The presented research was aimed to determine the mechanical properties of the nanotubular oxide layer covered with hydroxyapatite coating. The Ti-13Zr-13Nb alloy was oxidised in 1M phosphoric acid with an addition of 0?5% HF for HF solution at 20 V voltage. The electrochemically assisted deposition of hydroxyapatite was performed at cyclic polarisation in NH 4 H 2 PO 4 and CaCl 2 solution at 80uC. The mechanical properties were determined by nanoindentation, nanocreep and nanoscratch tests. The surface examinations were made with the light, scanning electron and atomic force microscopes. The measurements showed the significant difference between an oxide layer and nanotubular oxide coated with hydroxyapatite. The observed differences may be explained by an appearance of mechanically strong oxide layer, to which the ceramic hydroxyapatite layer is not tightly bound. The obtained results suggest that the nanotubular oxide layers should be covered with nanohydroxyapatite coatings, which would come inside the nanotubes resulting in better adhesion.
Crystal structure and phase composition of stainless steel substrates (AISI 304 type) was studied and it was found that they adopted the cubic symmetry. The calculated elementary cell parameter for the mayor Fe-Ni phase (weight fraction 99%) was a = 3.593 Å, whereas the mean grain size was = 2932 Å. Morphology of the stainless steel substrate surface was studied with profilometry. Mechanical properties of the stainless steel substrates and stainless steel substrates coated with ceramic layer of barium strontium titanate were studied with microhardness tester. For measurements performed according to the Vickers method the average microhardness was found HV = 189 or HV = 186 for the "in-line" and "mapping" measurement pattern, respectively. The sol-gel method was used to coat the surface of the stainless steel substrate with a thin ceramic layer of the chemical composition Ba 0.6 Sr 0.4 TiO 3 . It was found that the stainless steel substrate covered with sol-gel deposited ceramic coating exhibited the average hardness within the range HV = 217 up to HV = 235 for loading force F = 98 mN and F = 0.98 N, respectively. The Knopp method was also used and it was found that the stainless steel substrate with Ba 0.6 Sr 0. 4TiO 3 coating exhibited hardness HK = 386.
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