Correlation between thermal properties and aluminum fractions in CrAlN layers deposited by PVD technique

Abstract

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. The CrAlN coatings are a good alternative to conventional CrN coatings especially for high temperature oxidation-resistance applications. Different CrAlN coatings were deposited on silicon (100) by PVD (Physical vapor deposition) technique from two targets (chromium and aluminum) in a reactive nitrogen atmosphere at aluminum applied negative voltage (À300, À500, À700 and À900 V). The composition, structural, mechanical and thermal properties of the as-deposited coatings were systematically characterized by energy dispersive analysis of X-rays, X-ray diffraction, nanoindentation, and the ''Mirage effect'' experiments. The X-ray diffraction (XRD) data show that in general CrAlN coatings were crystallized in the cubic NaCl B1 structure, with the (1 1 1) and (2 0 0) diffraction peaks observed. Two-dimensional surface morphologies of CrAlN coatings were investigated by atomic force microscope (AFM). The results show that with increasing aluminum proportion the coatings became more compact and denser and their increased correspondingly, showing a maximum hardness of about 36 GPa (30 at% of Al) which is higher than that of CrN. Moreover, the results in this work demonstrate that the variation of aluminum fraction alter the resulting columnar grain morphology and porosity of the coatings. However, the thermal properties are greatly affected by these morphological alterations. The correlation between aluminum fraction in CrAlN coatings and its thermal properties revealed that the conductivity and the diffusivity are influenced primarily by size and shape distribution of the pores and secondarily by a decrease of the stitch parameter dimension.

Improving tribological performance of CrN coatings in seawater by structure design

“…The highly mobile adatoms can move or diffuse into the inter-grain voids under the high energy ion bombardment, break down the large columnar grain growth. Therefore, a denser structure was attained [22]. As the wear failure for CrN1 sliding in seawater environment was demonstrated to occur at the interface between coating and substrate, Cr was chosen as an interlayer to improve the anti-wear property of CrN coatings under this environmental.…”

Influence of Al Content on the Microstructure and Properties of the CrAlN Coatings Deposited by Arc Ion Plating

“…It has been reported that the Al 2 O 3 phase is more thermally stable and protective than the Cr 2 O 3 phase at high temperatures [7][8][9]. Because of these benefits, the CrAlN coating is considered as a good alternative to the conventional coatings especially for the high temperature oxidation-resistance applications [10].…”

Insight into Al existing form and its role on microstructure and properties of Cr1−xAlxN films

“…It can be seen that all the Cr 1−x Al x N films demonstrate B1‐type crystal structure, suggesting that the crystalline structure of the Cr 1−x Al x N films is similar to that of CrN film. As the Al content increases from 0 to 0.84, the diffraction angle shifts toward higher 2 θ angle, which can be ascribed to the substitution of some of the Cr atoms by smaller Al atoms in CrN lattice . Moreover, the increase of strong Al‐N bond results in the contraction of the CrN lattice.…”