V. G. Vostrikov

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 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.

Accumulation of deuterium in radiation-damaged tungsten

Experimental studies have been performed to determine the effect of high-level radiation damage on the accumulation of deuterium and erosion of tungsten samples exposed to deuterium plasma. Tungsten samples were exposed first to fast helium ions having an energy of 3–4 MeV (providing from one to ten displacements per atom) and then to deuterium plasma up to a dose of 1025 ion/m2. The effects of deformation and modification of the surface microstructure have been observed. The concentrations of helium and deuterium have been measured by the methods of elastic nuclear proton backscattering and nuclear recoil detection of helium ions. A high concentration of deuterium in the damaged layer of a tungsten sample has been measured, and helium has been detected in a layer ∼5 μm thick. The proposed method shows promise for determining the lifetime of materials used in fusion reactors and measuring the concentration of tritium accumulated in these materials.

Study of hafnium-oxide coatings by means of nuclear backscattering spectrometry

Single-layer coatings made of hafnium oxide and double-layer structures with an intermediate nickel layer, the total thickness of which is 70 μm, are obtained via plasma spraying with a supersonic jet in a rarefied atmosphere. A nozzle extension capable of implementing a Prandtl–Meyer expansion fan is used to generate nanostructured coatings. The coatings are investigated via the nuclear backscattering of spectrometry 7.6 MeV protons, scanning electron microscopy, X-ray microanalysis, and X-ray diffraction. The studies of the surface and transverse microsection of the coatings indicate that they comprise not only deformed particles of the sprayed powder with sizes of greater than 20 μm but also layers and conglomerates of nanoparticles with sizes of 30–60 nm. Depth profiling of the elemental composition performed by means of the nuclear backscattering spectrometry of protons demonstrates that transition layers exist at the interface between the substrate and coating layers characterizing the average size of the coating microparticles. A comparison of thicknesses defined by two methods allows estimation of the overall porosity of the hafnium-oxide layer. In accordance with X-ray diffraction data, the cubic and monoclinic phases of hafnium oxide with a high fraction of the amorphous component are formed in the coating.

Study of nanostructured coatings prepared by low-pressure plasma spraying with a supersonic jet

Zirconia coatings on copper prepared by the low-pressure plasma spraying of a ZrO2 + 5% Y2O3 powder through a mesh mask exhibit high resistance and low thermal conductivity in tests in the nitrogen plasma stream of a plasmatron. Data on the coating structure and its changes during thermal testing derived by scanning electron microscopy, X-ray diffraction analysis, and nuclear backscattering spectrometry are discussed.

Study of the structure of ceramic-polymer functional coatings via nuclear backscattering spectrometry

Coatings prepared by the microarc oxidation (MAO) of aluminum alloys AMg-3 and V-95 with subsequent filling with poly-p-xylylene by vapor-phase polymerization on a surface are studied. It is found that filling with the polymer makes it possible to reduce the through porosity of MAO coatings by a factor of more than 5. It is shown that nuclear backscattering spectrometry with 7.5 MeV protons is an efficient and nondestructive method for measuring the composition and thickness of layered ceramic-polymer coatings.

Investigation of the structure of carbon-ceramic composite using of electron microscopy and nuclear backscattering spectrometry

The structure and composition of carbon-ceramic composite FEBUS reinforced with carbon fibers based on viscose, as well as its precursors, are studied using the methods of scanning electron microscopy with energy dispersion analysis and nuclear backscattering spectrometry of 7.5 MeV protons. It is shown that impregnation of the composite precursor with Si (up to ∼30 at %) scarcely leads to siliconizing of the reinforcing fibers. With the stoichiometry of SiC taken into account, the fraction of the carbide component in the composite reaches ∼40%; the remaining ∼60% is the carbon component.