Kinetics of the oxidation of Ba2 YCu3Ox ceramics

1988 ◽  
Vol 3 (4) ◽  
pp. 619-625 ◽  
Author(s):  
H. M. O'Bryan ◽  
P. K. Gallagher
Keyword(s):  
High Temperature ◽  
Oxide Layer ◽  
Large Volume ◽  
Linear Relation ◽  
Oxygen Stoichiometry ◽  
Gravimetric Analysis ◽  
X Ray ◽  
Kinetics Of ◽  
Volume Decrease

The kinetics of the oxidation of dense and porous samples of Ba2 YCu3Ox ceramic have been determined by gravimetric analysis at 400–700 °C. At 600 °C and above, the rate decreases as the thickness of the oxidized layer increases. At 500 °C and below, the kinetics show a linear relation that indicates that the oxidized layer does not protect the ceramic. Dilatometric, microscopic, and high-temperature x-ray data suggest that fractures in the oxide layer at the lower temperatures are caused by the large volume decrease that accompanies the change in oxygen stoichiometry.

scholarly journals High-Temperature Oxidation Properties and Microstructural Evolution of Nanostructure Fe-Cr-Al ODS Alloys

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 526
Author(s):  
Zhengyuan Li ◽  
Lijia Chen ◽  
Haoyu Zhang ◽  
Siyu Liu
Keyword(s):  
High Temperature ◽  
Oxide Layer ◽  
Microstructural Evolution ◽  
High Temperature Oxidation ◽  
Oxide Dispersion Strengthened ◽  
Al Alloy ◽  
Temperature Oxidation ◽  
X Ray ◽  
Plasma Sintering ◽  
Ods Alloys

The oxidation behavior and microstructural evolution of the nanostructure of Fe-Cr-Al oxide dispersion strengthened (ODS) alloys prepared by spark plasma sintering were investigated by high-temperature oxidation experiments in air at 1200 °C for 100 h. The formation of Al2O3 scale was observed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) line scans. The oxidation rate of Fe-Cr-Al ODS alloys is lower than that of conventional Fe-Cr-Al alloys, and the oxide layer formed on the Fe-Cr-Al alloy appeared loose and cracked, whereas the oxide layer formed on the Fe-Cr-Al ODS alloys was adherent and flat. This is due to the high density of dispersed nano-oxides hindering the diffusion of Al element and the formation of vacancies caused by them. In addition, the nano-oxides could also adhere to the oxide layer. Besides, the microstructure of the Fe-Cr-Al ODS alloy had excellent stability during high-temperature oxidation.

In situ high temperature X-ray diffraction study of the kinetics of phase separation in the uranium-plutonium mixed oxide (U0.55Pu0.45)O2-x

2014 ◽  
Vol 1645 ◽  
Author(s):  
Romain VAUCHY ◽  
Renaud.C. BELIN ◽  
Anne-Charlotte ROBISSON ◽  
Fiqiri HODAJ
Keyword(s):  
Phase Separation ◽  
Room Temperature ◽  
Mixed Oxides ◽  
Oxygen Stoichiometry ◽  
X Ray Diffraction ◽  
Fundamental Interest ◽  
X Ray ◽  
Uranium Plutonium ◽  
Kinetics Of

ABSTRACTUranium-plutonium mixed oxides incorporating high amounts of plutonium are considered for future nuclear reactors. For plutonium content higher than 20%, a phase separation occurs, depending on the temperature and on the oxygen stoichiometry. This phase separation phenomenon is still not precisely described, especially at high plutonium content. Here, using an original in situ fast X-ray diffraction device dedicated to radioactive materials, we evidenced a phase separation occurring during rapid cooling from 1773 K to room temperature at the rate of 0.05 and 2 K per second for a (U0.55Pu0.45)O2-x compound under a reducing atmosphere. The results show that the cooling rate does not impact the lattice parameters of the obtained phases at room temperature but their fraction. In addition to their obvious fundamental interest, these results are of utmost importance in the prospect of using uranium-plutonium mixed oxides with high plutonium content as nuclear fuels.

High Temperature X-ray Diffraction Study of the Oxidation Products and Kinetics of Uranium–Plutonium Mixed Oxides

2014 ◽  
Vol 53 (24) ◽  
pp. 12757-12766 ◽  
Author(s):  
Michal Strach ◽  
Renaud C. Belin ◽  
Jean-Christophe Richaud ◽  
Jacques Rogez
Keyword(s):  
High Temperature ◽  
Diffraction Study ◽  
Mixed Oxides ◽  
Oxidation Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
Uranium Plutonium ◽  
Kinetics Of

Synthesis of Novel Carbon Spheres and Study on Graphitization Process

2013 ◽  
Vol 634-638 ◽  
pp. 2293-2296
Author(s):  
Ai Li Ma ◽  
Cheng Qian Li ◽  
Wu Qing Du ◽  
Jie Chang
Keyword(s):  
High Temperature ◽  
Microwave Plasma ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Carbon Spheres ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cvd Method ◽  
Graphitization Degree ◽  
Scanning Electron

In this paper, carbon spheres were synthesized by CVD method. These carbon spheres exhibit diameters of about 200 nm. Thermal gravimetric analysis indicated the good stability in high temperature of the carbon spheres. The products were treated by microwave plasma and high temperature vacuum heat treatments respectively. The products were characterized by X-ray diffraction, Raman spectroscopy and Field Emission Scanning Electron Microscope. The study indicated that the original products, with perfect morphology and low graphitization degree, were converted to crystal. The different techniques were considered for the influence on the graphitization degree.

scholarly journals Effect of kerosene combustion atmosphere on the mild steel oxide layer

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Dongbai Xie ◽  
Hao Hong ◽  
Shuwang Duo ◽  
Qiang Li
Keyword(s):  
High Temperature ◽  
Metal Oxide ◽  
Mild Steel ◽  
Oxide Layer ◽  
Oxidation Products ◽  
Metallic Material ◽  
X Ray ◽  
Combustion Atmosphere ◽  
Fire Scene ◽  
In Fire

AbstractIn arson cases, accelerants were usually used by criminals to achieve the purpose of rapid arson. Therefore, fire investigators aim to determine whether accelerants was used in the fire scene. Metallic material has to react with corrosive gas around it at high temperature and the oxidation products may store the information of reactants. Accelerants present in fire scenes impart some oxidative characteristics on metallic materials. The aim of this work is to figure out the possibility to identify the presence of accelerant in a fire according to the oxidation patterns of metallic material. This paper researched the oxidation behavior of mild steel at high temperature in a simulated flame environment. The surface morphological and cross-sectional microstructural features of the samples were characterized by X-ray diffractions, X-ray photoelectron spectroscopy and scanning electron microscopy with energy-dispersive spectroscopy analysis after oxidation. The carbon in the combustion atmosphere had a carburizing effect on the metal oxide layer. It was mostly C–C, C–O and C=O of organic matter could be used as in fire investigation. Various oxidizing atmosphere composite systems promote the formation of metal oxide layers. And bidirectional oxidation mode in the oxide layer further accelerates the oxidation rate. The (wustite) FeO phase was not found in the oxide layer because of the strong oxidation of the combustion atmosphere. These results offer complementary information in fire characteristics, which combining the characterization of surface scale with traditional chemical analysis of recovering ignitable liquid residues from fire debris are expected to offer crucial information for determining the presence of combustion accelerants at a fire scene.

Evaluation on Microstructure Stability and Thermal Resistant Ability at High Temperature of Ternary-Blended Geopolymer

2021 ◽  
Vol 321 ◽  
pp. 73-79
Author(s):  
Hoc Thang Nguyen
Keyword(s):  
High Temperature ◽  
Rice Husk Ash ◽  
High Thermal Stability ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microstructure Stability ◽  
Before And After ◽  
Materials Used

Stability of microstructure and heat resistant ability at high temperature is one of the important properties in ceramics or silicate materials which are normally exposed with fire such as refractories and insulation or other materials used in furnaces. This study used a ternary-blended geopolymer which was synthesized from an optimized mixture of red mud (RM), rice husk ash (RHA), diatomaceous earth (DE), and water glass solution (WGS) with silica modulus of 2.5. The geopolymer samples were tested thermal properties of heat resistance (%), volumetric shrinkage (%), mass loss (%) at 1000°C to evaluate thermal resistant ability. Changes of microstructure of the ternary-blended geopolymer samples were also characterized before and after exposed at high temperature using methods of X-ray diffraction (XRD), Thermogravimetric analysis or thermal gravimetric analysis (DTA-TGA), and Scanning electron microscope (SEM). The experimental results showed the ternary-blended geopolymer has high thermal stability and unchanged microstructure even at high temperatures. Hence, the geopolymer in this study is suggested to apply as an insolation with the upper limit of temperature to work at 1000°C.

Sign in / Sign up

Export Citation Format

Share Document