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Dynamic Method for Production of Diamonds of Specified Shape

#3901


Dynamic Method for Production of Diamonds of Specified Shape

Tech Area / Field

  • CHE-OTH/Other/Chemistry
  • PHY-OTH/Other/Physics

Status
3 Approved without Funding

Registration date
08.10.2008

Leading Institute
VNIIEF, Russia, N. Novgorod reg., Sarov

Collaborators

  • Los Alamos National Laboratory, USA, NM, Los-Alamos\nTNO Prins Maurits Laboratory, The Netherlands, Rijswijk

Project summary

Goal of Project is experimental verification of methods for dynamic synthesis of diamonds of specified shape.

Present-day tempo of growth of electronic industry, precision mechanics, microtechnology requires use of new materials with unique properties in these areas. This material can be a diamond combining properties of dielectric and properties of insulator of super high temperatures.

Two methods, namely, static and dynamic methods, are used for production of artificial diamonds. When using the static method, the graphite-diamond phase transition occurs under effect of high pressure for long time. This method requires involvement of massive presses and expensive concomitant equipment.

The dynamic method (use of charges of high explosive (HE) – ammonite, mixture of ammonite and saltpeter, cast trotyl) is more economical. However, produced diamonds have small fraction (submicron particles). For their further use, compaction of synthesized particles is required. This process is rather complicated.

We suggest the method of dynamic synthesis of diamonds having specified shape. Comparing to the used technologies, the advantage of the suggested method is that it is very effective, reliable, relatively simple and rather cheap method for production of artificial diamonds as fibers (threads) and as films.

For production of diamond fibers, graphite threads are placed in a matrix made of metal according to specially-verified technology. Then the matrix is subjected to dynamic loading. During loading, metal provides heat removal from carbon-containing elements. Density of metal in compressed state is higher than density of the diamond phase. Due to generation of reflected shock waves, it allowed to keep high pressure in carbon for long time up to removal of high temperatures and stabilization of the diamond phase.

To produce diamond films, a package is preliminarily collected using layers of carbon-containing substance and heat-conducting material (metal). The both sides of the graphite layer contact the metal. The collected package is preliminarily cooled down in liquid nitrogen. Then it is loaded by shock-wave pulse. After double–triple loading of the carbon-containing layer by reflected shock waves, pressure in it and in metal becomes equal. This experimental scheme allows to reduce pressure of initial pulse and temperatures of shock-wave heating of graphite, and it allows to form loading conditions, which provide the graphite – diamond phase transition in the area of thermodynamic stability of the latter. Two-sided contact of the carbon-containing layer and metal provides intensive heat removal from this layer and cools it down quickly lower the temperature, when accelerated reverse transition of diamond to graphite occurs.

As a result of conversion activities, RFNC-VNIIEF experts accumulated rich experience in development of explosive technologies and introduction of them to industry. For conduction of explosive works (detonation of HE charge having weight up to several tens kilograms), we are traditionally using buildings and unclassified test sites. The equipment-methodical complex is constantly used for recording of dynamic parameters of short-time processes (HE detonation characteristics, velocities of plate launching, etc.). Laboratories, which are equipped with up-to-date techniques for chemical analysis of various substances and compositions, are constantly involved in work.

The Institute staff includes high-skilled experts: researchers – experimentalists, theorists – calculators, chemists – analysts, designers – technologists.

In particular, in laboratory researches, after dynamic loading of metal matrix with crystalline graphite fibers located in it, we produced the final product, which consisted of diamond of face-centered cubic modification. The fibers consist of tightly packed diamond particles having round or polyhedral shapes with diameter of 20 m, length of 3 mm. After dynamic loading of thin layer of graphite, which was located between two metal disks, we produced a product that is a film made of polycrystalline diamond having diameter of 45 mm and thickness of 10 m.

Under the project frameworks, it is planned to study experimentally the mechanism of effect of shock waves on samples of carbon-containing material and metal prepared according to special technology, to study physical processes of dynamic phase transition “graphite-diamond” in the area of thermodynamic stability of the latter, to verify the scheme of overall chemical analysis of produced final product, to suggest experimental and technological scheme for production of the final product as fibers and films of artificial diamonds. It is planned to perform preliminary calculation evaluations of the process for optimization of experimental works. The tests will determine:

  • optimum regimes of shock-wave loading for providing dynamic phase transition “graphite-diamond” in the area of thermodynamic stability of the latter;
  • limiting conditions concerning temperatures of shock-wave heating of carbon-containing substance for production of thermodynamic stable diamond phase and exclusion of the process of reverse phase transition of diamond to graphite;
  • optimum schemes of chemical analysis of final product after pulse loading of composite (carbon-containing substance – metal);
  • embodiment of explosive devices for conduction of dynamic synthesis of artificial diamonds having specified shape.

At the final stage, we will suggest a technological variant, technical parameters, and capabilities of explosive devices for production of artificial diamonds as fibers and films.

The Project efforts will help to use potential of high-skilled scientists and engineers earlier involved in weapon development for development of new advanced industrial technologies. Thus, two basic objectives of the ISTC will be reached:

  • reorientation of scientific potential of scientists and engineers, who was earlier involved in weapon development;
  • advancement of industrial technologies.

Within the Project framework the following efforts will be performed:
  1. Review of current status of studies on the problem of dynamic synthesis of artificial diamonds.
  2. Selection of scheme for chemical analysis of final product after pulse loading of composite (carbon-containing substance).
  3. Numerical-experimental researches for selection of optimum regimes for shock-wave loading of studied composite (carbon-containing substance – metal). Results of the researches will be tested by methods of chemical analysis.
  4. Numerical-experimental researches for determination of limiting conditions concerning temperatures of shock-wave heating of carbon-containing substance. Results of the researches will be tested by methods of chemical analysis.
  5. Design verification of explosive devices for conduction of dynamic synthesis of artificial diamonds having specified shape.
  6. Analysis of results obtained under the project frameworks. Formulation of technology, technical parameters and embodiment of explosive devices intended for production of artificial diamonds as fibers and films.

The program of experimental studies will be discussed and coordinated with the foreign collaborators. It is planned to discuss results obtained during the Project efforts at workshops with participation of the foreign collaborators.


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