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Abstract: This work attempts to reveal the microstructure of interface and the relation between interface mixing and hardening mechanism in TiN/CNx multilayer films. The growth and microstructure of these interfacial layers are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Investigation result indicates that the interface species are mainly composed of Ti–C–N, the growth of interlayer mainly depends on the deposition temperature. The thickest interlayer (about 2.5nm) is produced at 300°C, and the interlayer disappears at 500°C. Nanoindentation testing indicates that the film with a maximum interlayer thickness of about 2.5nm exhibits superhardness up to 40GPa. Based on the experimental results, it is suggested that the interfacial intermixing and the crystal quality of TiN are the main reasons for the superhardness effect in TiN/CNx nanostructured multilayers. [ABSTRACT FROM AUTHOR]

Abstract: Carbon nitride (CN x ) films were deposited by direct current magnetron sputtering at different N2 fractions and a substrate temperature of 450°C. The composition and microstructure of CN x films were investigated by high resolution transmission electron microscopy, X-ray absorption near-edge spectroscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. The CN x films change from amorphous to fullerene-like nanostructure as the N2 fraction is ranged from 0.05 to 0.1, and then to nitridized graphite nanocrystals in amorphous matrix at pure N2, and the curvature of the basal planes decreases with the increase of N content in CN x films. Meanwhile, the structural analysis provides the identification of spectral signatures related with the formation and promotion of FL arrangements, and the formation of C-sp3 sites has been generally considered as the cross-linking path in fullerene-like CN x . Their mechanical and tribological properties were also investigated in detail, aiming at illustrating excellent mechanical, friction and wear behaviours of the fullerene-like CN x film with respect to its high hardness and elastic recovery and less dependence on humidity and oxygen as compared with the amorphous CN x film. [ABSTRACT FROM AUTHOR]

Abstract: Titanium incorporated amorphous carbon nitride films were deposited by direct current magnetron sputtering. The films change from amorphous to nanocomposite structure, the relative fraction of sp 3 C–N bonding decreases significantly from 2.17 to 1.64 with the increase of Ti content from 2.7at.% to 12.3 at.%. For the films with high Ti content, the nanocrystalline TiN embedded in a-CN x matrix, while principally TiN did not appear to be well formed for the film containing low Ti content. Potentiodynamic polarization, in vitro human osteoblasts and murine fibroblast cell adhesion tests were employed to assess the corrosion performances of Ti6Al4V alloy coated with the films in Tyrode''s solution, and the biocompatibility of Ti-incorporated a-CN x films, respectively. Titanium incorporation increases the corrosion resistance of a-CN x films, and the higher corrosion potential and lower corrosion current density are observed for the alloy coated with the film containing lower Ti content. The high osteoblast adhesion and activation demonstrate the enhanced biocompatibility of Ti alloy coated with Ti-incorporated a-CN x films. The improved biocompatibility in biological environment is attributed to structural change after titanium introduction. [Copyright &y& Elsevier]

Abstract: Carbon nitride (CN x /CN x ) multilayers with sequential sp3-rich and sp2-rich layers were deposited on c-Si substrate by direct current magnetron sputtering. The composition, microstructure and morphology of the films were investigated by the X-ray photoelectron spectroscopy and transmission electron microscopy. In the films, the sp3 C–N rich and the sp2 C–N rich layers exhibit amorphous feature and graphite-like structure, respectively, and the multilayered structure is continuous over relatively well defined and smooth layer interfaces. The mechanical properties of the films were measured by the nanoindentation and nanoscratch tests. The multilayer films showed lower compressive stress and higher hardness than their monolayer components. Meanwhile, the a-CN x multilayer film with a bilayer period of 60nm exhibited the improved mechanical properties, and the lowest friction coefficient and the highest wear resistance. [Copyright &y& Elsevier]

Abstract: Amorphous carbon nitride (a-CN x ) films with functional gradient Ti–TiN/CN x underlayer were deposited by direct current magnetron sputtering. Microstructure and composition of the films were characterized by means of X-ray diffraction (XRD), Raman spectroscopy, atomic force microscope (AFM) and transmission electron microscopy (TEM). Mechanical and tribological properties were investigated by nanoindenter, scratch and ball-on-disk tribometer. The a-CN x -based films suffer a graphitization process with the increasing deposition temperature, thus the hardness and elastic modulus decrease. With the design of the Ti–TiN/CN x gradient underlayers, some important advantages of relatively thick CN x films can be achieved, such as increased hardness, improved adhesion strength, and the wear resistance of the a-CN x -based films can be also improved significantly. [ABSTRACT FROM AUTHOR]