The influence of the moisture content of the atmosphere on alumina scale formation and growth during high temperature oxidation of PM2000

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.

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High-Temperature Oxidation and Oxide Scale Formation in Plasma-Sprayed CoNiCrAlYRe Coatings

Metallurgical and Materials Transactions A ◽

10.1007/s11661-014-2509-5 ◽

2014 ◽

Vol 45 (12) ◽

pp. 5362-5370 ◽

Cited By ~ 3

Author(s):

Giovanni Di Girolamo ◽

Alida Brentari ◽

Caterina Blasi ◽

Luciano Pilloni ◽

Emanuele Serra

Keyword(s):

High Temperature ◽

Oxide Scale ◽

High Temperature Oxidation ◽

Scale Formation ◽

Temperature Oxidation ◽

Plasma Sprayed

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Optimization of the Fluorine Effect for Improving the Oxidation Resistance of Tial-Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.706-709.1061 ◽

2012 ◽

Vol 706-709 ◽

pp. 1061-1065 ◽

Cited By ~ 5

Author(s):

Alexander Donchev ◽

Michael Schütze ◽

Andreas Kolitsch ◽

Rossen Yankov

Keyword(s):

High Temperature ◽

Oxidation Resistance ◽

High Temperature Oxidation ◽

Inorganic Compounds ◽

Oxidation Mechanism ◽

Surface Region ◽

Alumina Scale ◽

Temperature Oxidation ◽

Bulk Properties ◽

Tial Alloys

The oxidation resistance of TiAl-alloys can be improved drastically by treating the surface of the components with small amounts of fluorine. The oxidation mechanism is changed. Hence, 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 fluorine treatment. The different methods only influence the surface region of the components so that the bulk properties are not affected. Recent results achieved with F-containing inorganic compounds showed that the fluorine effect can be improved even further. TiAl-specimens were treated only with fluorine and with F-containing compounds 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 results are discussed in terms of a later use of the fluorine effect for technical applications.

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