scholarly journals Mechanism and Kinetics of Thermal Embrittlement of Austenitic Chromium-Nickel Steel during Long-Term High-Temperature Holding

2022 ◽  
Author(s):  
K.A. Okhapkin
Keyword(s):  
Experimental Data ◽  
High Temperature ◽  
Structural Changes ◽  
Nickel Steel ◽  
Thermal Embrittlement ◽  
Calculation Results ◽  
Mechanism And Kinetics ◽  
Kinetics Of ◽  
Equilibrium Content

Abstract. This article describes a model of structural changes in austenitic chromium-nickel steel during long-term thermal soakings. The time for reaching equilibrium content of Cr23C6 carbide at a temperature of 600 °C is calculated. The calculation results are compared with experimental data on the kinetics of thermal embrittlement of steel at a temperature of 600 °C after thermal holding for up to 15000 hours.

Mechanism and Kinetics of Phase Transformations in Refractory Alloy 45Kh26N33S2B2 Under Long-Term High-Temperature Holds. Part 2

2014 ◽  
Vol 56 (3-4) ◽  
pp. 124-130 ◽  
Author(s):  
A. I. Rudskoy ◽  
S. Yu. Kondrat’ev ◽  
G. P. Anastasiadi ◽  
A. S. Oryshchenko ◽  
M. D. Fuks
Keyword(s):  
High Temperature ◽  
Phase Transformations ◽  
Refractory Alloy ◽  
Mechanism And Kinetics ◽  
Kinetics Of

Studies on the Behavior Some Paints in Electro-insulating Fluid Based on Vegetable Esters

2018 ◽  
Vol 69 (5) ◽  
pp. 1139-1144
Author(s):  
Iosif Lingvay ◽  
Adriana Mariana Bors ◽  
Livia Carmen Ungureanu ◽  
Valerica Stanoi ◽  
Traian Rus
Keyword(s):  
Structural Changes ◽  
Oxidation Processes ◽  
High Oleic ◽  
Painting Materials ◽  
Insulating Paper ◽  
Different Types ◽  
Mechanism And Kinetics ◽  
Kinetics Of ◽  
Natural Ester

For the purpose of using three different types of painting materials for the inner protection of the transformer vats, their behavior was studied under actual conditions of operation in the transformer (thermal stress in electro-insulating fluid based on the natural ester in contact with copper for electro-technical use and electro-insulating paper). By comparing determination of the content in furans products (HPLC technique) and gases formed (by gas-chromatography) in the electro-insulating fluid (natural ester with high oleic content) thermally aged at 130 �C to 1000 hours in closed glass vessels, it have been found that the presence the investigated painting materials lead to a change in the mechanism and kinetics of the thermo-oxidation processes. These changes are supported by oxygen dissolved in oil, what leads to decrease both to gases formation CO2, CO, H2, CH4, C2H4 and C2H6) and furans products (5-HMF, 2-FOL, 2 -FAL and 2-ACF). The painting materials investigated during the heat treatment applied did not suffer any remarkable structural changes affecting their functionality in the electro-insulating fluid based on vegetable esters.

scholarly journals Parameters of temperature disturbance triggering the propagation of the quench front on an extremely overheated surface

2021 ◽  
Vol 2119 (1) ◽  
pp. 012079
Author(s):  
I P Starodubtseva ◽  
A N Pavlenko
Keyword(s):  
Experimental Data ◽  
High Temperature ◽  
Front Propagation ◽  
Solid Contact ◽  
Temperature Disturbance ◽  
Metal Plates ◽  
Leidenfrost Temperature ◽  
Dynamical Pattern ◽  
Temperature Surface

Abstract The results of computational experiments simulating the triggering of the quench front propagation on the superheated vertically oriented metal plates are presented. The plates are quenched by a gravitationally flowing down liquid nitrogen film. The temperature of the test samples at the beginning of the process was higher than the critical temperature and the Leidenfrost temperature, which means that direct long-term liquid-solid contact is impossible. For this reason, the front is initially motionless. As a result of numerical simulation, a dynamic pattern of the quench front propagation on a high-temperature surface was obtained. Analysis of the results allowed to find the realistic values of heat sink into the cooling medium, as well as the parameters of the local temperature disturbance, its spatial extent and amplitude, at which the conditions are created for triggering the process of quench front propagation on the high-temperature surface. Direct comparison of the numerical simulations results with experimental data on the velocity, geometry of the quench front and on the dynamical pattern of the process confirmed the reliability of the results obtained.

scholarly journals Role of Ionic Headgroups on the Thermal, Rheological, and Foaming Properties of Novel Betaine-Based Polyoxyethylene Zwitterionic Surfactants for Enhanced Oil Recovery

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 908 ◽  
Author(s):  
Muhammad Shahzad Kamal ◽  
Syed Muhammad Shakil Hussain ◽  
Lionel Talley Fogang
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Oil Recovery ◽  
Structural Changes ◽  
Foam Stability ◽  
Foaming Properties ◽  
Zwitterionic Surfactants ◽  
Reservoir Conditions ◽  
Thermal Stability Of

Long-term thermal stability of surfactants under harsh reservoir conditions is one of the main challenges for surfactant injection. Most of the commercially available surfactants thermally degrade or precipitate when exposed to high-temperature and high-salinity conditions. In this work, we designed and synthesized three novel betaine-based polyoxyethylene zwitterionic surfactants containing different head groups (carboxybetaine, sulfobetaine, and hydroxysulfobetaine) and bearing an unsaturated tail. The impact of the surfactant head group on the long-term thermal stability, foam stability, and surfactant–polymer interactions were examined. The thermal stability of the surfactants was assessed by monitoring the structural changes when exposed at high temperature (90 °C) for three months using 1H-NMR, 13C-NMR, and FTIR analysis. All surfactants were found thermally stable regardless of the headgroup and no structural changes were evidenced. The surfactant–polymer interactions were dominant in deionized water. However, in seawater, the surfactant addition had no effect on the rheological properties. Similarly, changing the headgroup of polyoxyethylene zwitterionic surfactants had no major effect on the foamability and foam stability. The findings of the present study reveal that the betaine-based polyoxyethylene zwitterionic surfactant can be a good choice for enhanced oil recovery application and the nature of the headgroup has no major impact on the thermal, rheological, and foaming properties of the surfactant in typical harsh reservoir conditions (high salinity, high temperature).

scholarly journals Endothelin research and the discovery of macitentan for the treatment of pulmonary arterial hypertension

2016 ◽  
Vol 311 (4) ◽  
pp. R721-R726 ◽  
Author(s):  
Martine Clozel
Keyword(s):  
Pulmonary Arterial Hypertension ◽  
Arterial Hypertension ◽  
Structural Changes ◽  
Term Treatment ◽  
Vasopressin Release ◽  
Long Term Treatment ◽  
Pulmonary Arterial ◽  
Kinetics Of

Endothelin receptor antagonists (ERAs) are used for the treatment of pulmonary arterial hypertension (PAH). Macitentan, a dual (ETA+ETB) ERA approved for the long-term treatment of PAH, was discovered through a tailored research program aimed at improving efficacy and safety over the existing ERAs. The goal of improved efficacy was based on the understanding that not only the ETA receptor but also the ETB receptor contributed to the hemodynamic and structural changes induced by endothelin-1 (ET-1) in pathological conditions and on the predefined requirements for optimal tissue penetration and binding kinetics of the antagonist. The goal of improved safety was based on the discovery of the role of ETB receptors in vascular permeability and vasopressin release and on the elucidation of the mechanism by which bosentan (the first approved oral dual ETA/ETB ERA) caused liver enzyme changes. Our intention was to design a molecule that would block ETA and ETB receptors optimally and would not interfere with bile salt elimination. This review takes us through the drug discovery journey that led to the discovery, development, and registration of macitentan.

Annealing induced structural changes and microcracking in Mo-Mo3Si

2002 ◽  
Vol 753 ◽  
Author(s):  
X.-L. Wang ◽  
J. H. Schneibel ◽  
Y. D. Wang ◽  
J. W. Richardson
Keyword(s):  
Electron Microscopy ◽  
Experimental Data ◽  
High Temperature ◽  
Structural Changes ◽  
Thermal Stresses ◽  
Annealing Temperature ◽  
Composition Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

ABSTRACTCast Mo-Mo3Si intermetallic composites develop microcracks after annealing at high temperature. Neutron diffraction, x-ray diffraction, composition analysis, and scanning electron microscopy have been used to characterize the structural changes induced by annealing of Mo-Mo3Si. It is shown that the observed cracking cannot be attributed to differential thermal stresses that developed on cooling from the annealing temperature. Instead, the experimental data suggest that the cracks were initiated at high temperature, possibly due to diffusion of Si atoms from supersaturated α-Mo to Mo3Si.

Unravelling the redox mechanism and kinetics of a highly active and selective Ni-based material during the oxidative dehydrogenation of ethane

2021 ◽  
Author(s):  
Carlos Alvarado-Camacho ◽  
Jeroen Poissonnier ◽  
Joris Thybaut ◽  
Carlos O. Castillo
Keyword(s):  
Oxidative Dehydrogenation ◽  
High Selectivity ◽  
Promising Alternative ◽  
Redox Mechanism ◽  
Long Term Stability ◽  
Highly Active ◽  
Ethane Oxidative Dehydrogenation ◽  
Mechanism And Kinetics ◽  
Kinetics Of

Ethane oxidative dehydrogenation (ODH-C2) is a promising alternative for producing ethylene. Even if SnO2-NiO catalysts are characterized by their long-term stability and high selectivity to ethylene, also in the absence...

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