Evaluación de la capacidad de soporte de carga de recubrimientos duros depositados sobre la aleación de aluminio 7075-T6

E. T. Moreno; Y. Y. Santana; A. C. Castro; E. S. Puchi-Cabrera; M. H. Staia

doi:10.3989/revmetalm.2007.v43.i6.89

Authors

E. T. Moreno Universidad Central de Venezuela, Facultad de Ingeniería, Escuela de Metalurgia y Ciencia de los Materiales
Y. Y. Santana Universidad Central de Venezuela, Facultad de Ingeniería, Escuela de Metalurgia y Ciencia de los Materiales
A. C. Castro Universidad Central de Venezuela, Facultad de Ingeniería, Escuela de Metalurgia y Ciencia de los Materiales
E. S. Puchi-Cabrera Universidad Central de Venezuela, Facultad de Ingeniería, Escuela de Metalurgia y Ciencia de los Materiales
M. H. Staia Universidad Central de Venezuela, Facultad de Ingeniería, Escuela de Metalurgia y Ciencia de los Materiales

DOI:

https://doi.org/10.3989/revmetalm.2007.v43.i6.89

Keywords:

7075-T6 aluminium alloy, Duplex coatings, Electroless Ni-P, ZrN (PVD), Spherical indentation, Critical load

Abstract

In the present work, the effect of the thickness of an electroless NiP load-support interlayer coating, on the initiation and development of plastic deformation in a 7075-T6 aluminium alloy substrate coated with a duplex coating has been investigated. The duplex system has been obtained by means of the deposition of an electroless Ni-11 wt. % P (EN) onto the aluminium alloy substrate, followed by the deposition of a ZrN film (PVD) on top of the EN coating. The duplex systems that were investigated involved two different EN deposits, with thicknesses of 30 and 60 mm, respectively. The coatings were characterized regarding their morphology, thickness and absolute hardness. Indentation tests with spherical indenters were performed employing 6 mm diameter WC-6Co balls and normal loads of 10, 15, 25, 50 and 75 N. All the indentations were modeled by means of the Elastica 2.1. code, in order to determine the through-thickness von Mises effective stress profile of the samples and the critical load for the initiation of the plastic deformation of the aluminium alloy substrate. The experimental results have been validated by means of such a theoretical analysis. It has been determined that the duplex system with an EN interlayer of 30 mm does not constitute a satisfactory load-support interlayer, for the load values employed in the tests. However, for the coated system with an EN interlayer of 60 mm, the critical load for the initiation of plastic deformation in the aluminium alloy substrate was found to be ~ 16 N, which indicates that such a load-support interlayer avoids the plastic deformation of the substrate at normal loads less than ~ 15 N.

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