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1.
Performance results of MEMS coated with a conformal DLC 总被引:4,自引:0,他引:4
Steven A. Smallwood Kalathil C. Eapen Steven T. Patton Jeffrey S. Zabinski 《Wear》2006,260(11-12):1179-1189
A MEMS electrostatic lateral output motor has been successfully coated with a diamond like carbon (DLC) coating to protect against wear. Experiments were performed to characterize coating chemistry and performance. Friction results from accelerated screening tests using a miniature, lightly loaded ball on flat tribometer showed that the DLC coating maintained low friction longer compared to uncoated silicon. DLC on DLC experiments showed the lowest friction, and those that were run in 30% RH showed a much longer lifetime than ones run in dry air. Uniformity of DLC coverage on MEMS was verified by Auger electron spectroscopy (AES), microRaman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). Micrographs revealed that there is about a 3:1 ratio of DLC coating for a line of sight deposition region to a non line of sight deposition region. DLC coated MEMS outperformed uncoated MEMS by 16X in air and 300X in vacuum, albeit performance in vacuum was lower than in air. A very clear difference in wear debris was seen between devices run in air and in vacuum. Cylindrical rolls were dominant in the devices that were run in air and platelets were dominant on devices run in vacuum. Ultimately, the DLC coating was found to greatly improve performance over uncoated MEMS. 相似文献
2.
Kazuhisa Miyoshi Masao Murakawa Shuichi Watanabe Sadao Takeuchi Shojiro Miyake Richard L.C. Wu 《Tribology Letters》1998,5(2-3):123-129
The main criteria for judging coating performance were coefficient of friction and wear rate, which had to be less than 0.1
and 10-6 mm3/(N.m), respectively. Carbon‐ and nitrogen‐ion‐implanted, fine‐grain, chemical‐vapor‐deposited (CVD) diamond and diamondlike
carbon (DLC) ion beam deposited on fine‐grain CVD diamond met the criteria regardless of environment (vacuum, nitrogen, and
air).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
A. Vanhulsel F. Velasco R. Jacobs L. Eersels D. Havermans E.W. Roberts I. Sherrington M.J. Anderson L. Gaillard 《Tribology International》2007,40(7):1186-1194
The environment of space offers special challenges for the lubrication of components in sliding and rolling mechanisms. Hydrogenated diamond-like carbon (DLC) films are being studied as solid lubricant coatings to simultaneously fulfil specifications regarding wear resistance and low friction behaviour under ambient atmosphere and in vacuum.In this paper, the tribological behaviour of highly hydrogenated DLC coatings (50 at% hydrogen) is assessed. Coating composition was optimised on flat AISI 52100 steel substrates based on ball-on-disc tribotest results in air, vacuum and dry nitrogen environments. The developed DLC coatings can be tailored to yield ultra-low friction values in vacuum (μ=0.008). The average friction coefficient range obtained in humid air, dry nitrogen and vacuum for the range of applied loads were, respectively, 0.22 to 0.27, 0.02 to 0.03, and 0.007 to 0.013.New in this work is that optimised DLC coatings were applied to ball bearings for space applications. The torque and life tests of coated pairs of angular contact bearings in air revealed that relatively high bearing torques are generated which increase with time, but the amount of coating wear generated during in-air operation appears relatively light. In vacuum, low torques are generated after a prolonged running-in period. Low-torque life exceeds that observed for MoS2 by a factor of about two. It is concluded that, in contrast to MoS2 coated bearings, DLC-coated bearings for space applications might therefore be capable of undergoing in-air ground testing without too much disruption of the subsequent in-space performance. 相似文献
4.
In this study, the authors investigated the tribological performance of diamond and diamondlike carbon (DLC) films as a function of temperature. Both films were deposited on silicon carbide (SiC) by microwave plasma chemical vapor deposition and ion-beam deposition processes. Tribological tests were performed on a reciprocating wear machine in open air (20 to 30% relative humidity) and under a 10 N load using SiC pins. For the test conditions explored, the steady-state friction coefficients of test pairs without a diamond or DLC film were 0.7 to 0.9 and the average wear rates of pins were 10?5 to 10?7 mm3/N·m, depending on ambient temperature. DLC films reduced the steady-slate friction coefficients of the test pairs by factors of three to five and the wear rates of pins by two to three orders of magnitude. Low friction coefficients were also obtained with the diamond films, but wear rates of the counterface pins were high due to the very abrasive nature of these films. The wear of SiC disks coated with either diamond or DLC films was virtually unmeasurable while the wear of uncoated disks was substantial. Test results showed that the DLC films could afford low friction up to about 300° C. At higher temperatures, the DLC films graphitized and were removed from the surface. The diamond films could withstand much higher tempera-lures, but their tribological behavior degraded. Raman spectroscopy and scanning electron microscopy were used to elucidate the friction and wear mechanisms of both films at high temperatures. 相似文献
5.
Jin Woo Yi Jong-Kuk Kim Myoung-Woon Moon Kwang-Ryeol Lee Seock-Sam Kim 《Tribology Letters》2009,34(3):223-228
The tribological behavior of alternating-layered diamond-like carbon (DLC) films was examined under a variety of humid conditions.
Alternating deposited layers with Si-incorporated DLC (Si-DLC) and DLC films were prepared using a hybrid coating system.
The residual stress of the alternating-layered films was reduced while the hardness was relatively less dependent on the number
of alternating-layered sets. A ball-on-disk type tribological test was carried out under the following humid conditions: dry,
50% and 90% relative humidity. The friction coefficient for higher number of alternating-layered sets decreased with increasing
humidity conditions but there was no dependency on the wear rate. 相似文献
6.
D. Klaffke 《Lubrication Science》2006,12(1):29-46
The potential of coatings to protect components against wear and to reduce friction has led to a large variety of protective coatings. In order to check the success of coating modifications and to find solutions for different purposes, initial tests with laboratory tribometers are usually done to give information about the performance of a coating. Different Ti‐based coatings (TiN, Ti(C,N), and TiAlN) and NiP were tested in comparison to coatings with an additional diamond‐like carbon (DLC) top coating. Tests were done in laboratory air at room temperature with oscillating sliding (gross slip fretting) with a ball‐on‐disc arrangement against a ceramic ball (Al2O3). Special attention was paid to possible effects of moisture (relative humidity). The coefficient of friction was measured on line, and the volumetric wear at the disc was determined after the test from microscopic measurements of the wear scar and additional profiles. The friction and wear behaviour is quite different for the different coatings and depends more or less on the relative humidity. The DLC coating on top of the other coatings reduces friction and wear considerably. In normal and in moist air the coefficient of wear of the DLC top‐layer coating is significantly less than 10−6 mm3/Nm and the coefficient of friction is below 0.1. In dry air, however, there is a certain tendency to high wear and high friction. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
7.
Tribological behavior of hydrogenated diamond-like carbon (DLC) films and Si incorporated DLC (Si-DLC) films deposited on Si (100) wafer by r.f.-plasma assisted chemical vapor deposition were investigated by ball-on-disk type tribometry in various environments. The friction tests were performed in ambient air of relative humidity ranging from 0% to 90% or dry oxygen environment. We focused on the tribochemical reactions by analyzing chemical composition, chemical bond structure and agglomerated shape of the debris. High and unstable friction behavior was observed in both humid air and dry oxygen environments. In these environments, Auger spectrum analysis showed that the debris contained large amounts of Fe. Significant incorporation of Fe in the debris resulted from the wear of the steel ball, which might be enhanced by the surface oxidation of the ball. These results show that the humidity dependence of friction coefficient is not an inherent tribological property of DLC films but results from the surface reaction of the steel ball in humid environments. Two possible reasons for the Fe rich debris affecting the friction behavior are presented. Reduced dependence of the friction coefficient on the relative humidity observed for Si-DLC films is discussed in terms of the two possible reasons. 相似文献
8.
Three types of diamond-like carbon (DLC) films, pure DLC, F-containing DLC, and a Si-containing DLC film, were deposited on a WC–Co substrate by a plasma-enhanced CVD technique. Friction and wear properties were determined using a ball-on-plate type reciprocating friction tester in water, comparing the water results to those in ambient air. The friction coefficient of DLC and F–DLC films in water was considerably lower than that in air. With Si–DLC, the friction was almost the same level in both water and air, and was less than 0.1. The specific wear rate of films in water was much smaller than that in air and varied around the low level of 10–8 mm3/Nm in water, The mating ball wear was also less than 10–8 mm3/Nm. With DLC and F–DLC films, the transferred amount of material on the friction surface of a mating ball was larger in a water environment than that in air. With a Si–DLC film, the difference in the transferred amount when exposed to either the water or air environment was negligible. 相似文献
9.
10.
Silicon-doped diamond-like carbon (Si-DLC) films possess the potential to improve wear performance of DLC films in humid atmospheres and at higher temperatures. But many experimental results of Si-DLC films show that their structures and tribological properties changed greatly with silicon content. Therefore, molecular dynamics (MD) simulations were used to study the sliding friction process between DLC and Si-DLC films on un-lubricated boundary condition. The results show that a part of sp2 bonding of the Si-DLC films is converted into sp3 bonding with the addition of silicon atoms, and the sp3/sp2 ratio increases with the increase in silicon content. A transfer film between the DLC and Si-DLC films is formed and the friction force changes with the silicon content. Moreover, the simulations have showed that the silicon addition promotes the bonding of interfilms being formed. 相似文献
11.
In this paper, we investigate the sliding friction and wear behavior of a hydrogenated diamond-like carbon (DLC) film in ultrahigh
vacuum (UHV) and under partial pressures of water vapor, oxygen, nitrogen and hydrogen. The initial friction coefficient of
the film in UHV was ~0.15, but decreased steadily to values as low as 0.03 after about 30 sliding passes. During longer duration
tests, the friction coefficient increased again to values as high as ~0.15 and such an increase in friction coincided with
hydrogen desorption from the contacting surfaces (as detected by a mass spectrometer). Heating DLC to temperatures higher
than 360 K also caused desorption of hydrogen and a resulting marked increase in friction. The presence of molecular nitrogen,
oxygen and hydrogen in the test chamber did not have any noticeable effect on friction, but the presence of thermally dissociated
or ionized hydrogen within the close proximity of sliding surfaces had a beneficial effect by restoring the low friction behavior
of the DLC films. The introduction of water vapor into test chamber had an adverse effect on friction. The results of this
study confirm that hydrogen is key to low friction behavior of hydrogenated DLC films and that the presence of water molecules
has an adverse effect on their friction behavior. 相似文献
12.
Effect of Humidity on the Tribological Properties of Carbide-Derived Carbon (CDC) Films on Silicon Carbide 总被引:2,自引:0,他引:2
The effect of humidity on the tribological behavior of carbide-derived carbon (CDC) films prepared by high-temperature chlorination of silicon carbide was examined. Pin-on-disk tribological tests indicate that CDC, unlike graphite or glassy carbon, performs better in dry nitrogen (less than 0.05 friction coefficient at 0% humidity) than in humid air. This versatility is explained by the onion-like structure of the nanoporous CDC coating. 相似文献
13.
Multi-environmental lubrication performance and lubrication mechanism of MoS2/Sb2O3/C composite films 总被引:1,自引:0,他引:1
MoS2–Sb2O3–C composite films exhibit adaptive behavior, where surface chemistry changes with environment to maintain the good friction and wear characteristics. In previous work on nanocomposite coatings grown by PVD, this type of material was called a “chameleon” coating. Coatings used in this report were applied by burnishing mixed powders of MoS2, Sb2O3 and graphite. The solid lubricant MoS2 and graphite were selected to lubricate over a wide and complementary range including vacuum, dry air and humid air. Sb2O3 was used as a dopant because it acts synergistically with MoS2, improving friction and wear properties. The MoS2–Sb2O3–C composite films showed lower friction and longer wear life than either single component MoS2 or C film in humid air. Very or even super low friction and long wear-life were observed in dry nitrogen and vacuum. The excellent tribological performance was verified and repeated in cycles between humid air and dry nitrogen. The formation of tribo-films at rubbing contacts was studied to identify the lubricating chemistry and microstructure, which varied with environmental conditions. Micro-Raman spectroscopy and Auger electron spectroscopy (AES) were used to determine surface chemistry, while scanning electron microscopy and transmission electron microscopy were used for microstructural analysis. The tribological improvement and lubrication mechanism of MoS2–Sb2O3–C composite films were caused by enrichment of the active lubricant at the contact surface, alignment of the crystal orientation of the lubricant grains, and enrichment of the non lubricant materials below the surface. Sb2O3, which is not lubricious, was covered by the active lubricants (MoS2 – dry, C – humid air). Clearly, the dynamics of friction during environmental cycling cleaned some Sb2O3 particles of one lubricant and coated it with the active lubricant for the specific environment. Mechanisms of lubrication and the role of the different materials will be discussed. 相似文献
14.
Due to strongly tribological atmosphere sensitivity of carbon-based coatings, it is of extreme significance to investigate their friction and wear behaviors in different atmospheres. In this letter, duplex nc-TiC/a-C(Al) nanocomposite carbon-based coating coupled with high hardness, low internal stress and high adhesion strength was successfully fabricated using magnetron sputtering process. The friction and wear behaviors of as-fabricated coating were evaluated in dry N2, humid N2, air, dry O2, and humid O2 atmospheres, respectively. Results show that the as-fabricated coating possesses very high friction and wear due to the strong covalent bond interactions at the sliding interface caused by the free ??-bonds on the coating surface in dry N2 atmosphere. Whereas the free ??-bonds can be efficiently terminated and passivated by water and/or oxygen molecules to weaken the strong covalent bond interactions to result in low friction and wear of coating in humid N2, air, dry O2, and humid O2 atmospheres. The compact and homogeneous carbonaceous tribo-layer on the counterpart is mainly responsible for the lowest friction and wear of coating in humid N2 atmosphere. Whereas the tribo-layer can be restrained to a certain extent by the tribo-chemical reaction, especially it results in a nearly negligible carbonaceous tribo-layer on the counterpart in dry O2 atmosphere, which is mainly responsible for largely increased friction and wear of coating. 相似文献
15.
The tribological behavior of micro- and nano-crystalline diamond films is evaluated in dry sliding and water lubricating condition. The main wear mechanism is found to be abrasive wear mode induced by self-polishing. Non-diamond components and higher compressive residual stresses are detected in flat MCD films after dry sliding, in comparison to NCD. Origin of decreased friction coefficient in CVD diamond tribosystems under water lubrication is attributed to the effect of water on the formed graphic material and the chemisorbing of diamond surface with H2O, hydrogen or hydroxyl ions. For the MCD/NCD or NCD/MCD contact, the surface roughness of ball largely determines the stable friction coefficient in dry sliding, where NCD film usually presents higher wear rate. 相似文献
16.
Jason A. Bares Anirudha V. Sumant David S. Grierson Robert W. Carpick Kumar Sridharan 《Tribology Letters》2007,27(1):79-88
Small amplitude (50 μm) reciprocating wear of hydrogen-containing diamond-like carbon (DLC) films of different compositions
has been examined against silicon nitride and polymethyl-methacrylate (PMMA) counter-surfaces, and compared with the performance
of an uncoated steel substrate. Three films were studied: a DLC film of conventional composition, a fluorine-containing DLC
film (F-DLC), and silicon-containing DLC film. The films were deposited on steel substrates from plasmas of organic precursor
gases using the Plasma Immersion Ion Implantation and Deposition (PIIID) process, which allows for the non-line-of-sight deposition
of films with tailored compositions. The amplitude of the resistive frictional force during the reciprocating wear experiments
was monitored in situ, and the magnitude of film damage due to wear was evaluated using optical microscopy, optical profilometry, and atomic force
microscopy. Wear debris was analyzed using scanning electron microscopy and energy dispersive spectroscopy. In terms of friction,
the DLC and silicon-containing DLC films performed exceptionally well, showing friction coefficients less than 0.1 for both
PMMA and silicon nitride counter-surfaces. DLC and silicon-containing DLC films also showed significant reductions in transfer
of PMMA compared with the uncoated steel. The softer F-DLC film performed similarly well against PMMA, but against silicon
nitride, friction displayed nearly periodic variations indicative of cyclic adhesion and release of worn film material during
the wear process. The results demonstrate that the PIIID films achieve the well-known advantageous performance of other DLC
films, and furthermore that the film performance can be significantly affected by the addition of dopants. In addition to
the well-established reduction of friction and wear that DLC films generally provide, we show here that another property,
low adhesiveness with PMMA, is another significant benefit in the use of DLC films. 相似文献
17.
The friction and wear of synthetic diamond with and without N+ implantation and CVD diamond coatings were studied in air, water and methanol. It was shown that water effectively reduced the friction of the synthetic diamond and CVD diamond at lighter loads, but methanol did not. Wear of the diamond was minimal in methanol. N+ ion implantation was less effective at reducing the friction. 相似文献
18.
A duplex treatment involving nitrogen ion pre-implantation and gradient interfacial transition was performed to obtain a high-performance
graphite-like carbon (GLC) coating on a Ti6Al4V alloy. Characteristics of the as-deposited coating systems were systemically
investigated by Raman spectrometry, scanning electron microscopy, atomic force microscopy, nano-indentation, and scratch tests.
The friction and wear behaviors in distilled water and sea water environments were evaluated by a ball-on-disk tribometer.
The results showed that the GLC multilayer coating on nitrogen ion-implanted Ti6Al4V possessed a greater hardness and adhesion
strength than to that on un-implanted Ti6Al4V. The tribological performances of these duplex process systems showed a great
improvement in both the distilled water and sea water environments. In particular, the Cr/CrN/GLC coatings on nitrogen ion-implanted
substrates demonstrated the best friction and wear behaviors. These striking improvements were attributed to the greatly enhanced
interface strength between substrate and coating by the nitrogen ion implantation process and improved adhesion strength between
gradient layers by the appropriate gradient interlayers with a similar thermal expansion coefficient. 相似文献
19.
In this study, sputtered W–S–N(C) films were deposited by rf magnetron sputtering with increasing N or C content. The coatings
were tribologically tested in a pin-on-disk apparatus with increasing applied normal loads in two different environmental
conditions, normal room atmosphere and dry nitrogen atmosphere.
W–S–N(C) films without or with low N(C) addition had high wear rates, whatever the environment was, but induced low wear in
the counterbody material and low friction coefficients. The coatings alloyed with high N content showed excellent wear resistance
and a very low friction coefficient (<0.05) when tested in dry nitrogen but the opposite behaviour under room conditions.
For their part, high C-containing coatings showed an excellent tribological behaviour in both environments, not as good as
N-alloyed films in dry nitrogen but much better under room conditions. The wear and friction coefficients were lower in dry
nitrogen than in humid air. Globally, the alloying with N(C) resulted in wear rates in W–S–N(C) films two orders of magnitude
lower than in an unalloyed one, keeping the friction coefficient at the same level or even lower.
The wear behaviour was interpreted as a function of several factors including; the mechanical strength of the coatings, the
adhesion of the films to the substrate, the porosity and the structural arrangement of the film. 相似文献
20.
Solid lubricated surfaces are now widely used in the tool industry, and the new concept of ‘soft tools’ recently introduced has emphasized low-friction surfaces. The present paper deals with a novel ‘burnishing’ process based on ionic bombardment of powder graphite coating/substrate systems. This process may influence both the coating and the coating/substrate interface, and it is effective for improving lubrication even at low doses of bombarding ions. The present study will discuss the friction and wear properties of graphite-powder coatings on a silicon wafer bombarded with 200 keV ion beams of argon, nitrogen and hydrogen ions, the last two as molecular ions. The coefficients of friction and wear rates of the coatings were found to be strongly dependent on the ion-bombarding species and ion dose. The argon ion bombardment increased the coefficient of friction and wear rate of the powder coating. However, at the interface of the silicon substrate, the ion-induced burnishing improved the tribological behaviour of the silicon material. Bombardment with nitrogen and hydrogen ions showed a marked improvement in the tribological properties of the graphite powder coating. Thus a reduction in wear rate by three orders of magnitude was observed in the case of nitrogen, and for both ions it was noted that ion-beam burnished graphite was lubricating in a dry environment, which has not been reported previously. The perspectives of ion bombardment as a burnishing process will be discussed and the observed effects will be qualitatively explained in the context of the theory for ionic penetration into solids. 相似文献