Mechanical behavior of DLC coatings under various scratch conditions

Geoffrey Pagnoux (1, 2, 3) , Siegfried Fouvry (1) , Michaël Peigney (2) , Benoit Delattre (3) , Guillaume Mermaz-Rollet (3)

1 LTDS - Laboratoire de Tribologie et Dynamique des Systèmes
2 msa - Matériaux et Structures Architecturés
3 PSA - PSA Peugeot - Citroën

In lubricated sliding contact systems with Diamond-Like Carbon (DLC) coated solids, several studies have shown DLC coatings are highly sensitive to asperities breaking through the lubricant film within the contact area. Those asperities produce damages similar to those obtain from scratch tests, from where coating delamination can initiate and propagate. In the present study, controlled scratches have been performed on DLC-coated samples by varying the tip radius, the normal load and the sliding speed. From one hand, the different fracture mechanisms are compared to those observed on a coated cam-tappet system. They both lead to similar damage and wear, from substrate plasticity to gross spallation, via tensile and angular cracking. On the other hand, a numerical analysis is conducted with a finite element model. It reveals the fracture mechanism can be qualitatively predicted. Additional computations show the scratch severity increases by considering a thinner coating. This upholds the observed experimental coupling between tribochemical wear, scratch networks and coating delamination.

Mots clés: DLC; scratch; coating failure; FE model; wear

Domaines: Mécanique des solides [physics.class-ph]

Geoffrey Pagnoux, Siegfried Fouvry, Michaël Peigney, Benoit Delattre, Guillaume Mermaz-Rollet. Mechanical behavior of DLC coatings under various scratch conditions. Internation Conference on Fracture Fatigue and Wear, Sep 2014, Kyushu, Japan. ⟨hal-01093241⟩