Understanding and formalization of the fretting-wear behavior of a cobalt-based alloy at high temperature

A Dreano, S Fouvry, G Guillonneau - Wear, 2020 - Elsevier
Wear, 2020Elsevier
The purpose of this study is to investigate the mechanisms involved in the wear of cobalt-
based interfaces at high temperature. The studied contact is a cobalt-based alloy subjected
to fretting against an alumina sample. At high temperature, a protective third body is
spontaneously created at the interface and presents excellent tribological properties. The
formation of the so-called “glaze layer” leads to an absence of wear. The investigation
presents on complete description of the high-temperature tribolayer with microstructural …
Abstract
The purpose of this study is to investigate the mechanisms involved in the wear of cobalt-based interfaces at high temperature. The studied contact is a cobalt-based alloy subjected to fretting against an alumina sample. At high temperature, a protective third body is spontaneously created at the interface and presents excellent tribological properties. The formation of the so-called “glaze layer” leads to an absence of wear.
The investigation presents on complete description of the high-temperature tribolayer with microstructural, chemical and mechanical characterizations. The glaze layer regime is mainly related to a threshold temperature above which a thin cobalt-rich layer is formed by a tribo-sintering process. A formalization of the tribo-sintering process is proposed to predict the necessary number of fretting cycles NGL to form the glaze layer. The tribo-sintering process prevents wear debris ejection by continuously re-incorporating the wear debris particles in the glaze layer. The re-incorporation of the wear debris may be the reason for the absence of wear of the fretted interface from a macroscopic point of view. Finally, the paper presents an extended friction energy wear approach taking into account tribo-oxidation and tribo-sintering considerations. The formulation is able to predict wear for a large range of tribological parameters (temperature, frequency, sliding amplitude, number of cycles), for the Co-based/alumina contact.
Elsevier
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