The importance of structural arrangement on the friction performance of transition metal dichalcogenides sputtered films
Speaker:Prof. Albano Cavaleiro, Full Professor, University of Coimbra, Portugal
Date & Time:13 Jan 2014 (Monday) 16:00 - 18:00
Venue:J323
Organized by:Department of Electromechanical Engineering

Abstract

The utopia of achieving frictionless mechanical contacts through the use of materials with optimized surface properties is the driving force for extensive research studies performed in the field of coatings tribology. Transition metal dichalcogenides (TMD) due to their layered structure and weak inter-layer bonding, has been a traditional solution for lowering the friction in mechanical contacts. As friction and wear is a materials surface problem, the focus of research in this field has been on the deposition of coatings of this family using sputtering techniques. The two main drawbacks which have impeded a widespread application of TMD coatings for reducing friction are the low loading bearing capacity and the high sensibility to moisture. Alloying TMD has been largely used for improving their tribological behavior, allowing to overcome those drawbacks. Our approach that goes beyond the state of the art is to control the deposition parameters, including the type and amount of alloying element, in order to tailor the structure at nanometer level allowing a suitable self-adaption phenomenon at the contact surface, for achieving a quasi-perfect TMD crystal at the coating surface, assuring very low friction in all atmospheres. The selection of the appropriate alloying element will permit to reach a high loading bearing capacity to sustain contact stresses over 1 GPa.

The aim of this talk is to present the latest developments within alloying of TMD-based magnetron sputtering deposited coatings, with either carbon or nitrogen. The focus will be directed to the importance of the alloying element on the control of the structure at nanometer level either in achieving amorphous or nanocomposite structures consisting of TMD crystals of different shapes embedded in C-based amorphous matrixes.

Biography

Albano Cavaleiro is Full Professor in the University of Coimbra, Portugal. In 1990, he received a Ph.D. from Coimbra University on the field of Mechanical Engineering, with a thesis on the surface modification of materials by the sputtering deposition of thin coatings. Presently, he is head of the research group ”Surface Engineering Group” of Centre for Mechanical Engineering of the University of Coimbra and head of LED&Mat at Instituto Pedro Nunes. His field of research and publications is very diversified as e.g. on materials and surface engineering, structural transformations, deposition and characterization of thin films, tribology, nanocrystalline / nanocomposite materials and fuel cells. He participated in more than 30 research projects from which he was responsible in more than 20. He was invited for talks in about 30 international conferences on his field. He supervised 14 PhD students and have an extensive evaluating activity for national and international research agencies. He published more than 250 papers from which about 200 in international journals of SCI.