MECHANICAL PROPERTIES OF ZrO2-Al2O3
NANOSTRUCTURED PVD COATINGS EVALUATED BY NANOINDENTATION
A. Portinha1, V. Teixeira1*, J. Carneiro1,
S. N. Dub2, R. Shmegera2
1 University of Minho - Physics Department, Campus de Azurem, 4800 Guimaraes,
Keywords: nanolayers, ceramic coatings, nanoindentation, mechanical properties
2 Institute for Superhard Materials, Department No.11,
2 Avtozavodskaya St., Kiev, 04074 Ukraine
fax: +351-253510401, tel.: +351-253510465/400,
ZrO2-Al2O3 thin nanostructured
coatings and stabilised ZrO2-Y2O3 coatings have
been deposited by magnetron sputtering in rotating mode with two metallic targets
in order to stabilise at room temperature the high temperature phases of
The structural studies were carried out using X-Ray Diffraction (XRD) analysis
and for coatings with a content of 2wt% of Al2O3 the tetragonal phase of Zirconia
can’t be stabilised. Scanning Electron Microscopy (SEM) and Atomic Force
Microscopy (AFM) were used to characterise the coatings morphology and
The mechanical behaviour of ZrO2-Al2O3
thin films under point loading conditions
was studied by nanoindentation using Berkovich indenter with 130 nm tip radius.
Low load tests were used to study the effect of the deposition parameters on the
hardness and elastic modulus of coatings.
The hardness of the films reaches 15.3 GPa for a ZrO2-Al2O3 nanostructured
coating sputtered with -70V applied bias. High peak load tests were used to
estimate the film adhesion to steel substrates and for 120mN peak load the film
showed goog adhesion properties.
The residual stresses were also determined using the Stoney equation and the
highest compressive residual stress found was about -3 GPa corresponding to the
sample with highest hardness.
full paper (pdf, 110 Kb)