Alginate biopolymer coatings obtained by electrophoretic deposition on Ti15Mo alloy

In this work, the electrophoretic deposition method has been developed for the fabrication of bioactive alginate coatings on the surface of Ti15Mo implant alloy. Thin ZnO lm was deposited cataphoretically as the interlayer prior to anaphoretic deposition of alginate (Alg) which was performed from aqueous solution containing 1 g dm3 of NaAlg at room temperature. The deposition voltage and time varied in the range 20 50 V and 30 120 min, respectively. The microstructure of Alg coatings was studied by scanning electron microscope, and the surface roughness was analysed using atomic force microscopy. Structure was studied by grazing incidence X-ray di raction. Chemical composition and functional group were examined using energy dispersive spectrometry and attenuated total re ectance Fourier transform infrared spectroscopy methods, respectively. It was found that controlling the deposition conditions it is possible to obtain amorphous Alg coatings of variable thickness and porosity. Mechanism of electrophoretic deposition of bioactive Alg coatings on the Ti15Mo alloy surface was discussed

Corrosion behavior of friction stir welded lap joints of AA6061-T6 aluminum alloy

In this work, the corrosion behaviors of friction-stir lap welding of 6061-T6 Al-alloy are studied. The friction-stir lap welding was performed under different welding conditions (rotation speed and welding speed). The corrosion behavior of the parent alloy, the weld nugget zone (WNZ), and the heat affected zone (HAZ) of each welded sample working as an electrode, were investigated by the Tafel polarization test in 3.5 wt. (%) NaCl at ambient temperature. The morphology of the corroded surface of each region was analyzed by scanning electron microscopy together with energy dispersive spectroscopy (SEM-EDS). The results showed that the corrosion resistance of the parent alloy was better than the WNZ and the HAZ in both welding conditions. Localized pit dissolution and intergranular corrosion were the dominant corrosion types observed in the parent alloy, WNZ, and HAZ. The parent alloy, WNZ, and HAZ exhibited similar corrosion potentials (Ecorr) after T6 heat treatment. This treatment had a better effect on the corrosion resistance of the welded regions than the parent alloy

Hyperfine interactions in Tb0.27Dy0.73(Fe1–xCox)2 compounds at 77 K

The synthesis of materials, crystal structure and 57Fe Mössbauer effect studies at 77 K were performed for intermetallics Tb0.27Dy0.73(Fe1–xCox)2. The starting compound Tb0.27Dy0.73Fe2 of this Fe/Co substituted series is known as Terfenol-D. XRD measurements evidence a pure cubic Laves phase C15, MgCu2-type. The determined unit cell parameter decreases across the series. Co substitution introduces a local area, in the subnanoscale, with random Fe/Co neighbourhoods of the 57Fe atoms. Mössbauer effect spectra for the Tb0.27Dy0.73(Fe1–xCox)2 series collected at 77 K consist of a number of locally originated subspectra due to random composition of Fe and Co atoms in the nearest neighbourhood. Hyperfine interaction parameters: isomer shift, magnetic hyperfine field and a quadrupole interaction parameter were obtained from the fitting procedure of the spectra, both for the local area and for the sample as bulk. As a result of Fe/Co substitution, a Slater-Pauling type curve for the average magnetic hyperfine field vs. Co content in the Tb0.27Dy0.73(Fe1–xCox)2 series is observed. It is found that the magnetic hyperfine fields corresponding to the local area sorted out against Co contribution in the Fe/Co neighbourhoods also create a dependence similar to the Slater-Pauling type curve