Rolling contact fatigue resistance of PVD CrN and TiN coated austempered ductile iron

D.A. COLOMBO; M.D. ECHEVERRÍA; LAINO SEBASTIAN; R. DOMMARCO; J. M. MASSONE

WEAR

ELSEVIER SCIENCE SA

Lugar: Amsterdan; Año: 2013 vol. 308 p. 35 - 45

0043-1648

This work studies the rolling contact fatigue (RCF) behavior of PVD CrN and TiN coated ADI samples. Theeffect of the substrate surface finishing method (grinding and polishing) and coating material on RCF lifeis also evaluated. Coatings were applied in an industrial reactor. Deposition times were adjusted to obtainsimilar coating thicknesses in both coating materials. RCF tests were performed in a flat washer typetesting rig, using a thrust ball bearing as a counterpart. The maximum contact pressure (p0) was set at1000 and 1400 MPa.The results obtained indicate that the RCF tests performed at p0¼1000 MPa cause no failures on thesamples analyzed, while those performed at p0¼1400 MPa cause failures in both uncoated and coatedsamples. Failures in coated samples are mainly characterized by coating delamination and, to a lesserextent, by spall formation in the substrate. Graphite nodules present on the substrate surface act aspreferential sites for coating fracture and subsequent delamination. The RCF resistance of coated samplesis lower than that of uncoated samples regardless of the substrate surface finishing method employed.The surface hardening produced by the abrasive cutting of grinding improves the RCF resistance of theuncoated and coated samples.