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Your search keyword '"Nikpour, Saman"' showing total 10 results
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10 results on '"Nikpour, Saman"'

6. A Bio-Tribocorrosion Comparison between Additively Manufactured and Forged Ti6al4v Parts

Author

Matin, Sina, Toorandaz, Sahar, Nikpour, Saman, Abdolvand, Hamidreza, Toyserkani, Eshan, and Hedberg, Yolanda S

Subjects
Corrosion, laser powder bed fusion, Chemistry, titanium alloy, microstructure, tribology, protein
Abstract

Ti6Al4V has been used widely as a biomedical alloy and is increasingly manufactured by additive manufacturing due to customized shapes. As implant material, it is frequently exposed to both friction and corrosive environments. This study investigates the effect of the fabrication process (laser powder bed fusion and forging) on the tribocorrosion behavior of Ti6Al4V in various environments including diluted hydrochloric acid to simulate the acidic environment in a crevice (HCl), phosphate-buffered saline (pH 7.3) with 10 g/L bovine serum albumin (PBS+BSA), and PBS+BSA with 30 mM H2O2. While the presence of BSA hindered the repassivation (reforming of the protective passive surface oxide), the presence of H2O2 accelerated it. HCl resulted in a localized tribocorrosion process. The highest plastic deformation rate was found in the PBS+BSA solution followed by HCl and PBS+BSA+H2O2. In addition, AM parts presented a higher microhardness and smaller grain sizes compared to forged materials. There was no influence of the manufacturing process on the coefficient of friction (COF) in HCl and PBS+BSA solutions, however, a significantly higher COF was found for forged samples in PBS+BSA+H2O2 than AM samples. Tribocorrosion was more extensive for forged than AM Ti6Al4V in all solutions.

Published
2023
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8. Effect of Amino Acids on the Corrosion and Metal Release from Copper and Stainless Steel.

Author

Zee, Alyssa Vander, Laundry-Mottiar, Lila, Nikpour, Saman, Matin, Sina, Henderson, Jeffrey D., Eduok, Ubong, Hedberg, Jonas F., Zagidulin, Dmitrij, Biesinger, Mark C., Noël, James J., and Hedberg, Yolanda S.

Subjects
AMINO acids, COPPER, METALS, ORTHOPEDIC apparatus, INTRAUTERINE contraceptives, STAINLESS steel
Abstract

copper (Cu) and stainless steel 316 L are widely used for biomedical applications, such as intrauterine devices and orthopedic/dental implants. Amino acids are abundantly present in biological environments. We investigated the influence of select amino acids on the corrosion of Cu under naturally aerated and deaerated conditions using a phosphate-free buffer. Amino acids increased the corrosion of Cu under both aeration conditions at pH 7.4. Cu release was also significantly (up to 18-fold) increased in the presence of amino acids, investigated at pH 7.4 and 37 °C for 24 h under naturally aerated conditions. Speciation modelling predicted a generally increased solubility of Cu in the presence of amino acids at pH 7.4. 316 L, investigated for metal release under similar conditions for comparison, released about 1,000-fold lower amounts of metals than did Cu and remained passive with no change in surface oxide composition or thickness. However, amino acids also increased the chromium release (up to 52-fold), significantly for lysine, and the iron release for cysteine, while nickel and molybdenum release remained unaffected. This was not predicted by solution speciation modelling. The surface analysis confirmed the adsorption of amino acids on 316 L and, to a lower extent, Cu coupons. [ABSTRACT FROM AUTHOR]

Published
2023
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