Research on Diamond-Like Carbon Coatings for Low-Friction Valve Lifters

Yasuda, Yoshiteru; Kano, Makoto; Mabuchi, Yutaka; Abou, Sadayuki

doi:10.4271/2003-01-1101

Cited by 50 publications

(32 citation statements)

References 6 publications

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“…As a result, a very thin and low-shear-strength tribofilm is formed on the ta-C sliding surface. 15,17,22 It appears that superlubricity is directly related to the trialcohol chemical functions ͑ −OH͒ of the glycerol molecule. However, as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Superlubricity and tribochemistry of polyhydric alcohols

et al. 2008

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The anomalous low friction of diamondlike carbon coated surfaces lubricated by pure glycerol was observed at 80°C. Steel surfaces were coated with an ultrahard 1 µm thick hydrogen-free tetrahedral coordinated carbon ͑ta-C͒ layer produced by physical vapor deposition. In the presence of glycerol, the friction coefficient is below 0.01 at steady state, corresponding to the so-called superlubricity regime ͑when sliding is then approaching pure rolling͒. This new mechanism of superlow friction is attributed to easy glide on triboformed OHterminated surfaces. In addition to the formation of OH-terminated surfaces but at a lower temperature, we show here some evidence, by coupling experimental and computer simulations, that superlow friction of polyhydric alcohols could also be associated with triboinduced degradation of glycerol, producing a nanometer-thick film containing organic acids and water. Second, we show outstanding superlubricity of steel surfaces directly lubricated by a solution of myo-inositol ͑also called vitamin Bh͒ in glycerol at ambient temperature ͑25°C͒. For the first time, under boundary lubrication at high contact pressure, friction of steel is below 0.01 in the absence of any long chain polar molecules. The mechanism is still unknown but could be associated with friction-induced dissociation of glycerol and interaction of waterlike species with steel surface.

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Section: Resultsmentioning

confidence: 99%

Superlubricity and tribochemistry of polyhydric alcohols

et al. 2008

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“…Although the applications of the amorphous carbon film have been increased recently to reduce friction for the sliding parts in the automotive engine [1][2][3][4][5] and to improve the oxygen barrier property of the poly(ethylene terephthalate) (PET) bottle for the soft drink, 6,7) there are several technical issues to be improved, as shown in Table I. The optimum material combination of diamond-like carbon (DLC) coating with the environment friendly lubricant to reduce friction markedly is required to be found in near future to improve the environmental problems.…”

Section: Introductionmentioning

confidence: 99%

Low Friction Property of Diamond-Like Carbon Coating Films and Oxygen Transmission Ratio of Amorphous Carbon Films Deposited by Advanced Coating Processes

Watanabe¹,

Kano²,

Yoshida³

et al. 2012

Jpn. J. Appl. Phys.

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The topics of the applied technology of amorphous carbon film to reduce friction using diamond-like carbon (DLC) coated by the vacuum arc ion plating process and to improve the gas barrier property using the amorphous carbon film by the atmospheric pressure plasma process are introduced with the basic experimental results. For reducing friction, the super low friction coefficient below 0.01 has been found when the tetrahedral amorphous carbon coating deposited by T-shape filtered arc deposition method [ta-C(T)] was evaluated the friction property under oleic acid lubrication at pure sliding condition. It was thought that the low share strength tribofilm composed of water and oleic acid mono-layer seemed to be formed on the sliding interface. For gas barrier performance, the amorphous carbon film deposited by the atmospheric pressure plasma chemical vapour deposition (CVD) technique on poly(ethylene terephthalate) (PET) substrate was improved the oxygen transmission ratio (OTR) around 30% compared with that of uncoated PET substrate. These advanced performance obtained by the optimum material combination of DLC with lubricant and the original atmospheric pressure plasma CVD technique are expected to be applied on the actual application for the different types of the industrial fields in near future. #

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“…According to the literature, with increasing temperature the formation of graphitic layer (tribofilm) occurs due to a transformation of sp 2 to sp 3 phase of DLC coatings in dry sliding conditions 34 . When the oil is added among surfaces in contact, they are separated by a thin layer of carboxylic acid preventing the formation of tribofilm, as well as, reduce the contact temperature and contribute to interactions between oil additives and DLC surface 6,10 .…”

Section: Friction and Wearmentioning

confidence: 99%

“…Some authors 3,4,8 mention several studies using DLC coatings in internal combustion engine components because of their excellent tribological behavior in severe environments. DLC has also been mentioned as an applicable coating in valve lifters, obtaining good results for friction and wear 9,10 . In recent studies, Kalin et al (2006 and showed a decrease in the friction coefficient and wear of DLC coatings under lubricated conditions 11,12 .…”

Section: Introductionmentioning

confidence: 99%

Enhanced DLC wear performance by the presence of lubricant additives

et al. 2011

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Lubricant additives play significant role for reducing friction and wear of mechanical elements. The additives presented in 5W30 oil were developed for metal surfaces. However, they have been used in engine pieces covered with DLC coatings because they also offer the potential to reduce friction losses and wear in automotive applications. The friction and wear tests were carried out by using a UMT-CETR ball-on-disk tribometer in rotational mode under 5W30 synthetic oil at 100 °C. The X-ray photoelectron spectroscopy (XPS) showed the presence of Mo and S in the wear tracks. These elements are from decomposition of ZDDP and MoDTC additives producing MoS 2 in DLC surface, which offers enhanced durability by low wear rate.

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Research on Diamond-Like Carbon Coatings for Low-Friction Valve Lifters

Cited by 50 publications

References 6 publications

Superlubricity and tribochemistry of polyhydric alcohols

Superlubricity and tribochemistry of polyhydric alcohols

Low Friction Property of Diamond-Like Carbon Coating Films and Oxygen Transmission Ratio of Amorphous Carbon Films Deposited by Advanced Coating Processes

Enhanced DLC wear performance by the presence of lubricant additives

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