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.

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.

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.

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.

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.

scholarly journals Mechanism and kinetics of the oxidation of synthetic α-NiS

2008 ◽  
Vol 73 (2) ◽  
pp. 211-219 ◽  
Author(s):  
Nada Strbac ◽  
Dragana Zivkovic ◽  
Ivan Mihajlovic ◽  
Boyan Boyanov ◽  
Zivan Zivkovic
Keyword(s):  
Activation Energy ◽  
Oxidation Process ◽  
Second Stage ◽  
Stability Diagrams ◽  
Calculation Process ◽  
Reac Tions ◽  
Desulfurization Process ◽  
Mechanism And Kinetics ◽  
Kinetic Investigations ◽  
Kinetics Of

The results of an investigation of the mechanism and kinetics of the oxidation process of synthetic ?-NiS are presented in this paper. The mechanism of ?-NiS oxidation was investigated based on the comparative analysis of DTA-TG-DTG and XRD results, as well as the constructed phase stability diagrams (PSD) for the Ni-S-O system. The kinetic investigations of the oxidation process were performed under isothermal conditions (temperature range 823-1073 K). The obtained degrees of desulfurization were used in the calculation process according to the Sharp model and the kinetic parameters, inclu?ding the activation energies and the rate constants of the characteristic reac?tions, for the oxidation of ?-NiS were determined. These results enabled the formulation of a kinetic equation for the desulfurization process: -ln (1 ? ?) = = k1? = 27.89 exp(-9860/T)?, with an activation energy of 82?4 kJ mol-1, for the first stage of the process and -ln (1 ? ?) = k2? = 1.177 exp(-4810/T)?, with an activation energy of 40?2 kJ mol-1, for the second stage.

scholarly journals Oxidation Behavior of Zr-based Amorphous Alloys at 400˚- 450˚C in Air

2019 ◽  
Vol 6 (1) ◽  
pp. 24
Author(s):  
Triwikantoro Triwikantoro ◽  
Romdhoni Graha Pribadi ◽  
Fatimatul Munawaroh
Keyword(s):  
Crystallization Temperature ◽  
Amorphous Alloys ◽  
Oxidation Behavior ◽  
Intermetallic Phase ◽  
Isothermal Oxidation ◽  
Thermo Gravimetric ◽  
Parabolic Law ◽  
Thermo Gravimetric Analyzer ◽  
Kinetics Of ◽  
Dominant Phase

<em><span lang="EN-US">The study of oxidation behavior of amorphous alloys based on Zirconium with 2 variations in composition was carried out: Zr<sub>64.5</sub>Cu<sub>17</sub>Ni<sub>11</sub>Al<sub>7.5 </sub>and Zr<sub>69.5</sub>Cu<sub>12</sub>Ni<sub>11</sub>Al<sub>7.5 </sub>at temperatures of 400 - 450˚C in air. Amorphous Zr-based alloys were thermally characterized using Differential Scanning Calorimeter (DSC) to determine the crystallization temperature and glass transition temperature. The oxidation characterization was carried out using a Thermo gravimetric Analyzer (TGA) at temperatures of 400, 425, and 450˚C for 4 hours in air. The phase analysis of the oxidation product was identified using X-Ra</span><span>y Diffaction</span><span lang="EN-US"> (XRD). Based on DSC data the crystallization temperature for Zr<sub>64.5</sub>Cu<sub>17</sub>Ni<sub>11</sub>Al<sub>7.5</sub> and Zr<sub>69.5</sub>Cu<sub>12</sub>Ni<sub>11</sub>Al<sub>7.5 </sub>is 426 and 442˚C respectively. The oxidation kinetics of the two alloys follow parabolic law and the oxidation rate increases with the addition of temperature. Oxides formed during isothermal oxidation in the Zr<sub>64.5</sub>Cu<sub>17</sub>Ni<sub>11</sub>Al<sub>7.5 </sub>and Zr<sub>69.5</sub>Cu<sub>12</sub>Ni<sub>11</sub>Al<sub>7.5</sub> alloys are t-ZrO<sub>2</sub> (tetragonal) as the dominant phase and ZrO<sub>2</sub> (monoclinic) and CuO as the minor phase. The intermetallic phase is also formed in both samples, t-Zr<sub>2</sub>Ni and Zr<sub>2</sub>Cu.</span></em>

High-Temperature Thermal Cyclic Oxidation Behavior of Wide-Gap Brazed IN738 Superalloy

2008 ◽  
Vol 47-50 ◽  
pp. 894-897
Author(s):  
Yong Hwan Kim ◽  
K.T. Kim
Keyword(s):  
Weight Loss ◽  
Metal Powder ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Filler Metal ◽  
Parabolic Law ◽  
Wide Gap ◽  
Kinetics Of ◽  
In738 Alloy ◽  
Obvious Weight Loss

The microstructure and thermal cyclic oxidation resistance of the wide-gap region brazed with different filler metal powder (BNi-3 and DF 4B) comparing with that of Ni-based IN738 alloy were investigated. The microstructure characterization showed that Cr borides with a blocky morphology were existed in the brazed region in both filler metal powder. The normalized weight gain with cyclic oxidation showed that weight loss of the specimen brazed with BNi-3 filler metal occurred after 600 cycles. However, the specimen brazed with DF 4B filler metal had no obvious weight loss until 700 cycles. It was observed that the oxidation kinetics of the all oxidized specimens followed the quasi-parabolic law, and the oxide layer was mainly composed of NiO, Al2O3 and NiCr2O4.

Oxidation Behavior of Ni3Al-8Cr-0.1B Alloy Containing Zr Addition

1988 ◽  
Vol 133 ◽  
Author(s):  
Guo Jiangting ◽  
Sun Chao ◽  
Li Hui ◽  
Guan Hengrong
Keyword(s):  
Phase Transformation ◽  
Weight Gain ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Surface Zone ◽  
Tree Roots ◽  
Parabolic Law ◽  
Zr Addition ◽  
Kinetics Of ◽  
Zirconium Addition

ABSTRACTThe isothermal oxidation behavior of Ni3A1 + 8Cr + 0.1B alloy containing zirconium addition was studied over a temperature range 850 to 1150°C and for periods up to 100 h. The results show that isothermal oxidation kinetics of the alloys at various temperatures obey a parabolic law. The addition of zirconium to Ni3A1-8Cr-0.1B alloy improves oxidation resistance at 850 to 950°C. However, the additive results in a considerable weight gain at 1050 to 1150°C. The structure of scale and phase transformation of the surface zone beneath the scale have been investigated. The addition of zirconium leads to the formation of adherent scale at all temperatures, since the internal oxides, like “tree roots” between the oxide scale and the substrate, are developed during oxidation.

The Isothermal Oxidation Behavior of Ti2AlN and Ti2AlN/TiN in Air

2011 ◽  
Vol 306-307 ◽  
pp. 808-813 ◽  
Author(s):  
Ming Yan ◽  
Yan Lin Chen ◽  
Ying Chang ◽  
Jiu Xin Jiang ◽  
Bing Chu Mei
Keyword(s):  
Oxidation Behavior ◽  
Single Phase ◽  
Oxidation Process ◽  
Isothermal Oxidation ◽  
Second Step ◽  
Outward Diffusion ◽  
Parabolic Law ◽  
Oxygen Oxidation ◽  
Better Than ◽  
Oxidation Behaviors

The isothermal oxidation behaviors at 800-1000°C for 20h in air of bulk Ti2AlN and Ti2AlN/TiN were investigated by TG, XRD and SEM coupled with EDS. The oxidation behaviors generally follow the parabolic law. The activation energies of Ti2AlN and Ti2AlN/TiN composite are 614.93 KJ∙mol-1and 541.35 KJ∙mol-1respectively. The antioxidation property of Ti2AlN/TiN composite is better than Ti2AlN. Oxidation process of single-phase Ti2AlN is composed by the outward diffusion of Al3+and Ti4+, and inward diffusion of oxygen. Oxidation process of Ti2AlN/TiN composite consists of two parts: firstly, the oxidation of TiN, the oxidation temperature is 500 °C; the second step is the oxidation of Ti2AlN, carried out mainly in the 800-1000 °C.

Oxidation of Zr2[Al(Si)]4C5 and Zr3[Al(Si)]4C6 in air

2008 ◽  
Vol 23 (12) ◽  
pp. 3339-3346 ◽  
Author(s):  
L.F. He ◽  
Y.W. Bao ◽  
M.S. Li ◽  
J.Y. Wang ◽  
Y.C. Zhou
Keyword(s):  
Oxidation Behavior ◽  
Oxidation Products ◽  
Oxide Scales ◽  
Duplex Structure ◽  
Compact Layer ◽  
Long Period ◽  
Parabolic Law ◽  
Initial Stage ◽  
Kinetics Of ◽  
Better Than

The oxidation behavior of Zr2[Al(Si)]4C5 and Zr3[Al(Si)]4C6 in air has been investigated. The oxidation kinetics of bulk Zr2[Al(Si)]4C5 and Zr3[Al(Si)]4C6 at 900–1300 °C generally follow a parabolic law at a very short initial stage and then a linear law for a long period with the activation energy of 237.9 and 226.8 kJ/mol, respectively. The oxide scales have a duplex structure, consisting of mainly an outer porous layer of ZrO2, Al2O3, and aluminosilicate/mullite, and a thin inner compact layer of these oxides plus remaining carbon. The oxidation resistance of Zr2[Al(Si)]4C5 and Zr3[Al(Si)]4C6 has been improved compared with Zr2Al3C4, and is much better than ZrC due to larger fraction of protective oxidation products, Al2O3 and aluminosilicate/mullite.

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