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Research Advanced Production Engineering

Advanced self-healing nanocomposite coatings

The surface of a component is usually the most important engineering factor. While it is in use it is often the surface of a work-piece that is subjected to wear and corrosion. The complexity of the tribological properties of materials and the economic aspects of friction and wear justify an increasing research effort. In industrialized countries some 30 % of all energy generated is ultimately lost through friction. In the highly industrialized countries losses due to friction and wear are put at between 1% and 2% of Gross Domestic Product. To an increasing degree, therefore, the continuous search is on surface modification techniques and advanced coatings that can largely decrease friction and significantly increase the wear resistance of materials. Appealing lubrication properties are found in compounds with a lamellar crystal structure, like layered transition-metal dichalcogenides (LTMD), i.e. compounds of transition-metal atoms (group IVb, Vb, VIb) and chalcogens (S, Se, Te). They belong to a class of solids exhibiting a marked two-dimensional behavior, despite their three-dimensional atomic structure. Thanks to its unique highly anisotropic crystal structure, LTMD would be an excellent solid lubricant. However, LTMD exhibit poor tribological properties in oxygen or moist environments and low load bearing capacity. These backsets make LTMD based coatings less attractive for operation in harsh environments and under high contact load. Therefore the ultimate goal of this project is to lift these drawbacks and to produce LMTDs in which the porous structure with microcracks are healed and the tribo-system becomes self-adaptive and even self-curing (prevention is better than cure!). Here we propose to prepare transitional metal dichalcogenides nanocomposite coatings using sophisticated magnetron sputtering methods. The coating itself will consist of at least two different compounds, e.g. LTMD in the form of nano-platelets and amorphous diamond-like carbon (DLC) acting as the supporting matrix. We will abandon the standard idea to deposit “ideal” coating and instead focus on the self-adaptive systems. The revolutionary idea is to allow the reorientation of the LTMD phases to the “frictionless” direction inside the matrix. The main advantages of this approach are the ultralow friction due to self-lubrication and the high flexibility of the coating operating in different environments ranging from vacuum to humid air, from room to elevated temperature, or from nano to macro-tribology.

Project leader & first supervisor

Prof. Dr. Yutao Pei

PhD student

H.T. Cao

Second supervisor

Prof. Dr. Jeff Th. M. De Hosson

Last modified:27 August 2015 4.43 p.m.