Contact fatigue behavior of α-Al PROOF 2 O -Ti(C,N) CVD coated WC-Co under dry and wet conditions

Abstract

The response to cycling contact fatigue load of a WC-6%Co carbide coated with a Ti(C,N)/α-Al2O3 CVD multilayer was investigated in dry and wet conditions. Imprints in dry conditions were characterized by small thin cracksformingacircumferenceatthemaximumradiioftheimprint.Thedamagedcoatingwastotallypresentin thefinalimprintofthedrytest.Wetindentationsshowcaseanareaintheimprintwherethe α-Al2O3 layerhas beenremovedthroughoutaringbutwaskeptatthecenteroftheindentation,suggestingthatthecoatingdamageundercyclingcontactloadinwetconditionsisdominatedbyα-Al2O3degradation,associatedwithafretting effectortangentialloadsacceleratingthefatigue-corrosionofthealuminalayer.