Abstract:HardnessDeuterated amorphous carbon films (a-C:D) have been studied in the last few years in order to investigated possible isotopic effects in the film properties. When compared with films deposited in methane atmosphere, an important reduction of the deuterium content of the films was observed and the reasons for that are not well understood. In this work, we deposited amorphous carbon films by PECVD using methane and deuterated methane gas mixtures as precursor atmospheres. We also investigated the effects … Show more
“…Consequently, one must affirm that the different isotopic systems change only the phonon distribution. Moreover, as determined in a previous work 22 , the ERDA profiles guarantee a homogenous concentration of deuterium and hydrogen as a function of depth, which rules out any possible influence of the deuterium and hydrogen distributions on the friction results. Figure 2 Friction force of a diamond spherical dome sliding on a-C:D/H thin films (isotopic systems) with different deuterium content at an average indentation depth of ~(75 ± 10) nm.…”
Section: Resultssupporting
confidence: 64%
“…1b) 22 . The signal width is proportional to the a-C:D/H thin film thickness and the signal shape (the slope after the maximum) is consistent with a scattering mechanism leading to conclude that both concentration profiles are constant throughout the film (see Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Here, m
tip is the dynamical effective mass of the diamond tip, η is the damping constant of the inelastic interaction process, v is the sliding velocity between both surfaces in relative motion, σ is adsorbate areal density and A is the contact area. By knowing that the atomic densities of the a-C:D/H studied films are the same 22 , the above estimated contact area factors, and the dynamical effective mass of the diamond tip and sliding velocity are constant in all the measurements, the η is our most important parameter to analyze. From these considerations, one can conclude that the damping constant η is the key factor to compare in the experimental results, i.e., any observable change in the friction forces should be ascribed to the influence of deuterium in the energy dissipation process.…”
Section: Resultsmentioning
confidence: 99%
“…Details of these measurements are described elsewhere 22 . Structural details of the a-C:D/H thin films were studied by Raman spectroscopy (Raman Confocal NTegra Spectra NT-MDT/473 nm laser) and Fourier transform Infrared (FTIR) spectroscopy (PerkinElmer FTIR Spectrometer/model Spectrum 400).…”
The friction phenomenon is a ubiquitous manifestation of nature. Models considering phononic, electronic, magnetic, and electrostatic interactions are invoked to explain the fundamental forces involved in the friction phenomenon. In order to establish the incidence of the phonon prompting at the nanoscale friction by direct contact, we study a diamond spherical dome sliding on carbon thin films containing different amount of deuterium and hydrogen. The friction coefficient decreases by substituting hydrogen by deuterium atoms. This result is consistent with an energy dissipation vibration local mechanism from a disordered distribution of bond terminators.The understanding of the physical causes and how controlling friction properties is a cutting edge challenge in order to save energy, diminishing wear, increasing the lifetime and sustainability of mechanical devices, and improving performance 1, 2 . From Leonardo da Vinci's and Guillaume Amontons's ancient experiments up to the present time, the friction effects continue demanding enforces to explain the observed phenomenon 3, 4 . Indeed, the non-conservative forces acting in the physical interaction between two surfaces in relative motion is not explained by a unique and fundamental physical mechanism. This is in part due to the complexity of the dissipative forces involved in the phenomenon, strongly depending on the length scales of the sliding parts [5][6][7] . Furthermore, one of the most challenging fields in tribology concerns with the connection between the engineering (macro) phenomenological models and physical fundamental (atomic and nanoscale) laws.By the lack of better tools, molecular dynamics calculations are applied to inspect the macroscopic phenomenological three-term kinetic friction model (or part of it) to phenomena occurring at the nanoscale size 5,6 . This model assumes the combination of three effects, namely, the adhesion force in the presence of a lubricant at zero normal load (Derjaguin offset), the coefficient of friction (da Vinci-Amontons-Coulomb law) and the effective shear stress (Bowden-Tabor law) 6 . Although this approach brings valuable information for practical applications, several basic answers remain pending as, for example, the physical nature of the Derjaguin offset, the physical understanding of the origin of the friction coefficient, and the influence of the shear stress on the phenomenom. Therefore, an attempt to improve the understanding of the three-term kinetic friction model by using fundamental physical properties of the matter could help to unify several mechanisms prompting the friction at the nanoscale size that seem disconnected at the present.From a statistical thermodynamically point of view, the friction phenomenon is one of the physical manifestations of the fluctuation-dissipation theorem (FDT) 8 . This important theorem explains the transition from the microscopic reversibility physical process to a macro irreversibly phenomena involving energy dissipation, i.e., entropy increasing 9 . Recently, the FD...
“…Consequently, one must affirm that the different isotopic systems change only the phonon distribution. Moreover, as determined in a previous work 22 , the ERDA profiles guarantee a homogenous concentration of deuterium and hydrogen as a function of depth, which rules out any possible influence of the deuterium and hydrogen distributions on the friction results. Figure 2 Friction force of a diamond spherical dome sliding on a-C:D/H thin films (isotopic systems) with different deuterium content at an average indentation depth of ~(75 ± 10) nm.…”
Section: Resultssupporting
confidence: 64%
“…1b) 22 . The signal width is proportional to the a-C:D/H thin film thickness and the signal shape (the slope after the maximum) is consistent with a scattering mechanism leading to conclude that both concentration profiles are constant throughout the film (see Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Here, m
tip is the dynamical effective mass of the diamond tip, η is the damping constant of the inelastic interaction process, v is the sliding velocity between both surfaces in relative motion, σ is adsorbate areal density and A is the contact area. By knowing that the atomic densities of the a-C:D/H studied films are the same 22 , the above estimated contact area factors, and the dynamical effective mass of the diamond tip and sliding velocity are constant in all the measurements, the η is our most important parameter to analyze. From these considerations, one can conclude that the damping constant η is the key factor to compare in the experimental results, i.e., any observable change in the friction forces should be ascribed to the influence of deuterium in the energy dissipation process.…”
Section: Resultsmentioning
confidence: 99%
“…Details of these measurements are described elsewhere 22 . Structural details of the a-C:D/H thin films were studied by Raman spectroscopy (Raman Confocal NTegra Spectra NT-MDT/473 nm laser) and Fourier transform Infrared (FTIR) spectroscopy (PerkinElmer FTIR Spectrometer/model Spectrum 400).…”
The friction phenomenon is a ubiquitous manifestation of nature. Models considering phononic, electronic, magnetic, and electrostatic interactions are invoked to explain the fundamental forces involved in the friction phenomenon. In order to establish the incidence of the phonon prompting at the nanoscale friction by direct contact, we study a diamond spherical dome sliding on carbon thin films containing different amount of deuterium and hydrogen. The friction coefficient decreases by substituting hydrogen by deuterium atoms. This result is consistent with an energy dissipation vibration local mechanism from a disordered distribution of bond terminators.The understanding of the physical causes and how controlling friction properties is a cutting edge challenge in order to save energy, diminishing wear, increasing the lifetime and sustainability of mechanical devices, and improving performance 1, 2 . From Leonardo da Vinci's and Guillaume Amontons's ancient experiments up to the present time, the friction effects continue demanding enforces to explain the observed phenomenon 3, 4 . Indeed, the non-conservative forces acting in the physical interaction between two surfaces in relative motion is not explained by a unique and fundamental physical mechanism. This is in part due to the complexity of the dissipative forces involved in the phenomenon, strongly depending on the length scales of the sliding parts [5][6][7] . Furthermore, one of the most challenging fields in tribology concerns with the connection between the engineering (macro) phenomenological models and physical fundamental (atomic and nanoscale) laws.By the lack of better tools, molecular dynamics calculations are applied to inspect the macroscopic phenomenological three-term kinetic friction model (or part of it) to phenomena occurring at the nanoscale size 5,6 . This model assumes the combination of three effects, namely, the adhesion force in the presence of a lubricant at zero normal load (Derjaguin offset), the coefficient of friction (da Vinci-Amontons-Coulomb law) and the effective shear stress (Bowden-Tabor law) 6 . Although this approach brings valuable information for practical applications, several basic answers remain pending as, for example, the physical nature of the Derjaguin offset, the physical understanding of the origin of the friction coefficient, and the influence of the shear stress on the phenomenom. Therefore, an attempt to improve the understanding of the three-term kinetic friction model by using fundamental physical properties of the matter could help to unify several mechanisms prompting the friction at the nanoscale size that seem disconnected at the present.From a statistical thermodynamically point of view, the friction phenomenon is one of the physical manifestations of the fluctuation-dissipation theorem (FDT) 8 . This important theorem explains the transition from the microscopic reversibility physical process to a macro irreversibly phenomena involving energy dissipation, i.e., entropy increasing 9 . Recently, the FD...
“…In our previous study and another study examining the properties of a-C:D films, the hardnesses of the a-C:D films were lower than that of the a-C:H film even if the sp 2 /sp 3 ratios of these films were the same, suggesting that the void structures of these films might be different [13][14][15]. However, the void structures of the a-C:D and a-C:H films have not been investigated.…”
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
