Laser surface texturing for adaptive solid lubrication
TL;DR: In this paper, micro-reservoirs were machined by a focused UV laser beam on the surface of hard TiCN coatings produced by a cathodic vacuum arc deposition.
About: This article is published in Wear.The article was published on 2006-12-20. It has received 226 citations till now. The article focuses on the topics: Dry lubricant & Lubrication.
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TL;DR: In this paper, the Raman vibrational modes were investigated for excitation wavelengths at 632.8 and 488 nm using both micro-crystalline MoS2 powder and natural MoS 2 crystals.
Abstract: Molybdenum disulfide (MoS2) and molybdenum trioxide are investigated using Raman spectroscopy with emphasis on the application to tribological systems. The Raman vibrational modes were investigated for excitation wavelengths at 632.8 and 488 nm using both micro-crystalline MoS2 powder and natural MoS2 crystals. Differences are noted in the Raman spectra for these two different wavelengths, which are attributed to resonance effects due to overlap of the 632.8 nm source with electronic absorption bands. In addition, significant laser intensity effects are found that result in laser-induced transformation of MoS2 to MoO3. Finally, the transformation to molybdenum trioxide is explored as a function of temperature and atmosphere, revealing an apparent transformation at 375 K in the presence of oxygen. Overall, Raman spectroscopy is an useful tool for tribological study of MoS2 coatings, including the role of molybdenum trioxide transformations, although careful attention must be given to the laser excitation parameters (both wavelength and intensity) when interpreting Raman spectra.
556 citations
TL;DR: In this paper, the effects of surface textures under the operative lubrication regimes in the Stribeck curve, with a clear distinction between conformal-and non-conformal contacts, are discussed.
478 citations
TL;DR: In this article, the effects of edge structures on the edge stability, and electronic and magnetic properties of MoS2 nanoribbons by first-principles calculations were studied. And the authors predicted that S-terminated zigzag nanors are the most stable even without hydrogen saturation because of their low and negative edge energies.
Abstract: Two-dimensional materials have various applications in next-generation nanodevices because of their easy fabrication and particular properties. In this work, we studied the effects of edge structures on the edge stability, and electronic and magnetic properties of MoS2 nanoribbons by first-principles calculations. We predicted that S-terminated zigzag nanoribbons are the most stable even without hydrogen saturation because of their low and negative edge energies, although hydrogen saturation of the edge states can stabilize other nanoribbons with different edge structures. MoS2 zigzag nanoribbons are metallic and ferromagnetic. Importantly, their conductivity may be semiconducting (n- or p-type) or half metallic by controlling the edge structures saturated with H atoms. The magnetic states of the MoS2 zigzag nanoribbons are enhanced by H-saturation and are much stronger than those of graphene zigzag nanoribbons. The armchair nanoribbons are semiconducting, with bandgaps increased by the hydrogen saturation of their edge states, and are nonmagnetic. These MoS2 nanoribbons with versatile functions may have applications in spintronics, nanodevices, and energy harvesting.
245 citations
TL;DR: An overview of the progress made in surface metrology over the past ten years can be found in this paper, where the authors discuss technological shifts in association, filtration, numeric parametric techniques, fractals associated with function and standardisation.
Abstract: This paper gives an overview of the progress which has been made in surface metrology over the past ten years. It updates the surface classification system, and discusses the practical and theoretical reasons for the technological shifts which have occurred. This includes the use of surfaces with predetermined features as an alternative to traditional machined surfaces, and the move from simple to freeform shapes. The paper discusses technological shifts in association, filtration, numeric parametric techniques, fractals associated with function and standardisation. Many examples are given in order to contextualise the significance of these technological changes. This paper should help to predict the direction of future developments in surface metrology, and therefore emphasise its importance in functional applications in advanced manufacture.
237 citations
TL;DR: In this paper, surface texturing with different geometrical characteristics was made on the rake face of the WC/Co carbide tools, molybdenum disulfide (MoS 2 ) solid lubricants were filled into the textured rake-face.
Abstract: Surface texturing with different geometrical characteristics was made on the rake face of the WC/Co carbide tools, molybdenum disulfide (MoS 2 ) solid lubricants were filled into the textured rake-face. Dry cutting tests were carried out with these rake-face textured tools and a conventional tool. The effect of the texture shape on the cutting performance of these rake-face textured tools was investigated. Results show that the cutting forces, cutting temperature, and the friction coefficient at the tool-chip interface of the rake-face textured tools were significantly reduced compared with that of the conventional one. The rake-face textured tool with elliptical grooves on its rake face had the most improved cutting performance. Two mechanisms responsible were found, the first one is explained as the formation of a lubricating film with low shear strength at the tool-chip interface, which was released from the texturing and smeared on the rake face, and served as lubricating additive during dry cutting processes; the other one was explained by the reduced contact length at the tool-chip interface of the rake-face textured tools, which contributes to the decrease of the direct contact area between the chip and rake face.
226 citations
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TL;DR: In this paper, the authors present the state of the art in LST and the potential of this technology in various lubricated applications like mechanical seals, piston rings and thrust bearings.
Abstract: Surface texturing has emerged in the last decade as a viable option of surface engineering resulting in significant improvement in load capacity, wear resistance, friction coefficient etc. of tribological mechanical components. Various techniques can be employed for surface texturing but Laser Surface Texturing (LST) is probably the most advanced so far. LST produces a very large number of micro-dimples on the surface and each of these micro-dimples can serve either as a micro-hydrodynamic bearing in cases of full or mixed lubrication, a micro-reservoir for lubricant in cases of starved lubrication conditions, or a micro-trap for wear debris in either lubricated or dry sliding. The present paper reviews the current effort being made world wide on surface texturing in general and on laser surface texturing in particular. It presents the state of the art in LST and the potential of this technology in various lubricated applications like mechanical seals, piston rings and thrust bearings. The paper also describes some fundamental on going research around the world with LST.
1,123 citations
TL;DR: Laser Surface Texturing (LST) is probably the most advanced surface texturing technique as mentioned in this paper and it produces a very large number of micro-dimples on the surface and each of these microdimples can serve either as a micro-hydrodynamic bearing in cases of full or mixed lubrication.
Abstract: Surface texturing has emerged in the last decade as a viable option of surface engineering resulting in significant improvement in load capacity, wear resistance, friction coefficient etc. of tribological mechanical components. Various techniques can be employed for surface texturing but Laser Surface Texturing (LST) is probably the most advanced so far. LST produces a very large number of micro-dimples on the surface and each of these micro- dimples can serve either as a micro-hydrodynamic bearing in cases of full or mixed lubrication, a micro-reservoir for lubricant in cases of starved lubrication conditions, or a micro-trap for wear debris in either lubricated or dry sliding. The paper reviews the current effort being made world wide on laser surface texturing in particular. It presents the state of the art in LST and the potential of this technology in various lubricated applications like mechanical seals, piston rings, thrust bearings, magnetic recording etc. The paper also describes some fundamental on-going research around the world with LST.
914 citations
477 citations
TL;DR: The chameleon's ability to change skin color depending on environment to increase its chances of surviving served as an inspiration in the development of self-adaptive supertough wear-resistant coatings as mentioned in this paper.
446 citations
"Laser surface texturing for adaptiv..." refers background in this paper
...For example, “chameleon” coatings with WC/WS2/DLC nd ZrO2–Y2O3/Au/DLC/MoS2 compositions were designed n such a way that amorphous diamond-like carbon (DLC) and S2/MoS2 in their composition provide either graphitic carbon r hexagonal WS2/MoS2 [1–3]....
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...The hanges ensure that a correct lubricant occupies the contactng interface and always reduces wear and friction in aerospace ystems [1–3]....
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TL;DR: In this article, a chameleon changing its skin color to avoid predators, the coating changes its "skin" chemistry and structure to avoid wear, similar to the way chameleons change their skin colors to avoid predation.
Abstract: Nanocomposite tribological coatings were designed to respond to changing environmental conditions by self-adjustment of their surface properties to maintain good tribological performance in any environment. These smart coatings have been dubbed “chameleon” because, analogous to a chameleon changing its skin color to avoid predators, the coating changes its “skin” chemistry and structure to avoid wear. The concept was originally developed using WC, diamondlike carbon, and WS2 material combination for adaptation to a humid/dry environment cycling. In order to address temperature variation, nanocomposite coatings made of yttria-stabilized zirconia (YSZ) in a gold matrix were developed with encapsulated nanosized reservoirs of MoS2 and diamondlike carbon (DLC). Coatings were produced using a combination of laser ablation and magnetron sputtering. They were characterized by x-ray photoelectron spectroscopy, x-ray diffraction, transmission electron microscopy, x-ray energy dispersive spectroscopy, and micro-Ram...
138 citations