Nanoindentation analysis of cold welding effects in sliding contact systems

Konferenz: ICEC 2014 - The 27th International Conference on Electrical Contacts
22.06.2014 - 26.06.2014 in Dresden, Deutschland

Tagungsband: ICEC 2014

Seiten: 6Sprache: EnglischTyp: PDF

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Autoren:
Holzapfel, C. (Schleifring und Apparatebau GmbH, Am Hardtanger 10, 82256 Fuerstenfeldbruck, Germany)

Inhalt:
In many applications of sliding contacts noble metal sliding pairs are used. These systems usually exhibit an adhesive wear mechanism. During adhesive wear a layer of cold weldings is formed on at least one of the contacts. This layer consists of highly deformed material. Thus the mechanical properties of these cold weldings can largely differ from the original properties. In this study nanoindentation is used to characterize these phenomena. Nanoindentation allows studying nanohardness as well as the modulus of elasticity, hence probing different mechanical aspects of the system. In the present study a spring wire in V-groove geometry (applying an electrochemical coating system) is used. It will be shown that for the presently discussed system cold welding occurs both on the wire brushes as well as on the electroplating. The cold welding material exhibits a lower hardness than either the wire or the electroplating. This surprising finding is further discussed with respect to the existing literature and might be explained by chemical differentiation.