(BH4)2 formed in the Zn(BH4)2(+NaCl) samples prepared by milling ZnCl2 and NaBH4. At the first cycle at 320 oC, 90MgH2+1.67Zn(BH4)2(+NaCl)+5Ni+1.67Ti+1.67Fe absorbed 2.95 wt% H for 2.5 min and 4.93 wt% H for 60 min under 12 bar H2, and released 1.46 wt% H for 10 min and 4.57 wt% H for 60 min under 1.0 bar H2.
4,000원
9.
2015.01
구독 인증기관 무료, 개인회원 유료
TiH2 nanopowder was made by high energy ball milling. The milled TiH2 and CNT powders were then simultaneously synthesized and consolidated using pulsed current activated sintering (PCAS) within one minute under an applied pressure of 80 MPa. The milling did not induce any reaction between the constituent powders. Meanwhile, PCAS of the TiH2-CNT mixture produced a Ti-TiC composite according to the reaction (0.92TiH2 + 0.08CNT→0.84Ti + 0.08TiC + 0.92H2, 0.84TiH2 + 0.16CNT→0.68Ti + 0.16TiC + 0.84H2). Highly dense nanocrystalline Ti-TiC composites with a relative density of up to 99.7% were obtained. The hardness and fracture toughness of the dense Ti-8 mole% TiC and Ti-16 mole% TiC produced by PCAS were also investigated. The hardness of the Ti-8 mole% TiC and Ti-16 mole% TiC composites was higher than that of Ti. The hardness value of the Ti-16 mole% TiC composite was higher than that of the Ti-8 mole% TiC composite without a decrease in fracture toughness.
4,000원
10.
2015.01
구독 인증기관 무료, 개인회원 유료
Glancing angle deposition (GLAD) is a powerful technique to control the morphology and microstructure of thin film prepared by physical vapor deposition. Chromium (Cr) thin films were deposited on a polymer substrate by a sputtering technique using GLAD. The change in thickness and Vickers microhardness for the samples was observed with a change in the glancing angle. The adhesion properties of the critical load (Lc) by a scratch tester for the samples were also measured with varying the glancing angle. The critical load, thickness and Vickers microhardness for the samples decreased with an increase in the glancing angle. However, the thickness of the Cr thin film prepared at a 90o glancing angle showed a relatively large value of 50 % compared to that of the sample prepared at 0o. The results of X-ray diffraction and scanning electron microscopy demonstrated that the effect of GLAD on the microstructure of samples prepared by sputter technique was not as remarkable as the samples prepared by evaporation technique. The relatively small change in thickness and microstructure of the Cr thin film is due to the superior step-coverage properties of the sputter technique.
4,000원
