The work motivation is caused by the need to increase service life of aerospace components by developing the methods of thermal barrier coatings on structural materials The main aim of the paper is to study thermal barrier coating structures formed by plasma spraying of yttria-stabilized zirconia. The methods used in the study is the nuclear backscattering spectrometry. The results: Using the methods of nuclear backscattering spectrometry the authors have investigated the element composition, structure and thickness of plasma-sprayed yttria-stabilized zirconia coatings. The intermediate layer between coatings and base material was founded. The total porosity of the coatings, evaluated by comparison of massand geometric thicknesses, is 20...30 %. It was shown, that due to high speeds of low-pressure plasma spraying the mixed coatings can be formed in case of layer-by-layer deposition of nickel and yttria-stabilized zirconia powders. The total porosity tends to decrease with the increase number of layers. For the coating formed by plasma spraying through the mask with holes, the periodically changing coating thickness was determined.

Metal hydrides and their alloys are widely used in nuclear power engineering and are regarded as promising hydrogen accumulators. Due to the nature of materials used in reactors, nondestructive methods are required to determine the concentration of hydrogen and its content in hydrides under the influence of a harsh environment. In this paper, a technique based on nuclear backscattering spectrometry is proposed, which allows determination of the hydrogen content in a sample at a depth of up to 100 μm. The profiles of the hydrogen distribution in Al, Mg, Ti, Zr, and their hydrides are measured. Estimation of the radiation damage to the sample is performed using the example of polymer impregnation of the protective coating.

Zirconia coatings of a thickness up to 110 μm were obtained by plasma electrolytic oxidation (PEO) in silicate-alkaline and silicate-hypophosphite electrolytes. Layer-by-layer structure and total porosity of the coatings were investigated using proton nuclear backscattering spectrometry (NBS). The PEO coating obtained in the first electrolyte has a thick transition layer with decreasing oxygen content with the depth increasing. The coating formed in the second electrolyte has a thick layer of zirconia and a thin transition layer. When analyzing the NBS spectra, the thickness is determined without taking porosity into account (so called mass thickness). The total porosity of the coatings was evaluated by determining the difference between their geometric and mass thicknesses: 15 and 22%, respectively. The critical load of disruption is higher for the PEO coating formed in the silicate-hypophosphite electrolyte.

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.

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.

The coatings with a thickness more than 100μm were formed on Zr-1% Nb alloy and technical pure Zr by plasma electrolytic oxidation (PEO) in silicate–hypophosphite electrolyte at asymmetric electrical mode. It was found that the PEO coating thickness on Zr-1% Nb alloy is about 30% more than that on zirconium. The barrier layer for Zr-1% Nb alloy is not regular and has metallic inclusions. For zirconium, barrier layer is uniform and dense. The plasmatron high-temperature cycling (up to 2000K) has shown that the coatings surface keeps original microstructure but its morphology becomes some rougher. The thermal conductivity of PEO coatings is several times less than the one of reference sample of yttria-stabilized zirconia.

Zirconia coatings on copper prepared by the low-pressure plasma spraying of a ZrO 2 + 5% Y 2 O 3 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.

Покрытия из диоксида циркония на меди, получаемые плазменным напылением порошка ZrO2 + 5% Y2O3 в разреженной атмосфере через сетчатую маску, показали высокую стойкость и низкую теплопроводность при испытаниях на плазмотроне в потоке азотной плазмы. Методами растровой электронной микроскопии, рентгеноструктурного анализа и спектрометрии ядерного обратного рассеяния получены и обсуждаются данные о структуре покрытий и ее изменениях при тепловых испытаниях.

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.

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.

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.

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.