Diamond seal faces – the benefits

Otschik, J.; Schrüfer, A.; Thelke, J.; Kirchhof, Michael; Schmaderer, S.

doi:10.1016/s0262-1762(09)70450-x

Cited by 6 publications

(9 citation statements)

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“…Importantly, typical sliding speeds in seal applications can be of the order of 10 m/s and more [16], and therefore our models are relevant to realistic applications of microcrystalline diamond coatings.…”

Section: Methodsmentioning

confidence: 99%

“…The friction between diamond-coated surfaces in a humid environment is an interesting example of how tribochemically induced surface passivation can significantly alter the tribological performance of a technological material. Single-crystal and polycrystalline diamond coatings have excellent mechanical hardness, thermal conductivity, and chemical inertness, which make them an important tribo-material for bearing [15] and seal applications [16]. Clean diamond surfaces sliding against each other under vacuum conditions exhibit very high friction ( 𝜇~1 ) [17], resulting in amorphization [4] and considerable wear [13].…”

Section: Introductionmentioning

confidence: 99%

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Role of oxygen functional groups in the friction of water-lubricated low-index diamond surfaces

Kuwahara

Moras

Moseler

2018

Phys. Rev. Materials

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Large-scale quantum molecular dynamics simulations unveil eight friction regimes of water-lubricated low-index diamond surfaces. Four of these friction regimes are universal, i.e. they occur on diamond ( 111), (001) as well as (110). Dry sliding leads to immediate cold welding accompanied by amorphization (Regime I). Small amounts of water (less than 8 H 2 O per nm 2 ) can preserve crystallinity and lower friction by localizing shear to interfacial ether groups (Regime II). Further increase in water surface density results in passivating hydrogen/hydroxyl layers (Regime IV) and finally (for more than 20 H 2 O per nm 2 ) in free water layers between hydrogen/hydroxyl passivated diamond surfaces (Regime V). The other four friction regimes are special, i.e. they occur only on certain surfaces. An ultralow friction regime is established by aromatic Pandey surface passivation on diamond (111) surfaces (Regime III). On diamond (110) surfaces, Regime II coexists with three other regimes: while partial cold-welding via C-C bonds (Regime VI) or C-O-C bonds (Regime VII) leads to frictional shear stresses that are in-between the cold-welding regimes (I and II) and the non-cold-welding regimes (IV and V), the formation of an oxidized carbon monolayer consisting of keto and ether groups results in ultralow friction (Regime VIII). Regime VIII is also observed for diamond (001) surfaces. These findings are rationalized by the structural and energetic peculiarities of the different low-index surfaces. Our study provides guidelines for nanoscale control and manipulation of oxygen functional groups on carbon surfaces in boundary lubrication with water or other oxygen-containing lubricants.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Role of oxygen functional groups in the friction of water-lubricated low-index diamond surfaces

Kuwahara

Moras

Moseler

2018

Phys. Rev. Materials

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“…Although they entered commercial service relatively recently, diamond-coated mechanical seals already demonstrated their value in a number of applications. In one oil and gas application, in an environment of water, steam, and sand, a diamond-coated mechanical seal exhibited an operating life of more than 10,000 h [105]. In another setting, Goldschmidt and Gurtler [106] described the use of diamond-coated mechanical seals in pumps used in a pipeline that transports a multi-phase mixture of crude oil, gas, water, and various solids in the Panacocha oilfield in the Amazonian region of Ecuador.…”

Section: Mechanical Sealsmentioning

confidence: 99%

Applications of Diamond to Improve Tribological Performance in the Oil and Gas Industry

Wheeler

2018

Lubricants

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The use of diamond in tribological applications in the oil and gas industry is reviewed. The high hardness, strength, and corrosion resistance of diamond make it an attractive option for components that are susceptible to degradation by abrasive, erosive, or adhesive wear; such components may also be prone to corrosion owing to the nature of the environments to which they are often exposed. Applications such as drill bits, bearings, and mechanical seals benefit from the use of diamond, while choke valves are the subject of research programs to assess the suitability of chemical vapor deposition (CVD) diamond for these components. Also discussed are some of the conditions experienced by the components and how the properties of diamond enhance their operating lives.

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“…The surface topography of diamond coatings [3] affects their performance, including their friction [4], wear [5], adhesion [6,7], and biocompatibility [8]. Diamond is an important material that is used in many industrial applications [9] such as for mechanical seals [10], MEMS devices [11], biomedical applications [12], seals and bearings [13], and nuclear fusion [14] because it has low friction and wear [15,16], and because it is robust and chemically inert so that it can be operated in corrosive environments.…”

Section: Introductionmentioning

confidence: 99%

Comprehensive topography characterization of polycrystalline diamond coatings

Gujrati

Sanner

Khanal

et al. 2021

Surf. Topogr.: Metrol. Prop.

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The surface topography of diamond coatings strongly affects surface properties such as adhesion, friction, wear, and biocompatibility. However, the understanding of multi-scale topography, and its effect on properties, has been hindered by conventional measurement methods, which capture only a single length scale. Here, four different polycrystalline diamond coatings are characterized using transmission electron microscopy to assess the roughness down to the sub-nanometer scale. Then these measurements are combined, using the power spectral density (PSD), with conventional methods (stylus profilometry and atomic force microscopy) to characterize all scales of topography. The results demonstrate the critical importance of measuring topography across all length scales, especially because their PSDs cross over one another, such that a surface that is rougher at a larger scale may be smoother at a smaller scale and vice versa. Furthermore, these measurements reveal the connection between multi-scale topography and grain size, with characteristic scaling behavior at and slightly below the mean grain size, and self-affine fractal-like roughness at other length scales. At small (subgrain) scales, unpolished surfaces exhibit a common form of residual roughness that is self-affine in nature but difficult to detect with conventional methods. This approach of capturing topography from the atomic-to the macro-scale is termed comprehensive topography characterization, and all of the topography data from these surfaces has been made available for further analysis by experimentalists and theoreticians. Scientifically, this investigation has identified four characteristic regions of topography scaling in polycrystalline diamond materials.

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Diamond seal faces – the benefits

Cited by 6 publications

References 0 publications

Role of oxygen functional groups in the friction of water-lubricated low-index diamond surfaces

Role of oxygen functional groups in the friction of water-lubricated low-index diamond surfaces

Applications of Diamond to Improve Tribological Performance in the Oil and Gas Industry

Comprehensive topography characterization of polycrystalline diamond coatings

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