Page 8 - НАЦІОНАЛЬНА АКАДЕМІЯ НАУК УКРАЇНИ

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650 HV0.1, which was formed by the heat treatment of the anodized layers at a

temperature of 300°C with the subsequent hydration in a distilled water to form a thin

surface layer of the gibbsite phase with a hardness of 400 HV0.1 and a thickness of

5...10 μm. The wear resistance of such anodized samples increased by 5...10 times

compared to the D16 alloy.

The method of the pulsed hard anodizing was developed for the synthesis of one

or a mixture of two phases in the structure of the anodized layer (depending on the

electrolyte temperature during synthesis (–5…+5)○С). In this case, the Al2O3·H2O

(boehmite) phase provided the anodized layers with the high microhardness and

abrasive wear resistance, and the Al2O3·3H2O (gibbsite) phase provided the high

tribological properties due to a transfer of a thin protective film of gibbsite to the

counterbody. The content of the necessary phases (gibbsite, boehmite or their mixture)

in the anodized layer was regulated by adding hydrogen peroxide Н2О2 to the

electrolyte (10…50 ml/liter), heat treatment (100…400°С), or the electrolyte

temperature (from –5 to +5°С). The thickness of the anodized layer obtained by the

pulsed method is 15...20% greater, and its wear resistance is 1.5...3 times higher than

that obtained using the stationary synthesis mode, and 2.5...8 times higher compared to

the D16 alloy.

It was shown that during the synthesis of PEO layers on the surface of gas-

thermally sprayed coatings of the Al-Mg, Al-Ni, Al-Cu, Al-Ti systems, the low-

melting and low-flowing eutectics are formed from mixtures of oxides (Al 2O 3 + MgO),

(Al 2O 3 + NiO), (Al 2O 3 + CuO), (Al 2O 3 + TiO 2), which fill the discharge channels more

easily than the refractory oxide Al2O3 and, thereby, reduce the porosity of the layer

(from 8...10 to 3...5%), increase the corundum content in the plasma-electrolytic oxide-

ceramic layer from 30 to 70% and increase the microhardness (by 300...500 HV0.3)

and abrasive wear resistance (by 4...6 times) of the synthesized PEO layer. The

mechanism of wear of counterbodies during the frictional interaction with the PEO

layer was established. At a counterbody hardness of up to 300 HV0.3, the wear
occurred due to an abrasion of the counterbody surface by protrusions on the PEO

layer as cutters. Such a friction pair is a suitable for the use only at the specific loads up