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Transformations under Exposure of Compression Plasma

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Research of Chemical and Phase Transformations in Thin Layers and Nanoparticles under Exposure of Homogeneous Dense Plasma of Compression

Tech Area / Field

  • MAT-SYN/Materials Synthesis and Processing/Materials
  • PHY-PLS/Plasma Physics/Physics

Status
3 Approved without Funding

Registration date
24.08.2006

Leading Institute
Institute of Biochemical Physics, Russia, Moscow

Supporting institutes

  • Russian Academy of Sciences / Semenov Institute of Chemical Physics, Russia, Moscow

Collaborators

  • University of Illinois, USA, IL, Chicago

Project summary

This project is directed on comprehensive research of chemical and phase transformations in thin layers and nanoparticles from different materials under exposure of homogeneous dense plasma of compression, development of novel surface treatment and preparation of uniform nanoparticles.

The homogeneous dense plasma with unique parameters (the temperature more than 10000 oK and pressure up to 1000 atm) is generated by impulse gas impact in ballistic plasmatron of double step compression. The plasma is able to emit light radiation with intensity up to 100 J/cm2 and causes melting and negligible evaporating of thin surface layer of treated materials. Very high heating rates under compression and cooling rates under expansion (up to 5*106K/sec), and controlled retention time (from 10-4 to 10-2 sec) allow to use the plasma for technological purposes. Such plasma could not produce by other methods and was not applied to surface treatment and nanoparticles preparation earlier.

Fast heating and subsequent fast cooling can lead to chemical and phase transformations in thin layer of materials, modification of surface structure, surface deep hardening or even creation of an amorphous metallic film, because the films are created by fast cooling of a melted metal with the rate of 106-8 K/sec that corresponds to the rate of gas cooling. The maximal skin depth of the melted layer can make from 5 up to 100 microns depending on properties of treated materials. Thin superficial layer (10-100 nanometers) can be melted and treated only at reduction of time and intensity of light radiation.

Surface chemical reactions and phase transformations in thin layer of different materials in surrounding plasma of heated inert gas can be applied as very short-term surface treatment..Surface treatment by the compressed homogeneous dense plasma of compression could be executed in three main action modes: surface modification, cleaning and coating.

Surface modification can be targeted on improvement of different surface properties such as microhardness, corrosion resistance, tribological characteristics, surface quality and roughness.

Surface cleaning by FHTSP can be realized under the condition of simultaneously evaporating and blowing away the upper layer from the treated surface. Our estimations show an opportunity to remove a material’s layer up to 1-3 microns thick during single processing.

Coating creation is possible on the preliminary prepared surface as a result of surface solid-phase reactions or heterogenic chemical reaction with active species of dense plasma. The simplest variant of coating is thermal processing of preliminary prepared surface without changing in chemical compound. There are similar methods - laser alloying technology and technology of laser facing of protective coatings for restoration of the worn-out details.

On basis of compression plasma action on surface thin layers can be developed principally novel technology of surface treatment, which have not direct analogue. This technology get name: “Fast High-Temperature Surface Processing” (FHTSP).

We can highlight the following most perspective commercial applications of the FHTSP:

  • Hardening treatment of cutters, dies, moulds and other instruments;
  • Surface cleaning;
  • Recovering the worn-out parts and machine elements working in corrosive environments;
  • Pre-treatment and post–treatment of coatings;
  • Finishing treatment of metal and ceramic surfaces for reduction of surface roughness (gears, bearings);
  • Remelting and amorphization of parts surface with a complex shape in order to improve their corrosive resistance;
  • Alloying and cladding for improvement of hardness, and tribological and corrosive properties;
  • Creation, improving, sticking and hardening of thin covering layers of different types.

Our preliminary experiments with steel samples have indicated a positive effect. Durability of milling cutters and drills is 2-6 times higher after such high-temperature surface processing. The surface microhardness of steel improves and reaches 104 MPa on the depth of 100μ. Surface deep hardening is caused by high temperature and pressure and results in recovering microcrack, reducing surface roughness, considerable increasing surface hardness and strength.

It is of paramount importance that the proposed technology can combine low cost, small processing time (the whole procedure can be completed in approximately
0,5-2 minutes) and high quality of treated surfaces. The process is very fast, ecologically clean, cost- and energy-efficient, easily repeatable and automated.

Volumetric chemical reactions and phase transformations of different materials in compression plasma can be applied to production of various chemical compounds, including uniform nanoparticles. During the compression, we inject either vapour of metal or carbon (for example, by a blasted wire method); or liquid (gaseous) compounds containing metal (for example, iron carbonyl); or hydrocarbons into plasma. Formation of metal or carbon vapours is also possible by direct evaporation of fine-dyspersated particles inserted in carrier gas. The homogeneous volume of plasma containing metal or carbon is created. Process of nanoparticles formation occurs by controlled cooling of the whole volume at fast gas expansion as a result of return movement of the piston. Thus, it is possible to expect, that the prepared nanoparticles will be one grade, being formed at identical temperature and cooling rates modes.

General goal of this project is to research of chemical and phase transformations in thin layers and nanoparticles of different materials under exposure of homogeneous dense compression plasma of ballistic plasmatron, on this basis to develop technology of surface modification, cleaning and coating and to develop scientific foundation of new technological methods nanomaterials preparation from compression plasma.

The project contains four related Tasks.

The first Task is «Development of technique and equipment for generation of dense plasma by ballistic plasmatron of double step compression». It includes the following stages: Theoretical analysis of plasma generation with necessary parameters and modelling of treatment process; Computer modeling of process and calculation of working parameters of ballistic plasmatron and the technological chamber for plasma generation with optimum parameters for materials treatment; Study of the plasma dynamics; Design and manufacturing of treatment chamber with optimised plasma parameters.

The second Task is «Research of phase transformations in thin layers on surface of different materials under exposure of compression plasma». The second task includes the following subtasks: Study of metal, ceramic and other materials surface structure changing (phase, graininess, treatment depth, microhardness, dislocation density, etc) depending on plasma parameters (temperature, pressure, treatment duration, cooling rates); Investigation of melting-evaporating effects including roughness reduction and amorphous film creation; Study of changing of surface corrosion resistance and tribological properties of samples; Investigation of surface cleaning;

The third Task is «Research of chemical transformations in thin layers on surface of different materials under exposure of compression plasma». The third task includes the following subtasks: Investigation of surface solid-phase reactions and opportunities of coatings from different precursors; Study of surface structure of different types of coatings; Study of dependence of coatings structure and properties on thickness of precursor; Investigation of tribological properties of coated samples;

The fourth Task is «Study of volumetric effect of compression plasma: Development of uniform nanoparticles preparation technology by ballistic plasmatron». The fourth task includes the following subtasks: Computation and numerical modelling of prospective installations, choice of the optimum decision; Design and manufacturing of skilled installation for nanoparticles preparation; Development of input methods of different precursors in a gas phase; Development of nanoparticles gathering and output methods; Preparation and study of nanoparticles from different precursors.

The research group includes, mainly, scientists of Institute of Biochemical Physics of RAS and Institute of Chemical Physics of RAS. Within the framework of the created temporary working collective, as researchers and consultants will be involved the research fellows of Moscow State Institute of Steel and Alloys. The performance of the team-work design can bring in the essential contribution into development of new methods surface treatment and nanoparticles preparation. Most of participants of the project were earlier connected with the military industry, and have necessary competence in science of materials, nanotechnology and physics of plasma, studying processes of change of properties of a surface and plasmadynamics.

The project has practical importance for implementation of the ISTC purposes, as it grants to Russian weapon scientist and experts possibility for reorientation of the abilities on peace activity; encourages their integration in international scientific community; supports applied researches and development of technologies in the field of surface science and nanotechnology.

Role of Foreign Collaborators:

  • information exchange in the course of project implementation;
  • cross-checks of results obtained in the course of project implementation;
  • testing and evaluation of equipment/technologies developed in the course of the project;
  • conduction of joint seminars and workshops;
  • carrying out of joint experiments on basis of Collaborators.


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