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 제4호 (2014년 4월) 7건
1.
2014.04
구독 인증기관 무료, 개인회원 유료
Ti and Ti alloys have been extensively used in the medical and dental fields because of their good corrosion resistance, high strength to density ratio and especially, their low elastic modulus compared to other metallic materials. Recent trends in biomaterials research have focused on development of metallic alloys with elastic modulus similar to natural bone, however, many candidate materials also contain toxic elements that would be biologically harmful. In this study, new Ti based alloys which do not contain the toxic metallic components were developed using a theoretical method (DV-Xα). In addition, alloys were developed with improved mechanical properties and corrosion resistance. Ternary Ti-Ag-Zr alloys consisting of biocompatible alloying elements were produced to investigate the alloying effect on microstructure, corrosion resistance, mechanical properties and biocompatibility. The effects of various contents of Zr on the mechanical properties and biocompatibility were compared. The alloys exhibited higher strength and corrosion resistance than pure Ti, had antibacterial properties, and were not observed to be cytotoxic. Of the designed alloys' mechanical properties and biocompatibility, the Ti-3Ag-0.5Zr alloy had the best results.
4,000원
2.
2014.04
구독 인증기관 무료, 개인회원 유료
The current concern about these materials (MoSi2 and NbSi2) focuses on their low fracture toughness below theductile-brittle transition temperature. To improve the mechanical properties of these materials, the fabrication of nanostructuredand composite materials has been found to be effective. Nanomaterials frequently possess high strength, high hardness, excellentductility and toughness, and more attention is being paid to their potential application. In this study, nanopowders of Mo, Nb,and Si were fabricated by high-energy ball milling. A dense nanostructured MoSi2-NbSi2 composite was simultaneouslysynthesized and sintered within two minutes by high-frequency induction heating method using mechanically activated powdersof Mo, Nb, and Si. The high-density MoSi2-NbSi2 composite was produced under simultaneous application of 80MPa pressureand an induced current. The sintering behavior, mechanical properties, and microstructure of the composite were investigated.The average hardness and fracture toughness values obtained were 1180kg/mm2 and 3MPa·m1/2, respectively. These fracturetoughness and hardness values of the nanostructured MoSi2-NbSi2 composite are higher than those of monolithic MoSi2 orNbSi2.
4,000원
3.
2014.04
구독 인증기관 무료, 개인회원 유료
A thin Cu seed layer for electroplating has been employed for decades in the miniaturization and integration of printed circuit board (PCB), however many problems are still caused by the thin Cu seed layer, e.g., open circuit faults in PCB, dimple defects, low conductivity, and etc. Here, we studied the effect of heat treatment of the thin Cu seed layer on the deposition rate of electroplated Cu. We investigated the heat-treatment effect on the crystallite size, morphology, electrical properties, and electrodeposition thickness by X-ray diffraction (XRD), atomic force microscope (AFM), four point probe (FPP), and scanning electron microscope (SEM) measurements, respectively. The results showed that post heat treatment of the thin Cu seed layer could improve surface roughness as well as electrical conductivity. Moreover, the deposition rate of electroplated Cu was improved about 148% by heat treatment of the Cu seed layer, indicating that the enhanced electrical conductivity and surface roughness accelerated the formation of Cu nuclei during electroplating. We also confirmed that the electrodeposition rate in the via filling process was also accelerated by heat-treating the Cu seed layer.
4,000원
4.
2014.04
구독 인증기관 무료, 개인회원 유료
Metallic Cr film coatings of 1.2μm thickness were prepared by DC magnetron sputter deposition method on c-plane sapphire substrates. The thin Cr films were ammoniated during horizontal furnace thermal annealing for 10-240 min in NH3 gas flow conditions between 400 and 900˚C. After annealing, changes in the crystal phase and chemical constituents of the films were characterized using X-ray diffraction (XRD) and energy dispersive X-ray photoelectron spectroscopy (XPS) surface analysis. Nitridation of the metallic Cr films begins at 500˚C and with further increases in annealing temperature not only chromium nitrides (Cr2N and CrN) but also chromium oxide (Cr2O3) was detected. The oxygen in the films originated from contamination during the film formation. With further increase of temperature above 800˚C, the nitrogen species were sufficiently supplied to the film's surface and transformed to the single-phase of CrN. However, the CrN phase was only available in a very small process window owing to the oxygen contamination during the sputter deposition. From the XPS analysis, the atomic concentration of oxygen in the as-deposited film was about 40 at% and decreased to the value of 15 at% with increase in annealing temperature up to 900˚C, while the nitrogen concentration was increased to 42 at%.
4,000원
5.
2014.04
구독 인증기관 무료, 개인회원 유료
TiC-21mol% Mo solid solution (δ-phase) and TiC-99 mol% Mo solid solution (β-phase), and TiC-(80~90)mol%Mo hypo-eutectic composite were deformed by compression in a temperature range from room to 2300 K and in a strain raterange from 4.9×10−5 to 6.9×10−3/s. The deformation behaviors of the composites were analyzed from the strengths of theδ- and β-phases. It was found that the high strength of the eutectic composite is due primarily to solution hardening of TiCby Mo, and that the δ-phase undergoes an appreciable plastic deformation at and above 1420 K even at 0.2% plastic strainof the composite. The yield strength of the three kinds of phase up to 1420 K is quantitatively explained by the rule of mixture,where internal stresses introduced by plastic deformation are taken into account. Above 1420 K, however, the calculated yieldstrength was considerably larger than the measured strength. The yield stress of β-phase was much larger than that of pure TiC.A good linear relationship was held between the yield stress and the plastic strain rate in a double-logarithmic plot. Thedeformation behavior in δ-phase was different among the three temperature ranges tested, i.e., low, intermediate and high. Atan intermediate temperature, no yield drop occurred, and from the beginning the work hardening level was high. At the testedtemperature, a good linear relationship was held in the double logarithmic plot of the yield stress against the plastic strain rate.The strain rate dependence of the yield stress was very weak up to 1273 K in the hypo-eutectic composite, but it becamestronger as the temperature rose.
4,000원
6.
2014.04
구독 인증기관 무료, 개인회원 유료
Flexible BaTiO3 films as dielectric materials for high energy density capacitors were deposited on polyethyleneterephthalate (PET) substrates by r.f. magnetron sputtering. The growth behavior, microstructure and electrical properties of theflexible BaTiO3 films were dependent on the sputtering pressure during sputtering. The RMS roughness and crystallite size ofthe BaTiO3 increased with increasing sputtering pressure. All BaTiO3 films had an amorphous structure, regardless of thesputtering pressures, due to the low PET substrate temperature. The composition of films showed an atomic ratio (Ba:Ti:O)of 0.9:1.1:3. The electrical properties of the BaTiO3 films were affected by the microstructure and roughness. The BaTiO3 filmsprepared at 100mTorr exhibited a dielectric constant of ~80 at 1kHz and a leakage current of 10−8A at 400kV/cm. Also, filmsshowed polarization of 8µC/cm2 at 100kV/cm and remnant polarization (Pr) of 2µC/cm2. This suggests that sputter depositedflexible BaTiO3 films are a promising dielectric that can be used in high energy density capacitors owing to their high dielectricconstant, low leakage current and stable preparation by sputtering.
4,000원
7.
2014.04
구독 인증기관 무료, 개인회원 유료
In this research, a precipitation method was used to synthesize β-Ga2O3 powders with various particle morphologies and sizes under varying precipitation conditions, such as gallium nitrate concentration, pH, and aging temperature, using ammonium hydroxide and ammonium carbonate as precipitants. The obtained powders were characterized in detail by XRD, SEM, FT-IR, and TG-DSC. From the TG-DSC result, GaOOH phase was transformed to β-Ga2O3 at around 742˚C, and weight loss percent was about 14 % when NH4OH was used as a precipitant. Also, β-Ga2O3 formed at 749˚C and weight loss percent was about 15 % when (NH)2CO3 was used as a precipitant. XRD results showed that the obtained Ga2O3 had pure monoclinic phase in both cases. When (NH)2CO3 was used as a precipitant, the particle shape changed and became irregular. The range of particle size was about 500nm-4μm based on various concentrations of gallium nitrate solution with NH4OH. The particle size was increased from 1-2μm to 3-4μm and particle shape was changed from spherical to bar type by increasing aging temperature over 80˚C.
4,000원
