Effects of prior surface damage on high-temperature oxidation of Fe-, Ni-, and Co-based alloys

Blau, Peter J.; Brummett, Tracie M.; Pint, Bruce A.

doi:10.1016/j.wear.2008.12.082

Cited by 24 publications

(13 citation statements)

References 13 publications

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“…It is evident that when heats were applied at longer time caused the grain to grow denser and compact compared to shorter duration. However, when the sample undergone thermal oxidation at much higher temperature for a long duration, more SiO2 precipitates in the vicinity of the alloy which is beneath the oxide layer and at the oxide layer interface (Blau et al, 2009). This will causes most of the oxide interlayer peels-off from the substrate and not suitable for further experiments (Mas Ayu, 2015).…”

Section: Resultsmentioning

confidence: 99%

Thermal oxidation process improved corrosion in cobalt chromium molybdenum alloys

Ayu

Daud²,

Shah³

et al. 2017

Int. j. adv. appl. sci.

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The corrosion phenomena are always give bad impact to any metal products including human implants. This is due to the corrosion impacts are harmful for hard tissues and soft tissues. There are many methods to prevent the process of corrosion on implant materials such as coating with bioceramic materials and modify the implant surface with surface modification techniques. However, until now there is still no gold standard to overcome this problem and it is remain in researching process. Thus, the aim of this research is to investigate the potential and economical surface modification method to reduce the corrosion effects on Cobalt-Chromium-Molybdenum (Co-Cr-Mo) based alloy when insert in human body. The thermal oxidation process was selected to treat Co-Cr-Mo surface substrate. Firstly, Co-Cr-Mo alloy was heated in muffle furnace at constant temperature of 850°C with different duration of heating such as 3 hours and 6 hours in order to analyze the formation of oxide layer. The corrosion behaviours of untreated sample and oxidized sample were investigated utilizing potentiodynamic polarization tests in simulated body fluids (SBF). The Vickers hardness after corrosion testing was measured in order to evaluate the effect of thermal oxidation in reducing corrosion rate. Based on the results obtained it is clearly showed that substrates undergone thermal oxidation with 6 hours duration time performed better than 3 hours duration, with the hardness value 832.2HV vs. 588HV respectively. Dense oxide layer and uniform thickness formed on the oxidized substrates able to help in reducing the corrosion effects on Co-Cr-Mo alloy without degraded its excellent mechanical properties. The microstructures of oxidized substrates before and after corrosion test were also analyzed using FESEM images for better observations. It was determined that corrosion resistance of Co-Cr-Mo substrate can be increased with oxide layer formed on the alloys using thermal oxidation process.

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Section: Resultsmentioning

confidence: 99%

Thermal oxidation process improved corrosion in cobalt chromium molybdenum alloys

Ayu

Daud²,

Shah³

et al. 2017

Int. j. adv. appl. sci.

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“…Recently, Blau et al [15] highlighted from scratch tests that there existed a redistribution of chemical elements in the composition of materials. In fact, when a layer, for example oxide, is damaged by a scratch test, it is re-oxidized.…”

Section: Tribological Characteristics Of Oxide Layersmentioning

confidence: 99%

Tribology in metal forming at elevated temperatures

et al. 2015

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Abstract:The tribo-characteristics of metal forming at high temperatures have not yet been well understood due to the complex nature of thermal, microstructural, interaction, and process parameters. This is a review paper on the effects of temperature, coating, and lubrication to the tribological characteristics in hot forming as well as the tribometers for different metal forming processes at elevated temperatures mainly based on the experimental work. The tribological behaviors of oxides in hot forming, such as rolling and stamping, were reviewed and presented. Some commonly used surface coatings and lubricants in hot forming were given. Many types of tribometer were selected and presented and some of them provided a great potential to characterize friction and wear at elevated temperatures. Nevertheless, more testing conditions should be further investigated by developing new tribometers. Eventually, experimental results obtained from reliable tribometers could be used in theory and model developments for different forming processes and materials at high temperatures. The review also showed the great potential in further investigations and innovation in tribology.

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“…For example, phase changes can occur, precipitates can ripen, grains can coarsen, atomic species with increased mobility can segregate to grain boundaries, or to the surface. In fact, it was shown that alloying additions and oxidation products in exhaust valve-like alloys of Ni and Co can redistribute differently over time at high temperature depending upon whether surfaces are mechanically-damaged [3][4]. Consequently, there is no inherent reason to expect that a steady-state rate of deformation or wear will be maintained as the interfacial materials age.…”

Section: Features Of Worn Exhaust Valvesmentioning

confidence: 99%

“…To determine the magnitude of the abrasivity factor, more research is needed on threebody, high-temperature abrasive wear by oxide-metal mixtures, especially under repetitive impact with slip. Current experiments have shown how tribolayers similar in microstructure to those on valves can be generated in our laboratory [4,7 ], but the results have not been sufficiently quantitative for use in the current model.…”

Section: The Abrasion Termmentioning

confidence: 99%

“…The apparatus that was built is called the High Temperature Repetitive Impact apparatus (HTRI) and it is shown in Figure 3. In parallel with HTRI experiments, studies were done on the role of wear when it occurs in conjunction with oxidation and at elevated temperatures [3][4][5]. It was found that once damaged by abrasion, a surface exposed to high temperature forms different oxide compositions than a surface that is exposed to high temperature, but not in an abraded condition.…”

Section: Introduction Background and Project Objectivesmentioning

confidence: 99%

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A Wear Model for Diesel Engine Exhaust Valves

Blau¹

2009

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Executive SummaryThe work summarized here comprises the concluding effort of a multi-year project, funded by the U.S. Department of Energy, Office of Vehicle Technologies. It supports the development of a better understanding of advanced diesel engine designs in which enhanced power density, energy efficiency, and emissions control place increasing demands upon the durability of engine materials. Many kinds of metallic alloys are used in engines depending on the operating stresses, temperatures, and chemical environments. Exhaust valves, for example, are subjected to high temperatures and repetitive surface contacts that place demands on durability and frictional characteristics of the materials. Valves must continue to seal the combustion chamber properly for thousands of hours of cyclic engine operation and under varying operating conditions. It was the focus of this effort to understand the wear processes in the valve-seat area and to develop a model for the surface deformation and wear of that important interface. An annotated bibliography is provided to illustrate efforts to understand valve wear and to investigate the factors of engine operation that affect its severity and physical manifestation.The project for which this modeling effort was the final task, involved construction of a hightemperature repetitive impact test system as well as basic tribology studies of the combined processes of mechanical wear plus oxidation at elevated temperatures. Several publications resulted from this work, and are cited in this report. The materials selected for the experimental work were highperformance alloys based on nickel and cobalt. In some cases, engine-tested exhaust valves were made available for wear analysis and to ensure that the modes of surface damage produced in experiments were simulative of service. New, production-grade exhaust valves were also used to prepare test specimens for experimental work along with the other alloy samples.Wear analysis of valves and seats run for hundreds of hours in heavy-duty diesels provided insights into the kinds of complexity that the contact conditions in engines can produce, and suggested the physical basis for the current approach to modeling. The model presented here involves four terms, two representing the valve response and two for its mating seat material. The model's structure assumes that wear that takes place under a complex combination of plastic deformation, tangential shear, and oxidation. Tribolayers form, are removed, and may reform. Layer formation affects the friction forces in the interface, and in turn, the energy available to do work on the materials to cause wear. To provide friction data for the model at various temperatures, sliding contact experiments were conducted from 22 to 850 o C in a pin-on-disk apparatus at ORNL. In order to account for the behavior of different materials and engine designs, parameters in all four terms of the model can be adjusted to account for wear-in and incubation periods before the dominant wear processes evolve to ...

show abstract

Effects of prior surface damage on high-temperature oxidation of Fe-, Ni-, and Co-based alloys

Cited by 24 publications

References 13 publications

Thermal oxidation process improved corrosion in cobalt chromium molybdenum alloys

Thermal oxidation process improved corrosion in cobalt chromium molybdenum alloys

Tribology in metal forming at elevated temperatures

A Wear Model for Diesel Engine Exhaust Valves

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