Hypersonic Plasma Setup for Oxidation Testing of Ultrahigh Temperature Ceramic Composites

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Cristian Cley Paterniani Rita ◽  
Felipe de Souza Miranda ◽  
Felipe Rocha Caliari ◽  
Rosa Rocha ◽  
Alexei Essiptchouk ◽  
...  
Keyword(s):  
Thermal Flux ◽  
Protective Layer ◽  
Ceramic Composites ◽  
Vacuum System ◽  
Mechanical Resistance ◽  
Thermal Flow ◽  
Ultrahigh Temperature ◽  
Loss Of Mass ◽  
Oxidation Testing ◽  
Oxidation Mechanisms

Abstract In this study, a hypersonic plasma setup was constructed based on a vortex plasma heater with prenozzle gas-dynamic insertion. The prenozzle allows the improvement of the characteristics of the vacuum system according to the necessities of the experiments. The plasma setup produces a hypersonic thermal flow, which is capable to test the thermal oxidation of ultrahigh temperature ceramics (UHTC) composites, such as zirconium diboride (ZrB2). Thereby, ZrB2 samples were prepared with a variation of 10, 20, and 30% of silicon carbide (SiC) in volume, in order to investigate the oxidation mechanisms and microstructural properties of the samples tested under hypersonic thermal flow. The results of the oxidation tests showed that the samples with 10 and 30% of SiC undergo to the active oxidation and forms an unstable and fragile ZrO2 oxide. The formed ZrO2 does not withstand the drag force and the thermal flux of the hypersonic plasma jet, partially volatilizing the oxide layer, causing an accentuated loss of mass. For the oxidation tests of the sample with 20% of SiC, the gain of mass was observed due to the formation of ZrSiO4 passivation layer, which is a stable oxide and promotes mechanical resistance, and low degradation rate. These results can be associated with the variation of SiC, which demonstrates an ideal proportion of 20% of SiC in ZrB2, which influences the oxidation mechanisms and produce a protective layer.

A Perspective on Modeling Materials in Extreme Environments: Oxidation of Ultrahigh-Temperature Ceramics

MRS Bulletin ◽  
2006 ◽  
Vol 31 (5) ◽  
pp. 410-418 ◽  
Author(s):  
Angelo Bongiorno ◽  
Clemens J. Först ◽  
Rajiv K. Kalia ◽  
Ju Li ◽  
Jochen Marschall ◽  
...  
Keyword(s):  
Modeling And Simulation ◽  
Atomistic Simulation ◽  
Extreme Environments ◽  
Protective Layer ◽  
Ceramic Composites ◽  
Atomistic Modeling ◽  
Temperature Oxidation ◽  
Simulation Techniques ◽  
Oxidation Resistant ◽  
Ultrahigh Temperature

AbstractThe broader context of this discussion, based on a workshop where materials technologists and computational scientists engaged in a dialogue, is an awareness that modeling and simulation techniques and computational capabilities may have matured sufficiently to provide heretofore unavailable insights into the complex microstructural evolution of materials in extreme environments.As an example, this article examines the study of ultrahigh-temperature oxidation-resistant ceramics, through the combination of atomistic simulation and selected experiments.We describe a strategy to investigate oxygen transport through a multi-oxide scale—the protective layer of ultrahigh-temperature ceramic composites ZrB2-SiC and HfB2-SiC—by combining first-principles and atomistic modeling and simulation with selected experiments.

Oxidation of ZrB2-SiC Ultrahigh-Temperature Ceramic Composites in Dissociated Air

2009 ◽  
Vol 23 (2) ◽  
pp. 267-278 ◽  
Author(s):  
Jochen Marschall ◽  
Dusan A. Pejakovic ◽  
William G. Fahrenholtz ◽  
Greg E. Hilmas ◽  
Sumin Zhu ◽  
...  
Keyword(s):  
Ceramic Composites ◽  
Ultrahigh Temperature ◽  
Dissociated Air

Catalytic Atom Recombination on ZrB2/SiC and HfB2/SiC Ultrahigh-Temperature Ceramic Composites

2004 ◽  
Vol 41 (4) ◽  
pp. 576-581 ◽  
Author(s):  
Jochen Marschall ◽  
Adam Chamberlain ◽  
Daniel Crunkleton ◽  
Bridget Rogers
Keyword(s):  
Ceramic Composites ◽  
Ultrahigh Temperature

Catalytic and Radiative Behaviors of ZrB2-SiC Ultrahigh Temperature Ceramic Composites

2006 ◽  
Vol 43 (5) ◽  
pp. 1004-1012 ◽  
Author(s):  
Luigi Scatteia ◽  
Raffaele Borrelli ◽  
Giovanni Cosentino ◽  
Eric Beche ◽  
Jean-Louis Sans ◽  
...  
Keyword(s):  
Ceramic Composites ◽  
Ultrahigh Temperature

scholarly journals Valuation of the Durability of the Concrete Used in the Precast Great Soviet Panel System

2020 ◽  
Vol 29 (54) ◽  
pp. e10486
Author(s):  
Yamila Concepción Socarrás-Cordoví ◽  
Liliana González-Díaz ◽  
Eduardo Álvarez-Deulofeu ◽  
Mayra González-Fernández ◽  
Estrella Roca-Fernández ◽  
...  
Keyword(s):  
Statistical Methods ◽  
Seismic Behavior ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Mechanical Resistance ◽  
Reinforcing Steel ◽  
Velocity Surface ◽  
Loss Of Mass ◽  
Durability Of Concrete

The durability of the concrete of the precast Great Soviet Panel system is valued through the resistance to compression, ultrasonic pulse velocity, surface methods, humidity and potential of corrosion. The evaluation is approached, essentially, through experimental and statistical methods, nevertheless, historical-logical and technical methods, such as surveys and interviews, are used in order to gather a bigger amount of information on the resistance to compression of the elements in the original project. While analyzing the results, we can conclude that, in elements in a good technical-constructive state that conform the constructions in exploitation, concrete has an average resistance. However, in elements with the presence of pathological damages, the resistance is low due to the fact that elements show chemical deterioration processes caused by water exposure, which generates the formation of soluble paste compounds, loss of mass, and decrease in mechanical resistance, among other alterations. At the same time, carbonation of concrete is triggered, which, in turn, causes the corrosion of the reinforcing steel. This corrosion leads to the cracking of concrete, delamination of steel, decrease of the concrete-steel adhesion, and other manifestations that affect the durability of concrete. Therefore, the incidence of the durability of concrete should be valued in the structural seismic behavior of constructions.

Mechanical Resistance Improvement of Oxidized Metallic Hollow Spheres Stacking

2011 ◽  
Vol 62 ◽  
pp. 117-123
Author(s):  
Cecile Davoine ◽  
Sebastien Mercier ◽  
F. Popoff ◽  
A. Götzfried
Keyword(s):  
Hollow Spheres ◽  
Relative Weight ◽  
Small Samples ◽  
Mechanical Resistance ◽  
Compression Tests ◽  
Mechanical Stiffness ◽  
Significant Deterioration ◽  
Static Compression ◽  
Oxidation Mechanisms ◽  
Quasi Static Compression

The oxidation of stainless steel hollow spheres stacking has been studied at 800, 900 and 1,000°C in laboratory air in the range of 200h. The experimental results based on the relative weight gain of oxidized samples revealed an effect of the sphere’s size over the kinetic of oxidation: the quicker oxidation of the material constitued by smallest spheres suggests that the ratio of exposed surface is preponderant in the oxidation mechanisms. A quasi total transformation of the metal into oxides has been observed after 100h at 1000°C. Some simple quasi-static compression tests highlighted a significant deterioration in mechanical resistance for samples oxidized for 100h at 900 and 1,000°C. The global collapse of the oxidized samples could be imputed to the presence of oxides into the shells porosities by implying a decrease of their ductility. In order to improve the mechanical resistance of oxidized hollow spheres stacking, the adding of a dense metallic undercoat is proposed. The concept is tested by producing small samples of nickel-based hollow spheres stacking. The observation of oxidized samples shows that the shell of hollow spheres are not totally oxidized, providing a continuous metallic squeletton beneficial for mechanical stiffness at high temperatures.

scholarly journals Heat and mechanical resistance of zinc coating

2010 ◽  
Vol 58 (4) ◽  
pp. 49-56 ◽  
Author(s):  
Karel Horák ◽  
Michal Černý ◽  
Josef Filípek ◽  
Martin Fajman
Keyword(s):  
Cross Sections ◽  
Zinc Coating ◽  
Protective Layer ◽  
Intermetallic Phases ◽  
Effect Of Temperature ◽  
Heating Process ◽  
Mechanical Resistance ◽  
Accelerated Corrosion ◽  
Accelerated Corrosion Tests ◽  
Bend Tests

The article is aimed at studying the effect of temperature on structure of intermetallic phases of the protective zinc layer. The main objective of the article is a description of the structure and the changes that can occur during the heating process. The first part of the article deals with the description of the structure and mechanical properties of the interfacial phases and their arrangement. The main part of the article is aimed at study of brittle intermetallic phases, which arise due to increased temperature. For this reason, a set of samples of steel CSN 11 321 (DC01) was prepared. These samples were subjected to thermal heating in the tempering furnace. Subsequently metallographic cross sections were prepared, observed and assessed using SEM microscopy and EDS analysis. Also accelerated corrosion tests and pull off bend tests were performed. Conclusion of the article is trying to explain the influence of intermetallic phases on degradation of the protective layer.

Evaluation of Spheroidization on Erosive Wear of ASTM A106 Steel Used in Heat Exchangers

2018 ◽  
Vol 930 ◽  
pp. 416-421
Author(s):  
M.R. da Rocha ◽  
A.B.C. Arnt ◽  
Elidio Angioletto ◽  
H.A. Virgínia ◽  
G.B. Ugioni ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Heat Exchangers ◽  
Power Plants ◽  
Erosive Wear ◽  
Mechanical Resistance ◽  
Gradual Reduction ◽  
Wear Process ◽  
The Matrix ◽  
Loss Of Mass ◽  
Wear Tests

One of the problems encountered in heat exchangers working at high temperatures is the degradation caused by erosive processes, especially in coal-fired power plants. One of the factors that contribute to the degradation of the material is the microstructural changes, like the spheroidization of the carbides. This reduces the mechanical strength of the material and consequently accelerates its wear process. The objective of this work was to evaluate the effect of spheroidization under erosive wear conditions on ASTM A106 steel. The samples were submitted to different treatment times and temperatures, aiming to generate spheroidization in the samples, later submitted to erosive wear tests. Loss of mass, microstructures and mechanical strength were evaluated from the microhardness, with the evolution of the spheroidization process. The samples with higher level of spheroidization, obtained in the temperatures of 730 ° C in times above 50 hours presented greater reduction of hardness that resulted in greater losses of mass. In general, with the increase of spheroidization, there is reduction of mechanical resistance and erosive erosion, but with a gradual reduction in wear rate. This is possibly due to the increased ductility / toughness of the matrix, which delays the process of debris formation on the ASTM A106 steel surface during the hot erosive process.

Thermo-mechanical simulation of ultrahigh temperature ceramic composites as alternative materials for gas turbine stator blades

2021 ◽  
Vol 47 (1) ◽  
pp. 567-580 ◽  
Author(s):  
Kourosh Vaferi ◽  
Mohammad Vajdi ◽  
Sanam Nekahi ◽  
Sahar Nekahi ◽  
Farhad Sadegh Moghanlou ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Ceramic Composites ◽  
Mechanical Simulation ◽  
Turbine Stator ◽  
Alternative Materials ◽  
Ultrahigh Temperature
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