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
제24권 제1호 (2014년 1월) 11건
1.
2014.01
구독 인증기관 무료, 개인회원 유료
This study is experimentally investigated whether or not a relationship exists between the mechanical properties anddamping capacity of cold-rolled 316L stainless steel. Deformation-induced martensite was formed with surface relief anddirectionality. With the increasing degree of deformation, the volume fraction of ε- martensite increased, and then decreased,while α'- martensite increased rapidly. With an increasing degree of deformation, tensile strength was increased, and elongationwas decreased; however, damping capacity was increased, and then decreased. Tensile strength and elongation were affectedin the α'- martensite; hence, damping capacity was influenced greatly by ε- martensite. Thus, there was no proportionalrelationship between strength, elongation, and damping capacity.
4,000원
2.
2014.01
구독 인증기관 무료, 개인회원 유료
In the present work, WO3 and WO3-TiO2 were prepared by the chemical deposition method. Structural variations, surface state and elemental compositions were investigated for preparation of WO3-TiO2 sonocatalyst. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and transmission electron microscopy (TEM) were employed for characterization of these new photocatalysts. A rhodamine B (Rh.B) solution under ultrasonic irradiation was used to determine the catalytic activity. Excellent catalytic degradation of an Rh.B solution was observed using the WO3-TiO2 composites under ultrasonic irradiation. Sonocatalytic degradation is a novel technology of treating wastewater. During the ultrasonic treatment of aqueous solutions sonoluminescence, cavitaties and "hot spot" occurred, leading to the dissociation of water molecules. In case of a WO3 coupled system, a semiconductor coupled with two components has a beneficial role in improving charge separation and enhancing TiO2 response to ultrasonic radiations. In case of the addition of WO3 as new matter, the excited electrons from the WO3 particles are quickly transferred to TiO2 particle, as the conduction band of WO3 is 0.74 eV which is -0.5 eV more than that of TiO2. This transfer of charge should enhance the oxidation of the adsorbed organic substrate. The result shows that the photocatalytic performance of TiO2 nanoparticles was improved by loading WO3.
4,000원
3.
2014.01
구독 인증기관 무료, 개인회원 유료
In order to clarify the effect of Nb addition on the ductile-brittle transition property of sintered TiC, TiC-10 mol% Nb composites were researched using a three-point bending test at temperatures from room temperature to 2020 K, and the fracture surface was observed by scanning electron microscopy. It was found that the Nb addition decreases the ductile-brittle transition temperature of sintered TiC by 300 K and increases the ductility. The room temperature bending strength was maintained at up to 1800 K, but drastically dropped at higher temperatures in pure TiC. The strength increased moderately to a value of 320MPa at 1600 K in TiC-10 mol% Nb composites, which is 40% of the room temperature strength. Pores were observed in both the grains and the grain boundaries. It can be seen that, as Nb was added, the size of the grain decreased. The ductile-brittle transition temperature in TiC-10 mol% Nb composites was determined to be 1550 K. Above 1970 K, yieldpoint behavior was observed. When the grain boundary and cleavage strengths exceed the yield strength, plastic deformation is observed at about the same stress level in bending as in compression. The effect of Nb addition is discussed from the viewpoint of ability for plastic deformation.
4,000원
4.
2014.01
구독 인증기관 무료, 개인회원 유료
We report the nitrogen monoxide (NO) gas sensing properties of p-type CuO-nanorod-based gas sensors. We synthesized the p-type CuO nanorods with breadth of about 30 nm and length of about 330 nm by a hydrothermal method using an as-deposited CuO seed layer prepared on a Si/SiO2 substrate by the sputtering method. We fabricated polycrystalline CuO nanorod arrays at 80˚C under the hydrothermal condition of 1:1 morality ratio between copper nitrate trihydrate [Cu(NO2)2·3H2O] and hexamethylenetetramine (C6H12N4). Structural characterizations revealed that we prepared the pure CuO nanorod array of a monoclinic crystalline structure without any obvious formation of secondary phase. It was found from the gas sensing measurements that the p-type CuO nanorod gas sensors exhibited a maximum sensitivity to NO gas in dry air at an operating temperature as low as 200˚C. We also found that these CuO nanorod gas sensors showed reversible and reliable electrical response to NO gas at a range of operating temperatures. These results would indicate some potential applications of the p-type semiconductor CuO nanorods as promising sensing materials for gas sensors, including various types of p-n junction gas sensors.
4,000원
5.
2014.01
구독 인증기관 무료, 개인회원 유료
In this study, nano-sized cobalt oxide powder with an average particle size below 50 nm was prepared from a cobalt chloride solution by the spray pyrolysis process. The influences of reaction temperature on the properties of the generated powder were examined. The average particle size of the particles formed based on the spray pyrolysis process at a reaction temperature of 700˚C is roughly 20 nm. Moreover, most of these particles cannot appear with an independent type, thereby coexisting in a droplet type. When the reaction temperature increases to 800˚C, the average particle size not only increases to roughly 40 nm but also shows a more dense structure while the ratio of particles which shows a polygonal form significantly increases. As the reaction temperature increases to 900˚C, the distribution of the particles is from roughly 70 nm to 100 nm, while most of the particle surface is more intricately close and forms a polygonal shape. When the reaction temperature increases to 1000˚C, the particle size distribution of the powder shows an existing form from 80 nm to at least 150 nm in an uneven form. As the reaction temperature increases, the XRD peak intensity gradually increases, yet the specific surface area gradually decreases.
4,000원
6.
2014.01
구독 인증기관 무료, 개인회원 유료
This study was aimed at synthesizing and characterizing cerium-doped titania. Cerium-doped anatase titania powders were prepared by sol-gel process, with ammonium (IV) nitrate and titanium (IV) butoxide as the raw materials. The characteristics of pure TiO2 and cerium-doped TiO2 were investigated by XRD, TG/DTA, FE-SEM, and UV-vis spectroscopy. The results of this study show that anatase type of TiO2 was obtained in as-prepared and calcined TiO2 and Ce-TiO2 powder. A DTA curve was also observed as the crystallization temperature decreased with increasing cerium contents. We found that the crystallite size of the obtained anatase particles decreased from 55 nm to 25 nm and the particle size decreased with increasing cerium contents. Moreover, UV-vis spectra showed that anatase titania powders with various cerium contents effectively extend the light absorption properties to the visible region.
3,000원
7.
2014.01
구독 인증기관 무료, 개인회원 유료
Well-distributed ruthenium (Ru) nanoparticles decorated on porous carbon nanofibers (CNFs) were synthesized using an electrospinning method and a reduction method for use in high-performance elctrochemical capacitors. The formation mechanisms including structural, morphological, and chemical bonding properties are demonstrated by means of field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). To investigate the optimum amount of the Ru nanoparticles decorated on the porous CNFs, we controlled three different weight ratios (0 wt%, 20 wt%, and 40 wt%) of the Ru nanoparticles on the porous CNFs. For the case of 20 wt% Ru nanoparticles decorated on the porous CNFs, TEM results indicate that the Ru nanoparticles with ~2-4 nm size are uniformly distributed on the porous CNFs. In addition, 40 wt% Ru nanoparticles decorated on the porous CNFs exhibit agglomerated Ru nanoparticles, which causes low performance of electrodes in electrochemical capacitors. Thus, proper distribution of 20 wt% Ru nanoparticles decorated on the porous CNFs presents superior specific capacitance (~280.5 F/g at 10 mV/s) as compared to the 40 wt% Ru nanoparticles decorated on the porous CNFs and the only porous CNFs. This enhancement can be attributed to the synergistic effects of well-distributed Ru nanoparticles and porous CNF supports having high surface area.
4,000원
8.
2014.01
구독 인증기관 무료, 개인회원 유료
NiO-doped hibonite pigments were synthesized by the solid state method to get stabilized blue color pigment inboth oxidation and reduction atmospheres. Optimum substitution condition with NiO for hibonite blue pigment was investigated.Experimental results were comparable to those of previous cobalt-minimization studies performed with other phosphate- oroxide-based cobalt-containing ceramic pigments (having olivine (Co2SiO4), spinel (CoAl2O4), or with co-doped willemite((Co,Zn)2SiO4) structures). Composition was designed varying the NiO molar ratio increasing with SnO2. The optimumsubstitution content is 0.93mole NiO with 0.75mole SnO2. The characteristics of the synthesized pigment were analyzed byXRD, Raman spectroscopy, SEM, and UV-vis. Synthesized pigment was applied to a lime-barium glaze with 10wt% each andfired at an oxidation atmosphere of 1250oC/1h and a reducing atmosphere 1240oC/1h. Blue color was obtained with L*a*b*values at 43.39, −6.78, −18.20 under a reducing atmosphere and 41.66, −6.36, −14.7 under and oxidation atmosphere, respectively.
4,000원
9.
2014.01
구독 인증기관 무료, 개인회원 유료
The Mg-enriched magnesium aluminum silicate (MAS) glass is known for its higher mechanical strength and chemical resistance. Among such glasses, cordierite (Mg2Al4Si5O18) is well known to have a low thermal expansion and low melting point. Polycrystalline engineering ceramics such as alumina can be strengthened by a surface modification with low thermal expansion materials. The present study involves the synthesis of cordierite by a sol-gel process and investigates the effect of glass penetration on the surface of alumina. The cordierite powders were prepared from Al(OC3H7)3, Mg(OC2H5)2 and tetraethyl orthosilicate by hydrolysis and condensation reaction. The cordierite powders were characterized by X-ray diffraction (XRD, Rigaku), scanning electron microscope (SEM, JEOL: JSM-5610), energy dispersive spectroscopy (EDS, JEOL: JSM-5610), and universal testing machine (UTM, INSTRON). The X-ray diffraction patterns showed that the synthesized particles were μ-cordierite calcined at 1100˚C for 1 h. The shape of synthesized cordierite was changed from μ-cordierite to α-cordierite with increasing calcination temperature. Synthesized cordierite was used for surface modification of alumina. Cordierite powders penetrated deeply into the alumina sample along grain boundaries with increasing temperature. The results of surface modification tests showed that the strength of the prepared alumina sample increased after surface modification. The strength of a surface modified with synthesized cordierite increased the most, to about 134.6MPa.
4,000원
10.
2014.01
구독 인증기관 무료, 개인회원 유료
The corrosion resistance of submerged entry nozzle (SEN) materials were investigated for high-class steel manufacturing. Composite samples were fabricated by mixing ZrO2, Al2O3, MgO, mullite, spinel, and carbon. The raw materials were mixed with attrition milling, compacted in a uniaxial pressure of 200MPa and calcined at 1000˚C for 3 h in N2 atmosphere. The bulk density and apparent porosity of the calcined samples were measured by the liquid displacement method in water using Archimedes's principle. The corrosion resistance of the samples were measured by cup test with mold powder at 1550˚C for 2 h. The microstructure and elemental analysis of samples were observed by scanning electron microscopy (SEM), energy dispersive spectrum (EDS), and X-ray diffraction pattern (XRD). The XRD result shows that the starting raw materials were crystalline phase. The microstructure of fabricated specimen was investigated before and after corrosion tests at 1000˚C and 1550˚C for 2h. ZrO2-C composite showed good resistance in the slag corrosion test. Among the composite oxide materials, ZrO2-Al2O3-C and ZrO2-MgO-C showed better resistance than ZrO2-C in the slag corrosion test. The diameter variation index of ZrO2-C refractory was 16.1 at 1000˚C for 2 h. The diameter variation index of the ZrO2-Al2O3-C refractory was larger than that of the ZrO2-C refractory at 1550˚C for 2 h.
4,000원
11.
2014.01
구독 인증기관 무료, 개인회원 유료
Fe-based amorphous coatings were fabricated on a soda-lime glass substrate by the vacuum kinetic spray method. The effect of the gas flow rate, which determines particle velocity, on the deposition behavior of the particle and microstructure of the resultant films was investigated. The as-fabricated microstructure of the film was studied by field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM). Although the activation energy for transformation from the amorphous phase to crystalline phase was lowered by severe plastic deformation and particle fracturing under a high strain rate, the crystalline phases could not be found in the coating layer. Incompletely fractured and small fragments 100~300 nm in size, which are smaller than initial feedstock material, were found on the coating surface and inside of the coating. Also, some pores and voids occurred between particle-particle interfaces. In the case of brittle Fe-based amorphous alloy, particles fail in fragmentation fracture mode through initiation and propagation of the numerous small cracks rather than shear fracture mode under compressive stress. It could be deduced that amorphous alloy underwent particle fracturing in a vacuum kinetic spray process. Also, it is considered that surface energy caused by the formation of new surfaces and friction energy contributed to the bonding of fragments.
4,000원
