Wüest M. 51 Wykes M. 82 Yamaguchi M. 17 Ybarra G. 129 Yubero F ...

JUNE 28 WEDNESDAY AFTERNOON
JS2-WeA-P3 CARBIDES FORMATION IN TANTALUM THIN LAYERS DEPOS-
ITED ON STEEL SUBSTRATES. Y. Hadjar. Institut de Tronc Commun Sciences Exactes et
Technologie, Université de Batna, Algérie, R. Halimi, Laboratoire Couches Minces et Interfaces,
Université Mentouri, 25000 Constantine, Algérie.
In the present work we are intending to elaborate and to study thin film coating of tantalum carbides
on steel substrates. The procedure used in order to prepare the samples consist on depositing, by
electron gun evaporation, a thin film (4µm thickness) of tantalum on steel substrates containing 1
%wt. of carbon, then, annealing the system (substrate/coating) in vacuum at a temperature at which
the carbon of the substrate may diffuse into the Ta metallic film. This fact leads to the formation of
tantalum carbides. The effects of the annealing on the kinetic of tantalum carbides formation and
morphology have been investigated using X- ray diffraction (XRD), secondary ion mass spectroscopy
(SIMS) and scanning electron microscopy (SEM). The mechanical characterization was performed
by measuring microhardness and adhesion. It is found that at annealing up to 800°C the
compounds Ta 2 C and TaC are formed. During the subsequent heat treatment from 900°C to 1100°C
the final TaC phase grows at the expense of the Ta2C phase. Moreover, the microhardness and adhesion
of the films increase significantly with increasing annealing temperature. At a given temperature,
the microhardness increases, with the rise of the annealing time, to reach a maximum and then
decreases. The final coating layer has a golden color and presents a columnar structure. The formation
mechanisms are discussed.
Key words: hard coatings, tantalum carbides, thin films, diffusion.
Presenting author: R. HALIMI
E-mail: rachid_halimi@yahoo.fr
Presentation type: Poster
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