Effect of Y2O3 on Microstructure and Oxidation Behavior of Aluminide Coating on Ni-Based Superalloy

2015 ◽  
Vol 1095 ◽  
pp. 603-607 ◽  
Author(s):  
Yin Qun Hua ◽  
Zhen Rong ◽  
Kang Min Chen ◽  
Yun Xia Ye ◽  
Wen Hui Wu ◽  
...  
Keyword(s):  
Rare Earth ◽  
Oxidation Behavior ◽  
Aluminide Coating ◽  
Rare Earth Oxide ◽  
X Ray Diffraction ◽  
Aluminide Coatings ◽  
Lower Temperature ◽  
Α Al2o3 ◽  
Surface Morphologies ◽  
Kinetics Of

The oxidation behavior of Ni-based superalloy GH586 which is treated by pack-cementation aluminizing was investigated. Scanning electron microscope and X-ray diffraction were used to analyze the microstructure of aluminide coatings and the surface morphologies of the oxide scales. Results show that the main phase of the aluminide coatings was NiAl. The aluminide coating can be formed at lower temperature due to the addition of rare earth oxide in the mixture powders. The thickness of aluminide coating at 900°C was about 110μm, and another aluminide coating with rare earth oxide Y2O3 at 800°C was about 38μm. The oxidation kinetics of aluminized specimens approximately followed a parabolic oxidation law at 1000°C. The morphology of the oxidation scales was primarily θ-Al2O3 with minor α-Al2O3. The scales of the coatings with rare earth oxide Y2O3 after oxidation was more dense.

Effect of Compressive Stress on the High-Temperature Oxidation Behavior of a Fe-20Ni Alloy in Air

2018 ◽  
Vol 921 ◽  
pp. 168-176
Author(s):  
Chang Hai Zhou ◽  
Rui Yun Pan ◽  
Hai Tao Ma
Keyword(s):  
Compressive Stress ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Oxide Scales ◽  
External Scale ◽  
X Ray Diffraction ◽  
Temperature Oxidation ◽  
X Ray ◽  
High Temperature Oxidation Behavior ◽  
Kinetics Of

The oxidation behavior of Fe-20Ni alloy under compressive stress in air was studied at 800, 900 °C. The results examined by using scanning electron microscope (SEM) and X-ray diffraction (XRD) indicates that the oxide scales were consisted of an external scale and a subscale which has an intragranular scale (above 5 h at 800 °C and 900 °C) and an intergranular scale. Compared with the unstressed specimen, the growth kinetics of external scale was accelerated by an applied compressive stress. Besides, the compressive stress induced an increase in the growths of intragranular scale and intergranular scale formed on the specimens oxidized at 900 °C. However, the effect of compressive stress on the growth of intergranular scale and intragranular scale was not obvious in the case of 800°C. In addition, cracks developed in the subscale for the specimens oxidized under 2.5 MPa compressive stress when the oxidation time exceeded 20 h.

A study of barium strontium titanate thin films for use in bypass capacitors

1998 ◽  
Vol 13 (1) ◽  
pp. 197-204 ◽  
Author(s):  
B. A. Baumert ◽  
L-H. Chang ◽  
A. T. Matsuda ◽  
C. J. Tracy ◽  
N. G. Cave ◽  
...  
Keyword(s):  
Thin Films ◽  
Perovskite Phase ◽  
Electrical Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Barium Strontium ◽  
Aluminum Metallization ◽  
On Chip ◽  
Lower Temperature ◽  
Kinetics Of

Physical and electrical characterization techniques have been applied to the problem of developing a lower temperature process for spin-on Ba0.7Sr0.3TiO3 thin films and capacitors compatible with on-chip aluminum metallization. The films were prepared by spin-coating from carboxylate precursors and were processed at temperatures between 650 °C and 450 °C. Capacitors annealed at higher temperatures have a dielectric constant (κ) of 382, a C/A of 20 fF/μm2, and a leakage current density of 2 × 10−7 A/cm2 at 3.3 V. Those processed at 450 °C show occasionally promising but inconsistent results, correlated using TEM images with locally variable crystallization into the perovskite phase. The kinetics of the spin-on solution chemical decomposition and crystallization has been investigated through the use of x-ray diffraction (XRD), thermogravimetric analysis (TGA), and Raman spectroscopy.

Glancing Angle X-Ray Study of Crystallization of Amorphous Ge at the Ge-A1 Interface

1990 ◽  
Vol 202 ◽  
Author(s):  
S. M. Heald ◽  
J. K. D. Jayanetti ◽  
R. C. Budhani
Keyword(s):  
Initial Period ◽  
Time Characteristic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffusion Limited ◽  
Glancing Angle ◽  
Lower Temperature ◽  
Kinetics Of ◽  
Diffusion Limited Reaction ◽  
Good Agreement

ABSTRACTThe amorphous to crystalline transformation of Ge in Al/Ge thin film couples has been studied using glancing angle EXAFS, x-ray reflectivity and diffraction. It was found that crystallization occurs at a much lower temperature (118-150 °C) than for bulk Ge, and initiates at the Al/Ge interface. X-ray diffraction studies were made at 152 °C to study the kinetics of the reaction. After an initial period we find good agreement with a square root dependence of the time, characteristic of a diffusion limited reaction.

Thermal Evolution and Electrical Properties of Rare-Earth Oxide Doped Zirconia

1988 ◽  
Vol 121 ◽  
Author(s):  
B. S. Chiou ◽  
M. Y. Lee ◽  
J. G. Duh
Keyword(s):  
Activation Energy ◽  
Rare Earth ◽  
Ionic Radius ◽  
Thermal Evolution ◽  
Rare Earth Oxide ◽  
Zirconia Ceramics ◽  
Wet Chemical ◽  
Ir Analysis ◽  
Lower Temperature ◽  
The Rare Earth

ABSTRACTSynthesized zirconia ceramics are prepared through the coprecipita-tion process. Application of the wet chemical approach is aimed at the achievement of highly sintered ceramics at lower temperature. The thermal evolution of the synthesized CeO2-ZrO2 powder is investigated with the aid of DTA and TGA measurement. The exothermic peaks on the DTA thermogram are futher identified by the IR analysis. The effect of CeO on the occurrence of the peaks is probed. For other rare-earth oxiae doped ceramics, such as Nd2O3. and Dy2O3. containing zirconia, the bulk and grain boundary resistances are evaluated by the impedance spectroscopy. The dependence of the associated activation energy in the rare-earth oxide doped zirconia is discussed with respect to the variation of the ionic radius of the rare earth constituent.

Oxidation Behavior Research of the SiC/B4C Multiphase Ceramics

2015 ◽  
Vol 727-728 ◽  
pp. 288-291 ◽  
Author(s):  
Yun Long Zhang ◽  
Xiao Gang Song ◽  
Guo Jing Li ◽  
Yu Min Zhang
Keyword(s):  
Rare Earth ◽  
Oxidation Behavior ◽  
Rare Earth Oxide ◽  
Eutectic Phase ◽  
Oxidation Time ◽  
Pressureless Sintering ◽  
Micro Structure ◽  
Phase Constitution ◽  
Sintering Additives ◽  
Multiphase Ceramics

Inthis investigation, the rare-earth oxide Yb2O3 combined with Al2O3served as sintering additives and SiC and B4C powder were applied to fabricate SiC/B4C multiphase ceramics composites by pressureless sintering. The results proved thatcombination of Al2O3 and Yb2O3 sinter additives were effective fordensification of SiC/B4C composites. The influence of oxidation time onthe phase constitution, micro-structure and oxidation behavior of SiC/B4C composites was investigated.Theformation of eutectic phase Yb2Si2O7 phase waswrapped on the SiC surface and it reduced further oxidation of SiC particles.The oxidation kineticcurves followed a parabolic rule.

Effect of Ceria Additive on Microstructure and Properties of Laser-Cladded Bioceramic Coating

2010 ◽  
Vol 434-435 ◽  
pp. 586-589
Author(s):  
Min Zheng ◽  
Ding Fan ◽  
Jian Bin Zhang ◽  
Xiu Kun Li
Keyword(s):  
Corrosion Resistance ◽  
Rare Earth ◽  
Calcium Phosphate ◽  
Rare Earth Oxide ◽  
Resistance Testing ◽  
X Ray Diffraction ◽  
Microstructure And Properties ◽  
Transverse Flow Co2 Laser ◽  
Precursor Powders

The calcium phosphate bioceramic coating was fabricated on titanium alloy (Ti-6Al-4V) substrate by a 5kW continuous transverse flow CO2 laser. Due to the peculiar role of rare earth oxide in laser cladding, the effect of ceria additive on the microstructure and properties of laser-cladded bioceramic coating was investigated by means of scanning electron microscope (SEM), X-ray diffraction (XRD), microhardness and corrosion resistance testing. The results indicate that the appearance of rare earth oxide ceria in the precursor powders has an impact on the microstructure and properties of the laser-cladded bioceramic coating. Calcium phosphate bioceramic such as hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) are synthesized on the top surface of laser-cladded specimens. And the addition of rare earth oxide ceria in pre-placed powders has an influence on the formation of calcium phosphate bioceramic phases. Furthermore, it reveals that the laser-cladded bioceramic coating of ceria additive in pre-placed powders has more favorable microhardness and corrosion resistance compared with the coating without rare earth oxide.

Structural analysis of excess-anion C-type rare earth oxide: a case study with Gd1−xCexO1.5+x/2(x= 0.20 and 0.40)

2003 ◽  
Vol 36 (4) ◽  
pp. 1082-1084 ◽  
Author(s):  
V. Grover ◽  
S. N. Achary ◽  
A. K. Tyagi
Keyword(s):  
Rare Earth ◽  
Structural Analysis ◽  
Metal Ion ◽  
Rare Earth Oxide ◽  
Charge Balance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Lattice Space

Structural analysis of anion-rich C-type Gd2O3was carried by the Rietveld refinement of the powder X-ray diffraction data for compositions Gd0.8Ce0.2O1.60and Gd0.6Ce0.4O1.70. Both compounds have a body-centred cubic lattice (space groupIa\bar{3}, No. 206,Z= 32) with unit-cell parameters of 10.8488 (1) and 10.8542 (1) Å, respectively. Both of these compounds are iso-structural with the C-type rare earth oxides, with excess anions as required for charge balance. The structural analysis reveals that there are two different kinds of metal ion site, namely 8b(M1) and 24d(M2), and two different kinds of anion sites, namely 48e(O1) and 16c(O2). The excess anions occupy the 16c(xxx) sites. The two metal ions each form an approximately eightfold-coordination polyhedron with O1 and O2. The details of these two compositions are explained and compared with both the CeO2structure and the Gd2O3structure,i.e.the end member.

Reaction Process of Al-TiO2-C-Ti-Fe Multiphase System during Combustion Synthesis

2007 ◽  
Vol 336-338 ◽  
pp. 2340-2343 ◽  
Author(s):  
Song He Meng ◽  
Xing Hong Zhang ◽  
Wei Feng Zhang
Keyword(s):  
Intermetallic Compounds ◽  
Xrd Analysis ◽  
Reaction Process ◽  
Multiphase System ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Reaction Characteristics ◽  
Lower Temperature ◽  
Kinetics Of

The reaction process and kinetics of Al-TiO2-C-Ti-Fe system were investigated by differential scanning calorimetry (DSC) analysis, X-ray diffraction (XRD) analysis and scanning electron microscope (SEM). In order to obtain the information of reaction process for complicated system, the reaction characteristics of Al-TiO2, Al-TiO2-C and Al-TiO2-C-Ti systems are explored firstly. The results show that the reaction process varies with temperature in Al-TiO2-C-Ti-Fe system. At the lower temperature, the dominating reaction in Al-TiO2-C-Ti-Fe system is that between Al and Ti, Al and Fe, and so TiAlx, FeAlx, and Ti2Fe intermetallic compounds form. With the temperature increasing, the intermetallic compounds are decomposed. Then the decomposed Ti and Al react with C and TiO2 respectively and the stable TiC, Al2O3 and Fe three phases form in the final product.

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