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.

The Cyclic Oxidation Behavior of Ti2AlN and Ti2AlN/TiN Composites

2011 ◽  
Vol 393-395 ◽  
pp. 420-423
Author(s):  
Ming Yan ◽  
Yan Lin Chen ◽  
Ying Chang ◽  
Jiu Xin Jiang
Keyword(s):  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Single Phase ◽  
Oxidation Process ◽  
Second Step ◽  
Outward Diffusion ◽  
Shock Resistance ◽  
Oxygen Oxidation ◽  
Better Than ◽  
Oxidation Behaviors

The cyclic oxidation behavior of Ti2AlN and Ti2AlN/TiN composites were investigated at 800°C, 900°C and 1000°C. The phase composition, thickness of oxidation layer and element content of samples were investigated by XRD and SEM coupled with EDS. The cyclic oxidation behaviors generally follow a parabolic rate law, with good thermal shock resistance. 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 in the 800-1000 °C.

Isothermal Oxidation Behavior of a New Directionally Solidified Ni-Base Superalloy in Air at Different Temperature

2010 ◽  
Vol 654-656 ◽  
pp. 538-541
Author(s):  
Lei Wang ◽  
Yan Huang ◽  
Zhuo Zhao ◽  
Yang Liu ◽  
Jian Tao Wu ◽  
...  
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Oxidation Behaviour ◽  
Diffusion Activation Energy ◽  
Directionally Solidified ◽  
Temperature Range ◽  
Parabolic Law ◽  
Diffusion Activation ◽  
Base Superalloy

The isothermal oxidation behaviour under static atmosphere of a new directionally solidified Ni-base superalloy was investigated. The results showed that the oxidation kinetics curves of the alloy follow parabolic law in the temperature range of 750-950°C. The diffusion activation energy Q is to be about 244.86 kJ•mol-1 and the oxidation within this temperature range is mainly controlled by Cr3+ diffusion among Cr2O3 oxidation film. The oxidation resistance grade of the alloy is perfect anti-oxidation within 750-850°C, and anti-oxidation within 900-950°C. The oxidation film can be divided into TiO2, Cr2O3+TiTaO4+NiCr2O4, Al2O3 and TiN layers, from the surface to inside. Priority oxidation and the inside oxidation of Al are considered with the oxidation of Ti and the depletion of Cr, and it is the key point for the improving of oxidation resistance.

High Temperature Oxidation Behavior of TiNi Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 853-856 ◽  
Author(s):  
J.H. Ko ◽  
Dong Bok Lee
Keyword(s):  
Oxidation Behavior ◽  
Oxidation Mechanism ◽  
Tini Alloy ◽  
Oxide Scales ◽  
Temperature Oxidation ◽  
Outward Diffusion ◽  
Ni Alloy ◽  
Embedded Particles ◽  
High Temperature Oxidation Behavior ◽  
Better Than

The oxidation behavior of the equiatomic TiNi alloy was investigated at 600-900oC. The oxidation resistance of the TiNi alloy was better than the pure Ti alloy, but worse than the pure Ni alloy. The oxide scales consisted of TiO2, with and without embedded particles of TiNiO3 and Ni. The subscale matrix phase was (TiNi3+TiNi) at 600oC, TiNi3 at 700oC, (Ni+TiNi3) at 800oC, and Ni at 900oC. Oxidation was mainly governed by the inward diffusion of oxygen, and the outward diffusion of Ti and a bit of Ni. Detailed microstructures and the oxidation mechanism are proposed.

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 Behaviors of Inconel 740H in Air and Dynamic Steam

2016 ◽  
Vol 35 (7) ◽  
pp. 697-704
Author(s):  
Jintao Lu ◽  
Zhen Yang ◽  
Songqian Xu ◽  
Haiping Zhao ◽  
Y. Gu
Keyword(s):  
Surface Roughness ◽  
Oxidation Product ◽  
Oxidation Rate ◽  
Power Plants ◽  
Oxidation Behavior ◽  
Test Environment ◽  
Parabolic Law ◽  
Oxide Particles ◽  
Pure Steam ◽  
Oxidation Behaviors

AbstractInconel 740H alloy is a candidate material for 700°C advanced ultra-supercritical (A-USC) coal-fired power plants application as superheater/reheater tube. In this work, oxidation behavior of Inconel 740H alloy was studied in static air at 750°C and 850°C, and in dynamic pure steam at 750°C, respectively. The alloy was oxidized approximately following a parabolic law in three test environment. In the static air, the oxidation rate at 850°C was about 50 times of that at the 750°C. More NiCrMn spinal and TiO2 were detected after oxidation at 850°C. Cr2O3, however, was the main oxidation product at 750°C. In the pure steam, Cr2O3 was still the main oxidation product. The oxidation rate was about 2.6 times of that in static air, but the surface roughness was much smaller and edges of oxide particles were more blurred. There was no evidence of cracks or spallation in three test environments.

Improvement of oxidation-resistance of NiCrAlY coatings by application of CrN or CrON interlayer

2008 ◽  
Vol 23 (2) ◽  
pp. 341-352 ◽  
Author(s):  
W.Z. Li ◽  
Y. Yao ◽  
Q.M. Wang ◽  
Z.B. Bao ◽  
J. Gong ◽  
...  
Keyword(s):  
Diffusion Barrier ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Coating System ◽  
Effective Protection ◽  
Rapid Degradation ◽  
Crn Coating ◽  
Ion Plating ◽  
Oxidation Performance ◽  
Better Than

NiCrAlY coatings with and without CrN or CrON interlayer as diffusion barrier were deposited on superalloy DSM11 by arc ion plating (AIP). The oxidation performance of the coating systems was evaluated by isothermal oxidation tests at 1100 °C for 100 h. The element interdiffusion and oxidation behavior of the coating systems were described. It was found that the NiCrAlY coatings provided protective effect for the DSM11 substrate. However, serious interdiffusion between the coatings and substrate resulted in rapid degradation of the coatings. The addition of CrN or CrON interlayer between the coatings and substrate markedly decreased the interdiffusion. CrON interlayer performed better than CrN interlayer, which was attributed to the excellent diffusion barrier ability of Al2O3 layer formed in the interlayer at high temperature. Also, the NiCrAlY/CrON coating system exhibited more effective protection for DSM11 than the NiCrAlY/CrN coating system.

Improvement in the Oxidation Resistance of β-SiAlON Ceramics Produced from Mechanically Milled Powders

2012 ◽  
Vol 18-19 ◽  
pp. 281-290
Author(s):  
Onur Eser ◽  
S. Kurama
Keyword(s):  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Isothermal Oxidation ◽  
High Energy ◽  
Particle Sizes ◽  
Temperature Oxidation ◽  
Dry Air ◽  
Milled Powders

In the present study the oxidation behavior of β-SiAlON ceramics, which were produced from conventional and high energy mechanical milled powders, was investigated. High energy mechanically milled powders have lower particle sizes ( 130 nm) than those of conventional powders (216 nm) and fully densified at lower temperatures with less amount of additives. The amount of additive is an important parameter to improve the high temperature oxidation resistance of SiAlON ceramics. The cyclic and isothermal oxidation tests were carried out at 1300 and 1400°C in dry air environment. The weight gain of oxidized samples was measured during the oxidation process. The alteration of oxide layer was analyzed by XRD and SEM. The results indicate that oxidation resistance of the samples produced from mechanically milled powders with less amount of additive is higher than that of conventional one. Therefore, β-SiAlON ceramics which were sintered at 100°C lower temperatures with less amount of additive (3.5 wt. % Y2O3), showed a better oxidation resistance.

Oxidation Properties of Three Dimensional (3-D) Carbon Fiber Preform Coated by SiC-SiO2

2007 ◽  
Vol 280-283 ◽  
pp. 1693-1696 ◽  
Author(s):  
Peng Zhao Gao ◽  
Hong Jie Wang ◽  
Zhi Hao Jin
Keyword(s):  
Carbon Fiber ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Three Dimensional ◽  
Isothermal Condition ◽  
Gas Diffusion ◽  
Second Step ◽  
Fiber Preform ◽  
Uniform Coating ◽  
Oxidation Properties

A SiO2-SiC coating on 3-D carbon fiber perform (raw perform) was successfully prepared through several steps. The appearance and composition of the coating/3-D carbon fiber preform (coated perform=CP) was studied through IR, XRD and SEM. The isothermal weight-loss and non-isothermal thermogravimetric (TGA) were used to study the oxidation behavior of CP. The results showed that a uniform coating on every fiber of preform was achieved and the coating adhered well with fiber. The oxidation process of CP in isothermal condition was reaction-controlled in the first step, gas diffusion and reaction-controlled in the second step. The characteristic of the oxidation process in non-isothermal condition was self-catalytic.

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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