Temperature-Driven Oxidation Behavior of Pure Iron Surface Investigated by Time-Resolved EXAFS Measurements

ABSTRACTThe surface-front oxidation mechanism of iron was investigated by time-resolved, glancingangle Fe K-edge fluorescence EXAFS measurements at various oxidation temperatures of 200-700 C. The glancing angle was chosen according to the depth of the oxide layer, roughly 1500-2000A. The oxidation behavior under rapid heating(up to 600°C within 10 minutes) was compared with the slowly heated oxidation process using the Quick-EXAFS measurements. In the slowly heated process, Fe3O4 was the dominating phase at a relatively low temperature (300-400 C) initially. However, at a relatively high temperature (above 600°C), the Fe2O3 and FeO crystalline phases are gradually enriched as the successive oxidation process involving intrusive oxygen proceeded. Remarkably under a prolonged heat treatment above 600°C, the stable FeO phase that exists in a deep-lying interface structure and Fe2O3 phase eventually dominates the thick front-surface structure. In a quickly heated process, however, Fe3O4 phase is less dominating, which is contradictory to the commonly accepted oxidation models. The EXAFS results are discussed in conjunction with the x-ray diffraction features under the same heat treatment conditions.

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Cyclic Oxidation Resistance of Co-10Cr-5Al-0.3Y Alloy at 800 oc

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1015.505 ◽

2014 ◽

Vol 1015 ◽

pp. 505-508

Author(s):

Ling Yun Bai ◽

Hong Hua Zhang ◽

Huai Shu Zhang ◽

Yun Xiang Zheng ◽

Jun Huai Xiang

Keyword(s):

Oxidation Resistance ◽

Oxidation Rate ◽

Cyclic Oxidation ◽

Oxidation Behavior ◽

Oxidation Process ◽

Oxidation Mechanism ◽

Local Zone

The cyclic oxidation behavior of Co-10Cr-5Al alloys with and without 0.3 at% Y doped in atmosphere at 800oC was investigated. The addition of 0.3 at.% Y increased the oxidation rate of the alloy and changed the oxidation mechanism. The scales grown the alloys with and without Y were both composed of an outer Co2O3layer and an inner complex layer of Al2O3, Co2O3and Cr2O3, except that the addition of 0.3 at% Y enhanced the adhesion of the scale. 0.3 at% Y agglomerated in local zone which accelerated the oxidation rate and was not conductive to the oxidation process of the Co-10Cr-5Al alloy.

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Effect of ZrB2 addition on the oxidation behavior of Si-SiC-ZrB2 composites exposed at 1500°C in air

Journal of Applied Biomaterials & Functional Materials ◽

10.5301/jabfm.5000379 ◽

2017 ◽

Vol 16 (1) ◽

pp. 14-22

Author(s):

Claudio D’Amico ◽

Giovanni Bianchi ◽

Elisa Padovano ◽

Sara Biamino ◽

Alberta Aversa ◽

...

Keyword(s):

High Temperature ◽

Oxidation Behavior ◽

Oxidation Process ◽

Oxidation Mechanism ◽

Industrial Applications ◽

Reactive Infiltration ◽

Diffraction Patterns ◽

Carbide Ceramics ◽

Sic Composites ◽

Silicon Carbide Ceramics

Background: Silicon carbide ceramics obtained by reactive infiltration of silicon (SRI) have many industrial applications especially involving severe and high temperature conditions. In this study, the oxidation behavior in air of Si-SiC-ZrB2 systems at a high temperature (1500°C) for dwelling times of up to 48 hours was examined. Methods: The oxidation process was analyzed on the basis of elemental maps and X-ray diffraction patterns taken, respectively, on the core and on the surface of the specimens, together with weight gains and the average thicknesses of the resulting scale. Further, flexural strength at room temperature was examined as a function of different oxidation times. Results: The main chemical reactions and phase transformations involved in the oxidation process are reported. Several oxides were detected on the surface: zirconia, silica, zircon and 3-zirconium monoxide. All of the samples showed a parabolic oxidation kinetics, suggesting that the controlling mechanism was the diffusion; however, even after 48 hours, the oxidation process was not finished – indeed, all of the samples continued to gain weight. Conclusions: The oxidation of Si-SiC-ZrB2 material produced via SRI was slower compared with previously investigated ZrB2-SiC composites processed with a different techniques and tested in similar conditions. The oxidation mechanism was found to be consistent with the convection cells model.

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The growth mechanism of oxide scale with Pt on NiCoCrAlY coating in water vapor at 1050∘C

Modern Physics Letters B ◽

10.1142/s0217984921501116 ◽

2020 ◽

pp. 2150111

Author(s):

Chen Hua ◽

Peng Song ◽

Taihong Huang ◽

Xuan He ◽

Chao Li ◽

...

Keyword(s):

Heat Treatment ◽

Water Vapor ◽

Oxide Scale ◽

Oxidation Behavior ◽

Oxidation Process ◽

Alumina Scale ◽

Crack Initiation And Propagation ◽

Free Standing ◽

Good Adherence ◽

Initiation And Propagation

In this study, we focus on the oxidation behavior of the oxide scale with Platinum (Pt) on free standing NiCoCrAlY coating in air with water vapor at high temperature. The Pt layer is deposited on the NiCoCrAlY coating surface by electroplating, and then heat treatment at 1000[Formula: see text]C with Argon (Ar) protection. Cycle oxidation of the oxide scale with Pt is conducted in air and air with water vapor at 1050[Formula: see text]C. The results indicated that the spinels (NiCr2O[Formula: see text] are formed on the surface of the alumina scale in air and air with water vapor. However, this kind of spinel is inhibited in the air with water vapor and the scale on the coatings with Pt presents a good adherence during oxidation process. The thermal stress and crack initiation and propagation will be discussed.

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On the defects of enamel coatings

Voprosy Materialovedeniya ◽

10.22349/1994-6716-2018-96-4-145-150 ◽

2019 ◽

pp. 145-150

Author(s):

T. O. Soshina ◽

V. R. Mukhamadyarovа

Keyword(s):

Heat Treatment ◽

Surface Tension ◽

Electron Microscope ◽

Enamel Coating ◽

Surface Defects ◽

Linear Expansion ◽

Corrosion Properties ◽

Treatment Conditions ◽

Mechanical And Corrosion Properties ◽

Coefficient Of Linear Expansion

The defects destroy the integrity of the enamel, and the paper examines the influence of the physical-mechanical and corrosion properties of frits and heat treatment on the defectiveness of the enamel coating. The surface defects were scanned by electron microscope. It has been established that the defectiveness of enamel coatings depends on the melting index, temperature coefficient of linear expansion, surface tension of the frits, and heat treatment conditions. When burning rate of the enamel coating decreases, the fine-meshed structure of the enamel changes, and the size of the defects decreases.

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Time-Resolved, Laser-Induced Phase Transformation in Aluminum

MRS Proceedings ◽

10.1557/proc-35-87 ◽

1984 ◽

Vol 35 ◽

Cited By ~ 4

Author(s):

S. Williamson ◽

G. Mourou ◽

J.C.M. Li

Keyword(s):

Point Defect ◽

Long Range ◽

Rapid Heating ◽

Range Order ◽

Nucleation Theory ◽

Long Range Order ◽

Time Resolved ◽

Aluminum Films ◽

Thin Aluminum ◽

Initial Nucleus

ABSTRACTThe technique of picosecond electron diffraction is used to time resolve the laser-induced melting of thin aluminum films. It is observed that under rapid heating conditions, the long range order of the lattice subsists for lattice temperatures well above the equilibrium point, indicative of superheating. This superheating can be verified by directly measuring the lattice temperature. The collapse time of the long range order is measured and found to vary from 20 ps to several nanoseconds according to the degree of superheating. Two interpretations of the delayed melting are offered, based on the conventional nucleation and point defect theories. While the nucleation theory provides an initial nucleus size and concentration for melting to occur, the point defect theory offers a possible explanation for how the nuclei are originally formed.

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Heat Treatment Evaluation for the Camshafts Production of ADI Low Alloyed with Vanadium

Metals ◽

10.3390/met11071036 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1036

Author(s):

Eduardo Colin García ◽

Alejandro Cruz Ramírez ◽

Guillermo Reyes Castellanos ◽

José Federico Chávez Alcalá ◽

Jaime Téllez Ramírez ◽

...

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Tensile Strength ◽

Ductile Iron ◽

Volume Fraction ◽

Energy Impact ◽

Treatment Conditions ◽

Mold Casting ◽

Grade 3 ◽

Good Agreement

Ductile iron camshafts low alloyed with 0.2 and 0.3 wt % vanadium were produced by one of the largest manufacturers of the ductile iron camshafts in México “ARBOMEX S.A de C.V” by a phenolic urethane no-bake sand mold casting method. During functioning, camshafts are subject to bending and torsional stresses, and the lobe surfaces are highly loaded. Thus, high toughness and wear resistance are essential for this component. In this work, two austempering ductile iron heat treatments were evaluated to increase the mechanical properties of tensile strength, hardness, and toughness of the ductile iron camshaft low alloyed with vanadium. The austempering process was held at 265 and 305 °C and austempering times of 30, 60, 90, and 120 min. The volume fraction of high-carbon austenite was determined for the heat treatment conditions by XRD measurements. The ausferritic matrix was determined in 90 min for both austempering temperatures, having a good agreement with the microstructural and hardness evolution as the austempering time increased. The mechanical properties of tensile strength, hardness, and toughness were evaluated from samples obtained from the camshaft and the standard Keel block. The highest mechanical properties were obtained for the austempering heat treatment of 265 °C for 90 min for the ADI containing 0.3 wt % V. The tensile and yield strength were 1200 and 1051 MPa, respectively, while the hardness and the energy impact values were of 47 HRC and 26 J; these values are in the range expected for an ADI grade 3.

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Machinability Study of AA6061 Under Various Heat Treatment Conditions

Iranian Journal of Science and Technology Transactions of Mechanical Engineering ◽

10.1007/s40997-021-00425-5 ◽

2021 ◽

Author(s):

Yasser Zedan ◽

Keyhan Jabbari ◽

Seyed Ali Niknam ◽

Victor Songmene

Keyword(s):

Heat Treatment ◽

Treatment Conditions

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Effect of copper incorporation on phase transformation behavior of electroless nickel–phosphorous coating and its effect on the tribological behavior

Proceedings of the Institution of Mechanical Engineers Part L Journal of Materials Design and Applications ◽

10.1177/1464420720981602 ◽

2020 ◽

pp. 146442072098160

Author(s):

Abhijit Biswas ◽

Suman Kalyan Das ◽

Prasanta Sahoo

Keyword(s):

Heat Treatment ◽

Phase Transformation ◽

Tribological Behavior ◽

Electroless Nickel ◽

Two Phase ◽

Microstructural Changes ◽

Treatment Conditions ◽

Heat Treated ◽

Higher Temperature ◽

Effect Of Copper

The microstructural changes of electroless Ni–P–Cu coating at various heat-treatment conditions are investigated to understand its implications on the tribological behavior of the coating. Coatings are heat-treated at temperatures ranging between 200°C and 800 °C and for 1–4 h duration. Ni–P–Cu coatings exhibit two-phase transformations in the temperature range of 350–450 °C and the resulting microstructural changes are found to significantly affect their thermal stability and tribological attributes. Hardness of the coating doubles when heat-treated at 452 °C, due to the formation of harder Ni3P phase and crystalline NiCu. Better friction and wear performance are also noted upon heat treatment of the coating at the phase transformation regime, particularly at 400 °C. Wear mechanism is characterized by a mixed adhesive cum abrasive wear phenomena. Heat treatment at higher temperature (600 °C and above) and longer duration (4 h) results in grain coarsening phenomenon, which negatively influences the hardness and tribological characteristics of the coating. Besides, diffusion of iron from the ferrous substrate as well as greater oxide formation are noticed when the coating is heat-treated at higher temperatures and for longer durations (4 h).

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