CONICET | Buscador de Institutos y Recursos Humanos

This work studies the influence of TiN coating thickness on the rolling contact fatigue (RCF) behavior of austempered ductile iron. Coatings were applied in a PVD industrial reactor using processing parameters specifically selected for ADI. Deposition times were adjusted to obtain three different nominal thicknesses: 0.7, 1.4 and 2.1 µm. RCF tests were performed in a flat washer type testing rig under a lubricated contact. The maximum Hertz contact pressure was set at 1400 MPa. RCF tests results were analyzed using the two-parameter Weibull distribution. The rolling track of the tested samples was examined by using SEM.The results show that as coating thickness increases, into the analyzed range, the arithmetic average roughness of the coated samples increases slightly while the bearing area decreases more significantly, the elastic modulus and residual stresses of the coatings increase, nor the coating hardness neither the adhesion strength quality vary and finally, the RCF resistance of the coated samples decreases. A coating thickness of about 0.7 µm enhances the RCF resistance of ADI substrates while thicker coatings worsen ADI?s resistance. Failures in samples with a coating thickness of about 0.7 µm occurred exclusively by substrate spalling, while failures in samples with thicker coatings were mainly produced by coating delamination.