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

Abstract

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.

Influencia de las nanopartículas de Ag sobre las propiedades mecánicas y tribológicas y en el efecto citotóxico y bactericida de los recubrimientos de TaN(Ag)

“…En las Fig. 2 (a-b) correspondiente a los recubrimientos de TaN(Ag)-1 y TaN(Ag)-2, se observa la formación de una estructura densa columnar, de grano fino con cúpulas globulares (Liu et al, 2017). En la Fig.…”

Investigation of the nanostructure of as-deposited and post-coat annealed CrCuAgN PVD nanocomposite coatings

“…After the target cleaning process, a ~200nm thick nitrogen-free CrCuAg interlayer was deposited on the substrates before the deposition of CrCuAgN coatings, in order to enhance the coating-substrate adhesion. Then Nitrogen was introduced at an increasing rate of 1 sccm/min [17,33] until the final set value of 5 sccm was reached. Following the interlayer deposition process, a fixed nitrogen flow rate of 5 sccm was used for the deposition process of CrCuAgN coatings, in order to maintain the metallic states of these coatings.…”

“…), as a solidlubricating phases, embedded in a hard wear-resistant matrix such as a transition metal nitride [1][2][3][4][5][6][7], carbide [8,9] or oxide [10][11][12], and mixtures of these ceramic phases (in ternary/quaternary nanocomposite coating systems), have been attracting increasing research interest for more than a decade. Some combinations exhibit promising tribological performance for applications which involve transient and/or cyclic temperature changes [13][14][15], as well as good antimicrobial [16][17][18][19][20][21] and anti-biofouling [22][23][24] performance.…”

“…In a previous study [17], the effect of post-coat annealing (at 300 °C and 500 °C, respectively) on the surface morphology, phase composition and nanostructure of CrCuAgN coatings was investigated. Results showed that, with concentrations up to 16 at.%, N merely exists as a supersaturated interstitial solid solution in metallic Cr, with this solid solution being maintained even after a 2-hour post-coat anneal at 500 °C.…”

Nanocomposite Coatings: Preparation, Characterization, Properties, and Applications

“…This method is used generally for producing of the I/I nanocomposite coating [41][42][43][44][45][92][93][94][95][96][97], which includes the inorganic matrices and inorganic nanoparticles. For these coatings, PVD method includes the following: laser ablation [98], thermal evaporation [99], ion beam deposition [100], ion implantation [101,102], laser-assisted deposition [103], and atom beam cosputtering technique.…”