Faculty of Electrical Engineering

Czech Technical University in Prague

CTU in Prague

Advanced Materials Group

Web page: http://advamat.dce.fel.cvut.cz/
e-mail: advamat@fel.cvut.cz

Who we are

Tomáš Polcar - Head of the group

Ladislav Cvrček - PostDoc researcher
Collaboration with industry; coating deposition; biocompatible coatings.

Joao Vitor Pimentel - PhD student
Self-lubricant films based on transition metal dichalcogenides.

Karolina Tomesova - PhD student
Vacuum tribology; High-temperature vacuum tribology.

Group description

Advanced Materials Group was launched in January 2009 at the Department of Control Engineering and became one of the most successful groups in the field of material science at the faculty. The focus of our research is the area of surface engineering, namely thin solid films deposited by physical or chemical methods. Current research topics cover emerging deposition methods, development of coatings with unique optical, mechanical or tribological properties, and design of new testing equipment.

We published about 50 papers in impacted journals in last 5 years.

The group has been successful in joining excellent research performance (more than 40 impacted papers published in last 5 years; more than 150 citations; 5 invited talks at major conferences) and financial project support (project from national to EU level, in total more than 1.5M. in last 5 years). Moreover, the group has strong national and international collaboration with both academic and industrial partners participating in several research projects.

What is it good for?

Thin coatings (thickness from nanometers to microns) are applied on the surface of solid modifying properties of the substrate. In fact, it is a very difficult to imagine modern society without hard discs and monitors, where the coatings play vital part. You might touch them every day using decorative handles. You can see them on your glasses - or not, but they are there. Many parts of your car are coated to reduce friction, wear, or just noise.

Running projects

Self-adaptive low-friction coatings

The reduction of friction continues to be a hot-topic in mechanical engineering. Lower friction between mechanical parts in contact diminishes the energy consumption, vibrations, noise, contact temperature, and wear. Among many ways to fight the friction, solid lubricants in the form of thin films deposited by physical vapor deposition methods are widely used in industrial applications. Transition metal dichalcogenides (TMD) are suitable as solid lubricants due to their anisotropic layered structure, where the adjacent lamellae with strong covalent bonding interact through relatively weak van der Waals forces. Pure sputtered TMD films are almost friction-less at ultra-high vacuum sliding conditions; however, the films are sensitive to environmental attack, particularly in the presence of oxygen and water, which limits their mechanical properties and wear resistance. Alloying of TMD with other element has improved their properties, such as adhesion, hardness and load bearing capacity. Nevertheless, the high sensitivity to environmental attacks still remains the main restriction for full the industrial use of TMD-based coatings as self-lubricants. We deposit and analyze the tribological behavior of different TMD coatings alloyed with carbon (WSC, WSeC, MoSC and MoSeC systems) deposited by magnetron sputtering. Three TMD microstructures have been prepared: i) randomly oriented platelets in amorphous carbon matrix, ii) nanograins of TMD in amorphous carbon matrix and iii) mixture of carbide and TMD nanograins embedded into the carbon matrix. Special attention has been paid to the analysis of the frictional and wear mechanisms under different operating conditions, such as contact pressure, air humidity or temperature. Nanoscale analysis of the wear track revealed the formation of a thin tribolayer exclusively consisting of TMD platelets oriented to exhibit the lowest friction. In some cases, the depth reorientation of the originally randomly oriented TMD platelets as a reaction to the sliding process has been observed. Such self-adaptation explains the extremely low friction coefficient together with a high load-bearing capacity; moreover, the films are much less sensitive to environmental conditions compared to pure TMD. The project could be considered as a fundamental research; however, some coatings (W-S-C and Mo-Se-C systems) have been recently tested by several industrial partners with promising results.

High temperature tribology

The group pioneers high temperature tribology of hard protective coatings. Our aim is to simultaneously analyze oxidation resistance, thermal stability and sliding properties of different coatings at elevated temperature. We demonstrated that tribological behavior at elevated temperature cannot be estimated using oxidation tests and room temperature sliding. We observed unexpected failures of hard films at elevated temperature suggestion hot-adhesion problems bringing a new factor to be evaluated in the field of high-temperature coating industry. Our work is well acknowledged by industrial partners - we have published more than 10 papers with coating producers!

Biocompatible coatings

We participate in large industrial project focused on development of coating technology for medical implants, which will be used by national implant producers. From many potential bio-applications, two with the largest market impact have been selected: orthopedic and dental implants. I case of orthopedic implants, we develop and apply chemically stable coating decreasing friction and, particularly, the production of the wear debris and corrosion products, which limits functionality of present non-coated implants. The main issue of dental implants is interaction of implant surface with surrounding tissue. Carbon-based coating with optimized metal content significantly increases surface bioactivity and enhances tissue healing; moreover, the coating provides long-term protection against corrosion attacks. The role of AMG in the project is to test the wear resistance of the films in laboratory scale including knee simulator; the main issue is to optimize the polymer/coating contact.

Interface Design of Crystalline Materials with Improved Radiation Damage

The overall objective of the proposed project is to develop a multiscale predictive modelling framework able to identify suitable strategies for optimising the properties of existing NMMC systems and for identifying new ones with improved radiation damage resistance and mechanical properties, thus providing a suitable guideline to correlated experimental approaches. AMG will prepare specific coating and test their structural and mechanical properties before and after radiation exposure. Experimental results will be used to validate theoretical simulations.

Financial support

  • 2007-2009 - Self-lubricating coatings based on transition metal dichalcogenides; Grant Agency of the Czech Republic (~51 k€)
  • 2010-2013 - Advanced self-adaptive low friction coatings based on transition metal dichalcogenides alloyed with carbon, Grant Agency of the Czech Republic (~235 k€)
  • Industrial and academic partners.
  • 2009-2012 - BIOTIP - Functional coatings for medical implants; Ministry of Industry and Trade of the Czech Republic (240 k€)
  • 2010-2013 - Stability of bioactive layered structures in model human body fluids, Grant Agency of the Czech Republic (~65 k€)
  • 2011-2014 - RadInterface - Interface Design of Crystalline Materials with Improved Radiation Damage resistance Based on Multiscale Modelling Concepts, EC through FP7 (480 k€)

Scientific collaborations (only those with published papers)

  • University of Coimbra, Portugal
  • University of Uppsala, Sweden
  • University of Minho, Portugal
  • University of Groningen, Netherlands
  • Ecole Nationale Supérieure de Mécanique et des Microtechniques, France; Haute Ecole ARC Berne-Jura-Neuchâtel, Switzerland
  • Universidad del Valle, Colombia
  • Forschungszentrum Karlsruhe, Germany
  • HVM Plasma, Ltd, Czech Republic
  • Instituto Nacional de Investigaciones Nucleares, México
  • EPFL - Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, Switzerland

Selected recent results

  • T. Polcar, M. Evaristo, R. Colaço, C. Silviu Sandu, A. Cavaleiro, Nanoscale triboactivity: Response of Mo-Se-C coatings to sliding, Acta Mater 56 (2008) 5101-5111
  • T. Polcar, M. Evaristo, M. Stueber, A. Cavaleiro, Synthesis and structural properties of Mo-Se-C sputtered coatings, Surface and Coatings Technology 202 (2008) 2418-2422
  • T. Polcar, M. Evaristo and A. Cavaleiro, Self-lubricating W-S-C nanocomposite coatings, Plasma Processes & Polymers, 2009, 6, 417-424
  • T. Polcar, M. Evaristo, M. Stueber, A. Cavaleiro, Mechanical and tribological properties of sputtered Mo-Se-C coatings, Wear 266 (2009) 393-397
  • T. Polcar, M. Evaristo, A. Cavaleiro, Comparative study of the tribological behaviour of self-lubricating W-S-C and Mo-Se-C sputtered coatings, Wear 266 (2009) 388-392
  • T. Polcar, A. Cavaleiro, Review on self-lubricant transition metal dichalcogenide nanocomposite coatings alloyed with carbon, Surf. Coat. Technol. 2011, doi:10.1016/j.surfcoat.2011.03.004
  • T. Polcar, A. Cavaleiro, Self-adaptive low friction coatings based on transition metal dichalcogenides, Thin Solid Films 519 (2011) 4037-4044
  • J.V. Pimentel, T. Polcar, A. Cavaleiro, Structural, mechanical and tribological properties of Mo-S-C solid lubricant coating, Surface and Coatings Technology 205 (2011) 3274-3279
  • T. Polcar, D. Bharathi Mohan, et al, Properties of nanocomposite film combining hard TiN matrix with embedded fullerene-like WS2 nanoclusters, Thin Solid Films 519 (2011) 3191-3195
  • T. Polcar, R. Martinez, T. Vítů, L. Kopecký, R. Rodriguez, A. Cavaleiro, High temperature tribology of CrN and multilayered Cr/CrN coatings, Surf. Coat. Technol. 203 (2009) 3254
  • T. Polcar, A. Cavaleiro, Structure, mechanical properties and tribology of W-N and W-O coatings, International Journal of Refractory Metals and Hard Materials 28 (2010) 15-22
  • T. Polcar, T. Vitu, L. Cvrcek, et al., Effects of carbon content on the high temperature friction and wear of chromium carbonitride coatings, Tribology International 43 (2010) 1228-1233
  • T. Polcar, A. Cavaleiro, Structure and tribological properties of AlCrTiN coatings at elevated temperature, Surface and Coatings Technology 205 (2011) S107-S110
  • T. Polcar, A. Cavaleiro, High temperature properties of CrAlN, CrAlSiN and AlCrSiN coatings - structure and oxidation, Material Chemistry and Physics 129 (2011) 195-201
  • T. Vitu, T. Polcar, L. Cvrcek, R. Novak, J. Macak, J. Vyskocil, A. Cavaleiro, Structure and Tribology of Biocompatible Ti-C:H Coatings, Surf. Coat. Technol. 202 (2008) 5790-5793
  • T. Polcar, T. Vitu, L. Cvrcek, R. Novak, J. Vyskocil, Tribological behaviour of nanostructured Ti-C:H coatings for biomedical applications, Solid State Sciences 11 (2009) 1757-1761
  • A. Escudeiro, T. Polcar, A. Cavaleiro, Tribological behaviour a-C and a-C:H films doped with Ti in biological solutions, Vacuum 85 (2011) 1144-1148

Responsible person: doc. Ing. Milan Polívka, Ph.D.