INFINA (EX INFIP)   05545
INSTITUTO DE FISICA INTERDISCIPLINARIA Y APLICADA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Rolling contact behavior of PVD Ti/TiN coated austempered ductile iron
Autor/es:
D. COLOMBO; M. ECHEVERRÍA; J. MASSONE; A. MARQUEZ
Reunión:
Congreso; SBPMat 2014; 2014
Institución organizadora:
Sociedad Brasileira de Pesquisa de Materiales
Resumen:
Austempered ductile iron (ADI) is increasingly
being used for the manufacturing of mechanical components subjected to rolling
contact fatigue (RCF), such as gears and cams. Several authors studied the RCF
behavior of ADI with different nodule counts and austempering temperatures (1, 2). They found that ADI
resistance to RCF increases as austempering temperature decreases and nodule
count increases. Graphite nodules
act as preferential sites for crack nucleation. Consequently, the use of
surface treatments could offset the negative effect of the nodules.
The authors of the present work studied the
rolling contact fatigue (RCF) behavior of PVD CrN and TiN coated ADI (3). It was found that the RCF resistance of coated samples is lower than
that of uncoated samples. Failures in coated samples are mainly characterized
by coating delamination. Graphite nodules present on the substrate surface act
as preferential sites for coating fracture and subsequent delamination due to the
large properties difference with respect to coatings. Consequently, the
application of multilayer coatings could enhance ADI resistance to RCF by
modifying the properties gradient between substrate and coating.
On this basis, the aim
of this work is to study the RCF behavior of ADI samples coated with Ti/TiN by
a cathodic arc. The effect of the Ti interlayer thickness on the RCF life is also
evaluated. Coatings were applied in an experimental reactor using processing
parameters specifically selected for ADI. RCF tests were performed in a flat
washer type testing rig, using a thrust ball bearing as a counterpart. The
maximum contact pressure was set at 1400 MPa. RCF tests results were analyzed using
the two-parameter Weibull distribution.