High Temperature Corrosion of Fe-Cr, Fe-Al, Fe-Si and Fe-Si-Al Alloys in CO2-H2O Gases

2010 ◽  
Vol 654-656 ◽  
pp. 1948-1951 ◽  
Author(s):  
Thomas Gheno ◽  
Huan Li ◽  
Jian Qiang Zhang ◽  
David J. Young
Keyword(s):  
Internal Oxidation ◽  
Oxide Scales ◽  
Al2o3 Layer ◽  
Oxidation Rates ◽  
Cr Content ◽  
Corrosion Rates ◽  
Parabolic Kinetics ◽  
Wet Gas ◽  
Combustion Technology ◽  
Slow Growing

Iron and model alloys containing 2.25, 9, and 20 wt% Cr, 2, 4 and 6 wt% Al, 1, 2 and 3 wt% Si, and dilute Fe-Si-Al ternaries were reacted in dry and wet Ar-CO2 gases at 800°C. External oxide scales grew on Fe according to fast, linear kinetics in dry CO2. Additions of H2O accelerated the reaction until steady-state parabolic kinetics were achieved. High Cr content alloys developed slow-growing chromium-rich oxide scales. Dry CO2 mixtures produced faster rates than wet gas mixtures. Lower Cr alloys developed thicker iron oxide scales, featuring cavities, cracks and poor adherence, and sustained internal oxidation. The presence of H2O led to even higher oxidation rates. Aluminium additions to iron of up to 4 wt% provided no protection, but instead caused internal oxidation. A level of 6 wt% significantly slowed oxidation by forming a continuous Al2O3 layer. Silicon additions had little effect, apart from promoting internal oxidation. However, simultaneous alloying with aluminium and silicon strongly depressed corrosion rates. The effectiveness of different alloy additions is discussed, along with the effects of water vapour and carbon activities, in the context of oxyfuel combustion technology.

scholarly journals The Cyclic Oxidation and Hardness Characteristics of Thermally Exposed Titanium Prepared by Inductive Sintering-Assisted Powder Metallurgy

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 104
Author(s):  
Fahamsyah H. Latief ◽  
El-Sayed M. Sherif ◽  
Agus S. Wismogroho ◽  
Wahyu B. Widayatno ◽  
Hany S. Abdo
Keyword(s):  
Powder Metallurgy ◽  
Single Phase ◽  
Oxide Scales ◽  
Cyclic Tests ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxidation Rates ◽  
Parabolic Law ◽  
Kinetics Of ◽  
Hardness Values

The oxidation and hardness of thermally exposed titanium (Ti) prepared using inductive sintering-assisted powder metallurgy was evaluated through cyclic tests in air at 700–900 °C for 100 h (5 cycles). In general, the oxidation kinetics of the Ti samples followed the parabolic law and their oxidation rates increased with increasing oxidation temperatures. The rutile form of titanium dioxide (TiO2) was detected by X-ray diffraction in the oxide scales after oxidation at 700 °C and 900 °C. Furthermore, the TiO2 grain size and thickness were significantly influenced by an increase in the oxidation temperature. Lastly, the formation of rutile as a single-phase on the surface of oxidized Ti enhanced the hardness of the oxide scales, whereas the substrate had lower hardness values than the oxide scales due to diffusion of Ti atoms at the surface to form the TiO2 oxide scales.

Oxidation of Metallic Materials in Simulated CO2/H2O-Rich Service Environments Relevant to an Oxyfuel Plant

2011 ◽  
Vol 696 ◽  
pp. 194-199 ◽  
Author(s):  
W.Joe Quadakkers ◽  
T. Olszewski ◽  
J. Piron-Abellan ◽  
Vladimir Shemet ◽  
Lorenz Singheiser
Keyword(s):  
Water Vapour ◽  
Base Alloy ◽  
Gas Mixtures ◽  
Oxidation Behaviour ◽  
Oxide Scales ◽  
Martensitic Steels ◽  
Air Oxidation ◽  
Oxidation Rates ◽  
Service Environments ◽  
Nickel Base

In the present study the oxidation behaviour of a number of candidate alloys for heat exchanging components was investigated in model gas mixtures containing high amounts of CO2 and/or water vapour in the temperature range 550-700°C up to exposure times of 1000 h. During exposure in Ar/CO2 and Ar/CO2/H2O base gas mixtures at 550-650°C the oxidation rates and scale compositions of martensitic 9-12%Cr steels were similar to those previously observed in steam environments. Thin and protective Cr-rich oxide scales which are commonly found during air oxidation was observed locally on the specimens surfaces after oxidation in Ar-(1-3%)O2-CO2. The tendency for protective chromia base scale formation increased when 3% oxygen was added, especially for the 12%Cr steel. When iron base oxide scales were formed on the metal surface, the martensitic steels tended to exhibit carburisation whereby the extent was reduced by increasing the water vapour and oxygen contents. All three studied austenitic alloys exhibited very slow scale growth rates at 550°C, however, at and above 600°C the steels with lower Cr content started to form two-layered iron rich surface oxide scales whereby the outer oxide was prone to spallation upon thermal cycling. The high-Cr austenitic steel 310N and the nickel base alloy 617 formed very thin, Cr-rich oxide scales at all used test temperatures and atmospheres. For those two materials the oxidation behaviour in gases containing water vapour in combination with intentionally added oxygen was affected by formation of volatile chromium oxyhydroxide.

Altering the Oxidation Resistance of Iron Via ion Beam Alloying

1994 ◽  
Vol 373 ◽  
Author(s):  
Ivan H. Murzin ◽  
Donald I. Potter
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Vapor Deposition ◽  
Rate Constants ◽  
Oxidation Behavior ◽  
Ion Beam ◽  
Ion Beam Mixing ◽  
Oxidation Rates ◽  
Parabolic Kinetics ◽  
Transmission Electron

AbstractFe-Cr, Fe-Y and Fe-Cr-Y surface alloys were produced by direct ion implantation, ion beam mixing, and combinations of implantation and vapor deposition. The influence of these treatments on the oxidation behavior of iron was investigated in 1 atm. of oxygen at 520°C. The oxidation rates were less in all the ion beam alloyed iron samples than in untreated iron. The oxidation follows parabolic kinetics in most cases, with the rate constants, Kp, in the range (3-8)×10−6 mg2cm−4 sec−l versus 2.2×10−5 mg2 cm−4 sec−1 for untreated iron. Yttrium fluences between 5×1014 and 5×lO15 cm−2 did not alter the microstructures of iron significantly. However, fluences of 1×1016, 3×1016, 5x1016 and 1x1017 cm−2 caused the crystalline structure of iron to be replaced by an amorphous phase. The presence of this phase was demonstrated with selected area channeling patterns and transmission electron microscopy.

Comparison between Current Methods for Measurement of High Temperature Corrosion of Boiler Steels in Steam Environments

2008 ◽  
Vol 595-598 ◽  
pp. 323-332
Author(s):  
V. Lépingle ◽  
G. Louis ◽  
Dorian Allue
Keyword(s):  
Pure Water ◽  
High Temperature Corrosion ◽  
Measurement Methods ◽  
Oxide Scales ◽  
Scale Growth ◽  
Oxidation Processes ◽  
Corrosion Rates ◽  
Uniform Scale ◽  
Wrong Prediction ◽  
Boiler Steels

Thirteen boiler steels were exposed in pure water vapour at 650°C for 32 weeks (5,376h). To assess their oxidation kinetics, four current discontinuous measurement methods were used. The results show that, for the T91 steel, the different investigated methods give similar results; for the other steels, the evaluation of corrosion rates depends on the method used. Thus their lifetime prediction is often over- or undervalued. This is mainly the case for steels with scales that spall off and/or steels with a non-uniform scale growth (localised oxide nodules for a rather long exposure time). This is particularly true in the steam environments which lead to oxidation processes with oxide scales different from those in dry air or oxygen. So the use of steam oxidation data and/or relations among them has to be done with caution because it can lead to a wrong prediction of performance.

Predicting Internal Oxidation: Building on the Wagner Model

2011 ◽  
Vol 696 ◽  
pp. 1-11 ◽  
Author(s):  
David J. Young
Keyword(s):  
Internal Oxidation ◽  
Binary Alloy ◽  
Reactive Component ◽  
Internal Interface ◽  
Parabolic Kinetics ◽  
Internal Precipitation ◽  
Diffusion Effects ◽  
Multiple Oxidants ◽  
Low Solubility ◽  
Dilute Alloy

Wagner’s 1959 diffusion model of the internal oxidation process provided a method of predicting the rate at which a binary alloy was penetrated by dissolved oxygen as it precipitated the more reactive (but dilute) alloy component. Parabolic kinetics were predicted to depend on oxygen permeability in the unreacted alloy solvent and also, in cases where the reactive component was sufficiently mobile, the diffusion coefficient of the latter. The model has proven very successful, but is restricted to single oxidant-binary alloy systems, in which the precipitated oxide has extremely low solubility. This paper reviews recent results on a number of internal precipitation processes which cannot be described with the Wagner theory. These include formation of low stability carbides and nitrades; internal precipitation driven by multiple oxidants; the templating effects of prior precipitates on subsequently formed corrosion products; cellular precipitation morphologies; internal interface diffusion effects; volume changes in the reaction zone and the effects upon them of simultaneous external scaling.

Oxidation behavior of aluminum nitride

1993 ◽  
Vol 8 (3) ◽  
pp. 565-572 ◽  
Author(s):  
A. Bellosi ◽  
E. Landi ◽  
A. Tampieri
Keyword(s):  
Reaction Mechanisms ◽  
Oxidation Behavior ◽  
Surface Reaction ◽  
Oxidation Process ◽  
Reaction Products ◽  
Oxidation Rates ◽  
Parabolic Kinetics ◽  
Controlling Mechanism ◽  
Outward Migration ◽  
Thermal Stability Of

The evaluation of the thermal stability of three different fully dense AlN materials in the temperature range of 600 °C to 1400 °C in air indicates the strong effect of the starting composition on the oxidation process. The oxidation resistance of pure AlN and Y2O3-doped AlN was found to be good up to ≍1350 °C. The kinetics are linear (1100 ≤ T ≤ 1400 °C) and the process is governed by a surface reaction that gives rise to the formation of a porous, nonprotective oxide scale, where Al2O3 and Y-aluminates (i.e., AlN–Y2O3) have been found as crystalline reaction products. For AlN-CaC2, higher oxidation rates indicate that the outward migration of Ca modifies the reaction mechanisms. Linear kinetics in the range 1100 ≤ T ≤ 1200 °C are followed by parabolic kinetics at higher temperatures (T > 1250 °C); with regard to the latter behavior, an activation energy of 160 kJ/mole could indicate the diffusion of oxygen through the oxidation scale as the rate-controlling mechanism.

High-Temperature Oxidation of Ti3Al0.7Si0.3C2 Carbide at 1100 and 1200°C in Air

2015 ◽  
Vol 775 ◽  
pp. 176-179
Author(s):  
Dong Bok Lee
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Mixed Oxides ◽  
Oxide Scales ◽  
Temperature Oxidation ◽  
Layered Oxide ◽  
Oxidation Rates

The oxidation of Ti3Al0.7Si0.3C2 carbide at 1100 and 1200°C in air for up to 50 h resulted in the formation of rutile-TiO2, α-Al2O3 and SiO2. Depending on the location of the carbide, either thin, dense, single layered oxide scales or thick, porous, bi-layered oxide scales formed. The single layered scales consisted primarily of protective Al2O3. The bi-layered scale consisted primarily of an outer (TiO2+Al2O3)-mixed oxides, and an inner TiO2-rich, (Al2O3+SiO2)-containing oxides. Since the testing temperatures were high, the oxidation rates varied much depending on the location of the carbide.

Evaluation on the High-Temperature Oxidation Behavior of HP Steam Turbine Rotor Materials

2013 ◽  
Vol 750-752 ◽  
pp. 420-425
Author(s):  
Li Bin Niu ◽  
Takuya Shibata
Keyword(s):  
High Temperature ◽  
Steam Turbine ◽  
High Temperature Oxidation ◽  
Turbine Rotor ◽  
Oxide Scales ◽  
Temperature Oxidation ◽  
Steam Turbine Rotor ◽  
Oxidation Rates ◽  
High Temperature Oxidation Behavior ◽  
Oxidation Behaviors

High-temperature oxidation behaviors of super-clean 9CrMoV steel and 1CrMoV steel for HP steam turbine rotor materials were investigated. The super-clean 9CrMoV steel showed a superior high-temperature oxidation resistance with very small oxidation rates even though at 630°C, because the oxidation was restrained by the Cr-oxides formed near the base metal. On the other hand, the oxide scales formed on the 1CrMoV steel were composed of Fe-oxides, and the oxidation rate increased remarkably at the temperatures above 610°C.

scholarly journals Effect of Al on Microstructure and Properties of Hot-Rolled 2205 Dual Stainless Steel

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Qian Meng ◽  
Peiqing La ◽  
Liang Yao ◽  
Peng Zhang ◽  
Yupeng Wei ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steels ◽  
Volume Fraction ◽  
Elongation Rate ◽  
Al Content ◽  
Oxidation Rates ◽  
Corrosion Rates ◽  
The Matrix ◽  
Hot Rolled ◽  
Oxidation And Corrosion

The microstructure, mechanical properties, oxidation, and corrosion resistance of 2205 stainless steels without and with Al in a range of 0.5 to 2.5 wt.% were investigated in this paper. The results showed that the matrix phase transformed from austenite to ferrite. The volume fraction of the ferrite in the steels decreased at first and then increased and was the lowest in the steel with 0.5 wt.% Al. Most of the Al was dissolved in the ferrite and austenite phases in the steels. The ultimate tensile strength and elongation rate of the steels increased at first and then decreased with the increasing Al content, with the highest values in the steel with 0.5 wt.% Al. The yield strength of the steels slightly increased from 544 to 607 MPa due to the addition of Al. The oxidation rates of the steels with Al were much lower than that of the steel without Al, and the rate of the steel with 1.5 wt.% Al was the lowest, approximately 10 times lower than that of the steel without Al. The corrosion rates of the steels with 0.5 and 1.0 wt.% Al were slightly higher than that of the alloy without Al. In general, the steel with 1 wt.% Al had optimal properties.

scholarly journals Long-time Oxidation of Ti3(Al,Si)C2 Carbides at 400-800 oC

2020 ◽  
Vol 58 (3) ◽  
pp. 182-189 ◽  
Author(s):  
Junhee Hahn ◽  
Sang Whan Park ◽  
Dong Bok Lee
Keyword(s):  
Grain Size ◽  
Volume Expansion ◽  
Oxidation Behavior ◽  
Titanium Oxides ◽  
Oxide Scales ◽  
Oxidation Condition ◽  
Oxidation Rates ◽  
The Matrix ◽  
Long Time ◽  
Porous Oxide

Quarternay carbides of Ti<sub>3</sub>Al<sub>x</sub>Si<sub>1-x</sub>C<sub>2</sub> (x=0.3, 0.5, and 0.7) were oxidized at 400, 600, and 800 °C for 0.5-6 months in order to study their long-time oxidation behavior in air. When they were oxidized at 400-600 <sup>o</sup>C for 0.5-3 months, oxidation proceeded relatively slowly with moderate weight gains. However, further oxidation at 400-600 <sup>o</sup>C for 6 months resulted in the oxidation-induced microcracking of oxide scales due to large volume expansion and large stress induced owing to the formation of Al<usb>2</sub>O<sub>3</sub>, SiO<sub>2</sub>. TiO<sub>3</sub>, and TiO<sub>2</sub> in oxide scales. However, at 800 <sup>o</sup>C, microcracking of oxide scales, which could lead to pulverization of Ti<sub>3</sub>Al<sub>x</sub>Si<sub>1-x</sub>C<sub>2</sub>, did not occur due to stress relaxation in oxide scales. Instead, at 800 <sup>o</sup>C, Ti<sub>3</sub>Al<sub>x</sub>Si<sub>1-x</sub>C<sub>2</sub> oxidized rapidly to form thick, somewhat porous oxide scales, which consisted primarily of an outer TiO<sub>2</sub> layer with some Al<sub>2</sub>O<sub>3</sub>, an intermediate Al<sub>2</sub>O<sub>3</sub> layer with some TiO<sub>2</sub>, and an inner TiO<sub>2</sub> layer with some (SiO<sub>2</sub>+Al<sub>2</sub>O<sub>3</sub>). The overall longtime oxidation resistance of Ti<sub>3</sub>Al<sub>x</sub>Si<sub>1-x</sub>C<sub>2</sub> at 400-800 °C was considered to be poor. Factors that determined the oxidation rates of Ti<sub>3</sub>Al<sub>x</sub>Si<sub>1-x</sub>C<sub>2</sub> were; (1) How fast titanium oxidized to semi-protective titanium oxides, (2) How fast Al and Si oxidized to Al<sub>2</sub>O<sub>3</sub> and SiO<sub>2</sub> barrier oxides, and (3) Whether oxidation-induced microcracking occurred in oxide scales or not. The ratio of Al/Si in Ti<sub>3</sub>Al<sub>x</sub>Si<sub>1-x</sub>C<sub>2</sub> and the matrix grain size were apparently not dominant factors, because the basic oxidation mode of Ti<sub>3</sub>Al<sub>0.3</sub>Si<sub>0.7</sub>C<sub>2</sub>, Ti<sub>3</sub>Al<sub>0.5</sub>Si<sub>0.5</sub>C<sub>2</sub>, and Ti<sub>3</sub>Al<sub>0.7</sub>Si<sub>0.3</sub>C<sub>2</sub> was similar under the identical oxidation condition.

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