Dense Plasma for Surface Treatment
Development of Surface Treatment and Coatings Technology by a Homogeneous Dense Plasma Generated in Ballistic Plasmatron of Superadiabatic Gas Compression
Tech Area / Field
- MAT-SYN/Materials Synthesis and Processing/Materials
- PHY-PLS/Plasma Physics/Physics
3 Approved without Funding
Institute of Biochemical Physics, Russia, Moscow
- Russian Academy of Sciences / Semenov Institute of Chemical Physics, Russia, Moscow
- Los-Alamos National Laboratory, USA, NM, Los-Alamos\nUniversity of Illinois / College of Engineering, USA, IL, Chicago
Project summaryThis project is directed on development of novel surface treatment and coatings technology “Fast High-Temperature Surface Processing” (FHTSP). This is principally novel technology that utilizes homogeneous dense radiating plasma produced by superadiabatic gas compression in the ballistic installation. Such plasma could not produce by other methods and was not applied to surface treatment earlier.
Superadiabatic compression of gas is a modification of thermodynamic gas compression process (e.g. in a ballistic installation), when temperature in superadiabatic mode changes so that energy density of gas (related to initial volume) is considerable more (up to 10-20 times) than one in conventional adiabatic mode under given compression ratio or given final pressure.
De facto, superadiabatic gas compression executes in ballistic plasmatron of double step compression, and dense plasma is generated with unique parameters: the temperature more than 10000 oC and pressure up to 1000 atm. Very high heating rates under compression and cooling rates under expansion (up to 5*106 K/sec), and controlled plasma retention time (from 10-4 to 10-2 sec) characterize the process of high temperature and pressure creation
Fast High-Temperature Surface Processing of materials by using superadiabatic gas compression is very short-term treatment of materials surface surrounding plasma of heated inert gas. Such 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. Fast cooling can lead to 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 K/sec that corresponds to the rate of gas cooling.
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.
Surface treatment by the compressed homogeneous dense plasma 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.
Such parameters of surface roughness as an average arithmetic deviation of surface profile, height of irregularities of surface contour within the limits of base length, the greatest height of surface irregularities, i.e. all specified parameters determining height of roughness will considerably decrease. An average step of surface irregularities within the limits of base length will increase at correctly chosen modes of a surface processing.
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 or creation of the superficial layer which can be chemically different to the basic material is possible as a result of FHTSP use on the preliminary prepared surface or as a result of 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.
FHTSP is principally novel technology, which have not direct analogue. There is practically no background in this subject, no reference publications.
Fast High-Temperature Surface Processing greatly improves the quality of surface and therefore meets the following potential customer needs:
- Extension of instruments, gears, bearings, gadgets and various details lifetime.
- Improvement of device operating characteristics by highest surface quality of its elements.
- Improvement and simplification of technological processes of product manufacture.
Based on these customer needs we can highlight the following most perspective commercial applications of Fast High-Temperature Surface Processing:
- 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.
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. Preliminary estimations showed that treatment technology by homogeneous dense plasma is very cheap. The cost for single treatment action is mainly the cost of 1 liter of argon gas and it takes near 0.01 kW/h electrical energy, that is to say approximately 0.003$. Moreover the cost can reduce in 10 times by argon reuse.
Fast High-Temperature Surface Processing has evident advantages:
- The treatment will be especially effective for complex-shape objects, because the technology allows fast simultaneous treating of the whole object surface, even cavities.
- The process is very fast, ecologically clean, cost- and energy-efficient, easily repeatable and automated.
- The process recovers microcracks, reduces surface roughness and considerably increases surface hardness and strength.
General goal of this project is to develop technology of surface modification, cleaning and coating by Fast High-Temperature Surface Processing and equipment (treatment chambers) of superadiabatic gas compression for it.
The main objectives of this Project are:
- 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.
- Design and manufacturing of treatment chamber with optimised plasma parameters.
- Determination 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.
- Demonstration of significant treated surface hardening, roughness reduction and surface quality improvement.
- Determination of most perspective approaches for coatings creation.
The project contains three related Tasks.
The first Task is «Development of technique and equipment for Fast High-Temperature Surface Processing by superadiabatic ballistic plasmatron». It includes the following stages: Theoretical analysis of plasma generation with necessary parameters and modelling of treatment process; Study of the plasma dynamics; Design and manufacturing of treatment chambers.
The second Task is « Study of surface modification and cleaning by Fast High-Temperature Surface Processing of the different materials». The second task includes the following subtasks: Study of surface structure changing of different materials by FHTSP; Investigation of melting-evaporating effects in Fast High-Temperature Surface Processing; Study of changing of surface corrosion resistance and tribological properties of samples by FHTSP; Investigation of surface cleaning by FHTSP;
The third Task is « Study of coatings by Fast High-Temperature Surface Processing ». The third task includes the following subtasks: Investigation of 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 proposed new plasma-based technology can be applied in electronic and engineering industries, as dense plasma with different temperature, pressure, heating and cooling rates can be used for treatment and coatings of different metal and ceramic materials. All the large, most part of medium and small companies active in electronics and engineering industry would be potential consumers of the proposed technology. Practically all of the manufacturing companies would be the potential customers of the proposed technology. Obviously, the market of surface processing technologies and equipment is multibillion-dollars market of very persified products, which intensively grows together with total technological development.
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. Most of participants of the project were earlier connected with the military industry, and have necessary competence in science of materials 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.
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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