A DLC/diamond bilayer approach for reducing the initial friction towards a high bearing capacity

Proceedings of the Institution of Mechanical Engineers, Part J:

2017

In this study, the tribological properties of the monolayer micro-crystalline diamond and nano-crystalline diamond films, TiN/diamond and TiAlN/diamond bilayer films on cemented tungsten carbide substrates are evaluated by dry sliding against the medium carbon steel counterpart balls, in terms of the coefficient of friction, wear rate, worn surfaces, and chemical transitions in the contacting wear zones. The significant coefficient of friction reducing effect of top-layer TiN and TiAlN coating only happens on the nano-crystalline diamond film, where the stable coefficient of friction of TiN/nano-crystalline diamond or TiAlN/nano-crystalline diamond bilayer coating reduces 9% or 53% compared with the nano-crystalline diamond film. The formed ionic metal oxides such as Fe 2 O 3 or Fe 3 O 4 coming from the chemisorbing of the atmospheric molecular water, oxygen in the air and the delamination of steel ball due to the repeated friction interaction is supposed to be responsible for the coefficient decreasing effect. The TiN or TiAlN film on diamond layer exhibits lower positive wear rate compared with the TiN or TiAlN film itself, due to the load support ability improvement resulted from the high hardness of diamond interlayers. Among all the tested hard films, the TiAlN/nano-crystalline diamond bilayer coating exhibits the valid potential to be the optimized tool coating in carbon steel machining in terms of its low coefficient of friction and wear rate, which may come from the self-lubricated transfer tribolayer formation on the TiAlN layer, as well as the enhanced mechanical supporting capacity of the underneath smooth and hard nano-crystalline diamond interlayer.

Section: Introductionmentioning

confidence: 99%

Tribological properties of TiN/diamond and TiAlN/diamond bilayer films sliding against carbon steel

Lei

Yang

Proceedings of the Institution of Mechanical Engineers, Part J:

2017

“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Chen

Shen

Proceedings of the Institution of Mechanical Engineers, Part J:

et al. 2015

The frictional and wear performance of the microcrystalline diamond (MCD), nanocrystalline diamond (NCD) and MCD/diamond-like carbon (DLC) bi-layered film are comparatively investigated under water-lubricating conditions. A full factorial experimental plan is conducted with four sliding velocities ranging from 0.126 to 0.503 m/s and four normal loads from 2 to 8 N. The duration of each sliding process is 24 h. The results show that although the MCD/DLC film shows the lowest stable coefficient of friction ranging from 0.025 to 0.12, the top-layered DLC film does not show beneficial effect on enhancing the sliding stability of single-layered diamond films. Comparatively, the MCD film exhibits the superior sliding stability and wear resistance, which are regarded as the more critical characters that determinate the lifetime and performance of a metal drawing die. Therefore, a drawing production of aluminum pipes is conducted in the water-lubricating condition using the MCD-coated drawing die. A novel drawing device is designed for the water-lubricating metal drawing production. It is capable of providing a fully immersed drawing environment for the metal pipe and thus guarantee the lubrication and cooling effects. The result of the drawing production shows that utilizing the diamond-coated drawing die in the water-lubricating condition could elevate the production of a drawing die by over 100 times compared with using the tungsten carbide drawing dies in oil-lubricating condition. Moreover, good surface quality and geometrical precision could also be obtained by the diamond-coated drawing dies in the water-lubricating drawing.

“…18 Amaral et al also reported the reduction on the friction coefficient of MCD coating by depositing a top layer of DLC coating; moreover, they also found depositing an outlayer of the DLC coating could also increase the bearing capacity of the single-layered diamond coating. 19 Hanyu et al reported the improved antisticking property to aluminum alloy of CVD diamond coated cutting tools with a top-layered DLC coating. 20 Csorbai et al obtained a pinhole free thin diamond-DLC bilayered coating by depositing a layer of the DLC coating on the CVD diamond film and used it as the corrosion protection coating.…”

Section: Introductionmentioning

confidence: 99%

“…also reported the reduction on the friction coefficient of MCD coating by depositing a top layer of DLC coating; moreover, they also found depositing an outlayer of the DLC coating could also increase the bearing capacity of the single-layered diamond coating. 19 Hanyu et al. reported the improved antisticking property to aluminum alloy of CVD diamond coated cutting tools with a top-layered DLC coating.…”

Section: Introductionmentioning

confidence: 99%

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

Shen

Chen

Proceedings of the Institution of Mechanical Engineers, Part J:

2014

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.