CrN–Ag nanocomposite coatings: Effect of growth temperature on the microstructure

Mulligan, C.P.; Blanchet, Thierry A.; Gall, Daniel

doi:10.1016/j.surfcoat.2008.06.052

Cited by 51 publications

(23 citation statements)

References 23 publications

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“…Mulligan et al [11][12][13][14] found similar results and attributed the self-lubricating behavior to the presence of Ag nanoclusters on coating surface, whose dimensions increase with increasing temperature of annealing. In their studies the Ag out-of-bulk segregation is suggested to play a fundamental role in Ag surface enrichment and size increase of the Ag surface clusters, depending on Ag concentration, deposition temperature and annealing temperature.…”

Section: Introductionmentioning

confidence: 71%

“…In particular at 22 at.% Ag is supposed to open preferential diffusion paths in the CrN columnar structure, promoting Ag segregation even for annealing temperature slightly higher ( T = 100 C) than deposition temperature. 14 In the present work nanocomposite Cr x N 1−x -Ag coatings were deposited by means of magnetron sputtering technique. The coatings were afterward annealed in N 2 atmosphere ranging from RT to 800 C. The aim of the present study is to investigate the relationship between the deposition protocol and the chemical, structural and morphological properties, and the effect of annealing in the deposited film.…”

Section: Introductionmentioning

confidence: 99%

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Ag Surface Diffusion and Out-of-Bulk Segregation in CrN-Ag Nano-Composite Coatings

Incerti¹,

Rota²,

Ballestrazzi³

et al. 2011

J. Nanosci. Nanotech.

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CrN-Ag nanocomposite coatings are deposited on Si(100) wafers and 20MnCr5 steel disks in a mixed Ar+N2 atmosphere by reactive magnetron sputtering. Structure, composition and morphology were investigated by Scanning Electron Microscopy (SEM), Auger Electron Spectroscopy (AES), X-ray Photoemission Spectroscopy (XPS), X-ray Diffraction (XRD) and Focused Ion Beam (FIB) cross sectional analysis. The as deposited film matrix is mainly composed by CrN phase (78%), but a relevant part (28%) is composed by Cr2N. Ag agglomerates in the CrN matrix forming elongated grains 200-400 nm wide and 50-100 nm high, which extends on the top of CrN columns. At the surface Ag aggregates into two different structures: large tetrahedral crystalline clusters, with typical dimension ranging from 200 to 500 nm, and smaller Ag nanoparticles with diameter of 15-25 nm. The annealing in N2 atmosphere up to 500 degrees C does not affect size and distribution of the Ag grains in the sub-surface region, while it induces a size increase of the bigger Ag clusters on the surface, mainly related to Ag surface diffusion and clusters coalescence. Annealing at higher temperature leads to an evident Ag out-of-bulk segregation, generating Ag depleted voids in the near-surface region, and further increasing of the Ag clusters size at the surface. Tribological tests on as deposited CrN-Ag film reveal a coefficient of friction against a steel ball reduced with respect to CrN film, probably related to the presence of Ag which acts as solid lubricant, but the coating is removed after a very short sliding distance. The poor mechanical properties of the realized Ag-based coatings are confirmed by lower hardness and Young modulus values with respect to pure CrN.

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Section: Introductionmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Ag Surface Diffusion and Out-of-Bulk Segregation in CrN-Ag Nano-Composite Coatings

Incerti¹,

Rota²,

Ballestrazzi³

et al. 2011

J. Nanosci. Nanotech.

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“…All CrN layers were grown in a load-locked ultrahigh vacuum dc magnetron sputtering system, 33 with a base pressure of 1.3ϫ 10 −7 Pa ͑1 ϫ 10 9 Torr͒, onto two-side polished 20ϫ 20ϫ 0.5 mm 3 MgO͑001͒ wafers that were cleaned, mounted, and degassed for epitaxial growth as described in Ref. 34.…”

Section: Experimental Procedures and Optical Analysis Methodsmentioning

confidence: 99%

CrN electronic structure and vibrational modes: An optical analysis

Zhang

Gall

2010

Phys. Rev. B

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The optical properties of paramagnetic CrN over the wavelength range 250 nm-30 m were determined from transmission and reflection spectra of 44-11 000-nm-thick epitaxial CrN͑001͒ layers that were grown on MgO͑001͒ by ultrahigh vacuum magnetron sputtering at 700°C and were found to be pure cubic single crystals by x-ray diffraction -2, , and scan analyses. The imaginary part of the dielectric function exhibits a steep onset at ប = 0.64 eV as well as peaks at ប = 1.5 and 2.9 eV due to direct interband transitions and indicates a depletion in the density of states at the Fermi level with an upper limit for free carriers of 3 ϫ 10 19 cm −3 . This is attributed to local magnetic moments that cause splitting of the t 2g bands and the formation of an indirect band gap of 0.19Ϯ 0.46 eV, as estimated by comparing the optical transition energies with reported direct gap energies from calculations with different magnetic ordering and Coulomb interaction terms. The dielectric function shows a strong resonance at ប 0 = 48.7Ϯ 0.2 meV, and values of dc =53Ϯ 5 and ϱ =22Ϯ 2 below and above the resonance, respectively, providing values for transverse and longitudinal optical phonon frequencies at the zone center of 11.7 THz and 18.2 THz ͑corresponding to ប = 48.7Ϯ 0.2 and 75.6Ϯ 6.8 meV͒, respectively, and a Born effective charge of 4.4Ϯ 0.9. The vibrational frequencies are confirmed by Raman spectroscopy peaks at 800, 1170, and 1330 cm −1 which are attributed to 2TO͑X͒, 2LO͑X͒, and 2LO͑L͒ modes and correspond to single-phonon energies of 49.6 meV, 72.5 meV, and 82.5 meV, respectively. They are quantitatively comparable to those reported for ScN, a semiconductor with the same crystal structure as cubic CrN. In conclusion, both electronic interband transitions and optical phonon frequencies suggest that CrN is a Mott-Hubbard-type insulator with a small to negligible indirect band gap.

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“…In particular, coatings based on Cr-Ag-N [7,8,[17][18][19][20][21] and Cr-Cu-N [6,22,23] (as two typical coating systems), have been studied. For coatings in the Cr-Ag-N system, it is revealed that Ag precipitates often tend to exhibit a lamellar shape (height/width: ~ 1/2 to 1/3), with a uniform, but isolated distribution in the ceramic nitride matrix of the deposited coating [24,25]. However, for coatings in the Cr-Cu-N system, it is typically found that a metastable solid solution phase of Cu in bcc Cr (with Cu content of up to 60 at.%) will form at low deposition temperatures [26] (e.g.…”

Section: Introductionmentioning

confidence: 99%

CrCuAgN PVD nanocomposite coatings: Effects of annealing on coating morphology and nanostructure

Liu

Iamvasant

Liu

et al. 2017

Applied Surface Science

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CrCuAgN PVD nanocomposite coatings were produced using pulsed DC unbalanced magnetron sputtering. This investigation focuses on the effects of post-coat annealing on the surface morphology, phase composition and nanostructure of such coatings. In coatings with nitrogen contents up to 16 at.%, chromium exists as metallic Cr with N in supersaturated solid solution, even after 300 o C and 500 o C post-coat annealing.Annealing at 300 o C did not obviously change the phase composition of both nitrogen-free and nitrogen-containing coatings; however, 500 o C annealing resulted in significant transformation of the nitrogen-containing coatings. The formation of Ag aggregates relates to the (Cu+Ag)/Cr atomic ratio (threshold around 0.2), whereas the formation of Cu aggregates relates to the (Cu+Ag+N)/Cr atomic ratio (threshold around 0.5). The primary annealing-induced changes were reduced solubility of Cu, Ag and N in Cr, and the composition altering from a mixed ultra-fine nanocrystalline and partly amorphous phase constitution to a coarser, but still largely nanocrystalline structure. It was also found that, with sufficient Cu content (> 12 at.%), annealing at a moderately high temperature (e.g. 500 o C) leads to transportation of both Cu and Ag (even at relatively low concentrations of Ag, ≤ 3 at.%) from inside the coating to the coating surface, which resulted in significant reductions in friction coefficient, by over 50% compared to that of the substrate (from 0.31 to 0.14 with a hemispherical diamond indenter, and from 0.83 to 0.40 with an alumina ball counterface, respectively). Results indicate that the addition of both Cu and Ag (in appropriate *Manuscript Click here to view linked References 2 concentrations) to nitrogen-containing chromium is a viable strategy for the development of 'self-replenishing' silver-containing thin film architectures for temperature-dependent solid lubrication requirements or antimicrobial coating applications.

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CrN–Ag nanocomposite coatings: Effect of growth temperature on the microstructure

Cited by 51 publications

References 23 publications

Ag Surface Diffusion and Out-of-Bulk Segregation in CrN-Ag Nano-Composite Coatings

Ag Surface Diffusion and Out-of-Bulk Segregation in CrN-Ag Nano-Composite Coatings

CrN electronic structure and vibrational modes: An optical analysis

CrCuAgN PVD nanocomposite coatings: Effects of annealing on coating morphology and nanostructure

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