Air Oxidation Behavior of Two Ti-Base Alloys Synthesized by HIP

2016 ◽  
Vol 35 (4) ◽  
pp. 353-359
Author(s):  
S. Liu ◽  
Q. Q. Guo ◽  
L. L. Liu ◽  
L. Xu ◽  
Y. Y. Liu
Keyword(s):  
Oxidation Kinetics ◽  
Oxidation Behavior ◽  
Hot Isostatic Pressing ◽  
Air Oxidation ◽  
Isostatic Pressing ◽  
Parabolic Law ◽  
Cast Alloys ◽  
Ternary Additions ◽  
Kinetics Of

AbstractThe oxidation behavior of Ti-5Al-2.5Sn and Ti-6Al-4V produced by hot isostatic pressing (HIP) has been studied at 650–850°C in air for 24 h. The oxidation kinetics of both alloys followed the parabolic law with good approximation, except for Ti-5Al-2.5Sn oxidized at 850°C. Multi-layered scales formed on both alloys at 750°C and 850°C. Ternary additions of Sn and V accounted for the different morphology of the scales formed on these two alloys. In addition, the oxidation behavior of HIP alloys is compared with that of the corresponding cast alloys and the scaling mechanism is discussed.

Effect of lamellar microstructure on oxidation kinetics of Fe3Al sintered by hot isostatic pressing

2008 ◽  
Vol 50 (6) ◽  
pp. 1693-1700 ◽  
Author(s):  
J. Fedotova ◽  
G. Bonnet ◽  
F. Pedraza ◽  
J. Balmain ◽  
S. Dubois ◽  
...  
Keyword(s):  
Oxidation Kinetics ◽  
Hot Isostatic Pressing ◽  
Lamellar Microstructure ◽  
Isostatic Pressing ◽  
Kinetics Of

scholarly journals Influence of Grain Refinement on Oxidation Behavior of Two-Phase Cu–Cr Alloys at 973–1,073 K in Air

2016 ◽  
Vol 35 (10) ◽  
pp. 1005-1011
Author(s):  
T. J. Pan ◽  
J. Chen ◽  
Y. X. He ◽  
W. Wei ◽  
J. Hu
Keyword(s):  
Grain Size ◽  
Spatial Distribution ◽  
Oxidation Behavior ◽  
Second Phase ◽  
Two Phase ◽  
Reactive Component ◽  
Parabolic Law ◽  
Second Phase Particles ◽  
Kinetics Of ◽  
Lower Oxidation

AbstractThe oxidation behavior of grain-refined Cu–7.0 Cr alloy (GR Cu–7.0 Cr) in air at 973–1,073 K was investigated in comparison with normal casting Cu–7.0 Cr alloy (CA Cu–7.0 Cr). The oxidation of CA Cu–7.0 Cr alloy nearly followed parabolic law, while the oxidation kinetics of GR Cu–7.0 Cr slightly deviated from parabolic law. Both alloys almost produced multi-layered scales consisting of the outer layer of CuO and the inner layer of mixed Cr2O3 and Cu2O oxides plus internal oxidation zones of chromium. The grain-refined Cu–7.0 Cr alloy produced a more amount of Cr2O3 in the inner layer of the scale, and thus was oxidized at much lower oxidation rate than that of CA Cu–7.0 Cr with normal grain size. The experimental results indicated that the differences in oxidation behavior between two alloys may be ascribed to the different size and spatial distribution of the second-phase particles and the reactive component contents in localized zone.

Oxidation Behavior of As-Forged Fe-25wt%Cr Alloys at 1100°C in Air

2011 ◽  
Vol 695 ◽  
pp. 348-352 ◽  
Author(s):  
Hui Xie ◽  
Lei Jia ◽  
Xiao Feng Zhang ◽  
Zhen Lin Lu
Keyword(s):  
Oxidation Behavior ◽  
Oxidation Process ◽  
Hot Forging ◽  
Oxygen Ions ◽  
Second Stage ◽  
Parabolic Law ◽  
Transport Velocity ◽  
Fast Transport ◽  
Kinetics Of ◽  
Oxidation Scale

Fe-25wt%Cr alloys were fabricated by combining Powder Metallurgy (PM) with hot-forging treatment, and their oxidation behavior at 1100°C in air was investigated systematically by using XRD, SEM and EDS, respectively. The results showed that a composite oxidation scale containing both Cr2O3and FeCr2O4formed on the surface of as-forged Fe-25wt%Cr alloys after oxidation at 1100°C in air for 100 hours. The oxidation process of Fe-Cr alloys could be obviously divided into two different stages, and the kinetics of two-stage oxidation agreed well with the parabolic law. The first could be corresponding to the formation of protective Cr2O3layer, while the second could be thought as the growth of FeCr2O4and the further oxidation of the inner Cr2O3oxidation scale. The faster oxidation rate in the second stage could be attributed to both the diffusion of iron ions rapider than that of Cr in the Cr2O3layer and the fast transport velocity of oxygen ions along the cracks.

Oxidation Kinetics of the Sintered Iron Parts Steam Treated in an Industrial Continuous Furnace

2010 ◽  
Vol 660-661 ◽  
pp. 243-248
Author(s):  
Eduardo Nunes ◽  
Ivan Gilberto Sandoval Falleiros
Keyword(s):  
Oxidation Kinetics ◽  
Continuous Furnace ◽  
Steam Treatment ◽  
Sintered Iron ◽  
Second Stage ◽  
Parabolic Law ◽  
Controlling Mechanism ◽  
Iron Diffusion ◽  
Two Stages ◽  
Kinetics Of

It has been studied a steam treatment process in an industrial continuous furnace for sintered iron parts in a temperature range varying from 490 to 570 °C and sample´s sintered densities of 6,52 and 6,77 g / cm3 . The tests have showed oxidation kinetics with two stages, each of them obeying a parabolic law. The first stage was faster than the second. The oxidation time when the oxidation kinetics of the first stage has changed for the second stage showed off very sensitive to the process temperature and sintered densities of the parts which are in agreement with the process rate controlling mechanism that was found to be the iron diffusion through the oxide layer.

scholarly journals Oxidation Kinetics of Propane-Air Mixture over NiCo2O4 Catalyst Emitted from LPG Vehicles

2017 ◽  
Vol 12 (2) ◽  
pp. 191
Author(s):  
Suverna Trivedi ◽  
Ram Prasad ◽  
S. Chadha
Keyword(s):  
Oxidation Kinetics ◽  
Plug Flow ◽  
Tubular Reactor ◽  
Frequency Factor ◽  
Reaction Engineering ◽  
Precipitation Method ◽  
Air Oxidation ◽  
Temperature Ranges ◽  
Co Precipitation ◽  
Kinetics Of

This paper describes the kinetics of catalytic air oxidation of propane. The kinetics data were collected in a plug flow tubular reactor. The experiments were performed over the NiCo2O4 catalyst prepared by co-precipitation method followed by calcination at 400 oC. The kinetic data were collected under the following conditions: 200 mg of catalyst, 2.5 % of propane in air, total flow rate of 60 mL/min, and temperature ranges of 130-170 oC. The data were fitted to the power law rate equation. The activation    energy and frequency factor were found to be 59.3 kJ/g mol and 2.9×108 (mol)0.47.L0.53/g cat.h, respectively. Copyright © 2017 BCREC Group. All rights reservedReceived: 20th November 2016; Revised: 26th February 2017; Accepted: 26th February 2017How to Cite: Trivedi, S., Prasad, R., Chadha, S. (2017). Oxidation Kinetics of Propane-Air Mixture over NiCo2O4 Catalyst Emitted from LPG Vehicles. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (2): 191-196 (doi:10.9767/bcrec.12.2.798.191-196)Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.2.798.191-196 

Isothermal Oxidation Resistance of Zr3[Al(Si)]4C6-Based Composite Ceramics at 1000-1300°C in Air

2018 ◽  
Vol 281 ◽  
pp. 444-449 ◽  
Author(s):  
Lei Yu ◽  
Hui Liu ◽  
Kai Liang ◽  
Zhen Di Zang ◽  
Jia Cheng Shi ◽  
...  
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Oxide Thickness ◽  
Unit Surface Area ◽  
Composite Ceramics ◽  
Oxidation Rate Constant ◽  
Parabolic Law ◽  
Unit Surface ◽  
Kinetics Of

The isothermal oxidation behavior of Zr3[Al(Si)]4C6-ZrB2-ZrC composite ceramics at 1000-1300 °C in air has been investigated. The oxidation kinetics of the composites and generally follows a parabolic law. At the same oxidation temperature and time, the weight gain per unit surface area, oxidation rate constant and oxide thickness of the composites are higher than those of monolithic Zr3[Al(Si)]4C6 ceramic. With the incorporation of ZrB2 and ZrC, the oxidation resistance of the composites becomes poor. The surfaces of the oxide layer have a loose and porous structure, consisting of mainly ZrO2 and little mullite, and there are no dense oxide films preventing the inward diffusion of oxygen element effectively.

Isothermal oxidation of bulk Zr2Al3C4 at 500 to 1000 °C in air

2008 ◽  
Vol 23 (2) ◽  
pp. 359-366 ◽  
Author(s):  
L.F. He ◽  
Z.J. Lin ◽  
Y.W. Bao ◽  
M.S. Li ◽  
J.Y. Wang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Raman Spectra ◽  
Oxidation Kinetics ◽  
Oxidation Behavior ◽  
Oxygen Affinity ◽  
Isothermal Oxidation ◽  
Oxide Scales ◽  
X Ray Diffraction ◽  
X Ray ◽  
Parabolic Law

The isothermal oxidation behavior of Zr2Al3C4 in the temperature range of 500 to 1000 °C for 20 h in air has been investigated. The oxidation kinetics follow a parabolic law at 600 to 800 °C and a linear law at higher temperatures. The activation energy is determined to be 167.4 and 201.2 kJ/mol at parabolic and linear stages, respectively. The oxide scales have a monolayer structure, which is a mixture of ZrO2 and Al2O3. As indicated by x-ray diffraction and Raman spectra, the scales formed at 500 to 700 °C are amorphous, and at higher temperatures are α-Al2O3 and t-ZrO2 nanocrystallites. The nonselective oxidation of Zr2Al3C4 can be attributed to the strong coupling between Al3C2 units and ZrC blocks in its structure, and the close oxygen affinity of Zr and Al.

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