Abstract
ABSTRACT Optically transparent, colorless Al-O-N and Al-Si-O-N coatings with discretely varied O and Si contents were fabricated by reactive direct current magnetron sputtering (R-DCMS) from elemental Al and Si targets and O2 and N2 reactive gases. The Si/Al content was adjusted through the electrical power on the Si and Al targets, while the O/N content was controlled through the O2 flow piped to the substrate in addition to the N2 flow at the targets. The structure and morphology of the coatings were studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM), while the elemental composition was obtained from Rutherford backscattering spectrometry (RBS) and heavy ion elastic recoil detection analysis (ERDA). The chemical states of the elements in the coatings were analyzed by X-ray photoelectron spectroscopy (XPS). Based on analytical results, a model describing the microstructural evolution of the Al-O-N and also previously studied Al-Si-N [1, 2, 3, 4] coatings with O and Si content, respectively, is established. The universality of the microstructural evolution of these coatings with the concentration of the added element is attributed to the extra valence electron (e–) that must be incorporated into the AlN wurtzite host lattice. In the case of Al-O-N, this additional valence charge arises from the e – acceptor O replacing N in the AlN wurtzite lattice, while the e – donor Si substituting Al fulfills that role in the Al-Si-N system. In view of future applications of ternary Al-O-N and quaternary Al-Si-O-N transparent protective coatings, their mechanical properties such as residual stress (σ), hardness (HD) and Young’s modulus (E) were obtained from the curvature of films deposited onto thin substrates and by nanoindentation, respectively. Moderate compressive stress levels between −0.2 and −0.5 GPa, which suppress crack formation and film-substrate delamination, could be obtained together with HD values around 25 GPa.
Highlights
Protective coatings are of critical importance for obtaining a performance enhancement of machinery and equipment or to protect the latter when used in harsh environments [5]
Transparent thin films of Al-O-N and Al-Si-O-N with different O and Si contents were fabricated by reactive direct current magnetron sputtering (R-DCMS)
The structure, morphology, hardness HD, Young’s modulus E and stress state σ of these coatings, the chemical states and bonding of the constituents were analyzed as a function of the O and Si content
Summary
Protective coatings are of critical importance for obtaining a performance enhancement of machinery and equipment or to protect the latter when used in harsh environments [5]. 20 (2019) 1032 for transparent hard coatings is AlN, a group III nitride that forms as a polycrystalline wurtzite film when deposited by reactive direct current magnetron sputtering (R-DCMS). We use O, an electronegative group VI element, to obtain a specific film microstructure and with it modified physical properties of the resulting Al-O-N films. In addition to Al-O-N, we investigate quaternary Al-Si-O-N films fabricated by the simultaneous increase of the Si and O contents through the R-DCMS process. For both coating materials, AlO-N and Al-Si-O-N, we report the changes in hardness (HD), elastic modulus (E) and residual stress (σ) that occur with changing microstructure
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
