In a broad sense, coatings and films technology is a very important branch of science and industry. Development of coatings and films technology toward their functionality has been attracting much interest. Innovative coatings and films can be characterized as materials with special properties tuned for specific applications. Research and development of modern materials are substantially based on hybrid materials technology. Hybrid structures can consist of different materials (metals, ceramic, etc.) in different forms (bulk, layered, composites, gradient structures, etc.) in nano, micro, and macro level.
The research group in TTÜ deals with all aspects of physical vapour deposition (PVD) and chemical vapor deposition (CVD) technologies. The advanced diamond (see Fig. 1) and oxide coatings are under development. The coatings characterization includes investigation of tribological properties (room/high temperatures), mechanical properties by nanoindentation and nanoscratch (room/high temperatures), surface morphology and chemical composition, etc. Diamond coatings (see Fig. 1) have a wide range of tribological applications due to high Young’s modulus and hardness. Different types of coatings are used for protection of cutting tools in engineering and mining industry. High temperature wear resistance is important for cutting tools. Therefore, the study of tribological behaviour of diamond coatings at high temperatures is of special interest. Investigation and improvement of diamond coating properties, particularly the properties of the interface between the coating
and substrate is an important part of the current research.
In regard to oxide coatings, understanding and improvement of thermal resistance of the AlCr-based oxides is the specific research topic. There is a need for the development of new coatings for cutting tools used in modern machining processes.
Fig. 1. Two types of diamond coatings, polycrystalline (a,b) and nanocrystalline (c)
Extreme high temperature conditions occur during metal cutting processes suggesting to use coatings with special properties. One major role of the coatings for this type of application is to prevent surface oxidation and alternation of properties of the tools at high temperature. The selection of coatings is restricted to materials with phase stability and low wear rate at high temperatures, resistance against oxidation, low thermal conductivity, chemical inertness, appropriate thermal expansion coefficient, etc. Measurement of thermal expansion coefficient is another important aspect, as this coefficient characterizes an ability of a material to withstand the thermal stresses associated with heating and cooling. The project focuses also on the understanding of influence of the structure of oxides (chemical composition, type of phase, impurities, micro/macro defects, etc.) on the thermal and mechanical/tribological properties of oxides.
Applied study focuses improvement of wear resistance of tools by applying high-technological thin hard PVD coatings for specific tooling applications (fine blanking and sheet metal forming dies, cutting tools etc.).
Head of research group:
Sen. Res. Sc. Vitali Podgurski