Void Formation in the Growing Scale Induced by the Divergence of the Diffusive Ionic Flux in High Temperature Oxidation of Metals

2009 ◽  
Vol 289-292 ◽  
pp. 1-13 ◽  
Author(s):  
Toshio Maruyama ◽  
Mitsutoshi Ueda ◽  
Kenichi Kawamura
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Chemical Potential ◽  
Quantitative Estimation ◽  
Kinetic Equations ◽  
Void Formation ◽  
Ionic Flux ◽  
Temperature Oxidation ◽  
Ionic Fluxes ◽  
Formation Behavior

Voids are frequently generated and dispersed in oxide scales formed in high temperature oxidation of metals. The divergence of ionic flux may play an important role in the void formation in a growing scale. Kinetic equations were derived for describing chemical potential distribution, ionic fluxes and their divergence in the scale. The divergence was found to be the measure of void formation. Defect chemistry in scales is directly related to the sign of divergence and gives an indication of the void formation behavior. The quantitative estimation on the void formation was successfully applied to a growing magnetite scale in high temperature oxidation of iron at 823 K.

Void Formation in Growing Oxide Scales with Schottky Defects and P-Type Conduction

2008 ◽  
Vol 595-598 ◽  
pp. 1039-1046 ◽  
Author(s):  
Toshio Maruyama ◽  
Kojiro Akiba ◽  
Mitsutoshi Ueda ◽  
Kenichi Kawamura
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Volume Fraction ◽  
Void Formation ◽  
Oxide Scales ◽  
Temperature Oxidation ◽  
Ionic Fluxes ◽  
P Type ◽  
Type Conduction

A quantitative elucidation of the void formation in a growing scale with Schottky defects and p-type conduction during high temperature oxidation of metals. The evaluation of the divergence of ionic fluxes indicates that (1) Voids form in the scale preferentially in the vicinity of the metal/scale interface, (2) The volume of voids increases in a parabolic manner, (3) The volume fraction of voids and the scale is independent of time. The comparison between the calculation and the experimentally observed scale microstructure of NiO and CoO confirmed well the validity of the prediction.

Improvements in high temperature oxidation resistance by additions of reactive elements or oxide dispersions

1980 ◽  
Vol 295 (1413) ◽  
pp. 309-329 ◽  
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Void Formation ◽  
Temperature Oxidation ◽  
High Temperature Alloys ◽  
Actual Growth Rate ◽  
Actual Growth ◽  
Reactive Metals ◽  
Surface Scale

The improvement in oxidation resistance of high temperature alloys as a result of additions of rare earth elements, other reactive metals, or dispersions of stable oxides, has been known for many years. Two effects seem the most important: first, the adhesion between scale and alloy is markedly improved and this increases the alloy’s resistance to thermal cycling exposure; secondly, in some but not all cases the actual growth rate of the oxide is also reduced. The various models proposed to explain these phenomena are discussed in the light of currently available experimental evidence. The most significant of these involve modification to the early, transient stages of oxidation, doping of the oxide which changes its transport properties, mechanical keying of the surface scale to the substrate by the formation of intrusions of oxide penetrating into the alloy and the elimination of void formation at the alloy-scale interface. The efficacies of the various beneficial additions are compared.

Ionic Transport under Chemical Potential Gradients - Kinetic Demixing and Decomposition in Metal Oxides and Scale Growth in High-Temperature Oxidation

2011 ◽  
Vol 696 ◽  
pp. 28-33
Author(s):  
Manfred Martin
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Elevated Temperatures ◽  
Chemical Potential ◽  
Transport Processes ◽  
Temperature Oxidation ◽  
X Ray ◽  
Kinetic Decomposition ◽  
Potential Gradients

In oxides which are exposed to thermodynamic potential gradients, transport processes of the mobile components occur. These transport processes and the coupling between different processes are not only of fundamental interest, but are also the origin of degradation processes, such as kinetic demixing, kinetic decomposition, and changes in the morphology of the material. The kinetics of high temperature oxidation processes of metals can be studiedin situby X-ray absorption spectroscopy (XAS), optical microscopy and X-ray diffraction (XRD) at elevated temperatures and defined oxygen partial pressures. As an example, thein situXAS investigation of the oxidation of cobalt, forming layers of CoO and Co3O4, will be discussed.

Void formation in INCONEL MA-754 by high temperature oxidation

1986 ◽  
Vol 17 (1) ◽  
pp. 151-162 ◽  
Author(s):  
Alan H. Rosenstein ◽  
John K. Tien ◽  
William D. Nix
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Void Formation ◽  
Temperature Oxidation

scholarly journals Observation On Void Formed In Oxide Scale Of Fe-Cr-Ni Alloy At 1073k In Dry And Humid Environments

2012 ◽  
Vol 12 (5) ◽  
Author(s):  
Akbar Kaderi ◽  
Ahmad Zaki Mohd Zainal ◽  
Mohd Hanafi Ani ◽  
Raihan Othman
Keyword(s):  
High Temperature ◽  
Oxide Scale ◽  
High Temperature Oxidation ◽  
Volume Fraction ◽  
Void Formation ◽  
Cross Sectional ◽  
Temperature Oxidation ◽  
Humid Environment ◽  
Ni Alloy ◽  
The Cross

Void formation in oxide scale during high temperature oxidation is a common phenomenon. Over a long period of time voids will affect the mechanical property of scales by influencing the cracking and spalling. Voids formed in dry environment are different than that of formed in humid environment. With the presence of water vapor in humid environment the formation of void will increase, thus greater number of void compared to that in dry environment. Fe-Cr-Ni alloy samples were exposed isothermally at 1073 K in air (P_(O_2 )= 0.21atm = 2.1×?10?^(5 )Pa) and  humid (air + steam) environments. XRD analysis done to all samples confirms that Fe2O3, Fe3O4, NiCr2O4, FeCr2O4, Cr2O3 and NiO phases exist in the scale. EDX analysis done shows varying compositions of Fe,Cr,Ni and O in outer and inner oxide scale, oxide scale/metal interface and metal. Field emission scanning electron microscope (FE-SEM) was used to investigate voids formed in the cross sections of the oxidized samples. Volume fraction of voids in the oxide scale was calculated in accordance to the cross sectional area fraction of voids in the scale. It shows that Fe-Cr-Ni alloy samples exposed in humid environment has as high as 71% more voids than that exposed in dry environment. It is concluded that the humid environment increased the number of void formed in the oxide scale, thus facilitates the exfoliation of protective scale during the high temperature oxidation. ABSTRAK: Pembentukan gelembung udara di dalam lapisan oksida ketika proses pengoksidaan di suhu tinggi merupakan satu fenomena biasa. Pada satu jangka masa yang panjang gelembung-gelembung ini akan memberi kesan kepada sifat mekanikal oksida dengan mempengaruhi pembentukan keretakan dan pengelupasan oksida. Gelembung udara yang terbentuk di dalam persekitaran kering berbeza daripada yang terbentuk di dalam persekitaran lembap. Dengan adanya wap air, pembentukan gelembung akan bertambah berbanding yang terbentuk di dalam persekitaran kering. Sampel aloi Fe-Cr-Ni telah dioksidakan secara isoterma pada suhu 1073 K di dalam udara (P_(O_2 )= 0.21atm = 2.1×?10?^(5 )Pa) dan lembap (udara + wap air). Analisis Pembelauan Sinar – X (XRD) kepada semua sampel menunjukkan oksida yang terbentuk ialah Fe2O3, Fe3O4, NiCr2O4, FeCr2O4, Cr2O3 dan NiO. Analisis Penyebaran Tenaga Sinar – X (EDX) menunjukkan komposisi Fe, Cr, Ni dan O yang berubah - ubah di lapisan oksida luar dan dalam, oksida/ antara muka logam dan logam. Mikroskop Imbasan Elektron-Pancaran Medan (FE-SEM) digunakan untuk meneliti gelembung di dalam oksida pada keratan rentas sampel. Pecahan isi padu gelembung yang terbentuk pada oksida dikira dengan merujuk kepada pecahan luas keratan rentas pada oksida tersebut. Sampel aloi Fe-Cr-Ni yang dioksidakan di dalam persekitaran lembap mempunyai kandungan gelembung udara 71% lebih banyak berbanding dengan yang dioksidakan di dalam persekitaran kering. Kesimpulannya persekitaran lembap meningkatkan bilangan gelembung yang terbentuk di dalam lapisan oksida, sekaligus memudahkan pengelupasan oksida semasa pengoksidaan suhu tinggi.KEYWORDS: high temperature oxidatio;, Fe-Cr-Ni alloy; void formation; quantitative analysis of voi;, dry environment; humid environment

Behaviour of copper during the high temperature oxidation of steels produced by the electric furnace route

2003 ◽  
Vol 100 (1) ◽  
pp. 73-82
Author(s):  
Y. Riquier ◽  
D. Lassance ◽  
I. Li ◽  
J. M. Detry ◽  
A. Hildenbrand
Keyword(s):  
High Temperature ◽  
Electric Furnace ◽  
High Temperature Oxidation ◽  
Temperature Oxidation
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