In situ observation of whiskers, pyramids and pits during the high-temperature oxidation of metals

1984 ◽  
Vol 21 (1-2) ◽  
pp. 89-102 ◽  
Author(s):  
G. M. Raynaud ◽  
R. A. Rapp
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
In Situ Observation ◽  
Temperature Oxidation

scholarly journals High-temperature oxidation resistance of VCps-reinforced Fe-matrix composites using an in-situ reaction

AIP Advances ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 015319
Author(s):  
Pinghu Chen ◽  
Ruiqing Li ◽  
Ripeng Jiang ◽  
Songsheng Zeng ◽  
Yun Zhang ◽  
...  
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Matrix Composites ◽  
Temperature Oxidation ◽  
In Situ Reaction

In Situ Measurement of the Phase Transformation Behavior of Al2O3 Scale during High-Temperature Oxidation using Synchrotron Radiation

2011 ◽  
Vol 696 ◽  
pp. 63-69 ◽  
Author(s):  
Shigenari Hayashi ◽  
Isao Saeki ◽  
Yoshitaka Nishiyama ◽  
Takashi Doi ◽  
Shoji Kyo ◽  
...  
Keyword(s):  
High Temperature ◽  
Synchrotron Radiation ◽  
High Temperature Oxidation ◽  
Structural Changes ◽  
Lattice Parameter ◽  
Transformation Behavior ◽  
Initial Oxidation ◽  
Temperature Oxidation ◽  
Diffraction Peaks

Very thin Fe-coatings, ~50nm, were found to suppress metastable Al2O3 formation on Fe-50Al and Ni-50Al alloys in our previous study. The authors proposed a mechanism whereby α-Al2O3 precipitates from the Al-saturated Fe2O3, which was formed during initial oxidation, since α-Al2O3 and α-Fe2O3 have isomorphous structures. In order to confirm the proposed mechanism, in-situ measurements were made of structural changes in the oxide scales formed on FeAl with and without Fe coating during heating and subsequent isothermal high temperature oxidation by synchrotron radiation with a two-dimensional X-ray detector. Diffraction peaks from Fe2O3 were initially observed at around 350°C on Fe-coated samples. The lattice parameter of the Fe2O3 initially increased linearly due to thermal expansion, but then rapidly decreased due to the formation of a solid solution of Fe2O3-Al2O3. α-Al2O3 started to appear at around 800°C, but no peaks from metastable Al2O3 were observed. The diffraction peaks from the α-Al2O3 on Fe-coated samples consisted of two distinct peaks, indicating that the α-Al2O3 had two different lattice parameters. These results suggest that the α-Al2O3 was formed not only by precipitation from the Al-saturated Fe2O3, but also by oxidation of Al in the substrate.

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.

Analytical Formulas for In-Situ Combustion

SPE Journal ◽  
2011 ◽  
Vol 16 (03) ◽  
pp. 513-523 ◽  
Author(s):  
A.A.. A. Mailybaev ◽  
J.. Bruining ◽  
D.. Marchesin
Keyword(s):  
Oxygen Consumption ◽  
High Temperature ◽  
Heat Wave ◽  
High Temperature Oxidation ◽  
Reaction Rate ◽  
Temperature Oxidation ◽  
Light Oil ◽  
Oil Components ◽  
Combustion Regimes

Summary There is a renewed interest in using combustion to recover medium- or high-viscosity oil. Despite numerous experimental, numerical, and analytical studies, the mechanisms for incomplete fuel combustion or oxygen consumption are not fully understood. Incomplete oxygen consumption may lead to low-temperature oxidation reactions downstream. This paper shows that these features emerge in a relatively simple 1D model, where air is injected in a porous medium filled with inert gas, water, and an oil mixture consisting of precoke, medium oil, and light oil. Precoke is a component that is dissolved in the oil but has essentially the same composition as coke. At high temperatures, precoke is converted to coke, which participates in high-temperature oxidation. At high temperatures, medium-oil components are cracked, releasing gaseous oil. Light-oil components and water are vaporized. The model possesses an analytical solution, which was obtained by a concept introduced by Zeldovich et al. (1985). This concept, which underlies most analytical approaches such as the reaction-sheet approximation and large-activation-energy asymptotics, entails that reaction can occur only in a very small temperature range because of the highly nonlinear nature of the Arrhenius factor. For a temperature below this range, the reaction rate is too slow, and for temperatures above this range, the reaction rate is so fast that either the fuel or oxygen concentrations become zero. The model results, in the absence of external heat losses, show that there are two combustion regimes in which coke or oxygen is partially consumed. In one regime, the reaction zone moves in front of the heat wave; whereas, in the other regime, the order of the waves is reversed. There are also two combustion regimes in which the coke and oxygen are completely consumed. Also, here the reaction zone can move in front of or at the back of the heat wave. Each combustion regime is described by a sequence of waves; we derive formulas for parameters in these waves. We analyze our formulas for typical in-situ-combustion data and compare the results with numerical simulation. The main conclusion is that mainly two key parameters (i.e., the injected oxygen mole fraction and the fuel concentration) determine the combustion-front structure and when either incomplete oxygen consumption or incomplete fuel consumption occurs in the high-temperature oxidation zone.

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