This study was carried out to assess the effect of PAO-4 and mineral oil mixed with MoDTC and ZnDTP on the tribological performance of novel tetrahedral-amorphous-carbon (ta-C) coatings namely ...P:ta-C, and M:ta-C, were analysed using the Pin-on-Disk Tribo-tester with a fixed normal load, temperature, sliding distance and speed of 20 N, 80 °C, 250 m and 0.068 ms−1 for 60 min, respectively. The C:ta-C, P:ta-C, and M:ta-C showed excellent wear resistance when lubricated with MoDTC + ZnDTP. The formation of weak Zn-derived tribofilm on the P:ta-C coating contributed to the strong wear resistance and reduced friction coefficient. Moreover, the passive transfer of ferrous compounds from the SUJ2 disk induced the development of weak Zn-derived tribofilm on the P:ta-C and M:ta-C.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To enhance the tribological properties of Si3N4 based ceramics, surface textures of dimples combined with DLC coatings are fabricated on Si3N4/TiC ceramic surface by nanosecond laser and plasma ...enhanced chemical vapor deposition (PECVD). The dry friction and wear performances are evaluated by unidirectional sliding friction tests using a rotary ball-on-disk tribometer. Results reveal that the friction and wear properties of Si3N4/TiC ceramics are significantly enhanced by DLC coatings or dimpled textures, and the DLC coatings combined with dimpled textures show the best efficiency in reducing friction, adhesion and wear. This improvement can be explained by the synergistic effect of DLC coatings and surface textures, and the synergistic mechanisms are attributed to the formation of lubrication film and secondary lubrication, debris capture of dimpled textures, increased surface hardness and mechanical interlocking effect, and reduced contact area.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study investigates the use of 1,3-dimethylimidazolium dimethylphosphate ionic liquid (IL) additive in glycerol base oil for improving the lubrication-properties of tungsten-doped diamond-like ...carbon (WDLC) coatings. Tribological tests were conducted at various applied loads (5 N, 10 N, 20 N) and elevated temperature (100 °C), and the addition of 1 wt% of IL resulted in a significant reduction (∼50%) in friction-coefficient. In-situ neutron-reflectometry analysis revealed a multi-step tribofilm formation mechanism involving IL and W-clusters, resulting in the formation of a 1.24-nm thick tribofilm on the WDLC surface within the first 30-minutes of the friction experiment. The reaction kinetics for tribofilm formation are discussed involving dissociation of dimethylphosphate into dioxo-phosphate, which interacts with W-clusters to form tungsten phosphates and cations adsorbed on their surface.
Display omitted
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The DLC coatings are chemically inert, have low friction coefficient and good wear resistance. Depending on H content and sp3 bonds, they can be classified in “soft” or “hard” films. In this work, ...the corrosion and mechanical behavior, as well as the adhesion of thick DLC coatings are studied. The coatings, which are in fact silicon containing amorphous hydrogenated carbon films, were deposited by PACVD on nitrided austenitic stainless steel (duplex sample) and non-nitrided austenitic stainless steel (coated sample). The films were characterized by EDS and Raman spectroscopy, hardness was assessed by nanoindentation and microstructure was analysed by OM and SEM. To evaluate sliding wear behavior and friction, pin on disk tests were performed. The abrasive wear resistance was tested using the ASTM G65-95 Dry Sand/Rubber Wheel test. Erosion tests were conducted in water and sand flux. The corrosion resistance was evaluated by the Salt Spray Fog Test and electrochemical tests. The adhesion was tested using Scratch Test. The purpose was to systematically characterize the defects present in these thick DLC coatings relating them to adhesion, wear and corrosion resistance.
The thickness of the DLC coating was about 37μm, and its hardness was 12GPa. The coatings presented a low friction coefficient, about 0.09. In the abrasive tests, the mass loss was negligible and in erosion experiments, the mass loss was reduced to 30%. Regarding the corrosion performance, the behavior in the Salt Spray Fog Test was good only in the duplex samples. In potentiostatic tests in 3.5% NaCl using steps, the current density increased at higher potentials for the duplex sample. Concerning the film adhesion, the critical load was also higher in theses samples than in the coated ones. The nitrided layer was a good interface for reducing the stresses and improving the adhesion, which is relevant for the decrease of the propagation rate of corrosion, when traversing defects are formed in the coating.
•These DLC coatings had low hardness and low Young's Modulus.•These thick and soft DLC films presented low friction coefficient and excellent sliding wear resistance.•These coatings showed also outstanding behavior in abrasive wear tests.•The nitrided layer improved the adhesion and erosive wear of the DLC coatings.•The corrosion resistance is related not only to the adhesion but also to passing through defects.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The radio-frequency discharge growth of diamond-like carbon coatings from the Ar + C6H6 gas was theoretically analyzed with the aim to evaluate the role of Ar+ ions and C6H6+ ionized molecules ...bombardment on the growth rate and sp2/sp3 carbon phase composition. It has been shown that the growth rate changes nonlinearly with the increase of argon content in the gas. Firstly, it increases from 1.9 μm/h at PAr/(PAr+Pbenzol)=0.033 up to 2.15 μm/h at PAr/(PAr+Pbenzol)=0.5 with further rapid decrease down to 0.57 μm/h at PAr/(PAr+Pbenzol)=0.967. By using theoretical calculations as well as experimental methods it has been shown that sp3 content in the coatings increases within the range 0.31…0.41 with increase in the relative partial pressure of argon.
•Growth rate of coating synthesized from C6H6+Ar mixture is maximal at 50% Ar content.•Fraction of sp3 bonds and density of coating increase with the Ar content.•Predictions of proposed models are in qualitative agreement with experimental data.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper presents selected mechanical and tribological properties of DLC coatings (diamond-like carbon coatings) and the results of an applied texture to improve these properties under specific ...circumstances. It presents the results of the selection of parameters for the laser-texturing process of DLC coatings using a picosecond laser with a wavelength of 343 nm.
Diamond-Like Carbon (DLC) coatings have high wear resistance, hardness, biocompatibility and chemical inertness. Secondary structures, which formed at the track in dry friction conditions, provide ...friction reduction. Doping DLC with both metallic and non-metallic elements leads to a rearrangement of the structure of graphite clusters, a change in their properties, and facilitates the formation of secondary structures. In the present, the silicon atoms were used to create the compositional structure of DLC surface layers at the level of the crystal lattice. DLC-Si coatings with the thickness of 2 µm were deposited on a (Cr, Al, Si)N layer with the thickness of 3 µm formed on a steel substrate. DLC-Si layer was deposited by plasma-enhanced chemical vapor deposition using acetylene and tetramethylsilane. Nanoindentation in the wear mode was used to study the nanomechanical properties of the surface. Atomic force microscopy was used to visualize the surface morphology and wear traces. In this study, secondary structures were created in a microfriction process using a NanoScratch mode. The surface structures after microfriction was observed by atomic force microscopy, and the specific surface energy was measured. The specific volumetric wear rate of the coatings after microfriction was estimated. During microtribological testing with double squares the specific volumetric wear rate of DLC coatings was 5.39·10-14 m3/N·m for 0.8 %Si and 12.39·10-14 m3/N·m for 10 % Si. When tested in the form of scratches, the specific volumetric wear rate for the coating was for the DLC-0.8 % Si (1.22 – 10.71)·10-14 m3/N·m and for the DLC-10 % (6.17 – 49.55) ·10-14 m3/N·m.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Bionic shark-skin textures and DLC coatings were prepared on Si3N4/TiC ceramic. Sliding friction tests were performed against AISI 1045 steel ball on a ball-on-disk tribometer from 25 ℃ to 500 ℃ to ...evaluate the high-temperature tribological properties of Si3N4/TiC ceramic with a combination of shark-skin textures and DLC coatings (TC). Results showed that the TC sample achieved the lowest friction coefficient when the temperature was less than 300 °C, while as the temperature rose to 500 °C, the friction coefficient of all samples initially decreased and then increased, and that of the smooth sample (SS) was lower compared to the other samples (TS and TC) at the relatively steady stage. Finally, the mechanism was discussed.
•Shark-skin textures and DLC coatings were fabricated on Si3N4/TiC ceramic.•High-temperature tribological properties of textures and DLC coatings were studied.•The TC sample exhibited excellent anti-friction properties below 300 °C.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To improve the adhesion strength and enhance the wear resistance of diamond-like carbon (DLC) coatings, different negative bias voltages were utilized to deposit a-Si:C:H/H-DLC/DLC composite coatings ...on the 45 steel substrates using direct current plasma enhanced chemical vapor deposition technology. Influences of negative bias voltages on the surface morphology, microstructure, mechanical properties, and tribological performance were investigated. The results showed that as the bias voltages increased from −400 V to −600 V, the surface roughness and thickness of the coatings increased, reaching a maximum roughness of 0.426 μm and a maximum total thickness of 9.9 μm. Raman data illustrated the decrease of hydrogen contents and the increase in sp3 bonds content, matching well with the increasing hardness and elastic modulus. The residual stress tended to increase as the bias voltages, while the adhesion strength reached the maximum value of 62.45 ± 2.65 N at −550 V. Under the synergistic effects of surface roughness, interfacial adhesion strength, hardness and elastic modulus, the average friction coefficient and wear rate of the coatings initially decreased and then increased, reaching the best tribological performance at −550 V.
•PECVD was employed to deposit multilayer DLC coatings with a-Si:C:H bonding layer and H-DLC transition layer.•Bias voltages were adjusted to investigate the influences on the structure and properties of the DLC coatings.•DLC coating prepared at a bias voltage of -550V demonstrated the best tribological performance with a lowest wear rate.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
PDF
