Structure Stability of Ni-Base and Co-Base Alloys

2014 ◽  
Vol 782 ◽  
pp. 431-436 ◽  
Author(s):  
Božena Podhorná ◽  
Irena Andršová ◽  
Jana Dobrovská ◽  
Vlastimil Vodárek ◽  
Karel Hrbáček
Keyword(s):  
High Temperature ◽  
Temperature Stability ◽  
Structure Stability ◽  
Content Type ◽  
X Ray ◽  
Carbide Morphology ◽  
Alloy Carbide ◽  
Temperature Exposure ◽  
Very High ◽  
Carbide Content

This article summarises results of structure stability investigation of cast Ni-base and Co-base alloys after prolonged high temperature exposure at 900-1100 °C. Cast Ni (Co)-Cr-W-C alloys are resistant to high-temperature corrosion, due to high chromium content. Their heat resistance is caused by presence of carbides, which are stable at very high temperatures. Carbides precipitate in shape of large plate-like particles or carbide eutectics at casting cell boundaries, thus forming carbide skeleton of the alloy. Carbide morphology and temperature stability depends on chemical composition of the alloy, e.g. carbide content, type and content of carbide-forming elements. Microstructure changes were evaluated by stereological analysis and X ray-spectral microanalysis.

High temperature corrosion behaviour of aluminised FC 25 cast iron using pack cementation

2019 ◽  
Vol 66 (2) ◽  
pp. 236-241 ◽  
Author(s):  
Somrerk Chandra-Ambhorn ◽  
Neramit Krasaelom ◽  
Tummaporn Thublaor ◽  
Sirichai Leelachao
Keyword(s):  
Cast Iron ◽  
High Temperature ◽  
Corrosion Behaviour ◽  
Mass Gain ◽  
High Temperature Corrosion ◽  
Pack Cementation ◽  
X Ray Diffraction ◽  
Content Type ◽  
X Ray ◽  
Seat Insert

Purpose This study aims to apply the pack cementation to develop the Fe-Al layers on the surface of FC 25 cast iron in order to increase the high-temperature corrosion resistance of the alloy. Design/methodology/approach Pack cementation was applied on the surface of FC 25 cast iron at 1,050°C. The bare and aluminised alloys were subjected to the oxidation test in 20 per cent O2-N2 at 850 °C. Scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy and X-ray diffraction (XRD) were used for characterisation. Findings The layers of pack cementation consisted of Fe2Al5, FeAl2 and FeAl, and solid solution alloyed with Al. The oxidation kinetics of the bare cast iron was parabolic. Mass gain of the aluminised cast iron was significantly decreased compared with that of the bare cast iron. This was because of the protective alumina formation on the aluminised alloy surface. Al in the Fe–Al layer also tended to be homogenised during oxidation. Originality/value Even though the aluminising of alloys was extensively studied, the application of that process to the FC 25 cast iron grade was originally developed in this work. The significantly reduced mass gain of the aluminised FC 25 cast iron makes the studied alloy be promising for the use as a valve seat insert in an agricultural single-cylinder four-stroke engine, which might be run by using a relatively cheaper fuel, i.e. LPG, but as a consequence requires the higher oxidation resistance of the engine parts.

High Temperature Stability of MGCs Gas Turbine Components in Air and Combustion Gas Flow Environments

2004 ◽  
Author(s):  
Narihito Nakagawa ◽  
Hideki Ohtsubo ◽  
Kohji Shibata ◽  
Atsuyuki Mitani ◽  
Kazutoshi Shimizu ◽  
...  
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Gas Flow ◽  
Temperature Stability ◽  
High Temperature Strength ◽  
High Temperature Stability ◽  
Combustion Gas ◽  
Air Atmosphere ◽  
Low Nox Emission ◽  
Very High

Melt growth composites (MGCs) have a unique microstructure, in which continuous networks of single-crystal phases interpenetrate without grain boundaries. Therefore, the MGCs have excellent high-temperature strength characteristics, creep resistance, oxidation resistance and thermal stability in an air atmosphere at very high temperature. To achieve ultra-high thermal efficiency and low NOx emission for gas turbine systems, non-cooled turbine nozzle vanes and heat shield panels of combustor liners has been fabricated on an experimental basis. These components are thermally stable after heat treatment at 1700°C for 1000 hours in an air atmosphere. In addition, we have just started the exposure tests to evaluate the influence of combustion gas flow environment on MGCs.

scholarly journals High Temperature Stability of Amorphous Zn-Sn-O Transparent Conductive Oxides Investigated by In Situ TEM and X-ray Diffraction

2016 ◽  
Vol 22 (S3) ◽  
pp. 1582-1583
Author(s):  
Q. Jeangros ◽  
M. Duchamp ◽  
E. Rucavado ◽  
F. Landucci ◽  
C. Spori ◽  
...  
Keyword(s):  
High Temperature ◽  
Temperature Stability ◽  
In Situ Tem ◽  
High Temperature Stability ◽  
X Ray Diffraction ◽  
Transparent Conductive Oxides ◽  
X Ray

Performance Evaluation of BRA Modified Asphalt Mastic Based on Analysis of Microstructure and Rheological Mechanics Property

2011 ◽  
Vol 243-249 ◽  
pp. 4119-4124 ◽  
Author(s):  
Long Wen ◽  
Xiao Jiang Wang ◽  
Hao Liu ◽  
Hao Xiang Wu ◽  
Bao Lin Cui ◽  
...  
Keyword(s):  
High Temperature ◽  
Environmental Scanning Electron Microscopy ◽  
Temperature Stability ◽  
High Viscosity ◽  
Environmental Scanning ◽  
High Temperature Stability ◽  
X Ray ◽  
Modified Asphalt ◽  
Asphalt Mastic ◽  
Performance Grade

Buton rock asphalt (BRA) is possessed of both performance and economic advantages. In order to reveal the modification mechanism, X-ray diffraction experiment (XRD), X-ray fluorescence spectrum analysis and environmental scanning electron microscopy experiment (ESEM) are used to study on microstructure of BRA in this paper. It demonstrates that BRA can extremely adsorb free bitumen due to abundant microscopic pores, which consists of 70~80 percent Buton rock (BR) minerals and 20~30 percent pure rock asphalt (RA). RA with high viscosity is strongly adsorbed internal and outer of the surface of BR, which has high alkaline pH, high crystallization and strong surface activity. Then a special microstructure named “RA~BR” blend with stable property and strong spalling-resistance capability develops. Meanwhile, dynamic stability rheology test (DSR) is employed to study on the rheological mechanics property of BRA modified asphalt mastic. The high temperature performance grade (PG) level of BRA modified asphalt mastic with different mixing content is determined. The reasonable mixing content of BRA in matrix asphalt is 20~30 percent. The research proves that BRA modified asphalt possesses wonderful high temperature stability and has broad prospects for pavement application.

scholarly journals Synthesis of clathrate cerium superhydride CeH9 at 80-100 GPa with atomic hydrogen sublattice

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Nilesh P. Salke ◽  
M. Mahdi Davari Esfahani ◽  
Youjun Zhang ◽  
Ivan A. Kruglov ◽  
Jianshi Zhou ◽  
...  
Keyword(s):  
Atomic Hydrogen ◽  
High Pressures ◽  
Structure Stability ◽  
X Ray Diffraction ◽  
Detailed Chemistry ◽  
X Ray ◽  
3 Dimensional ◽  
Diamond Anvil ◽  
Laser Heated ◽  
Very High

Abstract Hydrogen-rich superhydrides are believed to be very promising high-Tc superconductors. Recent experiments discovered superhydrides at very high pressures, e.g. FeH5 at 130 GPa and LaH10 at 170 GPa. With the motivation of discovering new hydrogen-rich high-Tc superconductors at lowest possible pressure, here we report the prediction and experimental synthesis of cerium superhydride CeH9 at 80–100 GPa in the laser-heated diamond anvil cell coupled with synchrotron X-ray diffraction. Ab initio calculations were carried out to evaluate the detailed chemistry of the Ce-H system and to understand the structure, stability and superconductivity of CeH9. CeH9 crystallizes in a P63/mmc clathrate structure with a very dense 3-dimensional atomic hydrogen sublattice at 100 GPa. These findings shed a significant light on the search for superhydrides in close similarity with atomic hydrogen within a feasible pressure range. Discovery of superhydride CeH9 provides a practical platform to further investigate and understand conventional superconductivity in hydrogen rich superhydrides.

High Temperature Stability of Superconducting YBa2CU3Ox as Characterized by X-ray Diffraction

1988 ◽  
pp. 351-357
Author(s):  
M. O. Eatough ◽  
T. L. Aselage ◽  
K. D. Keefer ◽  
D. S. Ginley ◽  
B. Morosin
Keyword(s):  
High Temperature ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
X Ray Diffraction ◽  
X Ray

Ultrahigh vacuum sample mount for x-ray photoelectron spectroscopy up to very high temperature (150–1400 K)

2011 ◽  
Vol 29 (3) ◽  
pp. 031602 ◽  
Author(s):  
Mark S. Williamsen ◽  
Shishir K. Ray ◽  
Ying Zou ◽  
John A. Dudek ◽  
Somaditya Sen ◽  
...  
Keyword(s):  
High Temperature ◽  
Photoelectron Spectroscopy ◽  
Ultrahigh Vacuum ◽  
X Ray ◽  
Very High

High-Temperature Stability of Lead Zinc Niobate: In Situ X-Ray Diffraction

2010 ◽  
Vol 93 (11) ◽  
pp. 3902-3907 ◽  
Author(s):  
James V.> Shanahan ◽  
Erich H. Kisi ◽  
Jennifer S. Forrester ◽  
Heather J. Goodshaw ◽  
Jennifer S. Zobec ◽  
...  
Keyword(s):  
High Temperature ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lead Zinc Niobate ◽  
Lead Zinc

Research and evaluation of T91 superheater material for high temperature corrosion in biomass power plants

2015 ◽  
Vol 62 (3) ◽  
pp. 133-135 ◽  
Author(s):  
Hongliang Zhang ◽  
Fang Zhang ◽  
Wei Su ◽  
Ya Jiang ◽  
Yuchun Li
Keyword(s):  
High Temperature ◽  
Power Plants ◽  
Evaluation Method ◽  
Chloride Concentration ◽  
High Temperature Corrosion ◽  
Homogeneity Analysis ◽  
Content Type ◽  
Temperature Exposure ◽  
Biomass Power Plants ◽  
Dimensional Homogeneity

Purpose – The purpose of this paper was to evaluate corrosion resistance of superheater T91 material based on high temperature corrosion experiments with a condensate environment. Design/methodology/approach – The contributions of water temperature, chloride concentration and corrosion time were considered and analyzed for modeling corrosion kinetics. The corrosion tendency also was predicted, and the results were compared with higher temperature exposures of T91 tube material installed in a biomass power plant. Findings – High temperature exposure tests showed that the corrosion rates of T91 material would increase with temperature; there was a very evident corrosion acceleration point in 110°C. It was concluded that dimensional homogeneity analysis can serve as a viable evaluation method for T91 superheater material. Originality/value – Dimensional homogeneity analysis was used as evaluation method for anti-corrosion performance of T91 superheater material.

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