Microstructure and vacuum tribology of TiC–Ag composite coatings deposited by magnetron sputtering-pulsed laser deposition

Iamvasant

Applied Surface Science

et al. 2017

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.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Iamvasant

Applied Surface Science

et al. 2017

Surface and Coatings Technology

“…Early works have studied the combination of hard phases (TiN or TiC), that provide hardness, with silver as soft metal to play the role of lubricant, to investigate their tribological performance [11,12]. For the use in artificial implants, good biocompatibility is also required, in particular due to the known toxicity of the silver to the human body.…”

Section: Introductionmentioning

confidence: 99%

Influence of silver content on the tribomechanical behavior on Ag-TiCN bioactive coatings

Sánchez-López

Abad

Carvalho

et al. 2012

Surface modification of bulk materials used in biomedical applications has become an important prerequisite for better biocompatibility. In particular, to overcome the particle generation, low-wear coatings based on carbon (nitrogen) and containing antimicrobial elements such as silver are promising candidates. Thus, the present work explores the potentialities of silver-containing carbonitride-based (Ag-TiCN) thin films prepared by direct current unbalanced reactive magnetron sputtering. The silver content in the coatings was varied from 0 to 26.7 at.% by changing the targets and the fraction of C 2 H 2 and N 2 in the gas mixture with Ar. The obtained Ag-TiCN based coatings were characterized in terms of composition and microstructure. Mechanical and tribological properties of the films were studied by nanoindentation and reciprocating pin-on disk *Manuscript changes highlighted Click here to view linked References 2 testing in a fetal bovinum serum solution, respectively. Raman, SEM and energy dispersive X-ray (EDX) analysis was carried out in the contact region after tribological tests to obtain information about the friction mechanism. The cytotoxicity of the coatings was assessed by in vitro tests using fibroblast cells. The coatings comprised a mixture of TiC x N 1-x , Ag and a-C(N) x phases whose relative proportion varied depending on the Ag/Ti ratio. The mechanical, tribological and cytotoxicity were correlated with the chemical and phase composition. When the Ag/Ti ratios were below 0.20 (Ag contents < 6.3 at.%) the films resulted harder (18 GPa) with higher wear resistance (10 -6 mm 3 /Nm), showing similar friction coefficient (0.3) and good biocompatibility.

“…Also, nanostructured films are expected to give the possibility to tune the gas sensing properties by varying the size of the nanoparticles [4], and furthermore, by "locking" the nanoparticles into a matrix a more stable sensing layer could be achieved. Structures with such embedded crystallites of Ag have been synthesised with nc-TiC x /a-C and nc-TiC x /a-SiC as base material [5,6]. Pt is, however, preferred over Ag as a catalytic agent due to its higher melting point, i.e.…”

Section: Introductionmentioning

confidence: 99%

Carbide and nanocomposite thin films in the Ti–Pt–C system

Lewin

Buchholt

et al. 2010

Thin Solid Films

Thin films in the Ti-Pt-C system were deposited by non-reactive, DC-magnetron sputtering.Samples were characterised using X-ray photoelectron spectroscopy, X-ray diffraction, and transmission electron microscopy. A previously not reported metastable solid solution carbide, (Ti 1-x Pt x )C y with a Pt/Ti ratio of up to 0.43 was observed. This solid solution phase was present both as single phase in polycrystalline samples, and together with amorphous carbon (a-C) in nanocomposite samples. Annealing of nanocomposite samples lead to decomposition of the solid solution phase and formation of a nc-TiC x /a-C/nc-Pt nanocomposite. Test sensors for automotive gas exhausts manufactured from such a three-phase material suffers from complete oxidation of the coating at 400 °C with no observed sensor activity.