Isothermal and dynamic oxidation behaviour of Mo–W doped carbon-based coating

Mandal, Paranjayee; Ehiasarian, Arutiun P.; Hovsepian, P.Eh.

doi:10.1016/j.apsusc.2015.07.057

Cited by 12 publications

(3 citation statements)

References 25 publications

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“…As the sample is heated to 200ºC, more amount of Mo 2 C is developed and simultaneously amount of free graphitic carbon present in the as-deposited coating is decreased. The formation of Mo 2 C in the bulk of the coating at this rather low temperature range has been supported by XRD analyses of the coating after static annealing at 400ºC [38]. The hard Mo 2 C phase when abraded against comparatively softer steel counterpart results in simultaneous increase of the friction and wear rate of the counterpart.…”

Section: Coating Phase Composition and Microstructurementioning

confidence: 71%

Friction and wear behaviour of Mo–W doped carbon-based coating during boundary lubricated sliding

Hovsepian

Mandal

Ehiasarian

et al. 2016

Applied Surface Science

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A molybdenum and tungsten doped carbon-based coating (Mo−W−C) was developed in order to provide low friction in boundary lubricated sliding condition at ambient and at high temperature. The Mo−W−C coating showed the lowest friction coefficient among a number of commercially available state-of-the-art DLC coatings at ambient temperature. At elevated temperature (200°C), Mo−W−C coating showed a significant reduction in friction coefficient with sliding distance in contrast to DLC coatings. Raman spectroscopy revealed the importance of combined Mo and W doping for achieving low friction at both ambient and high temperature. The significant decrease in friction and wear rate was attributed to the presence of graphitic carbon debris (from coating) and 'in-situ' formed metal sulphides (WS 2 and MoS 2 , where metals were supplied from coating and sulphur from engine oil) in the transfer layer.

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Section: Coating Phase Composition and Microstructurementioning

confidence: 71%

Friction and wear behaviour of Mo–W doped carbon-based coating during boundary lubricated sliding

Hovsepian

Mandal

Ehiasarian

et al. 2016

Applied Surface Science

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“…Recently a new-generation nanostructured Mo and W doped graphitic carbon-based coating (Mo-W-C) has been developed by using a combined unbalanced magnetron sputtering (UBMS) and high-power impulse magnetron sputtering (HIPIMS) technology [21], and several studies have established the uniqueness of simultaneous doping of Mo and W in terms of achieving high thermal stability up to ~800 • C [22] and outstanding tribological properties at both ambient and elevated temperature conditions during boundary lubricated sliding [23]. The tribo-chemical wear mechanism has been identified as the key to achieve these excellent tribological properties at ambient temperature, and it is then rapidly accelerated with an increase in the test temperature.…”

Section: Introductionmentioning

confidence: 99%

Influence of Carbon: Metal Ratio on Tribological Behavior of Mo-W-C Coating

Mandal

2021

Applied Sciences

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Mo-W-C coatings with three different C/(Mo+W) ratios (5:1, 2.8:1 and 2.2:1) were deposited by using combined unbalanced magnetron sputtering (UBMS) and high-power impulse magnetron sputtering (HIPIMS) technology. The influence of the C/(Mo+W) ratio on coating microstructure and related tribological properties at ambient temperature and at 200 °C were studied in lubricated condition (up to 7500 m and 1800 m of sliding distances, respectively). Results showed that a decrease in the C/(Mo+W) ratio could be correlated with an increase in coating thickness, adhesion strength, hardness and elastic modulus values, and a decrease in the degree of graphitization. At ambient temperature, outstanding tribological properties (very low friction and negligible wear) were observed irrespective of the C/(Mo+W) ratio. At 200 °C, low C/(Mo+W) ratios (2.8:1 and 2.2:1) were found particularly beneficial to achieve excellent tribological properties. The keys to significant friction reduction at 200 °C were (i) in situ formation of MoS2 and WS2 due to tribo-chemical reactions and (ii) presence of amorphous carbon debris particles in the protective tribolayer. With an increase in sliding distance, the tribolayer gradually lowered the friction coefficient by protecting both the coating and counterpart from severe wear. On the other hand, a high C/(Mo+W) ratio (5:1) led to low friction but noticeable abrasive wear at 200 °C.

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“…The recent studies of nanostructured carbon-based coatings doped with Mo and W (Mo-W-C) revealed their high thermal stability up to ~800 °C and excellent tribological properties at different temperatures [ 16 , 17 , 18 ]. Moreover, Page et al [ 19 ] demonstrated that nanostructured Mo 2 C and WC with a large surface area can be used for catalytic processes as substitute materials for platinum group metal heterogeneous catalysts.…”

Section: Introductionmentioning

confidence: 99%

Microstructural, Electrical, and Tribomechanical Properties of Mo-W-C Nanocomposite Films

Smyrnova,

Ivashchenko,

Sahul

et al. 2024

Nanomaterials

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This study investigates the phase composition, microstructure, and their influence on the properties of Mo-W-C nanocomposite films deposited by dual-source magnetron sputtering. The synthesised films consist of metal carbide nanograins embedded in an amorphous carbon matrix. It has been found that nanograins are composed of the hexagonal β-(Mo2 + W2)C phase at a low carbon source power. An increase in the power results in the change in the structure of the carbide nanoparticles from a single-phase to a mixture of the β-(Mo2 + W2)C and NaCl-type α-(Mo + W)C(0.65≤k≤1) solid-solution phases. The analysis of electrical properties demonstrates that the nanograin structure of the films favours the occurrence of hopping conductivity. The double-phase structure leads to a twofold increase in the relaxation time compared to the single-phase one. Films with both types of nanograin structures exhibit tunnelling conductance without the need for thermal activation. The average distance between the potential wells produced by the carbide nanograins in nanocomposite films is approximately 3.4 ± 0.2 nm. A study of tribomechanical properties showed that Mo-W-C films composed of a mixture of the β-(Mo2 + W2)C and α-(Mo + W)C(0.65≤k≤1) phases have the highest hardness (19–22 GPa) and the lowest friction coefficient (0.15–0.24) and wear volume (0.00302–0.00381 mm2). Such a combination of electrical and tribomechanical properties demonstrates the suitability of Mo-W-C nanocomposite films for various micromechanical devices and power electronics.

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Isothermal and dynamic oxidation behaviour of Mo–W doped carbon-based coating

Cited by 12 publications

References 25 publications

Friction and wear behaviour of Mo–W doped carbon-based coating during boundary lubricated sliding

Friction and wear behaviour of Mo–W doped carbon-based coating during boundary lubricated sliding

Influence of Carbon: Metal Ratio on Tribological Behavior of Mo-W-C Coating

Microstructural, Electrical, and Tribomechanical Properties of Mo-W-C Nanocomposite Films

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