Investigation on the long-duration tribological performance of bilayered diamond/diamond-like carbon films

Abstract

The long-duration tribological performance of two bilayered diamond/diamond-like carbon films, namely microcrystalline diamond/diamond-like carbon and nanocrystalline diamond/diamond-like carbon films, is evaluated in 24-h dry sliding against the silicon nitride counterpart ball, in terms of the stable coefficient of friction, the sliding stability, and the specific wear rate of both the film and counterpart surface. Moreover, their sliding behaviors are illustrated from the aspect of sliding interface evolution. Characterization results indicate that the top-layered diamond-like carbon films significantly reduce the surface roughness of single-layered diamond film and determine the surface property of composite film. For the tribological performance, the top-layered diamond-like carbon coating significantly reduces the stable friction coefficient of the microcrystalline diamond film by 10–34%, but does not exhibit a similar effect on the nanocrystalline diamond film due to the severe delamination of diamond-like carbon coating. Either, the top-layered diamond-like carbon film does not show noticeable benefit on enhancing the sliding stability or wear resistance of single-layered diamond coating. The delamination of top-layered diamond-like carbon coating is supposed to play a critical role on such phenomenon. Furthermore, an enhanced tribomap is developed that is capable of providing a visualized and highly customized evaluation on tribological performance of sliding contacts according to the specific requirements a variety of applications. According to this tribomap, nanocrystalline diamond film always shows the superior performance to others.

Long-Duration Frictional and Wear Performance of the Diamond/DLC Bilayered Film under Water-Lubricating Condition

“…Therefore, the tribological performance of coating materials during a long-duration sliding process is supposed to have more determinate effect on the performance of the coated components or devices. Our previous study has already slighted a deep insight on the long-duration tribological performance of bilayered diamond/DLC films in dry sliding condition, including their friction and wear resistance behaviors, sliding stability, and wear mechanism [5]. The present study reports an investigation of the long-duration tribological performance of the MCD/DLC film under water-lubricating conditions.…”

Tribological behaviors of diamond films and their applications in metal drawing production in water-lubricating condition

“…On the worn surface of the MCD film, as presented in Figure 7(a), a large amount of wear particles could be observed to be trapped in the grain boundary area of its relative rough surface. Different from the worn surface produced in dry sliding condition, 15 no severe fracture or fragementation of diamond crystallites, or surface polishing effect occurs in the water-lubricating condition and thus most of diamond grains are maintained well. Such worn surface morphology provides adequent space to accommodate the generated wear debris and particles from the counterpart surface and thus produces a most stable sliding process after the ''run-in'' period.…”

“…The detailed deposition process and surface characterization of these three films have been reported in our previous study. 15 The MCD film surface presented rugged and wellfaceted sharp octahedral diamond crystallites (with grain size of $2-3 mm); while the NCD film surface exhibit cauliflower-structured clusters ($4-5 mm in diameter) which was composed of nanosized diamond crystallites. The thickness of single-layered MCD and NCD film was estimated as 2 mm; the thickness of the bi-layered MCD/DLC film was about 4 mm, including a 2 mm bottom-layered MCD film and a 2 mm toplayered DLC film.…”

“…10 Therefore, researchers recently proposed to fabricate bi-layered diamond/DLC composite films by depositing a top-layer DLC coating on CVD diamond film with expectation of obtaining a novel diamond/DLC composite film that is expected to be able to combine the advantages of two individual films and compensates disadvantages for each other. [11][12][13][14][15] It can be arrived from the above studies that combining CVD diamond and DLC coatings might be a potential method to develop novel tribological coating materials with superior tribological properties. Therefore, the combining application of the diamond/DLCcoated drawing dies and water-lubricating technique may provide an effective approach to improve the efficiency of metal drawing production.…”

Polycrystalline Diamond Characterisations for High End Technologies

“…Moreover, tribological action may cause rise of temperature under humid atmospheric condition for diamond material to degrade. So it is necessary for the CVD grown diamond to be well characterised for the wear and friction applications [30][31][32][33][34]. Thermal stability has been studied so far by many authors [35][36][37] but it lacks proper assessment of oxidation temperature [38][39][40] since only standard furnaces have been used so far.…”