共查询到20条相似文献,搜索用时 15 毫秒
1.
Y(NO3)3 and NH3·H2O were used as a raw materials,and nano-Y2O3 powder was successfully synthesized by a precipitation method.Employing TEOS as a raw material,SiO2 powder was successfully prepared by a alkoxide-hydrolysis method,and a Y2O3/SiO2 composite powder was obtained by coating.The Y2O3,SiO2,and Y2O3/SiO2 powders were characterized using X-ray diffraction(XRD),scanning electron microscopy(SEM),and Fourier transform infrared spectrophotometer(FT-IR);the Y2O3 and Y2O3/SiO2 powders were further examined ... 相似文献
2.
F. B. Destro M. Cilense M. P. Nascimento F. González Garcia L. R. O. Hein A. Z. Simões 《Protection of Metals and Physical Chemistry of Surfaces》2016,52(1):104-110
This study examines the effect of film thickness ranging from 230 to 404 nm on the corrosion resistance of Nb2O5 thin films grown by chemical solution deposition. The films were characterized to obtain the relationships between the deposition parameters and the most relevant physical properties (structural, surface morphology and corrosion resistance). From X-ray diffraction and XPS analyses we can conclude that the films were stoichiometric Nb2O5 and crystalline. The internal strain and morphology of the film changes as the number of layers increases indicating a thickness dependent grain size. The surface roughness, corrosion resistance were also affected by the film thickness. Electrochemical impedance spectroscopy (EIS) shows that the thicker film have higher passive and charge transfer resistance than the control samples. These results coating layer of Nb2O5 improves the corrosion resistance on an API 5L X80 steel alloy due to the formation of a film on the surface. 相似文献
3.
In this study, we investigated the state of Y2O3, as a major additive element in Fe-based ODS alloys, during mechanical alloying (MA) processes by thermodynamic approaches and experimental verification. For this purpose, we introduced Ti2O3 that formed different reaction products depending on the state of Y2O3 into the Fe-based ODS alloys. In addition, the reaction products of Ti2O3, Y, and Y2O3 powders were predicted approximately based on their formation enthalpy. The experimental results relating to the formation of Y-based complex oxides revealed that YTiO3 and Y2Ti2O7 were formed when Ti2O3 reacted with Y; in contrast, only Y2Ti2O7 was detected during the reaction between Ti2O3 and Y2O3. In the alloy of Fe–Cr–Y2O3 with Ti2O3, YTiO3 (formed by the reaction of Ti2O3 with Y) was detected after the MA and heat treatment processes were complete, even though Y2O3 was present in the system. Using these results, it was proved that Y2O3 decomposed into monoatomic Y and O during the MA process. 相似文献
4.
Ji-Ae Choi Seong-Rae Lee Won-Il Cho Byung-Won Cho 《Metals and Materials International》2011,17(4):649-654
We studied the microstructural and electrochemical properties of Ti-doped Al2O3 (Ti-Al2O3) coated LiCoO2 thin films depending on the Ti composition. The 1.27 at.% Ti-Al2O3 coated films had an amorphous structure with better conductivity than that of pure Al2O3 films. The Ti-Al2O3 coating layer effectively suppressed the dissolution of Co and the formation of lower Li conductivity SEI films at the interface
between the LiCoO2 film and electrolyte. The Ti-Al2O3 coating improved the cycling performance and capacity retention at high voltage (4.5 V) of the LiCoO2 films. The Ti-Al2O3 coated LiCoO2 films showed better electrochemical properties than did the pure Al2O3 coated LiCoO2 films. These results were closely related to the enhanced Li-conductivity and interfacial quality of the Ti-Al2O3 film. 相似文献
5.
Porous Y<Subscript>2</Subscript>O<Subscript>3</Subscript> microcubes: synthesis and characterization
In this work, a facile route using a simple solvothermal reaction and sequential heat treatment process to prepare porous
Y2O3 microcubes is presented. The as-synthesized products were characterized by X-ray powder diffraction (XRD), scanning electronic
microscope (SEM), energy dispersive spectrometer (EDS), thermogravimetric analysis (TG), and differential thermal analysis
(DTA). The thermal decomposition process of the Y2O3 precursor was investigated. SEM results demonstrated that the as-prepared porous Y2O3 microcubes were with an average width of about 20 μm and thickness of about 8 μm. It was found that the morphology of the
Y2O3 precursor could be readily tuned by varying the molar ratio of S2O82− to Y3+. Y2O3:Eu3+ (6.6%) microcubes were also prepared and their photoluminescence properties were investigated. 相似文献
6.
Aerosol deposition method is a technique to form dense films by impacting solid particles on a substrate at room temperature. To clarify the bonding mechanism between AD films and substrates, TEM observation and electron energy-loss spectroscopy (EELS) analysis of the interface between Al2O3 AD films and Cu substrates were conducted. The Al2O3 film was directly adhered to the Cu substrate without any void or crack. The film was composed of randomly oriented α-Al2O3 crystal grains of about 10-20 nm large. At the Al2O3/Cu interface, the lattice fringes of the film were recognized, and no interfacial layer with nanometer-order thickness could be found. EELS spectra near O-K edge obtained at the interface had the pre-peak feature at around 528 eV. According to previously reported experiments and theoretical calculations, this suggests interactions between Cu and O in Al2O3 at the interface. It is inferred that not only the anchoring effect but also the ionic bonding and covalent bonding that originates from the Cu-O interactions contribute to the bonding between Al2O3 AD films and Cu substrates. 相似文献
7.
V. V. Sagaradze K. A. Kozlov N. V. Kataeva A. V. Litvinov V. A. Shabashov 《The Physics of Metals and Metallography》2012,113(4):372-381
The kinetics of low-temperature dissolution of oxides Y2O3 and Fe2O3 in an iron matrix during mechanical alloying has been studied using electron microscopy. It has been shown that the dissolution
rate upon deformation of primary coarse oxides Fe2O3 in α iron (and, hence, saturation of the α matrix with oxygen) during treatment in a ball mill for up to 10 h is several
times higher than the dissolution rate of Y2O3 oxides. The high-temperature (1100°C) annealing of a mechanoalloyed mixture of Fe + 1.5% Y + 1.35% Fe2O3 leads to the precipitation of 60% (of the total number of particles) secondary oxides 2–5 nm in size and only of 5–7% secondary
nanooxides in a mechanoalloyed mixture of Fe + 2% Y2O3. 相似文献
8.
Olga Fabrichnaya Galina Savinykh Gerhard Schreiber Hans J. Seifert 《Journal of Phase Equilibria and Diffusion》2011,32(4):284-297
Phase equilibria in the ZrO2-Nd2O3-Y2O3 system at 1523-1873 K have been investigated by x-ray diffraction (XRD) and scanning electron microscopy combined with energy
dispersive x-ray spectroscopy (SEM/EDX). Temperatures of phase transformations were determined by differential thermal analysis.
Temperatures of invariant reactions in the ZrO2-Nd2O3 system F = A + Pyr and H = F + A were determined as 1763 and 2118 K respectively and thermodynamic parameters of phases were
re-assessed. Phase transformations in ternary systems were determined at 1732 K for composition ZrO2-48.46Nd2O3-5.38Y2O3 (mol%) and at 1744 and 1881 K for composition ZrO2-79.09Nd2O3-2.75Y2O3 (mol%). They were interpreted using XRD investigation before and after DTA as Pyr + B → F, Pyr → F and A → B, respectively.
The solubility of the Y2O3 in pyrochlore phase was found to exceed 10 mol%. The thermodynamic parameters of the ZrO2-Nd2O3-Y2O3 system were reassessed taking into account solubility of Y2O3 in the Nd2Zr2O7 pyrochlore phase (Pyr). It is assumed that Y3+ substitutes Nd3+ and Zr4+ in their preferentially occupied sublattices. Ternary parameter was introduced into fluorite phase (F) for better reproducing
of phase equilibria. Mixing parameters were reassessed for phase A (Nd2O3 based solution), monoclinic phase B and cubic phase C (Y2O3 based solution). The isothermal sections calculated for the ZrO2-Nd2O3-Y2O3 system are in the reasonable agreement with experimental results. 相似文献
9.
Sun-Gyu Park Seong-Rae Lee Won Il Cho Byung Won Cho 《Metals and Materials International》2010,16(1):93-98
We studied the dependence of Al2O3 coating thickness and annealing conditions on the surface morphology and electrochemical properties of Al2O3 coated LiCoO2 films. The optimum coating thickness allowing for the highest capacity retention was about 24 nm. A sample consisting of
Al2O3 coated on annealed LiCoO2 film with additional annealing at 400 °C had a uniform coating layer between the coating materials and cathode films. This
sample showed the best capacity retention of ∼91 % with a charge-cut off of 4.5 V after 30 cycles, while the bare cathode
film showed a capacity retention of ∼32 % under the same conditions. The formation of second phases such as Co-Al-O was observed
in the coating films by X-ray photoelectron spectroscopy (XPS). The Co-Al-O containing samples showed a higher initial capacity
because of their smaller grain size, but less capacity retention than the Al2O3 containing samples. 相似文献
10.
The thermodynamic database of the ZrO2-Gd2O3-Y2O3-Al2O3 system is up-dated taking into account new data on lattice stabilities of ZrO2, Gd2O3 and Y2O3 and heat capacity measurements for the monoclinic phase Gd4Al2O9 and phase with garnet structure Gd3Al5O12. New data for the heat capacities of Gd2Zr2O7 (pyrochlore) and GdAlO3 (perovskite) as well as on the enthalpy of formation of fluorite solid solutions (Zr1−x
Gd
x
)O2−x/2 were found to be in good agreement with calculated results. In comparison with the previous assessment, taking into account
new experimental data resulted in a change of the melting character of the Gd4Al2O9 phase from a peritectic one to a congruent one in the Gd2O3-Al2O3 system. Correspondently, in the ternary system ZrO2-Gd2O3-Al2O3, the melting character of the three-phase assemblage Gd2O3 (B), Gd4Al2O9 and GdAlO3 changed from eutectic to transition type U. The T
0-lines for T/M and F/T diffusionless transformations and driving force of partitioning to equilibrium assemblage T + F were
calculated in the ZrO2-Gd2O3-Y2O3 system. 相似文献
11.
Jae Seok Lee Jinhyung Lee Hyuksu Han Purushottam Kumar Rajiv K. Singh 《Journal of Thermal Spray Technology》2016,25(8):1570-1576
In this report, we investigated a single-step process for formation of high crystallinity Y2O3:Eu3+ red nanophosphor by flame spray pyrolysis (FSP) without post-heat treatments. Crystallinity of as-formed nanophosphor particle was improved by addition of urea to the nitrate-based liquid precursor. Urea increased the temperature in the flame zone thus ensuring Y2O3:Eu3+ formation at higher flame temperature. Higher temperature reached during combustion of urea promoted the formation of better crystallinity, nano-sized and spherical-shaped particles. The effect of urea in the precursor to obtain high-efficiency Y2O3:Eu3+ nanophosphor was studied. 相似文献
12.
NiFe2O4 nanorods have been successfully synthesized via thermal treatment of the rod-like precursor fabricated by Ni-doped α-FeOOH,
which was enwrapped by the complex of citric acid and Ni2+. The morphology evolution during the calcination of the precursor nanorods was investigated with transmission electron microscopy
(TEM), and the phase and the magnetic properties of samples were analyzed through X-ray diffraction (XRD) and vibrating sample
magnetometer (VSM). The results indicated that the diameter of the NiFe2O4 nanorods obtained ranged between 30 and 50 nm, and the length ranged between 2 and 3 μm. As the calcination temperature was
up to 600°C, the coercivity, saturation magnetization, and remanent magnetization of the samples were 36.1 kA·m−1, 27.2 A·m2·kg−1, and 5.3 A·m2·kg−1, respectively. The NiFe2O4 nanorods prepared have higher shape anisotropy and superior magnetic properties than those with irregular shapes. 相似文献
13.
Al-substituted M-type hexaferrite is a highly anisotropic ferromagnetic material. In the present study, we report the synthesis
and the characterization of BaAl4Fe8O19 powder from two microemulsion systems of po1yoxyethylene octylphenol ether/1, 2-propylene glycol, or ethanol/cyclohexane/water
and cetrimonium bromide/1, 2-propylene glycol/cyclohexane/water. Two microemulsion systems were found to give wide stable
regions. The synthesized powders were characterized with x-ray diffraction, scanning electron microscopy, and vibrating sample
magnetometer. The experiment results indicated that the surfactant, co-surfactant, and oil/water ratio remarkably affected
the particle size, size distribution, anisotropy and magnetic property of the powders. The powder prepared with microemulsion
of po1yoxyethylene octylphenol ether/1, 2-propylene glycol/cyclohexane/water exhibited best particle character, that is, uniform
thin particle morphology, large shape anisotropy, small particle size, large coercivity of 8.73 kOe, and saturation magnetization
of 20.821 emu·g−1. 相似文献
14.
In-Jin Shon Kwon-Il Na Chang-Yul Suh Sung-Wook Cho Se-Hoon Oh Wonbaek Kim 《Metals and Materials International》2011,17(5):737-741
Nano-powders of Ti3Al and 2Al2O3 were synthesized from 3TiO2 and 5Al powders by high energy ball milling. Nanocrystalline Al2O3 reinforced composite was consolidated by high frequency induction heated sintering within 2 minutes from mechanochemically
synthesized powders of 2Al2O3 and Ti3Al. The relative density of the composite was 99.5%. The average hardness and fracture toughness were 1340 kg/mm2 and 8 MPa·m1/2, respectively. 相似文献
15.
Cr 2 O 3-coated LiNi 1/3 Co 1/3 Mn 1/3 O 2 cathode materials were synthesized by a novel method. The structure and electrochemical properties of prepared cathode materials were measured using X-ray diffraction (XRD), scanning electron microscopy (SEM), charge-discharge tests, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The measured results indicate that surface coating with 1.0 wt% Cr 2 O 3 does not affect the LiNi 1/3 Co 1/3 Mn 1/3 O 2 crystal structure (α-NaFeO 2 ) of the cathode material compared to the pristine material, the surfaces of LiNi 1/3 Co 1/3 Mn 1/3 O 2 samples are covered with Cr 2 O 3 well, and the LiNi 1/3 Co 1/3 Mn 1/3 O 2 material coated with Cr 2 O 3 has better electrochemical performance under a high cutoff voltage of 4.5 V. Moreover, at room temperature, the initial discharging capacity of LiNi 1/3 Co 1/3 Mn 1/3 O 2 material coated with 1.0 wt.% Cr 2 O 3 at 0.5C reaches 169 mAh·g 1 and the capacity retention is 83.1% after 30 cycles, while that of the bare LiNi 1/3 Co 1/3 Mn 1/3 O 2 is only 160.8 mAh·g 1 and 72.5%. Finally, the coated samples are found to display the improved electrochemical performance, which is mainly attributed to the suppression of the charge-transfer resistance at the interface between the cathode and the electrolyte. 相似文献
16.
Anwar Ul-Hamid 《Journal of Materials Engineering and Performance》2003,12(1):87-94
A study was conducted to investigate the cyclic oxidation behavior of two oxide dispersion strengthened (ODS) Fe-Cr-Al based
alloys containing 0.17 wt.% and 0.7 wt.% Y2O3. The alloys were oxidized in air for 100 h at 1200°C based on a 24 h cycle period. X-ray diffraction (XRD) and analytical
transmission electron microscopy (TEM) were used to characterize the structure, morphology, and composition of the oxide scales.
Both alloys formed highly adherent and continuous layers of α-Al2O3 exhibiting a morphology indicative of inward scale growth. The role of Y2O3 was to promote adherence by segregating to the grain boundaries within the oxide. Concurrently, Y2O3 generated micro-porosity resulting in a scale of comparatively higher thickness in the alloy with 0.7 wt.% Y2O3. 相似文献
17.
Zhenbang Wei Yong Jiang Limeng Liu Laner Wu Zhenkun Huang 《Journal of Phase Equilibria and Diffusion》2016,37(2):149-154
Phase formation sequence of the yttrium aluminates in the Y2O3-Al2O3-SiC ternary system as temperature increases were investigated via x-ray diffraction (XRD). Results showed that YAM (monoclinic), YAP (perovskite) and YAG (garnet) were the yttrium aluminates presented in the solid-state reacted samples at a fixed Al2O3:SiC ratio of 1:1. Formation of the yttrium aluminates depended on the temperature. The YAM, YAP and YAG started to form below 1150 °C, at 1300 °C, and at 1450 °C, respectively. Accordingly, two behavior phase diagrams of the Y2O3-Al2O3-SiC ternary system were recognized, one is in the temperature range of 1150-1300 °C and the other is in 1300-1450 °C, respectively. Thereafter, the phase equilibrium was reached in the temperature range of 1450-1700 °C. Effects of SiC on the phase formation processes in the ternary system were discussed. 相似文献
18.
Precursor of nanocrystalline Zn0.5Ni0.5Fe2O4 was obtained by grinding mixture of ZnSO4·7H2O,NiSO4·6H2O,FeSO4·7H2O,and Na2CO3·10H2O under the condition of surfactant polyethylene glycol(PEG)-400 being present at room temperature,washing the mixture with water to remove soluble inorganic salts and drying it at 373 K.The spinel Zn0.5Ni0.5Fe2O4 was obtained via calcining precursor above 773 K.The precursor and its calcined products were characterized by differential scanning calorimetry(DSC) ,Fourier transform infrared(FT-IR) ,X-ray diffraction(XRD) ,and vibrating sample magnetometer(VSM) .The result showed that Zn0.5Ni0.5Fe2O4 obtained at 1073 K had a saturation magnetization of 74 A·m2·kg-1.Kinetics of the crystallization process of Zn0.5Ni0.5Fe2O4 was studied using DSC technique,and kinetic parameters were determined by Kissinger equation and Moynihan et al.equation.The value of the activation energy associated with the crystallization process of Zn0.5Ni0.5Fe2O4 is 220.89 kJ·mol-1.The average value of the Avrami exponent,n,is equal to 1.59±0.13,which suggests that crystallization process of Zn0.5Ni0.5Fe2O4 is the random nucleation and growth of nuclei reaction. 相似文献
19.
D. Ghosh S. Mukherjee S. Das S. K. Mitra 《Protection of Metals and Physical Chemistry of Surfaces》2016,52(4):737-743
This paper investigates the effect of yttria (Y2O3) coating on high temperature oxidation behaviour of low alloy 9 Cr–1Mo steel. The superficial coating is Y2O3 was prepared for experimental investigation. The isothermal corrosion study of uncoated and coated specimens was carried out in air oxidation environment at 973 K for 8 h. The corrosion rate and reaction kinetics were studied and the post corroded scales were characterized in SEM, EDS and XRD. The results clearly indicate that Y2O3 coated specimen improves the high temperature oxidation resistance than uncoated specimens. The improvement of oxidation resistance in presence of Y2O3 coating can be attributed to the changed mechanism of scale growth from outer cation migration to inner anion migration and enhancement of scale adhesion with the substrate. Further, enhancement of scale adhesion with the substrate in case of Y2O3 coating also improves the oxidation resistance. The detail mechanism of the oxidation of Y2O3 coated and uncoated specimen is further discussed in this paper. 相似文献
20.
In Sung Kim Soon Jong Jeong Jae Sung Song Pan Seok Shin 《Metals and Materials International》2002,8(6):577-582
The present study describes the dielectric properties of RF sputtered Ta2O5 thin films as a function of the buffer layer and annealing condition. The buffer layers were Ti or TiO2. And the thin film was annealed in various conditions. The X-ray pattern results showed that the phase of the RF sputtered
Ta2O5 thin films was amorphous and this state was kept stable to RTA (rapid thermal annealing) even at 700°C. Measurements of the
electrical and dielectric properties of the reactive sputtered Ta2O5 fabricated in two simple metal insulator semiconductor (MIS) structures, (Cu/Ta2O5/Ti/Si/Cu and Cu/Ta2O5/TiO2/Si/Cu) indicated that the amorphous Ta2O5 grown on Ti possesses a high dielectric constant (30–70) and high leakage current (10−1–10−4 A/cm2), whereas a relatively low dielectric constant (−10) and low leakage current (−10−10 A/cm2) were observed in the amorphous Ta2O5 deposited on the TiO2 buffer layer. In addition, the leakage current mechanisms of the two amorphous Ta2O5 thin films were investigated by plotting the relation of current density (J) vs. applied electric field (E). The Ta2O5/Ti film exhibited three dominant conduction mechanism regimes contributed by the Ohmic emission at low electrical field,
by the Schottky emission at intermediate field and by the Poole-Frenkel emission at high field. In the case of Ta2O5/TiO2 film, the two conduction mechanisms, the Ohmic and Schottky emissions, governed the leakage current density behavior. The
conduction mechanisms at various electric fields applied were related to the diffusion of Ta, Ti and O, followed by the creation
of vacancies, in the rapid thermal treated capacitors. 相似文献