Thermal treatment effect on structural and mechanical properties of Cr–C coatings
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Date
2018-03-04
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Publisher
Transactions of the IMF
Abstract
In the present study, the effect of thermal treatment on the mechanical and structural properties of
chromium carbide coatings with different thicknesses is evaluated. The coatings were deposited by
cathodic magnetron sputtering on XC100 steel substrates. Samples were annealed in vacuum, at
different temperatures ranging from 700 to 1000°C for 1 h, resulting in the formation of chromium
carbides. X-ray diffraction (XRD), microanalysis X/energy-dispersive X-ray spectrometer (EDS), X-ray
photoelectron spectroscopy (XPS) and scanning electron microscopy analysis were used to
characterise the samples. Mechanical properties were evaluated by nano-indentation tests and the
residual stress was calculated with the Stoney formula. The XRD analysis suggests the formation of
the Cr7C3, Cr23C6 carbides at 900°C. For thin films, they transformed totally to ternary (Cr, Fe)7C3
carbides and their partial transformation has been observed in the case of thick films at 1000°C,
without the formation of Cr3C2
. The EDS and XPS showed the diffusion mechanism between the
chromium film and the steel substrate for the Cr, Fe, C, O elements during the annealing treatment.
The increase of chromium film thickness from 0.5 to 2.64 µm, contributed to the significant
enhancement of mechanical properties such as hardness (H) (from 12 to 26.3 GPa) and Young’s
Modulus (E) (from 250 to 330 GPa), respectively.