Transformation of Nanodiamonds into Onion-Like Carbon Nanoparticles
Investigation of the Structural Characteristics of Transformation of Nanodiamonds into Onion-Like Carbon Nanoparticles and Development of the Principles of Designing Composite Materials on their Basis
Tech Area / Field
- MAT-SYN/Materials Synthesis and Processing/Materials
- PHY-SSP/Solid State Physics/Physics
3 Approved without Funding
State Enterprise Krasnaya Zvezda, Russia, Moscow
- Boreskov Institute of Catalysis, Russia, Novosibirsk reg., Akademgorodok\nMISIS (Steel and Alloys), Russia, Moscow
- Universiteit Antwerpen, Belgium, Antwerpen\nUniversity of Missouri, USA, MO, St Louis
Project summaryRecent years have witnessed an increased interest in nanodiamonds and onion-like carbon nanoparticles (onions), which have a great potential in various applications both as an independent product and in composite materials with a metal or ceramic matrix. Therefore, studies of the structure of these materials are a topical problem.
State of art in this fieldof science: The structure of nanodiamonds and carbon onions has been studied since the time the method of fabricating nanodiamonds had been developed. However, the data on graphitization from various investigators do not always coincide. The main explanation is the various conditions of nanodiamond formation with various manufacturers. The nanodiamond structure is at present actively investigated in Japan and Europe; there is an energetic interest in the USA.
Diamond nanopowders Diamond nanopowders are often called UDD (ultradisperse dia- monds) or USDD (ultradisperse synthetic detonation diamonds).
Diamond, due to its unique physicochemical characteristics, is widely used in technical applications. For this reason, interest in production of diamond crystals by artificial means, in particular, by detonation conversion of explosives, has been there since sufficiently long.
The project shall investigate nanodiamonds fabricated by the detonation technique. Carbon onions for the studies shall be produced from detonation-synthesized nanodiamond by annealing under vacuum.
The detonation method is distinguished by a relative simplicity: an explosive charge is exploded in a sealed protective armoured chamber; condensed products of explosive conversion, diamonds including, remain in the chamber after the explosion; the products are recovered from the chamber and cleared of impurities. The impurities are particles of metals used to fabricate armoured chambers and structural elements required for installing and exploding the charge (suspensions, wires, detonating capsules, etc.), as well as non-diamond forms of carbon. Condensed non-diamond carbon in various shapes is formed both in the detonation process together with the diamond phase and in the subsequent expansion of the detonation products (DP), when the diamond phase is subjected to partial graphitization.
Diamond nanoparticles formed in the detonation synthesis are characterized by narrow distribution particle sizes in interval 3-20 nm, with maximum of distribution near 4-6 nm. The condensed explosion products recovered from the armoured chamber after exploding an explosive charge contain, besides the diamond phase, non-diamond modifications of carbon and metal impurities. Depending on the method of synthesis, the content of the diamond phase in the condensed carbon explosion products are from 30 up to 75% of the weight of these products. Optimization of the diamond detonation synthesis process, as well as the use of special coolants makes possible a stable 75% yield of the diamond form in condensed explosion products. Subsequently, it is necessary to clear nanodiamond powders of metal impurities and non-diamond carbon, which is done by dissolving these impurities in mixtures of strong inorganic acids. Diamond nanopowders produced at present are of four degrees of purity: standard (no less than 95% of ultradisperse diamond in the carbon component), ozone, pure type 1 and pure type 2.
Onion-like carbon nanoparticles (carbon onions) to be studied in this Project shall be produced by annealing detonation synthesis nanodiamonds under vacuum. The result is a stable structure of carbon onion. It is this stability that attracts investigators.
The Project includes:
- studies of the structure of nanodiamonds
- annealings under vacuum at temperatures from 800 up to 1600°C
- studies of the structure of annealed nanodiamond particles and onion carbon nanoparticles by methods of transmission electron microscopy after various heat treatments
- studies of the physical and processing properties of these materials
- based on the results obtained, possible applications of materials produced from nanodiamonds shall be investigated (e.g., in catalysis, electrochemistry, etc.)
- principles of producing composite materials with reinforcing nanodiamond particles and carbon onion nanoparticles with metal matrix shall be developed
Proposed methods and approaches:
- Initial nanodiamond powders from different producers with different size of primary particles and agglomerates will be used for study. Onions will be produced by annealing initial nanodiamond powders under vacuum at various temperatures within the range of 800 up to 1600°C
- The structure and properties shall be studied by:
- methods of high resolution TEM
- methods of X-ray diffraction analysis (at room and elevated temperatures), X-ray photo-electronic spectroscopy, Auger spectroscopy, IR spectroscopy etc.;
- solid state nuclear magnetic resonance and other methods
Expected scientific results:
- The mechanism of graphitization of nanodiamonds
- A model of the onion-like carbon nanoparticle shall be developed
- The structure of both inpidual particles and agglomerates of nanodiamonds and onion-like carbon nanoparticles shall be studied
- Possibility of application of “nanparticles after annealing” in catalysis, electrochemistry etc. will be investigated
- Principles of developing composite materials with reinforcing nanodiamond particles and onion-like carbon nanoparticles shall be worked out
- Great interest is also obtained as the result of annealing, intermediate state (condition) formed from diamond core coated by graphite mono-layers, because such particles can have unique properties.
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