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Antifriction Carbon Coatings-Orientants

#4036


New Generation of Antifriction Carbon Coatings-Orientants

Tech Area / Field

  • MAN-MAT/Engineering Materials/Manufacturing Technology
  • MAN-TRI/Tribology/Manufacturing Technology

Status
3 Approved without Funding

Registration date
24.02.2010

Leading Institute
Moscow State University / Department of Chemistry, Russia, Moscow

Supporting institutes

  • Ufa State Technical University of Aviation, Russia, Bashkiria, Ufa\nBlagonravov Institute of Machine Science, Russia, Moscow

Collaborators

  • Pennsylvania State University / Department of Mechanical Engineering and Applied Mechanics, USA, PA, University Park\nG.E. Totten & Associates, LLC, USA, WA, Seattle\nUniversity of Lund / Physical Chemistry 1, Sweden, Lund\nInstitute of Precision Mechanics, Poland, Warsaw\nMcMaster University, Canada, ON, Hamilton\nTexas A&M University / Department of Mechanical Engineering, USA, TX, College Station\nTeer Coatings Lts., UK, Droitwich

Project summary

Up-to- date trends in engineering put in the forefront increasing of reliability and service life of friction units first of all operating under conditions of boundary lubrication, as well as extending the load and temperature ranges of their application. Besides there is a very important problem connected with power consumption during friction units operation. The way of these problems solving lies in the field of optimization of composition and structure of rubbing materials (particularly by using wear resistant and /or antifriction coatings), as well as lube oils characteristics optimization.

The antifriction diamond-like carbon (DLC) coatings-orientants of new generation proposed in the Project allow solving mentioned triboengineering problems due to both their high performance characteristics and their specific effect on molecular ordering in boundary lube layer what results in lube oils performances increase

The Purpose of the Project is to develop a nanotechnology of controlled synthesis of carbon coatings-orientants with altering structure, to prepare specimens of coatings on different substrates, to estimate their tribological properties under lab and stand tests in various lube oil compositions; to optimize the triad “structure of coating- substrate- lube oil” from the position of friction and wear minimization.

The proposed carbon coatings-orientants differ from other diamond-like coatings by higher mechanical characteristics and experimentally proved correlations between tribological properties of the coatings, their structure and the structure of boundary lubricating layers. Using this type of coatings it seems possible to regulate antifriction and antiscoring properties of materials of friction units of friction and wear minimization.

Usually one makes lube oils optimization by introducing in base oils some surface-active (surfactants) and/or chemically active additives, etc. The mentioned additives in the result of physical-chemical, chemical and colloidal-chemical interactions with surfaces of rubbing elements form there a thin layer of the products of these interactions. These layers have reduced shear strength as compared to that of substrate. This provides antifriction effect and prevents from scoring. However in a number of cases intensive development of the processes of complex interaction of additives with friction surfaces may lead to surface layers corrosive failure and gaps between rubbing elements increasing over permissible value.

It is known that is possible to consider the structure of lubricating boundary layers as an epitropic liquid crystalline phase (ELC). Lubrication action of ELC layers is determined by the level of molecules orientation in these layers relatively to solid surface subjected to lubrication. Orientation of molecules of lube oil in the interface of a solid and a lube layer repeats the orientation of the surface layer of the solid. Thus, it is possible to regulate the lube ability of boundary layers by varying the level of orientation in surface layers of solids. Boundary layers with highly ordering structure preset by the coating surface have improved lubricating ability, higher thermal stability, extending ranges of operating temperatures of oils, etc.

Tribology has some experience in using liquid crystals as additives for lube oils. However, creating a high level of molecules orientation in boundary lube layers these additives do not ensure sufficient adhesion of these layers to the lubricated surface.

Modification of rubbing surfaces by coatings-orientants can allow increasing both molecular structural ordering in boundary lubricating layers and their adhesion to the lubricated surface. However traditional coatings-orientants as a rule can’t be used due to low mechanical properties and insufficient adhesion to the substrate, etc. According to researches of the authors of the Project the coatings-orientants should meet the following requirements: to have good adhesion to substrate;, to be hard, heat resistant; to have some active center on the surface (N, O, OH, etc.). The carbon diamond-like coatings (DLC) best correspond to the listed requirements. At present time these coatings are used in micro- and nanomechanical systems (MEMS и NEMS)

It is known that the structure and properties of coatings as well as their orientation properties depend in a great extent on the conditions of their synthesis. The authors of the Project on the base of the experimental studies of DLC with different structure have shown that the most perspective orientants are carbon coatings with polycrystalline or monocrystalline structure and homeotropic orientation. Usage of the coatings of the mentioned types can allow reducing the number of additives in lube oils and correspondingly simplifying their composition and cutting down the cost. The authors of the Project had done a set of preliminary theoretical and experimental studies, which had shown the advantage of the proposed direction for friction reducing, as well as for lubricating ability and thermal stability of lube oils improvement.

The proposed carbon coatings-orientants can find application in different fields of science and industry, particularly in such as:

  • Nanomechanical systems (NMS)
  • Nanoelectromechanical systems (NEMS)
  • Microelectromechanical systems (MEMS)
  • Precision friction devices for electronics and clockworks;
  • Metal working industry (coatings for cutting tool.);
  • Computer technologies;
  • Liquid crystal technology;

Main objective of the Project

In the process of the Project implementation the following tasks are planned to accomplish:

  • The requirements to the coatings should be formulated ensuring optimization of service life of lubricated friction units;
  • Parameters of coatings synthesis should be optimized for the concrete solid substrates and lube oils;
  • Structure and composition of coatings should be examined at various stages of coatings synthesis working-off;
  • The mechanism of formation of highly orientated structure of molecules of different lube materials (fatty acids, hydrocarbons, mineral oils) adsorbed on coating surfaces should be studied;
  • Tribological and corrosion tests of coatings should be done at various stages of coatings synthesis working-off;
  • Optimal combinations of coating structure, substrate and lube oil should be found;
  • Recommendations on application of coatings and lube oils under study in real lubricated friction units including micro- and nano-electromechanical systems should be made.

The study of the triad < parameters of synthesis – structure – properties> will be performed by X-ray spectroscopy, Raman spectroscopy, optical and electron microscopy, micro- and nanoindentation tests etc. The evolution of physical, chemical, mechanical and tribological properties of carbon coatings will be carried out using modern analytic and test equipment by methods and standards accepted in Russia and abroad. The Institutes participating in the Project have accumulated many-year experience both in scientific and experimental researches and are recognized authorities in Russia and worldwide

Starting background: The Department of Chemistry of Lomonosov MSU personnel considerable experience in technology of synthesis of carbon coatings development, experience of IRAS IMASH personnel in theory and practice of tribological performances evaluation, as well as USAU experience in tribological and corrosion stand tests provide a good basis for the Project goals achievement and also will promote the Project implementation and further commercialization of its results.

The Project completely meets the ISTC tasks and goals because the specific technologies and methods developed for military applications will be used for a wide peaceful application

Expected results

The Project is focused on the experimental studies and experimental findings will possess a substantial novelty as there were no such investigations beforehand. The following development will be made on the basis of the experimental findings of the Project:

  • High-efficiently technology for synthesis of carbon monocrystalline and polycrystalline coatings of new generation;
  • Optimization of tribological performances of lubricated friction unites by using developed carbon coatings.

Basing on the test results substantiate conclusions will be made concerning prospects of coatings further application to solve high-priority triboengineering tasks in different fields of industry. According to the methodology accepted all the experimental studies within the Project will be concentrated in the following main directions:
  • Synthesis of carbon coatings-orientants and overall investigations of the structure and physical-chemical properties of the obtained coatings;
  • Laboratory and stand tribological tests of different combinations of coatings, metal substrates and lube oils;
  • Analysis of experimental data and finding “parameters of synthesis – structure – properties” relationships, definition of optimal technological conditions of coating synthesis;
  • Development of technology of controlled synthesis for production coatings-orientants for practical applications.


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