In the present paper, we develop a new in situ low-friction technology for diamond-like carbon coatings using surface discharge in ambient air. As a result, the friction coefficient dropped from 0.18 ...to 0.06 shortly after surface discharge. Surface profiles and Raman analysis revealed the effectiveness of surface discharge to provide a thick and soft transfer layer, providing the optimal low friction condition described by Halling. Finally, we clarified the optimum surface discharge design that low-energy surface discharge produced a thick transfer layer due to concentration of the produced debris, resulting in low friction.
•Anew in situ low-friction technology for diamond-like carbon coating was developed.•The surface treatment using discharge decreased friction of DLC from 0.18 to 0.06.•Thickness of the transfer layers on the mating material is strongly important for the reduction.•The detailed analysis based on the Halling’s theory shows excellent agreement.•Design guidelines for surface discharge are also provided.
Lithium (Li)‐metal anodes are of great promise for next‐generation batteries due to their high theoretical capacity and low redox potential. However, Li‐dendrite growth during cycling imposes a ...tremendous safety concern on the practical application of Li‐metal anodes. Herein, an effective approach to suppress Li‐dendrite growth by coating a polypropylene (PP) separator with a thin layer of ultrastrong diamond‐like carbon (DLC) is reported. Theoretical calculations indicate that the DLC coating layer undergoes in situ chemical lithiation once assembled with the lithium‐metal anode, transforming the DLC/PP separator into an excellent 3D Li‐ion conductor. This in situ lithiated DLC/PP separator can not only mechanically suppress Li‐dendrite growth by its intrinsically high modulus (≈100 GPa), but also uniformly redistributes Li ions to render dendrite‐free lithium deposition. The twofold effects of the DLC/PP separator result in stable cycling of lithium plating/stripping (over 4500 h) at a high current density of 3 mA cm−2. Remarkably, this approach enables more than 1000 stable cycles at 5 C with a capacity retention of ≈71% in a Li || LiFePO4 coin cell and more than 200 stable cycles at 0.2 C in a Li || LiNi0.5Co0.3Mn0.2O2 pouch cell with cathode mass loading of ≈9 mg cm−2.
An in situ lithiated DLC/PP separator suppresses Li‐dendrite growth and redistributes Li ions to render dendrite‐free lithium deposition, which results in stable cycling of lithium plating/stripping (over 4500 h) at 3.0 mA cm−2 and more than 200 stable cycles at 0.2 C in a Li || LiNi0.5Co0.3Mn0.2O2 pouch cell with a cathode mass loading of ≈9 mg cm−2.
•The coatings are distinguished by the low coefficient of friction and wear•Wear traces suggesting fretting appear on the coatings•Coating damage consists in micropullouts, abrasions and material ...buildups in places•No traces of fretting wear are noted on the CrN-a:C:H:W:Ti coating
FTIR Spectroscopy for Carbon Family Study Ţucureanu, Vasilica; Matei, Alina; Avram, Andrei Marius
Critical reviews in analytical chemistry,
11/2016, Letnik:
46, Številka:
6
Journal Article
Recenzirano
Fourier transform Infrared (FTIR) spectroscopy is a versatile technique for the characterization of materials belonging to the carbon family. Based on the interaction of the IR radiation with matter ...this technique may be used for the identification and characterization of chemical structures. Most important features of this method are: non-destructive, real-time measurement and relatively easy to use. Carbon basis for all living systems has found numerous industrial applications from carbon coatings (i.e. amorphous and nanocrystalline carbon films: diamond-like carbon (DLC) films) to nanostructured materials (fullerenes, nanotubes, graphene) and carbon materials at nanoscale or carbon dots (CDots). In this paper, we present the FTIR vibrational spectroscopy for the characterization of diamond, amorphous carbon, graphite, graphene, carbon nanotubes (CNTs), fullerene and carbon quantum dots (CQDs), without claiming to cover entire field.
The X-ray absorption near edge structure (XANES), X-ray photoelectron spectroscopy (XPS), valence band photoemission (VB-PES) and Raman spectroscopy results show that the incorporation of nitrogen in ...pulsed laser deposited diamond like carbon (DLC) thin films, reverts the sp3 network to sp2 as evidenced by an increase of the sp2 cluster and ID/IG ratio in C K-edge XANES and Raman spectra respectively which reduces the hardness/Young's modulus into the film network. Si-doped DLC film deposited in a plasma enhanced chemical vapour deposition process reduces the sp2 cluster and ID/IG ratio that causes the decrease of hardness/Young's modulus of the film structure. The Fe-doped DLC films deposited by dip coating technique increase the hardness/Young's modulus with an increase of sp3-content in DLC film structure.
•Fe, N and Si doped DLC films deposited by dip, PLD and PECVD methods respectively•DLC:Fe thin films have higher hardness/Young's modulus than DLC:N(:Si) thin films.•sp3 and sp2 contents are estimated from C K-edge XANES and VB-PES measurements.
In recent years innovation in carbon based materials have encouraged both researchers as well as industrialists to develop materials/composites with improved tribological properties. Researchers have ...been fascinated to develop diamond like carbon (DLC) or carbon nanotubes (CNTs) reinforced coatings to their good corrosion resistance, excellent wear resistance, good adhesion strength, and self -lubricious nature. The present review article is mainly focused on various techniques employed in order to process DLC/CNTs coatings as well as provide a summary of DLC/CNTs deposition on different substrates. The present study includes major types, properties and tribological behavior of carbon based materials and mechanisms involved in coating deposition. The study also discusses that deposition of DLC/CNTs coatings on the substrate materials enhances the wear, corrosion and mechanical properties of the substrate.
•The paper is principally concerned with discussion of carbon based materials deposited on a different substrate.•The paper includes discussion on deposition techniques, mechanism and parameters involved in carbon based coatings.•Major types, properties and tribological behaviour of carbon based coating (DLC/CNTs) have also been discussed.•Efforts have been made for the usage of DLC/CNTs film in the functional application.
Raman spectroscopy has developed into a leading tool for characterizing organic materials based on their rotational and vibrational spectral signatures. This article summarises progress to date in ...the Raman spectroscopy of important new carbon allotropes and nanomaterials, many of which have been synthesised only in the last two decades. This includes allotropes such as carbynes, graphynes, graphdiynes, graphene, graphite, highly-oriented pyrolytic graphite (HOPG), common fullerenes, carbon nanotubes, carbon onions, diamond, lonsdaleite, nanodiamond, ultra-nanocyrstalline diamond (UNCD), amorphous carbon (a-C), tetrahedral amorphous carbon (ta-C), amorphous diamond (a-D), and diamond-like carbon (DLC). Key spectral features are summarised for each carbon allotrope, where experimental data is available. This work aims to provide a useful “field guide” to assist other researchers in identifying new or unusual pure carbon samples.
Display omitted
•Reviews Progress in the Raman spectroscopy of new sp-, sp2-, sp3- hybridised carbon allotropes.•Raman spectra are related to their carbon lattice vibrational modes.•Noteworthy 1st- and 2nd-order spectral peaks are graphed for the most common allotropes.•Space groups and spectral peaks nm are tabulated for frequently-employed excitation sources.•Nanomaterials, amorphous carbons, and Mixed-hybridisation Allotropes are included.
Titanium alloys are characterized by poor tribological performance, and their conventional use has been restricted to non-tribological applications. Surface films and surface texturing are effective ...methods to improve the tribological properties of sliding surfaces. In this study, the patterns of micro-dimples with different densities and diamond-like carbon (DLC) films were fabricated on the surface of titanium alloy by laser surface texturing and magnetron sputtering, respectively. The effects of dimple densities and DLC phase transformation on the tribological behavior of the titanium alloy under dry friction and liquid lubrication conditions were investigated. The results showed that DLC film with appropriate dimple area density (44%) are effective in enhancing reducing-friction property of titanium alloy substrate because of the entrapment of wear particles in the dimples and dimple-induced graphitization during sliding motions, while the 24% textured specimen exhibited outstanding wear resistance.
•Combining LST technology with DLC coatings achieved a low friction and wear.•An appropriate number of dimples trapped wear debris and maintained coating hardness.•Dimples and dimples-induced DLC graphitization generated the friction-reducing.•Entrapment of wear debris and low DLC graphitization improved the wear-resistance.
Cr-doped diamond-like carbon (Cr-DLC) films with Cr contents ranging from 3 up to 20 at. % were synthesised in a codeposition process with HiPIMS (Cr deposition) and DC-pulsed technology (C ...deposition). The application of HiPIMS at low frequencies was observed to significantly enhance the energy density during the Cr plasma discharge due to the interaction of Cr–C species. The higher energy bombardment at low HiPIMS frequencies allowed doping with Cr the DLC structure avoiding the graphitization of the carbon structure. EELS spectroscopy was used to evaluate sp3 content and Raman was used for sp2 structural characterization of the films. Enhanced mechanical properties (hardness up to 30 GPa) were observed with nanoindentation for Cr-doped DLC at low frequencies. High temperature nanoindentation tests were also performed from room temperature to 425 °C in order to evaluate the evolution of hardness and Young Modulus with temperature. The results showed that the mechanical properties at high temperature mainly depend on the initial sp3-sp2 structure. Tribological tests were carried out in air from room temperature to 250 °C. Cr-doped DLC coatings deposited by low-frequency HiPIMS showed lower friction and wear compared to undoped DLC.
•Cr-doped DLC coatings were co-deposited by low-frequency/high current HiPIMS method.•Cr doping by low frequency HiPIMS preserves DLC sp3 content and reduces compressive stress.•Low at. % Cr-doped DLC exhibit high hardness (up to 29 GPa) and delayed graphitization (up to 400 C).•Low at. % Cr-doped DLC presents enhanced tribological behaviour at high temperatures by creating stable tribolayers.
Surface texturing and solid lubricants have demonstrated the ability to substantially reduce friction and wear under dry conditions. In recent decades, these two technologies have been combined to ...leverage the advantages of both for superior tribological performance. This review article first summarizes the state-of-the-art regarding surface texturing and solid lubricants, including soft metals, polytetrafluorethylene, diamond-like carbon and 2D layered materials. Then, the synergy between surface textures and solid lubricants is discussed, with particular emphasis on the underlying mechanisms. Finally, gaps in the existing understanding of these synergies are identified and opportunities for future research are suggested.
Display omitted
•This review focuses on the combination of surface textures and solid lubricants.•The limitations of surface textures and solid lubricants for dry sliding are identified.•Soft metals, PTFE, DLC and 2d layered materials as solid lubricants are considered.•Synergistic mechanisms between texturing and solid lubricants are discussed.•Current short-comings and opportunities for future research are identified.
PDF
