Abstracts Book - IMRC 2018

• SD7-P015
INFLUENCE OF AlN PHASE ON THE MECHANICAL AND
TRIBOLOGICAL PROPERTIES OF TiAlN COATINGS FOR WEAR
RESISTANT APPLICATIONS
Hernán Darío Mejía 1 , Aida Milena Echavarría 1 , Gilberto Bejarano Gaitan 1
1 Universidad de Antioquía, Ingeniería de Materiales, Colombia.
TiAlN coatings have been widely used in cutting and forming tools to improve their
wear resistance due to its high hardness, low chemical reactivity and high corrosion
resistance. However, these properties depend, among others, on the
microstructure, chemical composition and relationship between the TiN and AlN
phases that can be formed in the compound. In this work, TiAlN coatings with
different aluminum contents were developed obtaining several ratios of the TiN /
AlN phases. The coatings were deposited on samples of 420 stainless steel using
the magnetron sputtering technique applying a power of 1700W to the Ti- target
and 900, 1000 and 1300W to the Al- target, while the other process parameters were
kept constant. All the coatings presented a dense and homogeneous structure of
columnar growth with a thickness of approximately 2.5 micrometer. The chemical
and phase composition of the coated samples was evaluated by SEM / EDX, XRD
and XPS. Hardness, Young modulus, adhesion and wear resistance were
determined by nanoindentation, scratch test and pin on disc measurements,
respectively. It was found that the hardness and Young modulus increase and the
wear rate decreases initially with the increase of the power applied to the aluminum
target, but for a power greater than 1300W, these properties drops down 17.2 GPa
to 15.4 GPa and 218.9 GPa to 207.8 GPa, respectively, while the wear rate increases
1.7x10 -7 to 6.5x10 -7 mm 3 /N.m. The initial behavior of the coating’s properties is
mainly due to partial atomic substitution of Ti- atoms by Aluminum and the
consequent deformation of the crystal lattice of the TiAlN matrix, which lead to the
hardening of the latter. The reduction of the hardness and Young modulus, as well
as the increase of the wear rate for a power of 1300W applied to the Al- target is
associated with the formation of the incoherent phase of AlN, whose mechanical
properties are lower than those of the TiN and TiAlN.
Acknowledgment: This research was supported by COLCIENCIAS
(Administrative Department of Science, Technology and Innovation of
Colombia) project number 611-2015.
Keywords: TiAlN coatings, wear resistance, properties characterization
Presenting authors email: gilberto.bejarano@udea.edu.co