Tribological Performance Of Films Research Articles

Tribological performance of ternary TiMN films (M=AL, B, and Cr) deposited by cathodic arc on M2 steel

AbstractIn the industry, the titanium nitride (TiN) coating is widely used in cutting tools, decorative and corrosion protection film, but unfortunately, this coating presented a poor performance under some work condition. For that, different studies have been dedicated to improving its properties with the inclusion of a third element that modifies the film structure, chemical and mechanical properties. In this work, TiN layers with/without of Al, B, and Cr inclusion were studied in order to analyze their effect in the film tribological performance. These were deposited using cathodic arc PVD technic on AISI-M2 steel. They were chemical and structural characterized using EDX and XRD, respectively. While the film thickness was determinate using a ball-cratering technique. Their tribological performance was studied using a sliding reciprocating movement in dry conditions, under three loads, at 30 min against Al2O3 ball as counterbody. The resulting wear tracks were studied using optical microscopy in order to study the wear mechanism. Raman spectroscopy was used to determinate the chemical changes produced on wear zones and the lost material was measured with a stylus profilometer. As result, the structure and morphology were modified with the inclusion of the third element. The TiN with the inclusion of Al and B presented a higher friction force and wear rate than TiN films. While the TiN with Cr inclusion film presented the best tribological performance with lower wear rate and friction coefficient. The Raman studies did not showed considerable changes on the damage coted surface areas, except for TiAlN coating that show the M2 tool steel Raman spectra on the areas where the film was removed.

Tribochemistry dependent tribological behavior of superhard TaC/SiC multilayer films

TaC/SiC multilayer films with different thicknesses of SiC layer (tSiC) were deposited by alternating sputtering of TaC and SiC composite targets in the discharged Ar gas. The SiC layers were forced to crystallize to form a coherent interface with TaC layers at tSiC ≤ 0.8 nm, resulting in an enhancement in both hardness and fracture toughness. When tSiC reached 0.8 nm, the film exhibited the highest hardness (46 ± 2 GPa) and best toughness (4.2 ± 0.2 MPa m1/2). With further increase in tSiC, SiC lost crystallinity and transformed into amorphous state. The deterioration in coherent TaC/SiC interface resulted in the reduction of both hardness and toughness. The wear rate was also dependent on hardness and fracture toughness of multilayers films. The film with the lowest wear rate at tSiC = 0.8 nm was obtained. In addition, the alternating insertion of SiC layers into TaC layers tailored the optimization of film's tribological performance. Lubricious Ta silicate (TaSiOx) and amorphous carbon (a-C) on the surface of wear tracks were identified by SEM and XPS, and wear debris was identified by TEM. Consequently, it was believed that coefficient of friction (CoF) in multilayers was reduced when compared to the individual monolayers because of the synergistic effect of lubricious a-C and TaSiOx. Furthermore, steel and Al2O3 balls were also used as counterparts, and the same variation tendency was observed in both CoF and wear rate as when WC balls were used. Thus, improvement of wear-resistant ability and at the same time reduction of CoF can be simultaneously achieved in superhard TaC/SiC multilayers.

The tribological performance of fullerene‐like hydrogenated carbon films under ionic liquid lubrication

Fullerene‐like hydrogenated carbon films were deposited on Si substrate by plasma‐enhanced chemical vapor deposition. The microstructures of films were characterized by high‐resolution transmission electron microscopy and Raman spectrum. The tribological performance of films was tested by reciprocating ball‐on‐disc tester under 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ionic liquid. The surface morphology and chemical composition of wear tracks and wear rates were investigated by optical microscope, X‐ray photoelectron spectroscopy, and 3D surface profiler. The results indicated that the film with a typical fullerene‐like structure embedded into the amorphous sp2 and sp3 carbon networks could be prepared successfully, and the film shows a higher hardness (26.7 GPa) and elastic recovery (89.9%) compared with the amorphous carbon film. Furthermore, the film shows a lower friction coefficient at low contact load and friction frequency, and excellent wear‐resistance performance at high load and frequency under ionic liquid lubrication. Meanwhile, the wear life of fullerene‐like hydrogenated carbon films could be improved significantly using ionic liquid as a lubrication material. Copyright © 2015 John Wiley & Sons, Ltd.

Structure and mechanical properties of nc-TiC/a-C:H nanocomposite films deposited by filtered cathodic arc technique

nc-TiC/a-C:H nanocomposite films were prepared by filtered cathodic arc technique. The influence of C2H2/Ar flow ratio on the composition, structure, and mechanical properties of films was investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, nanoindentation, and ball-on-disc tribometry. The films show a nanocomposite structure in which TiC crystallites are embedded in the amorphous matrix of a-C:H phase. C content in films increases with the flow ratio of C2H2/Ar, simultaneously, the crystallite size of TiC decreases. Contrary to the nc-TiC/a-C:H films deposited by magnetron sputtering in which the sp3 C content increases with C2H2 flow rate, the increase of C2H2 flow rate leads to the increase of sp2 C content in films deposited by filtered cathodic arc technique. The nc-TiC/a-C:H films deposited by cathodic arc technique have a pronounced hardness maximum of 30 GPa under the C2H2/Ar flow ratio of 12. Tribological performance of films is controlled by the sp2 content in films. Higher sp2 content promotes the formation of graphite-like transfer layer during sliding, and results in lower wear rate and friction coefficient.

Characteristics and tribological performance of DLC and Si-DLC films deposited on nitrile rubber

The characteristics and tribological performance of DLC and Si-DLC films with and without Si–C interlayers were studied in this paper. The films were deposited on nitrile rubber using a closed field unbalanced magnetron sputtering ion plating system. The film properties and characteristics were determined by scanning electron microscopy (SEM), hydrophobicity studies, Raman spectroscopy and tribological investigations. Tribological performance of these films was investigated using a pin-on-disc tribometer under applied loads of 1N and 5N under conditions of dry and wet sliding. The effect of immersing the films in water on tribological performance was also examined. The results show that the morphology of the films had a crack-like network. At a substrate bias of −30V, the coatings were characterised by a very dense non-columnar microstructure. The highest value of the ratio of intensities of the D and G peaks (ID/IG) was 1.2 for Si-DLC film with Si–C interlayer. The lowest value of 0.7 was observed for DLC film. The contact angle (CA) of water droplets showed that the films were hydrophobic. These results are interpreted in terms of hybridisation of carbon in these coatings. The tribological investigation showed a dependence on both the tribological condition under investigation and the atomic percentage of Si in the films. At 5N normal load the lowest wear depth was observed for DLC films.

MICROSTRUCTURE AND TRIBOBOGICAL PERFORMANCE OF TI1-XALXN FILMS FABRICATED BY REACTIVE MAGNETRON SPUTTERING

Ti - Al - N Films with large scale chemical composition were fabricated on stainless steels by changing the relative substrate positions to targets using double-targeted reactive magnetron sputtering technique in one same process. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the composition and microstructure of films. Tribological performance of films was test at room temperature in air without any lubricant. Chemical composition of films altered with substrate positions from Ti 0.82 A 10.18 N to Ti 0.12 Al 0.88 N . XRD results indicated that before heat treatment sputtered films were amorphous, but different phases such as TiN , AlN and TiAlN were formed in films with different composition after heat treatment of 700° C × 1 h . Friction and wear tests indicated that films with x = 0.57, 0.65 hold the best tribological performance of Ti - Al - N films system because of the formation of hard phase TiAlN and different wear mechanism.

Tribological investigation of MPTS‐MPTES SAMs

PurposeThis paper's aim is to study the tribological properties of hyrid monolayer composited by γ‐mercapto‐propyl trimethoxysilane (MPTS) and γ‐methacryloxy propyltrimethoxysilane (MPTES), and estimated the action mechanism.Design/methodology/approachMPTS‐MPTES were self‐assembled on a hydroxylated silicon substrate to form a two‐dimensional hybrid monolayer. Atomic force microscope (AFM), X‐ray photoelectron spectrometry and contact angle measurement were used to characterize the MPTS‐MPTES hybrid self‐assembled monolayer (SAM). The macrofriction and wear behaviors of the film sliding against an AISI‐52100 steel ball were examined on a unidirectional friction and wear tester, and the worn surface morphologies were observed on an AFM.FindingsThe tribological results show that the friction coefficient of silicon substrate reduces from 0.86 to 0.18 after the formation of the MPTS‐MPTES hybrid SAM on its surface, and the thin film has a long wear life (2,620 sliding pass). It is demonstrated that the MPTS‐MPTES SAM exhibited good wear resistant property with a low friction coefficient, and the superior friction reduction and wear life were attributed to the low surface energy and the characteristics of the hybrid SAM.Research limitations/implicationsThe film's tribological performance under dynamic load is not estimated.Practical implicationsA hybrid monolayer with superior tribological property was synthesized on a silicon substrate by self‐assembly process, and maybe it is the potential solution for micro‐electromechanical‐system lubrication.Originality/valueThis paper provides a study way of hybrid SAM on a silicon substrate as lubricating coating.

Recent advances in the chromium nitride PVD process for forming and machining surface protection

This paper reports on the tribological properties of commercial Cr–N physical vapour deposition (PVD) processes for enhanced mechanical protection of forming and machining tools. The study is carried out on conventional tooling materials as substrates, i.e. high speed steels (M2) and cemented tungsten carbide. Electron beam (EB), magnetron sputtering (MS) and cathodic arc (CA) commercial Cr–N PVD processes from three different EU coating centers/companies are evaluated in terms of their tribological behaviour by standard characterization techniques for material properties: surface hardness and roughness, film adherence strength and wear resistance under sliding conditions. The results are discussed on the basis of their current applications and their influence on tool performance for manufacturing processes. Moreover, film tribological performance is correlated with their microstructural properties as obtained by electron microscopy and X-ray diffraction. In terms of surface hardness and adherence strength, CA Cr–N seems to outperform EB and MS coatings. However, EB and MS exhibit enhanced surface finish which might be more appropriate for some applications.