scholarly journals Consequences of Different Mechanical Surface Preparation of Ni-Base Alloys during High Temperature Oxidation

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3529
Author(s):  
Wojciech J. Nowak ◽  
Krzysztof Siemek ◽  
Kamil Ochał ◽  
Barbara Kościelniak ◽  
Bartek Wierzba
Keyword(s):  
Surface Roughness ◽  
High Temperature ◽  
High Temperature Oxidation ◽  
Surface Preparation ◽  
Optical Emission ◽  
Surface Region ◽  
Emission Spectrometry ◽  
Air Oxidation ◽  
Temperature Oxidation ◽  
Near Surface

The influence of surface roughness on its high temperature oxidation for an Ni-base superalloy was studied using laser profilometry, atomic force microscopy, mass change measurements, glow-discharge optical emission spectrometry, scanning electron microscopy, X-ray diffraction, and positron annihilation methods. The isothermal and cyclic air oxidation tests were performed at 1000 °C and showed dependence of oxidation behavior on surface roughness. Smoother surfaces oxidation resulted in the formation of a multilayered oxide scale consisting of NiO, Cr2O3, and internally oxidized Al2O3 while a rougher surface formed protective Al2O3 scale. The factors responsible for different oxidation behaviors were determined as higher concentration of vacancies and increased residual stresses in the near-surface region of studied alloys.

scholarly journals The Role of Substrate Surface Roughness on in-Pack Aluminization Kinetics of Ni-Base Superalloy

2020 ◽  
Vol 4 (1) ◽  
pp. 15 ◽  
Author(s):  
Wojciech J. Nowak ◽  
Małgorzata Tomków ◽  
Patrycja Wierzba ◽  
Kamil Gancarczyk ◽  
Bartek Wierzba
Keyword(s):  
Surface Roughness ◽  
High Temperature ◽  
High Temperature Oxidation ◽  
Substrate Surface ◽  
Surface Preparation ◽  
Temperature Oxidation ◽  
Diffusion Layers ◽  
Substrate Surface Roughness ◽  
Effect Of Surface

The Ni-base superalloys facing high temperature require further protection against high temperature oxidation. One of the most common methods providing high temperature oxidation resistance is the production of aluminide layers (NiAl-coatings). It is known that the thickness of produced diffusion layer can be controlled by the temperature and time of aluminization process. However, no research on the effect of surface roughness on aluminization kinetics was conducted so far. Then, to elucidate the effect of surface roughness on aluminization kinetics, diffusion layers were obtained by an in-pack aluminization method on the IN 617 alloy with differently prepared surfaces, namely polished, ground using 220 grit SiC paper and 80 grit SiC paper. The obtained results revealed that different surface preparation does not affect the chemical and phase composition of produced layers. However, a strong influence of surface preparation method on aluminide layers thicknesses was observed. Namely, it was found that the increase in substrate surface roughness results in an increase of aluminization kinetics. The dependence between surface roughness and thickness of aluminide layers was found to be logarithmic. Moreover, it was found that the aluminization kinetics is influenced, especially at early stages of the aluminization process.

scholarly journals Effect of Surface Roughness on Oxidation Resistance of Stainless Steel AISI 316Ti During Exposure at High Temperature

2020 ◽  
Vol 29 (12) ◽  
pp. 8060-8069
Author(s):  
Wojciech J. Nowak
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Oxidation Resistance ◽  
Surface Preparation ◽  
Surface Region ◽  
Lower Surface ◽  
Near Surface ◽  
Steel Aisi ◽  
Kinetics Of ◽  
Effect Of Surface

AbstractIn the present work, the influence of surface roughness on oxidation kinetics of AISI 316Ti stainless steel and its consequences in term of oxidation resistance were investigated. Namely, the effect of surface roughness on oxidation resistance was evaluated during different types of cyclic oxidation tests at 900 and 1000 °C. The obtained results revealed that alloy possessing higher surface roughness showed longer lifetime compared to that with lower surface roughness. It was also found that more severe cyclic conditions suppressed the positive effect of surface roughness on sample’s lifetime. The better oxidation resistance of rougher alloy was correlated with suppressed formation of Fe-rich nodules on ground surfaces and explained by the combined effect of introduced defects in the near-surface region and possible increase in residual stresses caused by mechanical surface preparation.

Comparison of Different Fluorine Treatments for the Protection of TiAl-Alloys Against High Temperature Oxidation

2010 ◽  
Vol 638-642 ◽  
pp. 1294-1299 ◽  
Author(s):  
Alexander Donchev ◽  
Michael Schütze
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Oxidation Mechanism ◽  
Surface Region ◽  
Alumina Scale ◽  
Jet Engines ◽  
Temperature Oxidation ◽  
Tial Alloys ◽  
Long Term Stability ◽  
One Year

The oxidation resistance of TiAl-alloys can be improved by several orders of magnitude by treating the surface of the materials with small amounts of halogens especially Cl and F. The oxidation mechanism changes due to the so called halogen effect. The formation of a fast growing mixed oxide scale on untreated alloys is suppressed, instead a thin protective alumina scale is formed on samples after optimum treatment. The different methods only influence the surface region of the components so that the bulk properties are not affected. Recent results achieved with complex TiAl-samples showed the potential that the fluorine effect could be used for TiAl-components in several high temperature applications e.g. jet engines. TiAl-specimens were treated with fluorine and chlorine in several ways and their performance during high temperature oxidation tests in air was investigated. Results of isothermal and thermocyclic oxidation tests are presented. The long term stability of the fluorine effect lasted for at least one year under thermocyclic exposure at 900°C in laboratory air. The results are discussed in terms of later use of the fluorine effect for technical applications.

High Temperature Oxidation of Chromium-Nickel Steels★

CORROSION ◽  
1959 ◽  
Vol 15 (3) ◽  
pp. 57-62 ◽  
Author(s):  
D. CAPLAN ◽  
M. COHEN
Keyword(s):  
Weight Gain ◽  
High Temperature ◽  
Stainless Steels ◽  
High Temperature Oxidation ◽  
Surface Preparation ◽  
Austenitic Stainless Steels ◽  
Chromium Steel ◽  
Temperature Oxidation ◽  
Thin Oxide Film ◽  
Scale Layer

Abstract The scaling of austenitic stainless steels Type 302, 309 and 330 has been investigated by weight gain vs time measurements in air at 1600 to 2000 F and subsequent examination of the scales. As had been found previously with chromium steel, the curves exhibit breaks indicating intermediate periods of rapid oxidation due to disruption of the protective scale layer. Accumulation of silica at the metal/scale interface is found to contribute to this disruption; voids are considered to have the same effect. A distinction is drawn between such breaks and the type which arises from the extraordinary protectiveness of an initial thin oxide film, which is markedly affected by surface preparation and prior treatment. 3.2.3

scholarly journals Effect of Surface Roughness on Early Stage Oxidation Behavior of Ni-Base Superalloy IN 625

2018 ◽  
Vol 1 (3) ◽  
pp. 32 ◽  
Author(s):  
Wojciech Nowak
Keyword(s):  
Surface Roughness ◽  
Oxidation Behavior ◽  
Early Stage ◽  
Surface Preparation ◽  
Horizontal Tube ◽  
Optical Emission ◽  
Emission Spectrometry ◽  
Ground Sample ◽  
Base Superalloy ◽  
Effect Of Surface

In the present work the effect of surface roughness on oxidation behavior during the early stages of high temperature exposure of Ni-base superalloy IN 625 is described. The surface roughness was described using standard contact profilometer as well as novel method, fractal analysis. It was found that the different surface preparation resulted in a difference in roughness with a parameter increase of at least one order of magnitude for the ground sample as compared with the polished sample. The oxidation test was performed in a horizontal tube furnace. Post-exposure analyses including glow discharge optical emission spectrometry (GD-OES) and scanning electron microscopy (SEM), which revealed that grinding lowers the oxidation kinetics of IN 625 from 1.76 × 10−12 cm2·s−1, obtained for polished sample, to 9.04 × 10−13 cm2·s−1. It was found that surface preparation influences the oxide scale composition and morphology. The hypothesis explaining the mechanism responsible for the changes in oxidation behavior is proposed as well.

scholarly journals Study of titanium oxidation kinetics at temperature above polymorphic transformation

2021 ◽  
Vol 4 (1(60)) ◽  
pp. 37-41
Author(s):  
Vasyl Trush ◽  
Alexander Luk’yanenko ◽  
Viktor Fedirko
Keyword(s):  
Surface Layer ◽  
High Temperature ◽  
Oxide Layer ◽  
Diffusion Zone ◽  
Polymorphic Transformation ◽  
High Temperature Oxidation ◽  
Temperature Oxidation ◽  
Near Surface ◽  
Titanium Oxidation ◽  
Kinetics Of

The object of research is the analytical description of the phenomena in the near-surface layer, which are caused by the interaction of titanium with oxygen at high temperatures. These are temperatures that exceed the polymorphic transformation of the metal. High-temperature oxidation gives titanium products unique performance properties. Of course, such characteristics are determined, first of all, by the state of the near-surface layer. Therefore, an understanding of oxidation processes will make it possible to predict the state of the near-surface layer after heat treatment. However, to date, no unified approach has been created to describe the mechanism and kinetics of high-temperature oxidation of titanium in the near-surface layer. Indeed, most of the existing approaches make it possible to predict the nature of oxidation in the bulk of the metal. Some scientific papers describe the kinetics of oxidation, taking into account only the formation and growth of oxide layers. However, simultaneously with oxide formation, a diffusion zone is formed, which significantly affects the kinetics. Therefore, today one of the most problematic areas of high-temperature titanium oxidation is the description of the processes that take place in the near-surface layer. In this work, to describe the kinetics of high-temperature oxidation of titanium, in addition to the formation and growth of the oxide layer, the formation and growth of the diffusion zone is taken into account. In the diffusion zone, under the influence of structural phase transformations, solid solutions of oxygen are formed in the alpha and beta phases. This approach made it possible to take into account additional factors and thereby more accurately describe the processes of high-temperature oxidation of titanium. As a result of the calculations, the thickness of the oxide layer of the diffusion zone is given depending on the oxygen concentration and the duration of treatment. And also the dependences of the kinetics of displacement of the boundary of the oxide-diffusion layer are given and a system of equations for calculating the ratio of the formed phase components is developed. Thanks to the proposed analytical approach, it will be possible to calculate the sizes of interphase boundaries on the basis of temperature-time parameters and oxygen concentration and thereby form a hardened near-surface layer with certain functional properties

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