Currently available methods of industrial nanodiamond synthesis

The main theoretical aspects of detonation decomposition of powerful mixed explosives with a negative oxygen balance accompanied by the formation of nanodiamonds (ultrafine-dispersed diamonds, UDDs) are described. The basic UDD synthesis parameters are considered, and the expediency of using trotyl-hexogen alloys is shown. The conditions of diamond phase conservation in the detonation products are specified. Various versions of industrial detonation synthesis of UDDs are considered. The most efficient technology of chemical cleaning of UDDs (with nitric acid at high temperatures and pressures) for producing UDDs with the highest purity is described.

     

Application of ultrafine-dispersed diamonds in electroplating

The results obtained upon the electrochemical deposition of composite coatings containing ultrafine-dispersed diamonds produced by detonation synthesis are generalized. The main advantages of such coatings over the well-known composite electrochemical coatings are revealed.     

Mass spectrometry of metastable ions from lagochiline-type diterpenoids

Low-and high-resolution mass spectra and spectra of metastable ions were studied using direct analysis of daughter ions (DADI) and metastable defocusing (MD) of lagochiline-type diterpenoids. Patterns in their fragmentation were found. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 56–60, January–February, 2007.     

Use of a computer to find the number of regular pentagons that can simultaneously touch a given one

Around an initial regular pentagon one describes a contour L on which one introduces a measure m. One investigates the difference S(M)=1/7m(L)?m(L∩M) where M is a pentagon touching the initial one and congruent to it. The geometric part of the investigation reduces the proof of the inequality S(M)<0 for all M to the proof of the negativity of two effectively computable functions F(u,v) and G(v) in the compact domain of the variation of the arguments. By the method of demonstrative computations, one calculates on a computer the values of these functions at the nodes of a rectangular net of the domain of the variation of the arguments by taking into account the monotonicity and one estimates the computational error. The results of the computation show that we have the inequality S(M)<0, from where it follows that the desired number is equal to six.     

Modified method for synthesis of detonation nanodiamonds and their real elemental composition

Modified technique for synthesis of detonation nanodiamonds by exploding a charge of high explosives in a water shell is described. Reducing agents are introduced into water. Their use enables solution of a number of problems: the carbon content of nanodiamonds is raised from 90 to 96 wt %, the content of incombustible admixtures is dramatically diminished from 3 to 0.1 wt %, and the yield of detonation nanodiamonds becomes two times higher. A new method for determining the elemental composition is described and the oxidation of nanodiamonds under heating in the presence of atmospheric oxygen is analyzed.     

Structure of oriented fibers based on poly(vinyl alcohol) modified by detonation nanodiamonds

A comparative study of the structure and mechanical and thermal characteristics of nanocomposite oriented fibers based on poly(vinyl alcohol) impregnated with the nanodiamonds prepared by detonation synthesis and fibers based on the initial unmodified polymer has been performed. The conditions and regimes of gel spinning of the nanocomposite fibers containing highly dispersed nanosized filler without its aggregation are defined. The introduction of nanosized filler particles up to 7 vol % is found to entail no marked changes in the temperature intervals of glass transition and melting in the corresponding DSC thermograms. In this case, the amorphous-crystalline structure of the matrix polymer likewise remains practically unchanged. Under the selected conditions of gel spinning, the resultant nanocomposite fibers with comparable draw ratios are characterized by a higher longitudinal elastic modulus, close values of breaking strength, and lower values of elongation at break as compared with those observed for the fibers based on the initial unmodified polymer. The nanomodified fibers show promise as reinforcing elements in construction materials for various purposes.     

Structure of the dispersive medium and sedimentation resistance of suspensions of detonation nanodiamonds

The specific features of the stabilization of suspensions formed by detonation nanodiamonds in polar and nonpolar media are investigated. It is demonstrated that the polydispersity of nanodiamond particles in an aqueous medium periodically changes in an ultrasonic field. The conditions are determined under which the optimum dispersity can be maintained for a long time. A technique is devised for chemical modification of the nanodiamond surface through the grafting of organosilyl groups. This technique makes it possible to prepare finely dispersed suspensions of nanodiamonds in nonpolar organic media. A model is proposed for an aggregate that consists of detonation nanodiamond particles and is stabilized through hydrogen bonds formed by functional groups of different types.     

Industrial Synthesis of Ultradisperse Detonation Diamonds and Some Fields of Their Use

The cluster nature of detonation-synthesized ultradisperse diamonds (UDD) is considered. The industrial cycle employed for obtaining ultradisperse diamonds is described, with different variations of this process and the basic principles of design of the necessary equipment noted. Priority product areas and advantages of use of ultradisperse diamonds in metal-diamond electrochemical coatings and polymer-diamond composites are discussed in detail.     

Study of Characteristics of the Cold Atmospheric Plasma Source Based on a Piezo Transformer

Russian Physics Journal - In this paper, we study a compact source of low-temperature cold atmospheric plasma based on a piezoelectric transformer used as a high-voltage source. This device can...