Evaluation of elastic properties of reduced NiO-8YSZ anode-supported bi-layer SOFC structures at elevated temperatures in ambient air and reducing environments

The present study is focussed on the oxidation behavior of nonoxide silicon-based ceramics. Various Si3N4 and SiC ceramics were examined after long term oxidation tests (up to 5000 h) at 1500°C in ambient air. The damage mechanisms were discussed on the basis of a comprehensive chemical and microstructural analysis of the materials after the oxidation tests. The diffusion of oxygen into the material and its further reaction in the bulk of the material were found to be the most critical factors during long term oxidation treatment at elevated temperatures. However, the resulting damage in the microstructure of the materials can be significantly reduced by purposeful microstructural engineering. Using Si3N4/SiC and Si3N4/MoSi2 composite materials provides the possibility to improve the high temperature stability. [S0742-4795(00)00301-X]

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Studies on mechanical behavior of LSFT-CGO dual-phase membranes at elevated temperatures in ambient air and slightly reducing environments

Ceramics International ◽

10.1016/j.ceramint.2013.12.121 ◽

2014 ◽

Vol 40 (6) ◽

pp. 7783-7790 ◽

Cited By ~ 4

Author(s):

Thangamani Nithyanantham ◽

Somnath Biswas ◽

Nagabhushana Nagendra ◽

Sukumar Bandopadhyay

Keyword(s):

Mechanical Behavior ◽

Elevated Temperatures ◽

Ambient Air ◽

Dual Phase

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Elastic properties of a crossply SiC f /Ti composite at elevated temperatures

Metallurgical and Materials Transactions A ◽

10.1007/s11661-001-0274-8 ◽

2001 ◽

Vol 32 (2) ◽

pp. 425-429 ◽

Cited By ~ 3

Author(s):

Hirotsugu Ogi ◽

Goh Shimoike ◽

Masahiko Hirao ◽

Hassel Ledbetter ◽

Kazuki Takashima

Keyword(s):

Elastic Properties ◽

Elevated Temperatures

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Tribological behaviour of low-pressure plasma sprayed WC-Co coatings at elevated temperatures

Industrial Lubrication and Tribology ◽

10.1108/ilt-05-2018-0194 ◽

2019 ◽

Vol 71 (2) ◽

pp. 258-266

Author(s):

Zhe Geng ◽

Huadong Huang ◽

Baoshan Lu ◽

Shaohua Wu ◽

Gaolian Shi

Keyword(s):

Wear Resistance ◽

Elevated Temperatures ◽

High Hardness ◽

Cobalt Content ◽

Ambient Air ◽

Low Pressure ◽

Tribological Behaviour ◽

Content Type ◽

Pressure Plasma ◽

Low Pressure Plasma

Purpose This paper aims to investigate the effect of coating microstructure, mechanical and oxidation property on the tribological behaviour of low-pressure plasma spraying (LPPS) tungsten carbide/cobalt (WC-Co) coatings. Design/methodology/approach WC-12Co and WC-17Co coatings were deposited via the LPPS spraying method. Tribological tests on the coatings were performed using a high-temperature ball-on-disc tribometer at temperatures from room temperature (RT, approximately 25 °C) up to 800 °C in ambient air. Findings WC-12Co coating contained brittle phases, pores and microcracks, which led to the low hardness, and finally promoted the splat delamination and the carbide debonding during wear. WC-17Co coating had higher cobalt content which benefited the coating to contain more WC particles, less brittle phases, pores and nearly no microcracks, and resulted in the high hardness and better wear resistance. Higher cobalt content also decelerated the oxidation rate of the coating and promoted the formation of cobalt oxides and CoWO4, which were able to maintain the load-bearing capacity and improve the tribological behaviour of the coating below 650°C. Above 650°C, the increase of oxidation degree and the decrease of mechanical property deteriorated the wear resistance of coatings. Originality/value The LPPS WC-Co coating with higher cobalt content had better tribological properties at different temperatures. The LPPS WC-Co coatings should not be used as wear-resistant coatings above 650 °C.

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On the permeability of transparent screens of extreme tenuity by radiant heat

Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London ◽

10.1098/rspl.1815.0319 ◽

1833 ◽

Vol 2 ◽

pp. 310-311

Keyword(s):

Thin Film ◽

Elevated Temperatures ◽

Ambient Air ◽

Radiant Heat ◽

The Other ◽

Small Aperture ◽

The One

The author states in this paper, that invisible radiant heat, from sources at elevated temperatures, freely permeates thin transparent screens in the same manner as light; but that as this doctine, established by Profesor Prévost and M. de la Roche has been controverted, he thinks it necessary to demonstrate it by fresh experiments: to this end he covered a small aperture with a film of glass almost iridescent, and keeping it constantly cold, by blowing on it, below the temperature of ambient air, he found that afi air-thermometer on one side of it was not affected by a heated iron ball on the other, if the temperature of the ball was low; but that as this temperature was raised, though not to the point of visible ignition, the effect on the thermometer became Sensible and even considerable. In another experiment, two air-thermometers, having their bulbs transparent, and as thin as possible, were placed equidistant from a heated ball just ceasing to be visible in the dark. The one was clear, the other coated inside with a thin film of pounded charcoal. The latter was most affected.

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Oxidation behavior of pressureless liquid-phase-sintered α-SiC in ambient air at elevated temperatures

Journal of Materials Research ◽

10.1557/jmr.2008.0196 ◽

2008 ◽

Vol 23 (6) ◽

pp. 1689-1700 ◽

Cited By ~ 12

Author(s):

F. Rodríguez-Rojas ◽

O. Borrero-López ◽

A.L. Ortiz ◽

F. Guiberteau

Keyword(s):

Activation Energy ◽

Liquid Phase ◽

Oxide Scale ◽

Oxidation Behavior ◽

Elevated Temperatures ◽

Low Cost ◽

Reaction Diffusion ◽

Ambient Air ◽

Outward Diffusion ◽

Nonoxide Ceramics

The long-duration oxidation behavior of a pressureless liquid-phase-sintered (LPS) α-SiC with 10 vol% Y3Al5O12 additives was studied by furnace oxidation tests in ambient air at 1100 to 1450 °C. The oxidation of this LPS SiC ceramic was found to be passive throughout these temperatures due to the formation of oxide scales, with a change in the oxidation behavior occurring at 1350 °C. It was also found that the oxidation behavior is very complex, exhibiting two distinct stages at all temperatures: (i) initial nonparabolic oxidation, where the rate-limiting mechanism is the outward diffusion of Y3+ and Al3+ cations from the secondary intergranular phase into the oxide scale with the activation energy of the oxidation being 504 ± 32 kJ/mol, followed by (ii) parabolic oxidation below 1350 °C, where the rate-determining mechanism is the inward diffusion of oxygen through the oxide scale with the activation energy being 310 ± 47 kJ/mol, or paralinear oxidation at and above 1350 °C, where oxidation is controlled by some mixed reaction/diffusion process. The existence of two oxidation regimes reflects the progressive crystallization of the oxide scale during the oxidation. Finally, guidelines are provided for the design and fabrication of low-cost, highly oxidation-resistant LPS SiC or other LPS nonoxide ceramics.

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Elastic Modulus, Thermal Expansion, and Pyrolysis Shrinkage of Norway Spruce Under High Temperature

Fire Technology ◽

10.1007/s10694-021-01123-z ◽

2021 ◽

Author(s):

Tito Adibaskoro ◽

Michalina Makowska ◽

Aleksi Rinta-Paavola ◽

Stefania Fortino ◽

Simo Hostikka

Keyword(s):

Mechanical Properties ◽

Thermal Expansion ◽

Elastic Modulus ◽

Norway Spruce ◽

Elastic Moduli ◽

Elevated Temperatures ◽

Ambient Air ◽

Time Dependent ◽

Temperature History ◽

Direction Parallel

AbstractThe orthotropic and temperature-dependent nature of the mechanical properties of wood is well recognized. However, past studies of mechanical properties at elevated temperatures are either limited to temperatures below 200 °C or focus only on the direction parallel to grain. The effect of time-dependent pyrolysis during measurement is often neglected. This paper presents a novel method for determining elastic modulus at high temperatures and thermal expansion coefficient in different orthotropic directions via Dynamic Mechanical-Thermal Analyser (DMTA). The method allows for drying, drying verification, and measurement in one chamber, eliminating the possibility of moisture reabsorption from ambient air. The repeatable measurements can be carried out in temperatures up to 325°C, adequate for observing time-dependent pyrolysis during measurement. Results of the measurements of Norway Spruce provide data of its mechanical response at temperature range previously not explored widely, as well as in the orthotropic direction. Time-dependent behaviour was observed in the thermal expansion and shrinkage experiment, where above 250°C the amount of shrinkage depends on heating rate. At such temperature, elastic moduli measurement also shows time dependence, where longer heating at certain temperature slightly increases the measured elastic modulus. Additionally, bilinear regression of the relationship between elastic moduli and temperature shows quantitatively good fit. Numerical simulation of the DMTA temperature history and wood chemical components mass losses show the onset of shrinkage and onset of hemicellulose mass loss occurring at around the same time, while decomposition of cellulose correlate with the sudden loss of elastic moduli.

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