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Corrosion protection of 316L stainless steel by (PVDF/HA) composite coating using a spinning coating technique

Hussein Asra Ali, Dawood Nawal Mohammed, Al-Kawaz Ammar Emad

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 2

art. no. e136810

EN

Polymer coatings are increasingly used in varied fields and applications from simple coatings of barrier to intricated nanotechnology based composite. In the present study, polyvinylidene fluoride(PVDF)/Hydroxyapatite (HA )coatings were produced by spin coating technique over 316L SS. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were used to observe the coated 316L SS substrates surface morphology. The corrosion protection efficiency of pure polyvinylidene fluoride and polyvinylidene fluoride/HA nanocomposite coatings on 316L SS was inspected using potentiodynamic polarization along with the ions release techniques in Hank’s solution. A superior biocompatibility and an improved protection performance against corrosion were obtained for the 316L SS samples with nanocomposite coatings compared with the pure polyvinylidene fluoride coatings and pristine 316L SS counterparts. The 316L SS samples coated by PVDF/HA nanocomposite showed enhanced corrosion protection within Hank’s solution. The corrosion of 316L SS samples within Hank’s solution increased from 92.99% to 99.99% when using 3wt% HA due to increasing the PVDF inhibition efficiency. Good agreements in the electrochemical corrosion parameters were obtained from using ions release and potentiodynamic polarization tests.

2

XPS analysis of AISI 316L (EN 1.4404) austenitic stainless steel surfaces after passivation in nitric acid HNO3

Rokosz K., Hryniewicz T., Rzadkiewicz S.

Autobusy : technika, eksploatacja, systemy transportowe

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2014

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R. 15, nr 6

244-247

EN

The XPS results of AISI 316L passive surface layer after mechanical MP and electrochemical (EP, MIX) polishing with additional passivation in 20 vol% nitric acid HNO3 at 50 °C for 30 min are presented. The studies revealed the highest iron Fe 2p and chromium Cr 2p signals from surface layer after electrochemical polishing without stirring EP and passivation in HNO3 whereas the lowest signals were recorded after mechanical polishing MP and similar passivation. After the passivation of abrasively treated MP samples done the atomic concentration of chromium compounds was over 93 at% and after passivation of electropolished EP and MIX samples the atomic percentage of chromium compounds was about 88 at% of the whole chromium concentration. The iron compounds after MP equaled about 65 at%, and after EP and MIX about 58 at% of the whole amount of detected iron. In all samples and all studied passive layers mainly oxides and hydroxides as well as sulfates and phosphates of iron and/or chromium were detected. Presented results can be used as reference data for the analysis of other passive layers usually obtained after chemical and electrochemical treatments as well as electro-machining operation.

PL

W artykule przedstawiono wyniki XPS warstw wierzchnich po pasywowaniu w 20 obj% HNO3 w temperaturze 50 °C przez 30 minut powierzchni na stopowej stali austenitycznej AISI 316L zarówno po wcześniejszej obróbce mechanicznej MP, jak i standardowym polerowaniu elektrochemicznym bez mieszania EP jak i z mieszaniem elektrolitu MIX. Odnotowano największą sygnał zarówno dla żelaza Fe 2p, jak i dla chromu Cr 2p w warstwie wierzchniej po standardowym elektropolerowaniu EP, natomiast najmniejszy sygnał został zarejestrowany dla pasywowanej powierzchni stali polerowanej mechanicznie. Po pasywacji, w pasywnej warstwie wierzchniej znajdowały się związki chromu i żelaza: odpowiednio po MP ponad 93 at% i 65at%, natomiast po EP i MIX około 88 at% i 58 at%. We wszystkich zbadanych warstwach pasywnych przeważały tlenki i wodorotlenki oraz fosforany i siarczany żelaza i/lub chromu. Zaprezentowane wyniki należy traktować jako punkty odniesienia do dalszych studiów nad warstwami pasywnymi otrzymywanymi poprzez chemiczne, elektrochemiczne oraz elektromechaniczne obróbki.

3

Cr/Fe Ratio by Xps Spectra of Magnetoelectropolished Aisi 316L SS Using Linear, Shirley and Tougaard Methods of Background Subtraction

Hryniewicz T., Rokosz K.

Advances in Materials Science

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2013

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Vol. 13, nr 1(35)

11--20

EN

In the paper, the analyses of Fe2p3/2 and chromium Cr2p3/2 XPS spectra with fitting by symmetrical and asymmetrical line shapes as well as using Linear, Shirley and Tougaard Method of Background Subtraction are presented. The calculations are performed on AISI 316L SS biomaterial after magnetoelectropolishing MEP operation. It was found, the chromium-to-iron ratio after magnetoelectropolishing MEP for other analyses could be in the range from 2.2 to 6.2 depending on the line shapes as well as type of backgrounds used to XPS spectra fitting. The most important for comparison the surface layers concerning the Cr/Fe ratio is to use the same line shape and backgrounds for all analyses.

4

XPS measurements of passive film formed on AISI 316L SS after electropolishing in a magnetic field (MEP)

Rokosz K., Hryniewicz T.

Advances in Materials Science

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2012

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Vol. 12, nr 4(34)

13-22

EN

Electrochemical polishing of metals and alloys is one of the most currently used finishing treatments, covering metallic biomaterials with complicated shapes (coronary stents, prostheses, etc.). A standard electropolishing (EP) process has been recently modified by including a magnetic field, and called the magnetoelectropolishing (MEP). Many surface properties and even mechanical features may be modified and improved by MEP. The changes are concerned with the surface film composition which undergo a modification. For the present studies, X-ray Photoelectron Spectroscopy (XPS) analysis was applied to measure the surface film composition on AISI 316L stainless steel. In conclusion both Cr-X/Fe-X compounds ratio as well as Cr/Fe total ratio of the 316L steel after EP and MEP were calculated and compared to reveal the advantage of the magnetic field used.