scholarly journals Investigation of a best oxidation model and thermal margin analysis at high temperature under design extension conditions using SPACE

2020 ◽  
Vol 52 (4) ◽  
pp. 742-754
Author(s):  
Dongkyu Lee ◽  
Hee Cheon No ◽  
Bokyung Kim
Keyword(s):  
High Temperature ◽  
Oxidation Model ◽  
Margin Analysis

Further Understanding on Deformation-Oxidation Model in Stress Corrosion Cracking Tip Based on Meso-Scale Mechanical Field

2011 ◽  
Author(s):  
He Xue ◽  
Zhijun Li ◽  
Xiaofeng Xue ◽  
Zhanpeng Lu ◽  
Tetsuo Shoji
Keyword(s):  
Growth Rate ◽  
Stainless Steel ◽  
High Temperature ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Pressure Vessels ◽  
Corrosion Cracking ◽  
Quantitative Prediction ◽  
Oxidation Model ◽  
Meso Scale

Stress corrosion cracking (SCC) is a common failure in stainless steel and nickel based alloys in high-temperature oxygenated aqueous systems. Because the propagating mode and morphology is particular at the SCC tip, it is necessary to investigate and understand in detail the mechanical state close to the SCC tip for improving the prediction accuracy of SCC growth rate in stainless steel and nickel based alloys in the nuclear pressure vessels and piping. By using a sub-model technique in commercial finite element analysis code, the meso-scale stress and strain field in the SCC tip constituted by the oxide film and base metal is simulated and analyzed in this study. And reasonable and operational mechanical parameters in the prediction method of SCC growth rate based on the slip-oxidation model are also discussed. The results of the investigation provide a new insight into the quantitative prediction of SCC growth rate in nuclear structural materials in high temperature water environments.

Influence of Reinforcing Phase on the Oxidation Model of ZrB2 Based Multi-Phase Ceramics

2014 ◽  
Vol 633 ◽  
pp. 189-192
Author(s):  
Jie Guang Song ◽  
Fang Wang ◽  
Xiu Qin Wang ◽  
Shi Bin Li ◽  
Gang Chang Ji
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
Weight Change ◽  
Oxidation Mechanism ◽  
High Density ◽  
Change Rate ◽  
Protection Layer ◽  
Oxidation Model ◽  
Multi Phase

ZrB2, YAG and Al2O3 are widely applied because of some excellent performances, but ZrB2 is easily oxidized in the high-temperature air. To make the ZrB2 ceramics obtain better oxidation resistance, high-density ZrB2-YAG-Al2O3 ceramics were prepared. The oxidation mechanism of ZrB2-YAG-Al2O3 ceramics is investigated. When YAG-ZrB2 ceramics are exposed to air at temperatures from 1100°C¡æ to 1600°C¡æ, the weight change rate of YAG-ZrB2 ceramics is fleetly increased, the reacted speed of ZrB2 and O to form B2O3 and ZrO2 is more faster. The quantity of melted B2O3 is increased and carried to the surface, B2O3 is reacted with Al2O3 to form Al18B4O33. Al18B4O33 is melted and coated on the surface of ceramics to form protection layer for the oxidation resistance of ceramics at high temperature, which shows the similar with the influence of reinforcing phase on the oxidation model of ZrB2 based multi-phase ceramics.

scholarly journals Air Ingress Analyses on a High Temperature Gas-Cooled Reactor

2001 ◽  
Author(s):  
Chang H. Oh ◽  
Richard L. Moore ◽  
Brad J. Merrill ◽  
David A. Petti
Keyword(s):  
High Temperature ◽  
Development Effort ◽  
Component Level ◽  
Pebble Bed ◽  
The Core ◽  
Graphite Oxidation ◽  
Loss Of Coolant Accident ◽  
Oxidation Model ◽  
Air Ingress ◽  
High Temperature Gas

Abstract A loss-of-coolant accident is one of the design-basis accidents for a high-temperature gas-cooled reactor (HTGR). Following the depressurization of helium in the core, if the accident is not mitigated, there exists the potential for air to enter the core through the break and oxidize the in-core graphite structure in the modular pebble bed reactor (MPBR). This paper presents the results of the graphite oxidation model developed as part of the Idaho National Engineering and Environmental Laboratory’s Directed Research and Development effort. Although gas reactors have been developed in the past with limited success, the innovations of modularity and integrated state-of-art control systems coupled with improved fuel design and a pebble bed core make this design potentially very attractive from an economic and technical perspective. A schematic diagram of a reference design of the MPBR has been established at a major component level (INEEL & MIT, 1999). Steady-state and transient thermal hydraulics models will be produced with key parameters established for these conditions for all major components. Development of an integrated plant model to allow for transient analysis on a more sophisticated level is now being developed. In this paper, preliminary results of the hypothetical air ingress are presented. A graphite oxidation model was developed to determine temperature and the control mechanism in the spherical graphite geometry.

Influence of Thermo-Mechanical Processing on the Microstructure of Beryllia Dispersed Nickel Alloys

1973 ◽  
Vol 31 ◽  
pp. 184-185
Author(s):  
M.S. Grewal ◽  
S.A. Sastri ◽  
N.J. Grant
Keyword(s):  
High Temperature ◽  
Nickel Alloys ◽  
Thermomechanical Processing ◽  
Cold Work ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Mechanical Processing ◽  
Uniform Dispersion ◽  
Oxide Particles ◽  
Nickel Base

Currently there is a great interest in developing nickel base alloys with fine and uniform dispersion of stable oxide particles, for high temperature applications. It is well known that the high temperature strength and stability of an oxide dispersed alloy can be greatly improved by appropriate thermomechanical processing, but the mechanism of this strengthening effect is not well understood. This investigation was undertaken to study the dislocation substructures formed in beryllia dispersed nickel alloys as a function of cold work both with and without intermediate anneals. Two alloys, one Ni-lv/oBeo and other Ni-4.5Mo-30Co-2v/oBeo were investigated. The influence of the substructures produced by Thermo-Mechanical Processing (TMP) on the high temperature creep properties of these alloys was also evaluated.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

Effect of Improved ThO2 Particle Dispersion in Nickel on High-Temperature Strength

1970 ◽  
Vol 28 ◽  
pp. 444-445
Author(s):  
E. R. Kimmel ◽  
H. L. Anthony ◽  
W. Scheithauer
Keyword(s):  
High Temperature ◽  
Metal Matrix ◽  
Oxide Particle ◽  
Oxide Phase ◽  
Dislocation Motion ◽  
Particle Dispersion ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Oxide Particles ◽  
The Stability

The strengthening effect at high temperature produced by a dispersed oxide phase in a metal matrix is seemingly dependent on at least two major contributors: oxide particle size and spatial distribution, and stability of the worked microstructure. These two are strongly interrelated. The stability of the microstructure is produced by polygonization of the worked structure forming low angle cell boundaries which become anchored by the dispersed oxide particles. The effect of the particles on strength is therefore twofold, in that they stabilize the worked microstructure and also hinder dislocation motion during loading.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

Albumins as Embedding Media for Electron Microscopy

1969 ◽  
Vol 27 ◽  
pp. 422-423 ◽  
Author(s):  
J. L. Farrant ◽  
J. D. McLean
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Temperature ◽  
Biological Material ◽  
Globular Proteins ◽  
The Past ◽  
Antibody Staining ◽  
Thin Sectioning ◽  
Embedding Medium

For electron microscope techniques such as ferritin-labeled antibody staining it would be advantageous to have available a simple means of thin sectioning biological material without subjecting it to lipid solvents, impregnation with plastic monomers and their subsequent polymerization. With this aim in view we have re-examined the use of protein as an embedding medium. Gelatin which has been used in the past is not very satisfactory both because of its fibrous nature and the high temperature necessary to keep its solutions fluid. We have found that globular proteins such as the serum and egg albumins can be cross-linked so as to yield blocks which are suitable for ultrathin sectioning.

An Environmental Wet Cell For High Voltage Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 18-19
Author(s):  
N.J. Tighe ◽  
H.M. Flower ◽  
P.R. Swann
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Image Quality ◽  
Inelastic Scattering ◽  
High Voltage ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Environmental Cell ◽  
Water Saturated ◽  
High Temperature Gas

A differentially pumped environmental cell has been developed for use in the AEI EM7 million volt microscope. In the initial version the column of gas traversed by the beam was 5.5mm. This permited inclusion of a tilting hot stage in the cell for investigating high temperature gas-specimen reactions. In order to examine specimens in the wet state it was found that a pressure of approximately 400 torr of water saturated helium was needed around the specimen to prevent dehydration. Inelastic scattering by the water resulted in a sharp loss of image quality. Therefore a modified cell with an ‘airgap’ of only 1.5mm has been constructed. The shorter electron path through the gas permits examination of specimens at the necessary pressure of moist helium; the specimen can still be tilted about the side entry rod axis by ±7°C to obtain stereopairs.

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