Frictional characteristics of diamond like carbon and tungsten carbide/carbon coated high carbon high chromium steel against carbon in dry sliding conformal contact for mechanical seals

Shankar, S.; Kumar, Pankaj

doi:10.1051/meca/2016036

Cited by 8 publications

(4 citation statements)

References 27 publications

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“…Diamond-like carbon (DLC) has superior mechanical properties 1 and wear protection, 2 which makes it attractive for solid lubrication in engineering systems such as extreme ultraviolet lithography instruments, 3,4 mechanical shaft seals, 5,6 bearings, 7 etc. The C−C connectivity in DLC changes with its chemical composition, 8,9 which is, in turn, very sensitive to deposition temperature 10 and precursor gases used during synthesis.…”

Section: Introductionmentioning

confidence: 99%

“…Diamond-like carbon (DLC) has superior mechanical properties and wear protection, which makes it attractive for solid lubrication in engineering systems such as extreme ultraviolet lithography instruments, , mechanical shaft seals, , bearings, etc. The C–C connectivity in DLC changes with its chemical composition, , which is, in turn, very sensitive to deposition temperature and precursor gases used during synthesis. ,− For example, when DLC is produced via a plasma-enhanced chemical vapor deposition (PECVD) using a precursor gas of C 2 H 2 , the DLC contains ∼30 at.% of hydrogen (H); this “mildly hydrogenated” DLC was previously called NFC-10, but will be called 30-HDLC in this study .…”

Section: Introductionmentioning

confidence: 99%

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Tribochemistry of Diamond-like Carbon: Interplay between Hydrogen Content in the Film and Oxidative Gas in the Environment

Jang

Rabbani

Ogrinc

et al. 2023

ACS Appl. Mater. Interfaces

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The lubricity of hydrogenated diamond-like carbon (HDLC) films is highly sensitive to the hydrogen (H) content in the film and the oxidizing gas in the environment. The tribochemical knowledge of HDLC films with two different H-contents (mildly hydrogenated vs highly hydrogenated) was deduced from the analysis of the transfer layers formed on the counter-surface during friction tests in O2 and H2O using Raman spectroscopic imaging and X-ray photoelectron spectroscopy (XPS). The results showed that, regardless of H-content in the film, shear-induced graphitization and oxidation take place readily. By analyzing the O2 and H2O partial pressure dependence of friction of HDLC with a Langmuir-type reaction kinetics model, the oxidation probability of the HDLC surface exposed by friction as well as the removal probability of the oxidized species by friction were determined. The HDLC film with more H-content exhibited a lower oxidation probability than the film with less H-content. The atomistic origin of this H-content dependence was investigated using reactive molecular dynamics simulations, which showed that the fraction of undercoordinated carbon species decreased as the H-content in the film increased, corroborating the lower oxidation probability of the highly-hydrogenated film. The H-content in the HDLC film influenced the probabilities of oxidation and material removal, both of which vary with the environmental condition.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tribochemistry of Diamond-like Carbon: Interplay between Hydrogen Content in the Film and Oxidative Gas in the Environment

Jang

Rabbani

Ogrinc

et al. 2023

ACS Appl. Mater. Interfaces

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“…Apart from the physical and chemical properties of the frictional pair materials, the friction conditions have a great influence on their tribological properties. Previous studies on the tribological performance of mechanical seal frictional pairs have mainly focused on dry friction, water lubrication, or oil lubrication [6,[18][19][20][21]. Under dry friction, graphite tends to transfer to the friction surface, reducing the direct contact between the frictional pairs [22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

The Tribological Performance of Frictional Pair of Gas–Liquid Miscible Backflow Pumping Seal in Oil–Air Environment

Liao

Zhao

et al. 2023

Lubricants

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The gas–liquid miscible backflow pumping seal (G-LMBPHS) is a non-contact mechanical seal that is suitable for high-speed bearing chambers. However, the tribological properties and wear mechanisms of the frictional pair of G-LMBPHS in an oil–air environment have not yet been comprehensively studied. In this study, the tribological properties of six frictional pairs, consisting of three hard materials (18Cr2Ni4WA, Al2O3 coating, and Cr2O3 coating) and two soft materials (metal-impregnated graphite [Metal-IG] and resin-impregnated graphite [Resin-IG]), were analyzed using a disc-on-disc tribometer. An oil–air environment was created using a minimal quantity lubrication (MQL) system and a closed chamber. The results show that the COF of the four frictional pairs consisting of two coatings and two graphites decreases gradually with increasing rotational speed, and the frictional pairs composed of Al2O3 coating and Resin-IG and Cr2O3 coating and Resin-IG have the lowest COF between 0.022 and 0.03. Therefore, the frictional pairs of G-LMBPHS are in a mixed lubrication condition. The lubricant in the oil–air environment is adsorbed and stored in pits on the surface of graphite and coatings, enhancing the hydrodynamic effect of the spiral grooves and reducing the COF by up to 45%. Metal-IG has better wear resistance than Resin-IG, and the frictional pair consisting of Cr2O3 coating and Metal-IG has the lightest wear. This study provides an important basis for the selection of G-LMBPHS frictional pairs in oil–air environments.

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“…To improve the mechanical-seal contact performance, metal-ring (rotor) coating (or film) treatment has become a very important research focus. Significant concern has been reported regarding friction and wear of the coatings in water and air, and mechanical seals are considered owing to their potential applications [6,[13][14][15][16][17]. The typical working conditions of the mechanical seal in a liquid rocket engine are low temperature, low viscosity, and high-PV values.…”

Section: Introductionmentioning

confidence: 99%

Friction and wear behavior of different seal materials under water-lubricated conditions

2020

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The shaft mechanical face seal in a high-speed turbopump of a liquid rocket engine often operates under extremely harsh conditions. For example, a low-temperature and low-viscosity fluid (such as liquid oxygen or liquid hydrogen) is used as a lubricant. The performance of the seal rings, especially the friction and wear behavior, directly determines whether the seal functions normal. In this study, the friction and wear behavior of several ring materials are tested using a pin-on-disk tribo-tester, and the wear morphology of the ring is investigated. The friction coefficients (COFs) and mass-wear rates under dry-friction and water-lubricated conditions, which are used to simulate low-viscosity conditions, are obtained. The results show that at a pressure-velocity (PV) value of 2.4 MPa•(m/s), the COF between the copper graphite (stator) and copper-chrome alloy disk (rotor) is low (with a value of 0.18) under the dry-friction conditions, and the 5-min wear mass of the copper graphite is approximately 2 mg. Under the water-lubricated conditions, compared with other materials (such as copper-chrome alloy, S07 steel, alumina ceramic coating, and nickel-based calcium fluoride), the S07 steel with a diamond-like carbon film is preferred for use in a high-speed turbopump under extreme conditions. The results of this study can provide theoretical and experimental guidance in the design of mechanical face seals in liquid rocket engines.

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Frictional characteristics of diamond like carbon and tungsten carbide/carbon coated high carbon high chromium steel against carbon in dry sliding conformal contact for mechanical seals

Cited by 8 publications

References 27 publications

Tribochemistry of Diamond-like Carbon: Interplay between Hydrogen Content in the Film and Oxidative Gas in the Environment

Tribochemistry of Diamond-like Carbon: Interplay between Hydrogen Content in the Film and Oxidative Gas in the Environment

The Tribological Performance of Frictional Pair of Gas–Liquid Miscible Backflow Pumping Seal in Oil–Air Environment

Friction and wear behavior of different seal materials under water-lubricated conditions

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