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Modification methods of layered metal dichalcogenides for a new lubricant, nanocrystal materials and coatings

Preparation of new nanocrystal tribomaterials, coatings and
structural lubricants on the basis of the development of
physico-chemical modification methods of layered transition
metal dichalcogenides.

One of the central problems of modern materials technology is how to improve the tribotechnical characteristics of the friction pair concurrent with the fulfilment of rigid requirements as to their dimensional accuracy. It is known that disulphides and diselenides of tungsten and molybdenum are effective lubricants under extreme conditions. Investigations into the synthesis of powdered transition metal dichalcogenides and on the preparation of deposited films on their basis by various methods show that the structure of crystallites and the texture of coatings significantly affects tribotechnical characteristics. The perfection of the crystal structure and its discrepancy in the stoichiometric formula (MeX2) of dichalcogenides is also a determining factor in its chemical behaviour. The technological parameters of the preparation methods are also of great importance for obtaining these compounds in the form of films or powder, with a given structure. One problem has still to be solved: the obtaining of coatings, by physical or chemical deposition, with a quality reproducibility (stoichiometry, thickness, contamination, structure, adhesion). The proposed project is based on the results of laboratory inestigations in the Institute of Organo-element Compounds of THE RUSSIAN ACADEMY OF SCIENCES (INEOS RAN), KURNAKOV Institute of General and Inorganic Chemistry of THE RUSSIAN ACADEMY OF SCIENCES (IONKh RAN), MOSCOW STEEL AND ALLOYS UNIVERSITY (MS&AU) and THE MOSCOW ACADEMY OF CHEMICAL MACHINE BUILDING (MGAKhM). A new method for the formation of nanocrystal materials by chemical dispersion of MeX2 particles, up to monolayered size is proposed. The process will make it possible to activate the basal planes of MeX2 to obtain a high level of adhesion of particles to the friction surface and high stability of lubricants on their basis. Decomposition of crystal transition metal dichalcogenides should be carried out as follows: 1. intercalation of layered matrixes with alkali metals 2. dissolving of these metals. It allows separate layers of MeX2 to be transferred into a colloid solution. It then modifies the dispersed material by fastening the nanoparticles of various organic and metallorganic fragments to the surface. Such dispersed material can also be used to prepare deposited films. Another part of the project deals with the obtaining of wear resistance coatings of a given composition or structure on underlying materials. PVD (Physical Vapour Density) and CVD (Chemical Vapour Deposition) methods will be used to obtain such coatings. Conditions have been determined whilst providing the performance of PVD technology to produce layered molybdenum dichalcogenide coatings. Laboratory samples are available. CVD methods are used to obtain composite coatings with under layers from tungsten and molybdenum. One of the very promising methods, that form such thin wear resistance coatings from molybdenum, tungsten and their alloys, is based on reduction of suitable fluorides with hydrogen. Such coatings have high adhesion to underlying material and can be deposited on complex-shaped parts of various construction materials (alloyed steels, copper alloys and others) at low temperature (up to 500 deg.C.). The upper layer is formed by chalcogeniding under mild conditions. We have laboratory results that offer possibilities of obtaining coatings with sequences of layers, including layers of intercalates on the basis of layered dichalcogenide matrix. Such coatings should have high thermal stability and high adhesion on the surface. The proposed methods of physicochemical modification therefore form the basis of further research with the object of producing new tribotechnical materials and coatings. As part of the project, there are also plans to work on procedure conditions, providing reproducibility in quality, and carry out an analysis of the infrastructure and tribotechnical tests of those materials and coatings.
Acronym: 
LUBRIMAT
Project ID: 
1 538
Start date: 
01-01-1996
Project Duration: 
48months
Project costs: 
260 000.00€
Technological Area: 
Market Area: 

Raising the productivity and competitiveness of European businesses through technology. Boosting national economies on the international market, and strengthening the basis for sustainable prosperity and employment.