Diamond detonation synthesis

Dolmatov VY (2001) Detonation synthesis uitradispersed diamonds properties and applications. Uspekhi Khimii 70(7) 687-708, in Russian... 

Dolmatov VY (2003) Ultradisperse diamonds of detonation synthesis production, properties and applications. State Polytechnical University, St. Petersburg... 

Vereschagin, A.L. Sakovich, G.V. Komarov, V.F. Petrov, E.A. Properties of ultrafine diamond clusters from detonation synthesis. Diamond Relat. Mater 1993, 3, 160-162. 

Today there are several other ways of diamond synthesis besides the HPHT method. For example, it is possible to utilize the pressure of a shock-wave generated in an explosion. This process mostly yields powdery products with particle sizes in the range of micrometers (1 mm at max.) that may be employed for industrial purposes as well. Moreover, very small diamonds (5-20 nm) can be made by reacting explosives in confined containers. Diamond films are produced on various substrates by chemical vapor deposition (CVD method using methane as a carbon source. Detonation synthesis and vapor deposition will be described in detail in Chapters 5 and 6. 

Figure 5.12 Industrial scale installation for the detonation synthesis of diamond at the Alit Corp. in Zhitomir (Ukraine). The reactor s volume is about 100m ( Alit Corp.).

Dolmatov VY. Detonation synthesis ultradispersed diamonds properties and apphca-tions. Rnss Chem Rev 2001 70 607. 

Hence the volume of a mixture of heterogenous molecules interacting by the vdW mechanism exceeds the additive value, and according to the Le Chatelier principle such mixture under high pressure will be separated. It follows that the diamond cluster size depends on the separation extent of components of the detonation cloud. In this context, it seemed reasonable to perform a detonation synthesis of c-BN under similar conditions (in a large chamber). No attempt in this direction has been... 

V yskubenko BA, Danilenko V V, Lin EE et al (1992) The effect of the scale factors on the size and yield of diamonds during detonation synthesis. Fizika Gorenia i Vztyva 28(2) 108-109... 

Batsanov SS (2009) Thermodynamic reason for delamination of molecular mixtures under pressure and detonation synthesis of diamond. Russ J Phys Chem A 83 1419-1421 Ree FH (1986) Supercritical fluid phase separations— implications for detonation properties of condensed explosives. J Chem Phys 84 5845-5856... 

The most frequently employed starting explosives in indnstrial-scale production of diamond by detonation synthesis are, as a rnle, trinitrotoluene (TNT) and hexogen (also called RDX = Research Department Explosive), with detonation performed in a water medium to reach a higher productivity. The most complicated stage in the industrial process is chemical isolation of NC diamond from the detonation carbon prodnced in an explosion, which is actually a mixture of micro- and nanoparticles of graphite, varions forms of sp -hybridized carbon and impurities originally contained in the explosive itself, and construction materials of the synthesis vessel. For details of the technology used in detonation diamond synthesis, the reader can be referred to Ref. 19 and Section 9.23.2 for the structure of the detonation diamond particles, their properties, and applications. 

Note that pilot production of diamond micrometer-sized powders by detonation synthesis was started by Dupont in the late 1970s, and in the Soviet Union, at the Institute of Problems in Chemical Physics, in 1982-1983, with graphite used as starting material in both cases. 

One major feature of the detonation synthesis of NDs is that it does not require graphite or any other additional source of carbon to support it It is the explosives themselves initiating the shock wave that acts as the source of the carbon to form diamond nanocrystals. For this purpose, their composition is chosen such as to ensure formation of free carbon in the chemical reactions running in the shock wave. This condition defines the so-called negative oxygen balance of the explosive composition. The explosive composition customarily used in detonation synthesis of diamond is the TNTRDX mixture taken in the 40 60-70 30 ratio. ... 

Selection of the optimum medium needed to sustain detonation synthesis of ND is governed by the need to prevent oxidation of the detonation products that can occur in contact with atmospheric oxygen, as well as to provide the maximum possible rate of cooling of the ND formed to preclude transition of the diamond to graphite. In industrial-scale production of detonation ND, the explosive charges are placed in carbon dioxide, water, or solid carbon dioxide ( dry ice ). ... 

Depending on the used medium, the side products (detonation carbon) produced in detonation synthesis contain 20-70 wt% diamond. The remainder is a mixture of various structural forms of ip -carbon, the state of hybridized electronic orbitals characteristic of graphite. The yield of the diamond phase is the highest with carbon dioxide in the solid state, and the lowest, when it is in gaseous form. The medium most frequently used in industrial synthesis is water. 

The shell is formed in the process of reverse diamond-to-graphite transition in the concluding stages of detonation synthesis, after the shock wave has passed and the pressure has dropped below the limit of thermodynamic stability of diamond. The thickness of the shell is largely determined by the conditions of the DND synthesis and in the course of DND isolation from detonation carbon, the thickness of the shell decreases. In the strongest regimes of i p -oxidation, the shell can be ranoved completely, except for separate single-layer 5p2 caj-, Q j islands, which result, as shown by calculations, from natural reconstruction of the free surface of diamond nanoparticles. 

In Chapter 2, the development of composite materials based on improved nanodiamonds is reported by P. Ya Detkov, V. A. Popov, V. G. Kuhchikhin and S. I. Chukhaeva. The authors describe methods for improving the quality of diamond nanopowders obtained by detonation synthesis, as well as some commercial applications of nanodiamonds. The authors prove that the synthetic detonation diamond is a promising material that can be used in many fields. Of special interest are its applications in compos ite materials both with a metal and polymer matrix. Commercial production of ultradisperse diamonds (or nanodiamonds) has been developed, and it is synthesized on a scale sufficient for particular industries. 

This chapter describes the methods of improving the quality of diamond nanopowders obtained by detonation synthesis, and some commercial applications of nanodiamonds that have been developed. 

In the latter case, transition of the carbon of an explosive into the diamond phase occurs as a result of explosive transformation of the explosive, that is, in the detonation wave. The method was called detonation synthesis. Diamonds are also formed in the degradation of some inert (nonexplosive) organic substances in the detonation wave, if they are used as additives to potent explosives. An attractive feature of detonation synthesis of diamonds is that it uses charges from explosives obtained in the disposal of weapons. Thus, the detonation synthesis of diamonds can help utilize explosives obtained in weapons dismantlement. 

Diamond particles formed in the detonation synthesis ate 2-6 nm in size. Particles of detonation diamond have a cubic lattice with lattice parameter a = 0.3575 nm (in natural diamond, a = 0.3566 nm). Due to the small size of particles, the detonation diamonds are called ultradisperse diamonds (UDD) or nanodiamonds. 

Besides the diamond phase, the condensed products of explosion recovered from the armored chamber after the explosion of a charge contain the nondiamond modifications of carbon and metal impurities. Depending on the method of synthesis, the diamond phase in the condensed carbon products of explosion is 30 to 75% of the weight of these products. Optimization of the detonation synthesis by the ratio of trinitrotoluene and hexogen in the mixture, by the ratio of the weight of exploded charge and the volume of the chamber and also the use of special coolants enables a stable 75% yield of the diamond phase in the condensed products of explosion. 

Huang E, Tong Y, Yun S (2004) Synthesis mechanism and technology of ultrafine diamond from detonation. Phys Solid State 46(4) 616-619... 

Explosives, as a special kind of material, can produce a special state of materials—detonation. In a long historical period of time, explosives liave been used for tlie purposes of destruction, elimination, or decomposition, and tliese purposes still account for tlie main utilization of explosives. In recent years it has been found that explosives can be used for the opposite purposes of construction, creation, and synthesis. Using the liigh pressure, high temperature and high mass speed produced by explosive detonation, new substances or substances with unique features can be produced. Two examples are given in this chapter shock-wave-induced chemical reactions for material synthesis and ultrafme diamond syntliesized by explosive detonation. Much research work l as been done in these fields in recent years, but the quantity and the deptli of these studies are far from sulficient. There remain many unsolved problems and unexplored fields. 

The experimental results indicate that in the range of nanometers other rules apply to the stability of different carbon structures than would on a macroscopic scale. This is evident, for example, from the spontaneous formation of various diamond materials with nanoscopic particles in different methods of preparation like CVD or detonation and shock wave synthesis. The products obtained include polycrys-taUine materials with particle dimension of 1-60 (tm that consist of primary par-... 

Depending on the method of their preparation, the individual nanodiamond particles do not exist as isolated crystallites, but they form tightly bound agglomerates. Apart from unordered sp - and sp -hybridized carbon, they may also include other impurities. The latter may originate either from synthesis or purification, for example, finely dispersed material from the reactor walls may contaminate the sample (Section 5.3). This is especially true for material produced by the detonation or shock wave method, whereas hydrogen-terminated diamond nanoparticles do not show this effect. 

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