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Development of superhard B-C-N coatings with the diamond structure for wear applications

Objective


Foreseen Results

The experience in developing special hardmetal substrates and underlayers as well as seeding them with nano-grained diamond and studying the superhard coatings has been gained at Moscow State University and Laboratory of Advanced Materials, Russia. The knowledge in the PCVD of thin coatings by use of boron-organic precursors and investigations of their composition and structure has been gained at the Max Planck Institute for Metals Research, Germany. Various techniques for testing physical, mechanical and protective properties of the coatings are widely employed at the University of Hull, Great Britain. The joint research activity of the scientists, having a vast experience on various aspects of developing superhard coatings, will ensure the objectives of the project are fulfilled.
At present, plasma chemical vapor deposition (PCVD) is employed for fabrication of coatings composed of superhard compounds (diamond and cubic boron nitride) for wear applications. Diamond has extremely high hardness, however it cannot be used as a tool material for machining of ferrous metals because of its poor chemical resistance with regard to Fe, Co and Ni at elevated temperatures. Cubic boron nitride (c-BN) can be employed for machining of ferrous metals, however, its hardness is considerably lower than that of diamond. Therefore, the synthesis of compounds, which would possess the properties of both diamond and c-BN, i.e. superhard ternary phases in the B-C-N system with the diamond crystal lattice, appears to be very promising. This could make entirely new types of superhard materials possible providing the unique combination of high hardness, chemical inertness and other properties complementing those of diamond and c-BN. These materials are expected to have outstanding performance compared to conventional coated hardmetals with respect to their tool lifetime, cutting speed and reliability.
The aim of the present work is to study the physicochemical fundamentals of depositing superhard coatings with the diamond structure in the ternary B-C-N system and create wear resistant materials of the new generation on the basis of these coatings.
WC-Co hardmetals specially developed as substrates for wear-resistant coatings will be employed for depositing the superhard layers. Special barrier underlayers obtained by steered and filtered arc-evaporation physical vapor deposition will be developed to achieve better physicochemical compatibility of the superhard coatings with the substrate. A laser ablation technique for seeding the substrate with nano-grained diamond or c-BN will be elaborated to enhance the deposition rate and obtain the fine-grained structure of the superhard coatings. Gaseous mixtures based on boron-organic precursors will be employed for the plasmachemical synthesis of the metastable B-C-N compounds. A wide range of various techniques including Auger electron, Raman and IR spectroscopy, transmission and scanning high resolution electron microscopy, etc. will be utilized to study the composition and fine structure of the coatings. Finally, physical, mechanical and protective properties as well as the performance of the coatings in wear, corrosion and sliding applications will be evaluated.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Max-Planck-Gesellschaft zur Förderung der Wissenschaften eV
Address
Heisenbergstraße 5
70569 Stuttgart
Germany

Participants (3)

Laboratory of Advanded Materials
Russia
Address
56,Warshavskoye Highway
113638 Moscow
Moscow State University 'Lomonosov'
Russia
Address
Vorobjevy Gory
119899 Moskva
University of Hull
United Kingdom
Address
Cottingham Road
HU6 7RX Hull