Determining the quantity of material worn away from a wall in a turbulent boundary layer as a consequence of chemical erosion when an inert inhomogeneous gas is added by injection through the entrained surface under conditions of substantial nonisothermicity

We propose an analytical method of calculating the entrainment of wall material when an inert gas is additionally injected to that wall in a turbulent boundary layer. The calculation is carried out for the case of carbon entrainment when additional argon and helium are injected through a carbon wall when b_g=const under conditions of substantial nonisothermicity.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 17, No. 1, pp. 31–36, July, 1969.     

Effect of Chromium on the Structure and Properties of Boride Diffusion Coatings

We have studied the effect of the chromium concentration in an impregnating borochromating powder mixture on the change in the lattice parameters of the rhombic FeB phase of boride coatings on carbon steels, their microhardness, and the BK _α energy spectra. An increase in the microhardness of the boride phases for chromium concentration 3.5-6 mass% in powder boron-impregnating mixtures is accompanied by a decrease in the FeB lattice parameters. Interpretation of the BK _α spectra has allowed us to establish that this fact is due to an increase in the covalent component of the Fesd ― Bp bond.

     

Valence-band electron structure in polycrystalline cubic boron nitride sintered in shock waves

Measurements have been made on the phase composition, valence-band electron-energy structure, the substructure, and the lattice parameters. Internal stresses have been determined in the BN_sp polycrystalline materials sintered in shock waves with various pressures at the fronts. The NK spectra show that the valence bands are shifted to energies that correspond to points of high symmetry U₁ and K₁ in the Brillouin zone. They represent sp hybridized states, which participate in direct bonds between the closest boron and nitrogen atoms. The reduction in the electron-state spaces in these energy regions is related to the internal stresses, which attain some gigapascals. These arise from the formation of point and line defects. The type of defect has a marked effect on the internal-stress sign and level.Translated from Poroshkovaya Metallurgiya, No. 7, pp. 94–101, July, 1993.     

Effect of Chromium on the Structure and Properties of Boride Diffusion Coatings

We have studied the effect of the chromium concentration in an impregnating borochromating powder mixture on the change in the lattice parameters of the rhombic FeB phase of boride coatings on carbon steels, their microhardness, and the BK _α energy spectra. An increase in the microhardness of the boride phases for chromium concentration 3.5-6 mass% in powder boron-impregnating mixtures is accompanied by a decrease in the FeB lattice parameters. Interpretation of the BK _α spectra has allowed us to establish that this fact is due to an increase in the covalent component of the Fesd ― Bp bond.     

Features of the fine structure of the X-ray CK α emission bands of multiwalled carbon nanotubes

The electronic structure of multiwalled carbon nanotubes of different diameters fabricated with and without the use of catalysts is investigated by means of ultrasoft x-ray spectroscopy. Nanodimensional narrowing of the CK _α bands of nanotubes with lesser diameter is discovered. A dependence of the electronic structure of multiwalled carbon nanotubes on the type of the catalyst applied is established. __________ Translated from Poroshkovaya Metallurgiya, Nos. 5–6(449), pp. 85–91, May–June, 2006.     

Determination of the relative heat and mass exchange coefficients and the critical separation parameters for a turbulent boundary layer under inhomogeneous blowing in conditions of nonisothermy

Results of a determination of the relative limit laws of heat exchange and the separation parameters are presented for the general case of a density distribution over a boundary layer in subsonic flow. The results of computations on a digital computer are in good agreement with the proposed approximate formulas.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 19, No. 4, pp. 737–741, October, 1970.     

X-ray spectral investigation of the electronic structure and chemical bonding in ultradispersed powders and the fine-grained materials obtained from them. I. Titanium nitride

The dependence of the electron energy spectrum of ultradispersed TiN powders on particle size was studied by the method of ultrasoft x-ray spectroscopy. A relative narrowing of the x-ray TiL_α and NK_α emission bands (which reflect the energy distribution of valence Np- and Tid-states) depended on the specific surface area of the powders and charge states of the Ti and N atoms. It was shown that narrowing of these bands is due to localization of the Np- and Tid-orbitals of surface atoms as a result of breaking Ti−N bonds. Broadening of the NK_α and TiL_α bands in certain energy ranges was observed after compacting ultradispersed powders. This is a result of Tid and Np orbital splitting caused by the formation of Ti−N bonds between the surface atoms of neighboring particles brought into contact at high pressure and temperature. Institute for Problems of Materials Science, Ukraine National Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 7–8(408), pp. 75–85, July–August, 1999.     

X-ray spectrographic study of the electron structure and chemical bond in ultrafine powders and finely-crystalline materials prepared from them.3 II. Titanium carbide 0261 0101 V 3

Ultrasoft x-ray spectroscopy is used to study the dependence of electron energy spectrum parameters in ultrafine TiC powders on particle size. It was established how the relative narrowing of CK_α- and TiL_α-bands, that reflect energy distribution of valence Cp- and Tisd-states, depends upon the specific surfaces of powders and the charge state of Ti and C atoms. Narrowing of these bands is observed in those energy ranges of the valence band where hybrid Cp+Tisd states are concentrated and it is connected with localization of Cp- and Tisd-orbitals of surface atoms as a result of breaking Ti?C-bonds and dehybridization of the states during powder grinding. Expansion of the test spectra within certain energy intervals during ultrafine powder compaction has been established. It is caused by splitting of Tisd- and Cp-orbitals as a result of forming three groups of bonds (Ti?Ti, C?C, and Ti?C) between the surface atoms of neighboring microparticles as they draw together at high pressure and room temperature. Differences in the interatomic reaction of the surface atoms of nanoparticles in contact within TiN and TiC were determined.     

X-ray emission C<Emphasis Type="Italic">K</Emphasis>α-spectra of tungsten carbides before and after shock-wave treatment

CKα spectra of hexagonal tungsten carbide subjected to shock-wave treatment in a three-loop apparatus at a detonation front pressure of about 20 GPa (and increasing with each loop) and detonation velocity of 7300 m/s are studied by ultrasoft X-ray emission spectroscopy. It has been found out that the changes in the WC spectra after shock-wave treatment in the first loop point to the formation of vacancies, with free carbon emerging to the surface and undergoing amorphization, the treatment in the second loop produces partially a diamondlike film on the surface, while the treatment in the third loop (with maximum pressure) brings about a metastable state. A comparison between the CKα spectra and theoretical calculations enables the authors to attribute the mechanisms of tungsten carbide stabilization to its electronic structure alterations due to the shock-wave treatment.