수소원자는 금속 표면에 흡착하여 해리되고 금속격자 사이를 이동해 다시 수소분자로 재결합되어 탈착할 수 있으며 이러한 과정으로 수소는 금속을 통해 투과할 수 있다. 특히 수소원자는 팔라듐에서 높은 용해도와 이동도를 보여 우수한 수소투과 특성을 나타낸다. 본 연구에서는 무전해 도금을 이용하여 Pd계 금속을 α-Al2O3 중공사막 지지 체에 증착시켜 수소투과 실험을 진행하였다. Pd을 증착하기 전, Seeding 과정을 통해 지지체에 Pd 핵을 심어 금속의 증착이 용이하도록 하였으며, 중공사막 지지체의 표면 특성에 따른 Pd 증착상태를 확인하였다.

본 연구에서는 올레핀/파라핀 분리용 NaY 제올라이트 분리막을 제조하기 위해서 알루미나 지지체 표면에 종결정을 진공여과법으로 코팅한 후 NaY 수열용 액을 이용하여 90°C-110°C에서 16-24시간 동안 이차성장 시켰다. 이때 올레핀 과 π-결합을 형성하는 Ag+ 이온을 NaY 결정 구조내에 포함된 Na+ 이온과 이 온교환시킴으로써 올레핀/파라핀 선택도와 안정성을 향상시키고자 하였다. 이온 교환된 NaY 제올라이트 분리막의 올레핀/파라핀 분리성능은 C3H6/C3H8= 90/10의 혼합기체를 이용하여 분석한 결과, 700 GPU의 투과도와 1.13의 선택도를 나타내었다. 낮은 선택도는 제조된 분리막에 비제올라이트 기공이 존재하기 때문으로 판단되었으며 향후 비제올라이트기공을 억제하기 위한 연구를 진행할 계획이다.

We performed temperature dependent current-voltage (I-V) measurements to characterize the electrical properties of Au/Al2O3/n-Ge metal-insulator-semiconductor (MIS) diodes prepared with and without H2O prepulse treatment by atomic layer deposition (ALD). By considering the thickness of the Al2O3 interlayer, the barrier height for the treated sample was found to be 0.61 eV, similar to those of Au/n-Ge Schottky diodes. The thermionic emission (TE) model with barrier inhomogeneity explained the final state of the treated sample well. Compared to the untreated sample, the treated sample was found to have improved diode characteristics for both forward and reverse bias conditions. These results were associated with the reduction of charge trapping and interface states near the Ge/Al2O3 interface.

Properties of coatings produced by warm spray were investigated in order to utilize this technique as a repair method for Al tire molds. Al-(0-10 %)Al2O3 composite powder was sprayed on Al substrate by warm spraying, and the microstructure and mechanical properties of the composite coating layer were investigated. For comparative study, the properties of the coating produced by plasma spray, which is a relatively high-temperature spraying process, were also investigated. The composite coating layers produced by the two spray techniques exhibited significantly different morphology, perhaps due to their different process temperatures and velocities of particles. Whereas the Al2O3 particles in the warm sprayed coating layer maintained their initial shape before the spray, flattened and irregular shape Al2O3 particles were distributed in the plasma sprayed coating layer. The coating layer produced by warm spray showed significantly higher adhesive strength compared to that produced by plasma spray. Hardness was also higher in the warm sprayed coating layer compared to the plasma sprayed one. Moreover, with increasing the fraction of Al2O3, hardness gradually increased in both spray coating processes. In conclusion, an Al-Al2O3 composite coating layer with good mechanical properties was successfully produced by warm spray.

Aluminum-oxide(Al2O3) thin films were deposited by electron cyclotron resonance plasma-enhanced atomic layer deposition at room temperature using trimethylaluminum(TMA) as the Al source and O2 plasma as the oxidant. In order to compare our results with those obtained using the conventional thermal ALD method, Al2O3 films were also deposited with TMA and H2O as reactants at 280 oC. The chemical composition and microstructure of the as-deposited Al2O3 films were characterized by X-ray diffraction(XRD), X-ray photo-electric spectroscopy(XPS), atomic force microscopy(AFM) and transmission electron microscopy(TEM). Optical properties of the Al2O3 films were characterized using UV-vis and ellipsometry measurements. Electrical properties were characterized by capacitance-frequency and current-voltage measurements. Using the ECR method, a growth rate of 0.18 nm/cycle was achieved, which is much higher than the growth rate of 0.14 nm/cycle obtained using thermal ALD. Excellent dielectric and insulating properties were demonstrated for both Al2O3 films.

이산화탄소 분리를 위해 이온성 액체/금속 산화물 복합막이 제조되었으며, 이온성 액체로서 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM+BF4 -)와 금속산화물로서 Al2O3가 사용되었다. 13 nm의 Al2O3가 이온성 액체 BMIM+BF4 - 에 도입되었을 때, 복합체 분리막의 성능은 CO2/N2 선택도 30.5과 CO2 투과도 45.7 GPU로 관찰되었다. neat BMIM+BF4 - 분 리막의 성능(CO2/N2 선택도 5와 CO2 투과도 17 GPU)에 비해서 성능이 증가한 이유는 Al2O3의 옥사이드 층과 이온성 액체 내 자유로운 이온농도의 상승으로 인해 CO2 용해도가 상승한 것으로 확인되었다. 특히 Al2O3 나노입자는 질소 기체에 대해 서 장애물로서 작용함으로써 질소기체의 투과도가 감소하여 결과적으로 이산화탄소 분리 성능은 급격히 증가하였다.

사용후핵연료 파이로프로세싱에서는 방사성 희토류 염화물(RECl3)을 함유한 LiCl-KCl 공융염폐기물이 발생되며, 핫셀시설에서 운영을 목적으로 단순한 형태의 공융염폐기물 처리공정을 개발하는 것이 필요하다. 본 연구에서는, LiCl-KCl 공융염폐기물 내 희토류 핵종 분리/고화공정의 단순화를 목적으로 Li2O-Al2O3-SiO2-B2O3계의 무기합성매질을 이용하여 LiCl-KCl 공융 염 내 희토류 핵종(Nd)을 분리한 후 분리생성물을 바로 고화하는 시험을 실시하였다. 공융염 내 희토류 염화물(NdCl3) 대비 0.67의 무게비에 해당하는 무기합성매질의 양으로도 Nd 핵종을 98wt% 이상 분리할 수 있었고, 이 때 얻은 희토류 핵종 포집생성물은 약 50wt% 수준의 희토류 산화물 함량을 보유하고 있었으며, 이 포집생성물을 화학적 내구성이 우수한 단일상의 균질한 유리고화체로 제조할 수 있었다. 이 결과들은 LiCl-KCl 공융염폐기물 내 희토류 핵종의 분리/고화공정을 단순화하기 위한 방안수립에 활용될 수 있을 것이다.

Al2O3 nanosol dispersed under ethanol or N-Methyl-2-pyrrolidone(NMP) was studied and optimized with various dispersion factors and by utilizing the silane modification method. The two kinds of Al2O3 powders used were prepared by thermal decomposition method from aluminum ammonium sulfate(AlNH4(SO4)2) while controlling the calcination temperature. Al2O3 sol was prepared under ethanol solvent by using a batch-type bead mill. The dispersion properties of the Al2O3 sol have a close relationship to the dispersion factors such as the pH, the amount of acid additive(nitric acid, acetic acid), the milling time, and the size and combination of zirconia beads. Especially, Al2O3 sol added 4 wt% acetic acid was found to maintain the dispersion stability while its solid concentration increased to 15 wt%, this stability maintenance was the result of the electrostatic and steric repulsion of acetic acid molecules adsorbed on the surface of the Al2O3 particles. In order to observe the dispersion property of Al2O3 sol under NMP solvent, Al2O3 sol dispersed under ethanol solvent was modified and solventexchanged with N-Phenyl-(3-aminopropyl)trimethoxy silane(APTMS) through a binary solvent system. Characterization of the Al2O3 powder and the nanosol was observed by XRD, SEM, ICP, FT-IR, TGA, Particles size analysis, etc.

Aluminum oxide (Al2O3) thin films were grown by atomic layer deposition (ALD) using a new Al metalorganic precursor, dimethyl aluminum sec-butoxide (C12H30Al2O2), and water vapor (H2O) as the reactant at deposition temperatures ranging from 150 to 300 oC. The ALD process showed typical self-limited film growth with precursor and reactant pulsing time at 250 oC; the growth rate was 0.095 nm/cycle, with no incubation cycle. This is relatively lower and more controllable than the growth rate in the typical ALD-Al2O3 process, which uses trimethyl aluminum (TMA) and shows a growth rate of 0.11 nm/ cycle. The as-deposited ALD-Al2O3 film was amorphous; X-ray diffraction and transmission electron microscopy confirmed that its amorphous state was maintained even after annealing at 1000 oC. The refractive index of the ALD-Al2O3 films ranged from 1.45 to 1.67; these values were dependent on the deposition temperature. X-ray photoelectron spectroscopy showed that the ALD-Al2O3 films deposited at 250oC were stoichiometric, with no carbon impurity. The step coverage of the ALD-Al2O3 film was perfect, at approximately 100%, at the dual trench structure, with an aspect ratio of approximately 6.3 (top opening size of 40 nm). With capacitance-voltage measurements of the Al/ALD-Al2O3/p-Si structure, the dielectric constant of the ALDAl2O3 films deposited at 250 oC was determined to be ~8.1, with a leakage current density on the order of 10−8 A/cm2 at 1 V.

Tensile tests and creep tests were carried out at high temperatures on an Al-Al4C3 alloy prepared by mechanical alloying technique. The material contains about 2.0 % carbon and 0.9 % oxygen in mass percent, and the volume fractions of Al4C3 and Al2O3 particles are estimated at 7.4 and 1.4 %, respectively, from the chemical composition. Minimum creep rate decreased steeply near two critical stresses, σcl (the lower critical stress) and σcu (the upper critical stress), with decreasing applied stress at temperatures below 723 K. Instantaneous plastic strain was observed in creep tests above a critical stress, σci, at each test temperature. σcu and σci were fairly close to the 0.2% proof stress obtained by tensile tests at each test temperature. It is thought that σcl and σcu correspond to the microscopic yield stress and the macroscopic yield stress, respectively. The lower critical stress corresponds to the local yield stress needed for dislocations to move in the soft region within subgrains. The creep strain in the low stress range below 723 K arises mainly from the local deformation of the soft region. The upper critical stress is equivalent to the macroscopic yield stress necessary for dislocations within subgrains or in subboundaries; this stress can extensively move beyond subboundaries under a stress above the critical point to yield a macroscopic deformation. At higher temperatures above 773 K, the influence of the diffusional creep increases and the stress exponent of the creep rate decreases.

금속 산화물과 혼합한 Pt-Sn/Al2O3 촉매의 프로판 탈수소 반응 성능의 향상 가능성에 대해 서 연구하였다. 금속 산화물로서 Cu-Mn/γ-Al2O3, Ni-Mn/γ-Al2O3, Cu/α-Al2O3를 제조하여 Pt-Sn/Al2O3 촉매와 혼합하고, 프로판 탈수소 반응 성능을 측정하였다. 이 결과들을 불활성 물질인 glass bead를 혼합한 Pt-Sn/Al2O3 촉매를 기준샘플로 삼아 비교하였다. 촉매와 금속산화물을 환원처리 하지 않고 반응 실험한 경우, 576.5℃에서 기준샘플의 전환율 8% 대비, Cu-Mn/γ-Al2O3를 혼합한 Pt-Sn/Al2O3 촉매가 14.9%의 높은 전환율과 96.8%의 선택도를 보였다. 촉매와 금속산화물을 환원 처 리하여 반응활성을 측정한 경우, Cu/α-Al2O3과 Pt-Sn/Al2O3의 혼합촉매가 기준샘플대비 초기에 높은 수율을 보였다. 그러나, 촉매를 환원 처리한 경우 전반적으로 전환율 상승이 크지 않았고, 이것으로 Cu-Mn/γ-Al2O3의 격자산소가 탈수소반응의 전환율 증가 영향을 주었음을 알 수 있었다.

Metal matrix composites(MMC) can obtain mechanical characteristics of application purposes that a single material is difficult to obtain. Al2 O3/AC8A composites were fabricated by low pressure infiltration process. The purpose is establishing the optimal casting conditions for composite preparation under low pressure. It is known the inorganic binder help infiltration. Therefore Al2O3 fiber preform's optimum sinter temperature is 1160℃, added inorganic binder is mixed binder(SiO2 sol:Al2O3 sol=5:2). And three fibers have been compared (Al2O3 80%/SiO2 20%, Al2O3 80%/SiO2 10% and Al2O3 97%/SiO2 3%). Al2O3/AC8A composites was made by each melting temperatures(650℃, 700℃, 750℃) and wear test was performed about effect of temperatures, kind of fiber, matrix and composites, aging time. Wear test is Ball on disk wear test. The resistance increased with the low melting temperature and Al2O3 80%/SiO2 20% fiber.

To increase the capacitance of an Al electrolytic capacitor, the anodic oxide film, Al2O3, was partly replaced by an Al2O3-ZrO2 (Al-Zr) composite film prepared by the vacuum infiltration method and anodization. The microstructure and composition of the prepared samples were investigated by scanning electron microscopy and transmission electron microscopy. The coated and anodized samples showed multi-layer structures, which consisted of an inner Al hydrate layer, a middle Al- Zr composite layer, and an outer Al2O3 layer. The thickness of the coating layer could go up to 220 nm when the etched Al foil was coated 8 times. The electrical properties of the samples, such as specific capacitance, leakage current, and withstanding voltages, were also characterized after anodization at 100 V and 600 V. The capacitances of samples with ZrO2 coating were 36.3% and 27.5% higher than those of samples without ZrO2 coating when anodized at 100 V and 600 V, respectively.

The morphology, crystal structure and size of aerosol nanoparticles generated by erosion of electrodes made of different materials (titanium, copper and aluminum) in a multi-spark discharge generator were investigated. The aerosol nanoparticle synthesis was carried out in air atmosphere at a capacitor stored energy of 6 J, a repetition rate of discharge of 0.5 Hz and a gas flow velocity of 5.4 m/s. The aerosol nanoparticles were generated in the form of oxides and had various morphologies: agglomerates of primary particles of TiO2 and Al2O3 or aggregates of primary particles of Cu2O. The average size of the primary nanoparticles ranged between 6.3 and 7.4 nm for the three substances studied. The average size of the agglomerates and aggregates varied in a wide interval from 24.6 nm for Cu2O to 46.1 nm for Al2O3.

In this study, to increase the strength and enhance the sintering property of Al2O3, Y2O3 and La2O3 were added; the effects of these additions on the sintering characteristics of Al2O3 were observed. Adding 1 % of Y2O3 to Al2O3 repressed the development of abnormal particles and reduced the grain boundary migration of Al2O3, curbing pores to capture particles; as such, the material showed a fine microstructure. But, when over 2% of Y2O3 was added, the sintering property was reduced because of abnormal particle grain growth and pore formation in particles. Adding 1 % of Y2O3 and La2O3 to Al2O3 led to the development of abnormal particles and formed pores in the particles; when over 3% of La2O3 was added, the sintering property was reduced because the shape of the Al2O3 particles changed to angled plates.

Porous thick film of alumina which is fabricated by freeze tape casting using a camphene-camphor-acrylate vehicle. Alumina slurry is mixed above the melting point of the camphene-camphor solvent. Upon cooling, the camphene- camphor crystallizes from the solution as particle-free dendrites, with the Al2O3 powder and acrylate liquid in the interdendritic spaces. Subsequently, the acrylate liquid is solidified by photopolymerization to offer mechanical properties for handling. The microstructure of the porous alumina film is characterized for systems with different cooling rate around the melting temperature of camphor-camphene. The structure of the dendritic porosity is compared as a function of ratio of camphene-camphor solvent and acrylate content, and Al2O3 powder volume fraction in acrylate in terms of the dendrite arm width.

Graphene could be damaged and contain impurities on its surface while several fabrications such as deposition, etching, and patterning because one needs photoresist masking operation to divide the section for deposition or not. In this paper, we investigated the effectiveness of selective atomic layer deposition for clean graphene surface. Atomic layer deposition (ALD) has strong point at very uniform conformity of 1 rms roughness. In this process, H2O is generally used by one of precursors. This H2O precursor make deposition of ALD on hydrophilic surface not hydrophobic. Therefore, we used this property at graphene which has hydrophobic surface. And then, we analyzed selective deposition of ALD on graphene which are grown on Cu foil and transferred by wet process not cleaved from HOPG.