Silicon addition as a way to control properties of tribofilms and friction of DLC coatings

Targeting Biomechanical Endurance of Dental-Implant Abutments Using a Diamond-Like Carbon Coating

“…16 The D-peak (1311 cm −1 ), G-peak (1515 cm −1 ), full width at half-maximum for the Gband (fwhm G ; 198 cm −1 ), I D /I G ratio (0.61), and hydrogen content (22.66%), were obtained to assess the sp 2 bonding structure. The G-peak center position obtained was lower than that reported in previous studies, either using the same DC-PECVD method (1540−1544 cm −1 ) or the same deposition chemical components (1549−1589 cm −1 ), 13,14,28,33 indicating a low internal stress in the DLC film in our study. In detail, the G-peak wavenumber indirectly reflects the degree of carbon disorder and structure order of the sp 2 sites of the DLC film.…”

“…The obtained I D / I G (0.61) ratio indirectly represents the defectiveness degree of the coating. , Values less than 1 characterize increased carbon disorder (D band), boosting the sp 3 carbon hybridization. , Thus, the G-band located at a lower wavenumber might be attributed to the strengthening of the sp 3 bond in the material, as described previously . Based on obtained results, the presence of silicon used as an interlayer in our study probably replaces the carbon atoms (sp 2 bonded clusters), leading to the formation of sp 3 bonds since Si does not form π bonds, only σ. , In agreement with previous data, − , the developed film also presented a high fwhm G , accounting for the observed high carbon disorder degree.…”

“…In detail, the G-peak wavenumber indirectly reflects the degree of carbon disorder and structure order of the sp 2 sites of the DLC film. , Since the bond disorder of sp 2 clusters decreases with the addition of hydrogen or silicon to the system . When it comes to silicon, it only increases the sp 3 content, consequently the stress felt by sp 2 tends to decrease due to increased bonding with Si atoms, shifting the position of the G-band toward lower wavenumbers . Thus, this reduction can be ascribed to the underlying silicon layer (70% hexamethyldisiloxane and 30% argon), which was formed before DLC deposition.…”

“…Diamond-like carbon (DLC), an amorphous hydrogenated material mainly composed of carbon, is extensively used in the biomedical field because of its protective properties (mechanical resistance, anticorrosion, chemical inertness, and biocompatibility). − However, DLC properties are directly associated with the three-dimensional chemical network of sp 2 and sp 3 hybridized carbon. − In detail, the sp 2 bonding (graphite-like behavior) is modulated by the amount of hydrogen, favoring a strong lubricating behavior. , Moreover, coatings with considerable density (compact structure) and rigidity (high hardness and elastic modulus) are obtained by the sp 3 hybridization of carbon atoms . Hence, DLC materials with higher amounts of sp 3 carbon atoms display elevated residual stress, allowing the intrinsic bucking defect at the film–substrate interface, which also hinder their practical application .…”

“…DLC interlayers containing silicon are commonly employed to improve the adhesion in metallic alloys owing to its chemical stability. ,,− The inner stress of the DLC material is responsible for the initiation/propagation of cracks at the tail between the contact zone on the surface or at the base of the coating and finally cause delamination from its substrate . Thus, adding a silicon interlayer increases adherence with the metallic substrates and consequently decreases the shear stress as a crack barrier shielding to increase material applicability .…”