Catalysis effect of metal doping on wear properties of diamond-like carbon films deposited by a cathodic-arc activated deposition process (original) (raw)
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Effect of source gas chemistry on tribological performance of diamond-like carbon films
Diamond and Related Materials, 2000
In this study, we investigated the effects of various source gases (methane, ethane, ethylene, acetylene, and methane+hydrogen) on the friction and wear performance of diamond-like carbon (DLC ) films produced from the source gases. Specifically, we described the anomalous nature and fundamental friction and wear mechanisms of DLC films derived from gas discharge plasmas with very low to very high hydrogen content. The films were deposited on steel substrates by a plasma-enhanced chemical vapor deposition process at room temperature and the tribological tests were performed in dry nitrogen. The tribological tests revealed a close correlation between the source gas chemistry and the friction and wear coefficients of the DLC films. Specifically, films grown in source gases with higher hydrogen-to-carbon ratios had much lower friction coefficients and wear rates than did films derived from source gases with lower hydrogen-to-carbon ratios. The lowest friction coefficient (0.002) was achieved with a film derived from 25% methane+75% hydrogen, whereas a coefficient of 0.15 was seen in films derived from acetylene. Similar correlations were observed for wear rates. Films derived from hydrogen-rich plasmas had the least wear, whereas films derived from pure acetylene suffered the highest wear. We used a combination of scanning and transmission electron microscopy and Raman spectroscopy to characterize the structural chemistry of the resultant DLC films.
1997
We investigated the tribological performance of diamondlike carbon (DLC) films derived from methane, acetylene, and hydrogen + methane source gases in a magnetron sputtering system and an ion-beam-deposition system. Films have been deposited on AISI 440C bearing-steel substrates and were tested in a pin-on-disk machine under a wide range of conditions in open air and in dry nitrogen. We found that the films grown in a hydrogen + methane plasma resulted in significant1pi.e. 0.01) and ball wear rates during tests in dry nitrogen (N2). The friction coefficients for the methane-derived films were also low (O.OLin dry N3 but the friction coefficients of the acetylene-produced films were 2-to lo-times higher than those recorded for the methane-and hydrogen + methanegrown films, especially in dry N2. The methane-and hydrogen + methane-grown films also resulted in very small wear losses on-counterface balls, regardless of the test environments. Raman spectroscopy and electron microscopy were used to elucidate the structural chemistry of each film and correlate rhe findings with tribological performance.
Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 2008
In this study, we investigated the effects of various source gases (methane, ethane, ethylene, and acetylene) on the friction and wear performance of diamond-like carbon (DLC ) films prepared in a plasma-enhanced chemical vapor deposition (PECVD) system. Films were deposited on AISI H13 steel substrates and tested in a pin-on-disk machine against DLC-coated M50 balls in dry nitrogen. We found a close correlation between friction coefficient and source gas composition. Specifically, films grown in source gases with higher hydrogen-to-carbon ratios exhibited lower friction coefficients and a higher wear resistance than films grown in source gases with lower hydrogen-to-carbon (H/C ) ratios. The lowest friction coefficient (0.014) was achieved with a film derived from methane with an H/C ratio of 4, whereas the coefficient of films derived from acetylene (H/C=1) was 0.15. Similar correlations were observed for wear rates. Specifically, films derived from gases with lower H/C values were worn out, and the substrate material was exposed, whereas films from methane and ethane remained intact and wore at rates that were almost two orders of magnitude lower than films obtained from acetylene.
Thin Solid Films, 2001
We deposited amorphous diamond-like carbon DLC films using an unbalanced magnetron sputtering method on M2 tool Ž. steels. The deposition process was controlled using a closed-loop optical emission monitor OEM , which regulated the flow of reactive gases of N and C H via a fast-responding piezo valve. By tuning the OEM settings for N and C H , we were able to 2 2 2 2 2 2 deposit a compound DLC coating consisting of Ti, TiN, TiCN, TiC and a-C:HrTi in sequence. Excellent mechanical and wear performance was achieved. Microstructure and tribological properties of DLC coatings were characterized using transmission electron microscopy, electron probe microanalysis, Raman spectroscopy, Vickers, and wear tests. The Raman intensity ratio I rI of the characteristic G and D bands decreases and the G line position moves toward 1550 cm y1 with the decrease of OEM D G settings, corresponding to a higher sp 3 content and higher microhardness. Wear tests demonstrate that the average friction coefficient of DLC films reduces from 0.33 to 0.14, and wear life increases from 900 to 24 000 m with the decrease of OEM settings. The Ti content, corresponding to enhanced wear properties, in DLC increases with OEM settings. Finally, we discovered that the phase transformation from TiC to DLC is strongly influenced by OEM settings, and is demarcated at an OEM setting of 20%.
Materials Science and Engineering: B, 1998
We have investigated the characteristics of diamond-like carbon (DLC), DLC doped with Cu, and DLC doped with Ti deposited by a sequential pulsed laser ablation of two targets. The composition of these films was determined by Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy (XPS). Raman spectroscopy and transmission electron microscopy studies showed typical features of DLC with a high fraction of sp 3 bonded carbon in the doped films as well as in the undoped films. Wear resistance measurements made on the samples by means of the 'crater grinding method' showed that DLC+ 2.75% Ti has the highest wear resistance, while that of pure DLC has the lowest amongst the samples. Careful analysis of the Raman data indicates a significant shift to shorter wavelength with the addition of metal, which means that the compressive stress in the DLC films has been reduced. We envisaged that the reduction in the compressive stress promotes the wear resistance of the coatings. The XPS studies showed evidence for the formation of TiC bonding in the Ti doped sample. Thus metal-doped DLC coatings are expected to improve the tribological properties and enhance the performance of components coated with metal-doped DLC.
Tribological properties of diamond-like carbon films prepared by mass-separated ion beam deposition
Diamond and Related Materials, 2002
In this work we studied the tribological properties of DLC coatings prepared by two deposition techniques. The emphasis was given on double layer Cr/DLC coatings deposited by a closed drift ion beam technique (anode layer source, ALS) with C 2 H 2 and N 2 carrier gases. For comparison, the same types of substrates were coated by unbalanced magnetron sputtering in the CemeCon CC800/9 deposition system. Pin-on-disk experiments showed that the DLC coatings possess excellent wear resistance (wear rate down to 12 μm 3 /Nm) and also low values of coefficient of friction (down to 0.055). The presence of a carbon transfer layer, which is mainly responsible for good tribological properties, was observed on the wear scars of ball surfaces by optical microscopy. In addition, we measured the Vickers microhardness (1000-3100 HV), performed the scratch test (L C in the range 40-100 N) and Rockwell indentation test to measure adhesion. Coating surface has been analyzed by atomic force microscopy (AFM) and by profilometry.
Surface & Coatings Technology, 2009
Nitrogen-rich layers are formed on the surface of JIS-SKH51 tool steel substrates using the plasma immersion ion implantation (PIII) technique. An unbalanced magnetron sputtering (UBMS) system is then used to coat the steel substrates with diamond-like carbon (DLC) films of various thicknesses. The adhesive strength and wear resistance of the DLC films are then examined by performing nanoscratch and nanowear tests. Finally, the microstructures of the DLC films are analyzed using TEM and Raman spectroscopy. The nanoindentation test results show that the PIII treatment yields an effective improvement in both the hardness and the Young's modulus of the SKH51 substrates. Moreover, cross-sectional observations show that the implantation depth and microstructure of the nitrogen-rich surface layer are dependent on the nitrogen/hydrogen flow ratio used in the PIII process. The nanoscratch test results show that the PIII treatment improves the adhesion of the DLC film to the steel substrate. Furthermore, the Raman spectroscopy results indicate that the use of hydrogen in the PIII process limits the increase in the I(D)/I(G) ratio by increasing the DLC film thickness. Finally, the nanowear test results show that the deposition of a DLC coating with a sufficient thickness yields a significant improvement in the wear resistance of the steel substrate.