Hard coatings

Nano-structured materials are a new class of materials that are distinguished from conventional polycrystalline materials by their extremely fine crystallite size from 100 nm down to several nm. Interest to nanostructured materials has been growing rapidly due to reports showing that they posses remarkable mechanical, electrical, magnetic and optical properties [1-7].Nanostructured coatings have recently attracted increasing interest because of the possibilities of synthesizing materials with unique physical–chemical properties [8-10].

Highly sophisticated surface related properties, such as optical, magnetic, electronic, catalytic, mechanical, tribological, chemical as well as magnetic, electronic and optical can be obtained by advanced nanostructured coatings, making them attractive for many modern industrial applications.   There are many types of design models for nanostructured coatings, such as nano-composite coatings, nano-modulated multilayer coating, nano-graded coatings. Design of nanostructured coatings needs consideration of many factors, e.g. the interface volume, crystallite size, single layer thickness, surface and interfacial energy, texture, epitaxial stress and strain, etc., all of which depend significantly on materials selection, deposition methods, processing parameters and what is especially important service condition of coated parts. Use of nano-structured coatings if needed is imperative in microelectromechanical systems (MEMS) where thickness of the moving parts is usually of several micrometers – in all these cases the thickness of protective wear resistant and corrosion resistant coatings or functional (magnetic, optical properties) coatings should be in nano-scale [ 11-13].

Super-hard materials with hardness above 40 GPa include diamond, DLC (Diamond Like Carbon) cubic-boron nitride, as well as heterostructures, with nano-modulated often periodic arrangements of nano-layers of two different materials or nano-composites where nano-precipitates are distributed on a nano-scale in amorphous or crystalline matrix.  Functionally gradient coatings with gradual change in composition accommodate internal stresses (that can be result of processing) and thus improve the performance of coatings especially in wear conditions. Functionally graded coatings usually have high hardness of the surface layer (coating on a metal alloy or on a metal-ceramic composite) with gradually decreasing hardness but increasing strength and fracture toughness in the region below the surface layer. Nano-modulated lamellar structures in addition to ceramic-metal and ceramic-ceramic systems include also biomimetic ceramic-organic multilayer nano-structures.
 In spite of growing interest and research activities to the nano-structured multifunctional coatings in the last years there is still a lack in understanding the effect of processing methods and processing parameters on microstructure and properties of nano-structured coatings including those that are used or are intended for use in wear and oxidation/corrosion service conditions.

The potential market for such coatings and coated articles is very wide range from large scale steel, Ni and Ti alloys sheet products to cutting and processing tools; wear resistant parts for automotive, aircraft/space and chemical industries; biocompatible and wear resistant surgical implants down to miniature parts for electronics and microelectronics, including MEMS. In Europe a large number of industrial companies including SME's will be able to develop and market new industrial products with success or research activities of NoE EXCELL in the field of multifunctional nano-structured coatings.

The present document, Deliverable D 4.2, presents two large projects that were prepared in the field of wear resistant and corrosion resistant nano-structured coatings by NoE EXCELL Partners after detailed discussions. Each project contains a number of Tasks and each Task can be considered as a Research Project whose preliminary results can be expanded into an independent Research Project. From the second side all Tasks of two projects were prepared with participation of most of EXCELL Partners and are taking into account the expertise, experience and facilities of EXCELL Partners and thus after overcoming fragmentation, joint efforts of EXCELL Partners will allow to achieve pronounced progress on the topic, compared to what was possible to achieve by separate efforts of EXCELL Partners.

The first project “Hard/superhard Wear and Corrosion Resistant Nanostructured Coatings/Thin Films on Steel” is an applied Project and deals with the development of methodology and techniques for processing and characterization of nano-structured hard/supehard coatings on steel products. EXCELL Partners plan on the basis of implementation (even partial) of Tasks of this applied Project to prepare Research Projects/Research Proposals that will be submitted to various funding organizations including large industries and SME's.

The second research project “Development of Techniques for Processing and Characterization of Hard/Superhard Nano-structured Wear and Corrosion Resistant Coatings – Fundamentals”,     will be devoted to gain new knowledge on the fundamentals of different aspects of processing and characterization of nano-structured thin films/coatings employing and developing modern experimental techniques as well as theoretical modelling.
Both projects have been designed following the same scheme: Project Leader (CR1 for Project 1 and CR2 for Project 2) will coordinate the research activities of the Project with the help of Task Leaders. Research activities in each task (11 Tasks in Project 1 and 5 Tasks in Project 2) will be coordinated by a Task Leaders, and carried out by a number of EXCELL Partners.

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