E. A. Romanovsky

Application of the particle backscattering methods for the study of new oxide protective coatings at the surface of Al and Mg alloys

Abstract Rutherford (1.5 MeV 4He+) and Nuclear (7.7 MeV H+) Backscattering Spectrometry were used for investigation of oxide protective coatings on the surface of Al and Mg alloys obtained by microarc oxidation (MAO). A model of microarc coating formation is proposed. For Mg alloy, the structure of MAO coating with very high corrosion resistance was determined.

Analysis of coatings and surface layers of materials by proton-backscattering spectrometry

Experience in the use and the potential of proton-backscattering spectrometry as applied to problems of modern materials science are discussed.

On carbon nitride synthesis at high-dose ion implantation

Abstract Rutherford backscattering spectrometry was used for the study of high dose 35 keV nitrogen ions implantation into graphites and glassy carbon. Quantitative data on depth profiles and its dependencies on irradiation fluence and ion beam density were obtained. The stationary dome-shaped depth profile with maximum nitrogen concentration 22–27 at.% and half-width more than twice exceeding projected range of ions is reached at fluence Φ ∼10 18 cm −2 . The dependence of the maximum concentration in the profile on ion current density was studied. The largest concentration was obtained at reduced ion current density.

Dispersive optical potential for nuclei with N and Z values changing toward the nucleon drip lines

A method for constructing dispersive optical potentials is proposed for calculating single-particle energies in isotopic chains of spherical and nearly spherical nuclei up to nucleon drip lines. The potential of this method is demonstrated by calculating the neutron and proton single-particle energies in calcium, nickel, and zirconium isotopes. The results agree well with experimental data available for stable isotopes. Predictive calculations of single-particle spectra are performed for isotopes lying far from the beta-stability valley. A comparison of the results with the energies of nucleon separation from nuclei of mass number A and A+1 revealed features of the single-particle spectrum that are characteristic of nuclei containing classical and nonclassical magic numbers of nucleons.

The study of ceramic-like oxide coatings on zirconium produced by plasma treatment in electrolytes

Ceramic-like oxide coatings on zirconium with a thickness of up to 300 μm produced by plasma treatment in an electrolyte demonstrate high thermal resistivity and low thermal conductivity during high-temperature testing in a plasmatron in a plasma flow. Data on the structure of coatings and its changes during thermal testing obtained using the methods of scanning electron microscopy, X-ray diffraction analysis, and nuclear backscattering spectrometry are discussed.

Investigation of the shell structure of 40 ⩽ A ⩽ 132 magic and near-magic nuclei within the mean-field model involving a dispersive optical potential

Amethod for determining parameters of a dispersive optical potential is presented. This method is aimed at calculating single-particle energies of neutron and proton states of magic and near-magic nuclei. It is based on the use of global parameters of the imaginary part of the traditional-optical-model potential and experimental data on single-particle energies in the vicinity of the Fermi surface that were determined by simultaneously evaluating data on nucleon-stripping and nucleon-pickup reactions on the same nucleus. The potential of the method for describing and predicting single-particle energies of 40 ⩽ A ⩽ 132 magic and near-magic nuclei is demonstrated.

L-shell X-ray production cross sections and alignment by proton impact

The cross sections of X-ray production from L-subshells of palladium atom by proton impact have been determined by measuring the intensity of the L X-ray lines. We obtained the alignment parameter by measuring the degree of the polarization of the L1-line excited by 0.2–0.5 MeV protons. The experimental cross sections agree well with the theoretical predictions of the ECPSSR model. The experimental alignment parameter differs markedly from that calculated in terms of the Hartree-Slater model, making allowance for the Coster-Kronig (CK) transitions in case used the values of the ionization cross section from the theory and the CK transition rates from Krauses compilation. In our experiment semiempirical value of the corrections to the L-subshell CK transitions for Pd has been derived from the results of measuring L-line intensities. The semiempirical correction factor improves the agreement of the theory with experimental data.

Investigation of zirconia coatings obtained under plasma action in electrolytes

The results of experiments on the production of zirconia (ZrO2)-based thermal barriert coatings on copper substrates under plasma action in electrolytes on preliminary applied zirconium layers are represented. Structural-morphological investigations by scanning electron microscopy, X-ray analysis, and nuclear backscattering spectrometry showed that micro-arc oxidation (MAO) makes it possible to produce Zr-ZrO2 coatings with a thermal barrier ZrO2 layer with a thickness of more than 100 μm, which is separated from the substrate of the base by a dense MAO barrier layer and a nonoxidized zirconium layer.

The study of zirconium alloy coatings produced by microarc oxidation using Rutherford and nuclear backscattering spectrometry

The effect of the electrolyte composition during microarc oxidation of the E110 zirconium alloy on the corrosion resistance of coatings is investigated using proton Rutherford backscattering spectrometry, nuclear backscattering spectrometry, and other methods.

Formation of Protective Coatings by Microarc Oxidation Using Aluminum and Calcium Hydroxide Nanopowders

The elemental composition and the morphology of ceramic-like microarc oxidation (MAO) coatings on a zirconium alloy are studied. The coatings are prepared by MAO in electrolytes with addition of aluminum and calcium hydroxide nanopowders. The electrolyte with aluminum hydroxide nanopowder enables preparation of relatively thick (up to 90 μm) and dense coatings composed of both zirconium oxide and oxides of other elements contained in the electrolyte. The electrolyte with calcium hydroxide nanopowder yields thinner MAO coatings that almost completely consist of zirconium oxide.