Radiation Resistance Of Coatings Research Articles

Effect of irradiation with continuous 28 MeV He2+ ion beam and short-pulsed 200 keV C+ ion beam on optical properties of multilayer Al-Si-N coatings

The article reports on radiation defect formation parameters and radiation resistance of multilayer coatings from thin layers of aluminum and silicon nitrides deposited on sodium-calcium-silicate glass and monocrystalline silicon substrates by reactive magnetron sputtering. The samples were irradiated with helium ions of 28 MeV on a cyclotron and carbon ions 200 keV on an accelerator in the mode of short-pulse implantation. The characteristics of local absorption and luminescence centers before and after irradiation and their probable nature were determined. The optical centers had been identified as point intrinsic defects of a growth and radiation nature. The accumulation of radiation defects in layers of amorphous silicon nitride a-Si3N4 prevailed over the accumulation in crystalline c-AlN layers due to the diffusion of defects in amorphous layers and the formation of secondary defects in them. Changes in optical properties led to the conclusion about the high radiation resistance of the coatings. The main reasons for the resistance of coatings to ion irradiation were the high concentration of growth defects, their strong interaction and the wide band gap of the nitrides. Coatings deposited on silicon substrates had a higher radiation resistance compared to the same coatings deposited on glass substrates.

Effect of Helium ion irradiation on the structure, the phase stability, and the microhardness of TiN, TiAlN, and TiAlYN nanostructured coatings

The radiation resistance of nanostructured TiN, TiAlN, and TiAlYN coatings is studied after 500-keV He+ ion irradiation in the fluence range 5 × 1016–3 × 1017 ions/cm2. The radiation-induced changes in the phase composition, the structure, the lattice parameters, the morphology, and the mechanical properties of coatings are investigated. Blistering is found to be absent, and the radiation fluence is shown to affect the strength properties of the thin coatings nonlinearly. A significant decrease in the grain sizes is detected upon ion irradiation, which causes an increase in the microhardness and the radiation resistance of the coatings. The TiN, TiAlN, and TiAlYN coatings are found to be radiation-resistant coatings, which do not undergo serious degradation during high-fluence ion irradiation.

Distinctive features of the reflection spectra and radiation resistance of coatings based on ZnO powders modified by SiO2 nanoparticles

The diffuse reflection spectra of coatings based on ZnO powders modified by SiO2 nanoparticles are investigated in the range of 360–2100 nm. Spectral variations caused by irradiation with accelerated electrons (E = 30 keV, Φ = 1 × 1016–7 × 1016 cm−2, P = 10−6 Torr, and T = 300 K) are analyzed. It is ascertained that the radiation resistance enhances insignificantly after the modified powders are heated for 2 h at 500°C. It is demonstrated that the low modification efficiency can be explained by the amorphous state of the silicon dioxide nanopowder.

Radiation resistance of heat-regulating coatings based on barium titanate modified with micro- and nanopowders of alumina and zirconia

Comparative analysis of diffuse reflectance spectra (360–2100 nm) of electron-irradiated (E = 30 keV, Φ ≤ 3 × 1016 cm−2) barium titanate coatings doped with Al2O3 and ZrO2 micro- or nanopowders (Ba0.6Al0.4TiO3 and BaTi0.7Zr0.3O3) shows that the use of nanopowders instead of micropowders for doping BaTiO3 increases the radiation resistance of the coatings.

Influence of the temperature of aluminum oxide micropowder modification with Al2O3 nanopowders on the optical properties and radiation resistance of coatings manufactured on their basis

Influence of the temperature of aluminum oxide micropowder modification with Al2O3 nanopowders in the interval 200–1000°C on the granulometric composition, diffusion reflection spectra in the wavelength range 360–2100 nm, and integral solar radiation absorption coefficient of coatings fabricated on the basis of these powders as well as on changes of these parameters upon exposure to electrons is investigated. It is demonstrated that with increase in the modification temperature, the average powder particle size decreases, the negative action is intensified, and the radiation resistance of coatings increases.

The effect of heating on optical properties and radiation resistance of coatings based on micro- and nanosized aluminum oxide powders

Comparative analysis of the effect of heating in air (at T = 800°C for 2 h) on the diffuse reflectance spectra in the range of 360–2100 nm and on the integrated coefficient of the solar radiation absorption of coatings based on Al2O3 micro- and nanopowders has been carried out. Their variation under electron irradiation has been studied. It is established that the heating of powders deteriorates the optical properties and radiation resistance of coatings.

Influence of neutron bombardment of diffused carbide and boride coatings on refractory metals

The effect of neutron bombardment on carbide and boride coatings on refractory metals was studied. It was found that a radiation dose of 1020 neutrons/cm2 produces cracking of the carbide coatings and exfoliation of the boride coatings. The radiation resistance of coatings of the kind studied depends to a large extent on the difference in the radiation-induced expansion of the coating and the substrate material.