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

• Published in: Wear Vol. 267; no. 1; pp. 380 - 386
• Main Authors: Blau, P.J., Brummett, T.M., Pint, B.A.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 15-06-2009; Elsevier
• Subjects: Applied sciences; Exact sciences and technology; Friction, wear, lubrication; High-temperature wear; Industrial metrology. Testing; Machine components; Mechanical engineering. Machine design; Oxidation; Scratch testing; Single-point abrasion; Superalloys; High-temperature wear; Scratch testing; Oxidation; Single-point abrasion; Superalloys; Scratching test; Temperature effect; Surface temperature; High temperature; Metal; Iron alloy; Modeling; Stylus; Surface effect; Valve; Iron base alloys; Damaging; Nickel base alloys; Abrasion test; High performance; Corrosive environment; Oxide layer; Surface layer; Thermogravimetry; Scratch hardness test; Abrasive wear; Internal combustion engine; Engine exhaust; Tribology
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/j.wear.2008.12.082

Multi-component metallic alloys have been developed to withstand high-temperature service in corrosive environments. Some of these applications, like exhaust valve seats in internal combustion engines, must also resist sliding, impact, and abrasion. The conjoint effects of temperature, oxidation, and mechanical contact can result in accelerated wear and the formation of complex surface layers whose properties differ from those of the base metal and the oxide scale that forms in the absence of mechanical contact. The authors have investigated the effects of prior surface damage, produced by scratch tests, on the localized reformation of oxide layers. Three high-performance commercial alloys, based on iron, nickel, and cobalt, were used as model materials. Thermogravimetric analysis (TGA) was used to determine their static oxidation rates at elevated temperature (850
°C). A micro-abrasion, ball-cratering technique was used to measure oxide layer thickness and to supplement the TGA results. By using taper-sectioning techniques and energy-dispersive elemental mapping, a comparison was made between oxide compositions grown on non-damaged surfaces and oxides that formed on grooves produced by a diamond stylus. Microindentation and scratch hardness data revealed the effects of high-temperature exposure on both the substrate hardness and the nature of oxide scale disruption. There were significant differences in elemental distribution between statically formed oxides and those that formed on scratched regions.