scholarly journals Effect of Long-Term High Temperature Oxidation on the Coking Behavior of Ni-Cr Superalloys

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1899 ◽  
Author(s):  
Stamatis Sarris ◽  
Manjunath Patil ◽  
Kim Verbeken ◽  
Marie-Françoise Reyniers ◽  
Kevin Van Geem
Keyword(s):  
Cross Section ◽  
Temperature Oxidation ◽  
X Ray ◽  
Microstructure Stability ◽  
Ni Content ◽  
Steam Cracking ◽  
Improved Stability ◽  
Section Analysis

The service time of an industrial cracker is strongly dependent on the long-term coking behavior and microstructure stability of the reactor coil alloy. Super alloys are known to withstand temperatures up to even 1400 K. In this work, several commercially available alloys have been first exposed to a long term oxidation at 1423 K for 500 h, so-called metallurgic aging. Subsequently, their coking behavior was evaluated in situ in a thermogravimetric setup under ethane steam cracking conditions (Tgasphase = 1173 K, Ptot = 0.1 MPa, XC2H6 = 70%, continuous addition of 41 ppmw S/HC of DMDS, dilution δ = 0.33 kgH2O/kgHC) and compared with their unaged coking behavior. The tested samples were also examined using scanning electron microscopy and energy diffractive X-ray for surface and cross-section analysis. The alloys characterized by increased Cr-Ni content or the addition of Al showed improved stability against bulk oxidation and anti-coking behavior after application of metallurgic aging due to the formation of more stable oxides on the top surface.

Analysis of crystallite size changes in a hematite and magnetite formed on steel used in the power idustry

2017 ◽  
Vol 1 (21) ◽  
pp. 65-73
Author(s):  
Monika Gwoździk
Keyword(s):  
Elevated Temperature ◽  
Oxide Layer ◽  
Cross Section ◽  
X Ray ◽  
Term Operation ◽  
Diffraction Line Profile ◽  
Crystallite Sizes ◽  
Scherrer Formula ◽  
Pipe Outlet

The paper presents results of studies on the crystallite sizes of oxide layer formed during a long-term operation on 10CrMo9-10 steel at an elevated temperature (T = 545° C, t = 200,000 h). This value was determined by a method based on analysis of the diffraction line profile, according to a Scherrer formula. The oxide layer was studied on a surface and a cross-section at the outer and inner site on the pipe outlet, at the fire and counter-fire wall of the tube. X-ray studies were carried out on the surface of a tube, then the layer’s surface was polished and the diffraction measurements repeated to reveal differences in the originated oxides layer.

An Advanced Technique for High Temperature X-Ray Elastic Constant and Stress Investigations

1992 ◽  
Vol 36 ◽  
pp. 411-422
Author(s):  
Chun Liu ◽  
Jean-Lou Lebrun ◽  
François Sibieude
Keyword(s):  
High Temperature ◽  
Elastic Constant ◽  
High Temperature Oxidation ◽  
Differential Method ◽  
Stress Evolution ◽  
Advanced Technique ◽  
Temperature Oxidation ◽  
X Ray ◽  
Refractory Alloys

AbstractA high temperature in situ X-Tay diffraction (HTXRD) instrument was devised for residual stress (RS) and X-ray elastic constant (XECs) investigations. The aim was to gain a better understanding of the stresses developed during high temperature oxidation, which is essential for the lifetime improvement of refractory alloys. The investigators use sin2ψ method to survey the stress evolution during oxidation in both the scale and the substrate, and differential method to determine the XECs that relate the measured/measurable deformation to the stress state of the materials studied. The stresses on the Ni/NiO system are measured in situ. The XECs are determined on XC75 steel samples. This paper presents the theories of stresses and XECs determined by HTXRD and briefly discusses the experimental results.

Vascular access during anaesthesia

2017 ◽  
Author(s):  
Andrew R. Bodenham
Keyword(s):  
Vascular Access ◽  
Practical Skills ◽  
X Ray ◽  
Applied Anatomy ◽  
Medical Terms ◽  
Core Skill ◽  
Management Of Complications ◽  
Improved Design

Vascular access, both arterial and venous, at peripheral and more central sites is relatively new in historical medical terms and has only really developed into mainstream practice in the last 60 years. Other routes of drug and fluid administration via the gut and inhalation preceded it by centuries. It is a core skill for anaesthetists and intensivists, yet is not always well taught or is left out of core training curricula, with the assumption that skills will just be picked up early along the way. Like many procedures, it can be surprisingly easy to learn the basics, but many hazards and difficulties await the less skilled or inexperienced operator. A thorough knowledge of applied anatomy, practical skills, and recognition and management of complications are essential for safe practice. The increasing use of ultrasound, ECG guidance, X-ray screening, and other devices, and improved design of access devices allow much safer and more successful procedures. Many patients will now have long-term devices in situ, which can be used during anaesthesia and critical care. Such devices are increasingly inserted or removed by anaesthetists. Space precludes a detailed description of actual techniques for all routes of access; only general principles will be covered in this chapter.

scholarly journals Alumina-based Coating for Coke Reduction in Steam Crackers

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2025
Author(s):  
Stamatis A. Sarris ◽  
Steffen H. Symoens ◽  
Natalia Olahova ◽  
Marie-Françoise Reyniers ◽  
Guy B. Marin ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Base Alloy ◽  
Product Distribution ◽  
X Ray ◽  
Barrier Coating ◽  
Sulfur Addition ◽  
Steam Cracking ◽  
On Line ◽  
Set Up ◽  
Section Analysis

Alumina-based coatings have been claimed as being an advantageous modification in industrial ethylene furnaces. In this work, on-line experimentally measured coking rates of a commercial coating (CoatAlloy™) have pointed out its superiority compared to an uncoated reference material in an electrobalance set-up. Additionally, the effects of presulfiding with 500 ppmw DMDS per H2O, continuous addition of 41 ppmw S per HC of DMDS, and a combination thereof were evaluated during ethane steam cracking under industrially relevant conditions (Tgasphase = 1173 K, Ptot = 0.1 MPa, XC2H6 = 70%, dilution δ = 0.33 kgH2O/kgHC). The examined samples were further evaluated using online thermogravimetry, scanning electron microscopy and energy diffractive X-ray for surface and cross-section analysis together with X-ray photoelectron spectroscopy and wavelength-dispersive X-ray spectroscopy for surface analysis. The passivating coating illustrated a better performance than the reference Ni-Cr Fe-base alloy after application of an improved pretreatment, followed by piddling changes on the product distribution. Presulfiding of the coating affected negatively the observed coking rates in comparison with the reference alloy, so alternative presulfiding and sulfur addition strategies are recommended when using this barrier coating.

Grazing Incidence X-Ray Scattering Studies of the Structure and Morphology of the Ni/Mgo(001), Co/Nio(111) and Nife/Nio(111) Interfaces During their in Situ Growth

1999 ◽  
Vol 562 ◽  
Author(s):  
G. Renaud ◽  
A. Barbier ◽  
C. Mocuta
Keyword(s):  
High Temperature ◽  
Magnetic Measurements ◽  
Grazing Incidence ◽  
Ex Situ ◽  
Crystallographic Structure ◽  
Temperature Oxidation ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

ABSTRACTCombined in situ structural and ex situ magnetic studies of the Co/NiO(111) and Ni81Fe19/NiO(111) interfaces are presented. The Co and Permalloy films were grown on NiO(111) single crystals. Structural studies were performed by Grazing Incidence X-ray Scattering during growth. The effect of the temperature of the substrate during deposition was investigated. Under specific growth conditions, almost pure FCC Co and NiFe films can be obtained, with small quantities of twins. Magnetic measurements were performed ex situ by Magneto-Optical Kerr Effect (MOKE). A strong correlation between the magnetic properties and the crystallographic structure of the Co film is evidenced. High coercive fields are measured for all samples. High temperature annealing of the NiFe film leads to an improved crystalline quality, but the interface becomes reactive and diffuse: part of the Fe diffuses into the NiO substrate and forms an interface compound, likely to be the spinel NiFe2O4. We also report an in situ grazing incidence X-ray scattering study of the Ni/MgO(001) interface during its formation at room temperature. In-plane measurements reveal that the interface is sharp and that the epitaxial relationship is complex. Two distinct lattices are found to exist: expanded Ni(001) and Ni(110). The latter exhibits several orientations with respect to the substrate depending on the thickness. The Ni(110) orientations disappear by annealing at high temperature, leaving only the Ni cube/cube orientation. The layer was also almost fully transformed into NiO(001) by high temperature oxidation.

Rechargeable nonaqueous lithium/Mo6S8 battery

1984 ◽  
Vol 62 (6) ◽  
pp. 527-531 ◽  
Author(s):  
P. J. Mulhern ◽  
R. R. Haering
Keyword(s):  
Discharge Rate ◽  
Active Material ◽  
Rate Capability ◽  
Constant Current ◽  
Electrochemical Cells ◽  
X Ray Diffraction ◽  
X Ray ◽  
Long Cycle Life

Electrochemical cells based on the intercalation of lithium into Mo6S8 were examined by derivative constant current chronopotentiometry, in situ X-ray diffraction, and long-term cycling. About three-quarters of the capacity of such cells oeeurs between 2.0 and 2.1 V with most of the remainder near 2.45 V. Li/Mo6S8 cells have a long cycle life, good discharge rate capability, and an energy density of at least 260 W∙h/kg (1 W∙h = 3.6 kJ) of active material. Such cells can be made by starting with cathodes made from ternary Chevrel phase compounds. AyMo6S8 (A = Cu, Fe, Ni), and electrochemically converting these materials to form LixMo6S8.

Effect of B on the Microstructures and High Temperature Oxidation Resistance of a Nb-Si System In Situ Composite

2007 ◽  
Vol 546-549 ◽  
pp. 1489-1494 ◽  
Author(s):  
Ai Qin Liu ◽  
Shu Suo Li ◽  
Lu Sun ◽  
Ya Fang Han
Keyword(s):  
High Temperature ◽  
Oxide Scale ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Temperature Oxidation ◽  
X Ray ◽  
Solid Solution Strengthening ◽  
Arc Melting ◽  
The Matrix

Nb-16Si-24Ti-6Cr-6Al-2Hf-xB(x=0, 0.5, 1, 2, 4, 6) in situ composites were prepared by arc-melting. Microstructure and the effect of boron on 1250C oxidation resistance of the composites were investigated by scanning electron microscopy(SEM) and X-ray energy disperse spectrum(EDS) as well as X-ray diffraction(XRD). The experimental results showed that the high temperature oxidation resistance of the alloy was remarkably improved by adding proper amount of boron. This may be resulted from several beneficial roles of boron, i.e., boron improves the resistance of Nb5Si3 by solid solution strengthening, inhibits the diffusion of oxygen in the matrix, improves the adherence between the oxide scale and the substrate and increases the cracking resistance of the oxide scale.

Preparation and Characteristic of PSMA/EG Composite Materials

2010 ◽  
Vol 163-167 ◽  
pp. 1951-1954
Author(s):  
Gui Xiang Hou ◽  
Hai Ning Na ◽  
Xiao Ming Sang
Keyword(s):  
High Temperature Oxidation ◽  
In Situ Polymerization ◽  
Expanded Graphite ◽  
Sem Analysis ◽  
X Ray Diffraction ◽  
Temperature Oxidation ◽  
X Ray ◽  
Graphite Nanosheets ◽  
Composite Granules

Graphite nanosheets prepared through high-temperature oxidation via powdering the expanded graphite. After soaking the expanded graphite with styrene(S) and maleic anhydride(MA) monomers, the polymer (Poly(S-co-MA))/expanded graphite(EG) (PSMA/EG) composite granules were obtained by in situ polymerization. Light microscope，scanning electron microscope and X-ray diffraction characterization were performed. SEM analysis indicate that the expanded graphite was mostly tore to sheets with thickness of 50–80 nm and with diameter of 1μm. Optical micrographs showed that the distribution of graphite platelets is found to be nearly uniform.

Zeolite - Salt Occlusion: A Potential Route for the Immobilisation of Iodine-129?

2003 ◽  
Vol 807 ◽  
Author(s):  
Neil C. Hyatt ◽  
Joseph A. Hriljac ◽  
Alia Choudhry ◽  
Laura Malpass ◽  
Gareth P. Sheppard ◽  
...  
Keyword(s):  
Weight Loss ◽  
Uniform Distribution ◽  
Crystalline Phase ◽  
Thermally Stable ◽  
X Ray Diffraction ◽  
Single Crystalline ◽  
X Ray ◽  
Elemental Silver

ABSTRACTReactions of zeolite Na-A with AgI, and the sodium, copper and lead forms of zeolites A, LTA, X and Y with NaI, have been examined as possible starting routes to the long term immobilisation of iodine-129. Heating the salts in air, at 500°C, with the sodium forms of the zeolites leads to the formation of occlusion products, where the iodide salt migrates into the zeolite pores. Detailed studies of the Na-A / 5AgI complex indicate it has a uniform distribution of Na, Si, Al, Ag and I, and is thermally stable to ca. 750°C, where there is a substantial weight loss as iodine is released. In situ powder X-ray diffraction studies have been used to monitor the occlusion reaction at 400°C, and show that the occlusion product decomposes to produce a single crystalline phase at 800°C prior to further decomposition at 850°C to a mixture of nepheline and elemental silver.

scholarly journals Evaluation of high-temperature corrosion on 13CrMo4-5 steel operated in the power industry

2018 ◽  
Vol 4 (21) ◽  
pp. 335-343
Author(s):  
Monika Gwoździk
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Elevated Temperature ◽  
Oxide Layer ◽  
Cross Section ◽  
High Temperature Corrosion ◽  
X Ray ◽  
Term Operation ◽  
Scanning Electron

The paper presents results of studies of steel and the oxide layer formed during a long-term operation (t=130,000h) on 13CrMo4-5 steel at an elevated temperature (T=455°C). The oxide layer was studied on a surface and a cross-section at the inner site of the pipe (in the flowing medium – steam side). The paper contains results of studies such as: light microscopy, scanning electron microscopy, X-ray phase analysis.

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