Detonation‐prepared nanocrystalline diamond powders usually contain hydrogen. Herein, the synthesis of practically hydrogen‐free nanodiamond particles by detonation of benzotrifuroxan (BTF) and their comprehensive characterization by elemental analysis, X‐ray diffraction, electron microscopy, DSC/TGA, and BTE specific‐surface determination is described. The effects of the porosity of BTF and of various neutral or carbonic admixtures to the explosive on the reaction thermodynamics as well as the yield and properties of the product were explored theoretically and experimentally. Hydrogen contamination of nanodiamond was investigated using solid‐state NMR spectroscopy and possible sources of hydrogen explored. Admixing hygroscopic solids to the explosive introduced 0.1 to 0.6 % of hydrogen, as did purification in acidic (rather than neutral) media.

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This paper proposed a new method for processing titanium alloys based on preliminary plastic impact. The reasons for the deterioration of the surface roughness of titanium alloys during machining are considered. This problem lies in the formation of outgrowths on tool cutting wedge, which leads to the cutting process taking place as in the titanium-titanium pair. The adsorption phenomenon leads to the fact that the outgrowth is saturated with gases from the environment, and a thick oxide film is formed. As a result, high temperatures arise during machining from 1100 to 1200°C, increasing the cutting forces P and friction Q, which introduce the technological system into an unstable self-oscillating process. The problem posed eliminated by the method of preliminary plastic deformation, which forms a local inhomogeneous structure. At the stage of processing the titanium billet, the cutting edge enters the region with a heterogeneous structure, destroying the chips and growth with an oxide film. Since most of the temperature, about 80% takes away with the chips, the amplitude of the self-oscillating process decreases, which reduces the surface roughness of the processed titanium alloys.

Currently, welded heterogeneous structures are widely used in mechanical engineering. The mechanical processing of such complex products is accompanied by a self-oscillating process. For reducing the intensity of vibration, boring bar with an adjustable stress-strain state has to be used. Studies that were carried out by authors made possible to establish the influence of the microstructure of steels after heat treatment and in various stress states on the damping capacity. Εstablished influence allowed to select steel for the manufacture of a boring bar, in the inner cavity of which an expanding cone was installed for creating of a stress-strain state. Subsequent investigations as well made possible to establish the influence of the microstructure and the stress-strain state of the boring bar on the dynamic characteristics of the boring process of the welded structure. Such an approach enables preliminarily estimating the level of vibration amplitude while boring a heterogeneous welded structure, and to provide the specified parameters for the surface roughness of a precision product at the manufacturing stage.