Friction properties of smooth nanocrystalline diamond coatings

Hollman, Patrik; Wänstrand, O.; Hogmark, Sture

doi:10.1016/s0925-9635(98)00215-5

Cited by 67 publications

(31 citation statements)

References 10 publications

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“…Different applications have been so far reported in which NCD films were used for high-frequency surface acoustic wave devices, 1,2 Micro-Electro-Mechanical Systems (MEMS), 3 MESFETs, 4 and enduring coating. 5,6 Due to its biocompability and chemical stability, NCD films have also attracted attention for bioelectrochemical applications. 7,8,9 In addition, considerable efforts have been dedicated to optimize the growth process: its dependence on gas preparation and precursor molecules, 10,11 as well as the influence of the substrate material.…”

Section: Introductionmentioning

confidence: 99%

Electronic and optical properties of boron-doped nanocrystalline diamond films

et al. 2009

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We report on the electronic and optical properties of boron-doped nanocrystalline diamond (NCD) thin films grown on quartz substrates by CH 4 /H 2 plasma chemical vapor deposition.Diamond thin films with a thickness below 350 nm and with boron concentration ranging from 10 17 cm -3 to 10 21 cm -3 have been investigated. UV Raman spectroscopy and AFM have been used to assess the quality and morphology of the diamond films. Hall effect measurements confirmed the expected p-type conductivity. At room temperature, the conductivity varies from 1.5x10 -8 Ω -1 cm -1 for a non-intentionally doped film up to 76 Ω -1 cm -1 for a heavily B-doped film. Increasing the doping level results in a higher carrier concentration while the mobility decreases from 1.8 cm 2 V -1 s -1 down to 0.2 cm 2 V -1 s -1 . For NCD films with low boron concentration, the conductivity strongly depends on temperature. However, the conductivity and the carrier concentration are no longer temperature-dependent for films with the highest boron doping, and the NCD films exhibit metallic properties. Highly doped films show superconducting properties with critical temperatures up to 2K. The critical boron concentration for the metal-insulator transition is in the range from 2x10 20 cm -3 up to 3x10 20 cm -3 . We discuss different transport mechanisms to explain the influence of the grain boundaries and boron doping on the electronic properties of NCD films. Valence band transport dominates at low boron concentration and high temperatures, 2 whereas hopping between boron acceptors is the dominant transport mechanism for boron doping concentration close to the Mott transition. Grain boundaries strongly reduce the mobility for low and very high doping levels. However, at intermediate doping levels where hopping transport is important, grain boundaries have a less pronounced effect on the mobility. The influence of boron and the effect of grain boundaries on the optoelectronic properties of the NCD films are examined using spectrally resolved photocurrent measurements and photothermal deflection spectroscopy. Major differences occur in the low energy range, between 0.5 -1.0 eV, where both Boron impurities and the sp 2 carbon phase in the grain boundaries govern the optical absorption.

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Section: Introductionmentioning

confidence: 99%

Electronic and optical properties of boron-doped nanocrystalline diamond films

et al. 2009

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“…For a-CN x coatings, many scientists have paid more attentions to their micro-and macro-tribological properties in various gas environments since 1996 [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36], but most of researches are usually related to the performance of a-CN x coatings in hard disk drive applications. It is known that the usage of DLC or a-CN x coating with water-based lubricant containing a little additive might create the new, ''green'' lubricant [37][38][39][40][41][42]. However, the studies on the friction and wear behavior of a-CN x coatings in water have not been carried out.…”

Section: Introductionmentioning

confidence: 99%

Friction and wear properties of CNx/SiC in water lubrication

2005

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Amorphous carbon nitride coatings (a-CN x ) were deposited on SiC disk by ion beam assisted deposition (IBAD). The tribological behavior of a-CN x coating sliding against SiC ball in water was investigated and compared with that of SiC/SiC system at room temperature. The influences of testing conditions on friction coefficient and specific wear rate of both kinds of tribopairs were studied. The worn surfaces on disks were observed by scanning electron microscope (SEM). The results indicate that the running-in period of a-CN x /SiC was shorter than that of SiC/SiC system in water. At a sliding velocity of 120 mm/s, the mean steady-state friction coefficients of SiC/SiC (0.096) was higher than that of a-CN x /SiC (0.05), while at 160 mm/s, lower friction coefficient (0.01) was obtained for SiC/SiC in water. With an increment of normal load, the mean steady-state friction coefficients after running-in first decreased, reaching a minimum value, and then increased. For self-mated SiC, the specific wear rate of SiC ball was a little higher than that of SiC disk, while for a-CN x /SiC, the specific wear rate of SiC ball were 10 times smaller than that of a-CN x coating. Furthermore, the specific wear rate of SiC ball sliding against a-CN x coating was reduced by a factor up to 100$1000 in comparison to that against SiC in water. The wear mechanism of SiC/SiC system in water is related to micro-fracture of ceramic and instability of tribochemical reaction layer. Conversely, wear mechanism for a-CN x /SiC is related to formation and transfer of easy-shear friction layer.

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“…In one method, they used a higher-than-normal carbonto-hydrogen ratio in a microwave plasma. In another, they applied a DC bias to the substrates to increase their nucleation density [20,21]. Although growth rates were somewhat reduced, the surface finish of the resultant diamond films was much smoother (i.e.…”

Section: Deposition and Film Microstructurementioning

confidence: 99%