Potentiodynamic Polarization Tests Research Articles

Investigation on Friction Stir Welding Parameters: Mechanical Properties, Correlations and Corrosion Behaviors of Aluminum/Titanium Dissimilar Welds

In industrial applications, welding of dissimilar metals such as aluminum (Al) and titanium (Ti) is a prerequisite for the development of hybrid components with improved mechanical and corrosion properties. However, dissimilar welding of the Al/Ti system is highly challenging due to differences in the physical and thermal properties of the two materials. In the present investigation, an attempt has been made to fabricate a dissimilar friction stir weld (FSW) of commercially pure Al and Ti and to elucidate the mechanism associated with superior joint formation. The process parameters, such as tool rotation speed, traverse speed and tool offset position have been optimized using Taguchi’s optimization technique. A detailed investigation of the weld with optimum process parameters has been carried out to reveal the mechanism of joint formation. The superior mechanical properties (24% higher ultimate tensile strength and 10% higher ductility than that of base Al) of the weld are attributed to the fabrication of a defect-free joint, formation of intercalated particles and an Al/Ti interlocking interface, homogeneous distribution of fine second-phase (Ti and/or intermetallics) particles in the weld nugget, reduction in the evolution of brittle Al3Ti intermetallic compounds (IMCs) and recrystallization and grain refinement of Al in the weld nugget. The potentio-dynamic polarization test indicated that the optimized Al/Ti weld has ~47% higher corrosion resistance than Al; it had a very mild corrosion attack due to the homogeneous dispersion of fine particles. The method and mechanism could have an immense influence on any dissimilar weld and metal matrix composites, improving their mechanical properties and corrosion resistance.

Corrosion resistance of hybrid plasma electrolytic oxidation coatings on AZ31B magnesium alloy in simulated body fluid

This study examines the effects of a hydroxyapatite/anatase TiO2/CeO2 coating on the corrosion of AZ31B magnesium alloy in a simulated body fluid. Plasma electrolytic oxidation (PEO) is used to create the coating, and the surface properties are analysed using X-ray diffraction (XRD), atomic force microscopy (AFM) and field-emission scanning electron microscopy (FE-SEM). Contact angle measurements adapted to compare the uncoated substrate (144.74 ± 2.08°) with the coated substrates, which exhibit contact angles of (107.92 ± 2.16°), (95.88 ± 2.06°) and (66.05 ± 2.09°) for the respective coating durations. Increasing the thickness of the coating improves its corrosion resistance. Specifically, a 6-minute PEO coating significantly increases the thickness and provides better protection against corrosion for the AZ31B magnesium alloy. Cross-sectional scans of the coated samples revealed an increase in specimen thickness from 32.92 μm to77.17 μm. Potentiodynamic polarisation tests in a simulated body fluid reveal that the 6-minute coated sample shows the highest corrosion resistance, with the lowest corrosion current density (1.9037 × 10-06) compared to other coatings, indicating strong protection against corrosion. This research proposes a novel method to enhance the corrosion resistance of PEO coatings on magnesium alloys by depositing a thicker layer of hydroxyapatite, anatase TiO2 and CeO2. This approach results in a stronger and more effective protective system against corrosion.

Mechanical, metallurgical, and corrosion investigations on wire arc additively manufactured low carbon steel

Current global 3D metal printing research is focused on powder bed fusion and direct energy deposition. Several materials are presently under research to assess their post-additive manufacturing properties, and to process them in industries using advanced manufacturing techniques. This study investigates the electrochemical, mechanical, and metallurgical properties of wire arc additively manufactured (WAAM) ER70S-6 alloy walls on AISI S235 plates, emphasizing ship component fabrication. The corrosion resistance of both materials is assessed through Electrochemical Impedance Spectroscopy and Potentiodynamic Polarization testing in a 3.5% NaCl solution. Surface and cross-sectional morphologies are analyzed using optical microscopy and scanning electron microscopy, while energy dispersive spectroscopy is employed to study the chemical composition of the corrosion products. Moreover, the hardness of the WAAM-deposited ER70S6 wall is found to be highest in the uppermost layers of deposition due to the presence of acicular ferrite and ferritic-bainite microstructure. Tensile and Charpy impact strength for AISI S235 and WAAM-deposited ER70S-6 exhibit similar performance at room and low temperatures. Interestingly, the WAAM sample demonstrates a 60% higher elongation than the AISI S235 sample. Hence, the findings from this experimental work suggest that WAAM-deposited carbon steel exhibits favourable corrosion resistance and comparable mechanical properties to AISI S235. Consequently, WAAM is emerging as a promising alternative to conventional manufacturing techniques for fabricating ship components, repairing and modifying hull structures, manufacturing nozzles, propeller blades, fin-like structures, structural components, and more.

Effect of iron powder on zinc reactivity and anticorrosion performance of zinc-rich epoxy coatings

This study investigated the impact of iron powder on zinc reactivity and anticorrosion performance of zinc-rich epoxy (ZRE) coatings. Incorporating iron powder into ZRE coatings enhanced their overall anticorrosion performance, as evidenced by improved cathodic protection and reduced rust creep in salt spray tests. Furthermore, salt spray and EIS tests on cracked ZRE coatings demonstrated the enhanced sacrificial cathodic protection and physical barrier property with the inclusion of iron powder, attributed to the promoted sacrificial oxidation of zinc particles at damaged areas. The enhanced zinc dissolution in the presence of iron powder was also observed in immersion tests and potentiodynamic polarization tests on compressed Zn and ZnFe pellets.

Enhanced the Electrochemical Stability of Al-Zn-Mg Alloy Through the Dual Incorporation of ZrO2 and V2O5 into the Alumina Layer

This study explores the impact of direct and indirect incorporation of metallic oxide particles namely ZrO2 and V2O5 on the corrosion behavior of the alumina layer obtained by the plasma electrolytic oxidation of Al-Zn-Mg alloy. To achieve this goal, plasma electrolytic oxidation coating was formed in an alkaline-aluminate-ZrO2 electrolyte, without and with NH4VO3. The morphological analysis reveals a porous structure influenced by gas bubble discharge and rapid cooling, featuring micro-pores, oxide nodules, and cracks. The incorporation of V2O5 particles is observed to decrease surface roughness and enhance the compactness of the oxide layer. The X-ray diffraction patterns reveal the presence of γ-Al2O3, α-Al2O3, ZrO2, and V2O5 particles exclusively in the sample coated in the electrolyte with NH4VO3. Potentiodynamic polarization tests in a 3.5 wt.% NaCl solution revealed enhanced corrosion resistance, attributed to reduced micro-defects through V2O5 and ZrO2 incorporation.

Air-based sputtering deposition of TiN(O)/a-TiNxOy multilayer films for enhanced mechanical properties and corrosion resistance

Extensive research has explored multilayer films for their distinctive mechanical and functional properties. This study employs an air-based sputtering technique, using air as a reactive gas under low vacuum conditions, to produce TiN(O)/a-TiNxOy multilayer films. By alternately adjusting the air/Ar flow ratios, the multilayer films with various modulation periods were created. The crystalline TiN(O)/amorphous TiNxOy multilayered structure was confirmed via cross-sectional microscopy and electron energy loss spectroscopy images and mappings. Hardness (H) and elastic modulus (E) initially increased, peaked, and then decreased with the modulation period, reaching a maximum hardness of 31.2 GPa and an elastic modulus of 343 GPa. The enhancements may be attributed to internal compressive stress, interface strain effects, and the inhibition of dislocation propagation throughout the films. Higher H/E ratios (0.09–0.11) and H3/E2 ratios (0.23–0.28 GPa) suggest enhanced resistance to elastic and plastic deformation, surpassing those of single-layered TiN(O). This enhancement is primarily attributed to the hard/soft multilayer design. Potentiodynamic polarization tests revealed improved corrosion resistance with decreasing modulation period, reaching optimal values Ecorr at −0.089 V and Icorr at 0.272 μA/cm2. This improvement is mainly ascribed to the multilayer design, which inhibits direct corrosion through grain boundaries. This air-based sputtering technique offers a facile approach for producing complex multilayer films, promising enhanced mechanical properties and corrosion resistance of coatings for various applications.

Effect of V Content on Corrosion Behavior of Al-V Alloys Produced by Mechanical Alloying and Subsequent Spark Plasma Sintering

Al-V alloys produced via high-energy ball milling have been reported to show simultaneous improvement of corrosion resistance and mechanical properties compared to traditional Al alloys. In these alloys, V content plays a crucial role in increasing or decreasing the corrosion resistance. Therefore, the effect of V and microstructure on corrosion of high-energy ball milled and subsequently spark plasma sintered Al-xV alloys (x = 2, 5, 10 at%) has been studied. Cyclic potentiodynamic polarization tests and electrochemical impedance spectroscopic analysis revealed the increment of V content up to 5 at% enhanced the corrosion resistance of the alloy. However, highly heterogeneous microstructure in Al-10 at%V resulted in significant localized corrosion over the immersion time. The electrochemical impedance spectroscopy studies over 14 days of immersion revealed underlying corrosion mechanisms.

Role of copper and zinc additives in the stiction phenomenon of automotive braking systems

AbstractThe braking system of a motor vehicle is a multi‐material system, subjected to various aggressive conditions. Corrosion of the brake disc during stationary periods can determine the onset of a high adhesion force (stiction) capable of compromising the reliability of the braking system during vehicle motion. The purpose of this work is to study the effect of the introduction of Cu and Zn in the friction material composition. This effect was investigated through electrochemical measurements (electrochemical impedance spectroscopy, potentiodynamic polarization, and stiction tests), conducted using an electrochemical cell simulating the parking brake, complemented by the examination of the brake disc and pad surfaces and water absorption tests. The results suggest that porous components, like vermiculite, in the composite friction material led to high contact force. Moreover, 10 wt% of Cu in the friction material does not significantly affect its stiction behavior in our testing configuration. In contrast, 10 wt% Zn in the friction material significantly reduces the stiction propensity by acting with a complex synergistic mechanism combining physical and chemical shielding effects.

Preparation and evaluation of HA–PP coating on AZ31B magnesium alloy for implant applications

To make Mg alloy implants have better corrosion resistance and reduced degradation rate in the human body, hydroxyapatite (HA), polypropylene (PP), and HA+PP coatings were added to the surface of AZ31B through dip coating. Coated samples were tested for weight differences, corrosion rate, surface roughness, and microscopic view. Scanning electron microscopy and energy dispersive spectroscopy analysis confirm coating on the substrate surfaces. The potentiodynamic polarisation test result shows that the corrosion rate in the uncoated substrate (10.138 mm/y) was higher compared to HA-coated = 0.5084 mm/y, PP-coated = 0.442 mm/y, and HA/PP-coated = 0.3275 mm/y. After 14 days, weight loss (5.5%) was highest in the uncoated and lowest in the HA-PP-coated (0.9%). Deposition of the bone mineral was higher on the HA-coated sample, showing superior bone integration properties. Hybrid coating improved electrochemical properties compared to HA coating on Mg alloy.

Influences of flame remelting and WC-Co addition on microstructure, mechanical properties and corrosion behavior of NiCrBSi coatings manufactured via HVOF process

We investigated the microstructures, mechanical properties, and corrosion behavior of NiCrBSi coatings upon the addition of the WC-Co powder in various amounts (0, 5, 10, 15, and 20 wt%) using the high velocity oxy-fuel process on low-carbon steel. Additionally, flame remelting was performed at 1100 °C for 1 min following thermal spraying of the coatings. The microstructures of the coatings were examined using X-ray diffractometry and scanning electron microscopy, and the mechanical properties of the coatings were assessed via Vickers microhardness and ball-on-disk tests. The corrosion behavior of the coatings was evaluated using potentiodynamic polarization testing in a 20 vol.% sulfuric acid solution. The results demonstrated that an increase in the WC-Co amount enhanced the hardness and wear resistance of the coatings. For 10–20 wt% WC-Co addition, small cracks were observed in the as-sprayed coatings owing to the heat applied during thermal spraying and rapid cooling, respectively. The presence of porosity directly affects the corrosion behavior of the coatings. Flame remelting led to better cohesion and the distribution of the γ-Ni and WC phases, reducing microdefects, such as pores and cracks. The mechanical properties of the coatings improved as the WC-Co amount increased after flame remelting, resulting in the formation of intermetallic compounds (FeB, CoSi2, and Ni2Si) along with the WC phase. The flame-remelted NiCrBSi/ 10 wt% WC-Co coating demonstrated high hardness and low wear and corrosion rates (1072.26 HV, 4.8 × 10−6 mm3/m, and 0.560 mm/year, respectively). Therefore, WC-Co addition and the flame remelting process significantly enhanced the properties of NiCrBSi coatings. This study highlights the substantial contributions of WC-Co addition and the flame remelting process in enhancing the mechanical properties and corrosion resistance of NiCrBSi coatings. These findings offer valuable insights for optimizing the performance of commercially available coatings in various real-world applications in maintaining power plants and industrial components like high-pressure pump piston rods, acid-resistant pumps in oil refineries.

The effects of heat treatment and surface state on the corrosion resistance of laser powder bed fusion 304L stainless steel in 3.5 wt% NaCl solution

The corrosion resistance of laser powder bed fusion (LPBF) 304L stainless steel (SS) in 3.5 wt% NaCl solution was evaluated at room temperature through potentiodynamic polarization and electrochemical impedance spectroscopy tests. For electropolished samples, annealing at 1200 °C slightly enhanced the corrosion resistance due to changes in crystal orientation and inclusion composition, and reduced residual strain. In contrast, annealing at 1050 °C significantly reduced the corrosion resistance mainly due to the disappearance of dislocation cells and the remained residual dislocations. Residual stress/strain and martensitic transformation induced by sandpaper grinding can also deteriorate the corrosion resistance. Only the as-received sample shows stable passivation regardless of the surface conditions.

Surface Modification of Zn-Cu Alloy with Heparin Nanoparticles for Urinary Implant Applications.

In this work, an investigation on the Zn-Cu alloy coated with heparin was conducted in order to explore the potentiality of its application as a feasible alternative for biodegradable implants, with the specific goal of addressing the issue of encrustation in the urinary system. The stability of the nanoparticles were characterized by dynamic light scattering. Typical surface characterization such as X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy were used to demonstrate a successful immobilization of the NPs. The in vitro corrosion behavior was studied by potentiodynamic polarization and immersion tests in artificial urine (AU) at 37 °C. The 8 weeks in vivo degradation, encrustation resistance, hemocompatibility, and histocompatibility were investigated by means of implantation into the bladders of rats. Both in vitro and in vivo degradation tests exhibited a higher degradation rate for Zn-Cu and NPs groups when compared to pure Zn. Histological evaluations and hemocompatibility revealed that there was no tissue damage or pathological alterations caused by the degradation process. Furthermore, antiencrustation performance and urinalysis results confirmed that the modified alloy demonstrated significant encrustation inhibitory properties and bactericidal activity compared to the pure Zn control. Our findings highlight the potential of this modified alloy as an antiencrustation biodegradable ureteral stent.

The characterization of Ag-doped tin indium oxide/copper electrodes prepared by cold pressing method and their electrocatalytic efficiency in hydrogen production

In the present study, tin indium oxide (SnIn2O3) powder was synthesized by hydrothermal technique. In order to improve the structural property of SnIn2O3, a small amount of silver (Ag) nanoparticles was added into SnIn2O3 powder. Finally, the prepared Ag-doped SnIn2O3 (Ag@SnIn2O3) were embedded into copper (Cu) powder with different ratios. The electrocatalytically improved hetero-structured Ag@SnIn2O3/Cu materials were obtained by cold pressing method. The structural and morphological properties of different Ag@SnIn2O3/Cu materials were studied via X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). XRD pattern depicted In2O3 have both cubic and hexagonal crystal structures. FE-SEM images show that Ag@SnIn2O3 nanoparticles are homogeneously dispersed into Cu powder. The size of nanoparticles of Ag@SnIn2O3/Cu materials increases with increasing the ratio of Ag@SnIn2O3. Electrochemical impedance spectroscopy (EIS) and potentiodynamic (PD) polarization tests were carried out to investigate the electrocatalytic activities of the materials toward hydrogen evolution reaction (HER). Energy consumption and energy efficiency values for the HER on the materials were also calculated. Furthermore, the polarization resistances of the 1-Ag@SnIn2O3/Cu, 2.5-Ag@SnIn2O3/Cu, 5-Ag@SnIn2O3/Cu, and 10-Ag@SnIn2O3/Cu materials were determined as 127.4, 103.1, 552.4, and 558.7 Ω cm2, respectively after 5 days of electrolysis periods.

Effects of Surfactants on the Corrosion Behavior of Aluminum Alloy in Graphene Nanofluid

In this study, the corrosion behavior of aluminum alloy was investigated in graphene nanoplatelet (GNP) nanofluids prepared with different surfactants. The surfactants include sodium dodecylbenzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), Tween 80, and Gum Arabic (GA). The corrosion properties of the alloy in the different GNP nanofluids were evaluated using potentiodynamic polarization tests at room temperature. The surface morphology of the aluminum alloy was analyzed using a scanning electron microscope coupled with an electron dispersive spectroscopy detector. The experimental results revealed that the addition of surfactants improves the resistance of the aluminum alloy to corrosion in the nanofluid. This was attributed to the adsorption of surfactants on the surface of the alloy to form a protective film layer, which reduces moisture permeability and enhances corrosion inhibition. The addition of GA was found to exhibit the highest inhibition efficiency. This was followed by Tween 80, SDS, and SDBS, which contributes the least inhibition. XRD post-corrosion analysis also reveals the presence of aluminum oxide and aluminum hydroxide phases on the surface of electrodes immersed in all the different GNP nanofluids.

Effect of Graphene Oxide as an Anodizing Additive for the ZK60A Magnesium Alloy: Correlating Corrosion Resistance, Surface Chemistry and Film Morphology

The aim of the present work was to study the effect of graphene oxide as an additive in the anodization bath of the ZK60A magnesium alloy on the corrosion resistance, film morphology and surface chemical composition. The anodizing process was conducted at a constant current density of 30 mA.cm−2 in an electrolyte consisting of 3 M de KOH, 0.15 M de Na2SiO3 and 0.1 M Na2B4O7.10H2O. Graphene oxide was added to this bath at three different concentrations: 0.5 g.L−1, 1.0 g.L−1 and 3.0 g.L−1. The ability of the graphene oxide nanofiller to enhance the corrosion resistance of the ZK60A alloy was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization tests in 3.5 wt.% NaCl solution. The surface chemical composition was assessed by X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) coupled with EDS analysis was employed to examine the anodized layer morphology and thickness. The results pointed to a beneficial effect of graphene oxide addition on the corrosion resistance of the anodized ZK60A which was dependent on the concentration of the nanofiller in the anodizing electrolyte.

The effect of solution aggressiveness on the corrosion-induced degradation mechanism of Al-Cu-Li 2198 alloy

Investigation on the corrosion-induced degradation mechanisms of Al-Cu-Li 2198 alloy is critical for the aircraft maintenance protocol. This article aims to identify the corrosion-induced degradation mechanisms of AA2198-T8; three (3) different accelerated corrosion tests with electrolytes of various aggressiveness, namely sodium chloride (NaCl), Harisson’s and exfoliation corrosion (EXCO) solution were exploited. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and immersion tests were used in this context. The EIS analyses revealed that exploitation of different electrolytes essentially affects corrosion-degradation mechanism. Intergranular corrosion attack was found to dominate in EXCO solution, while transgranular attack was evident in both, 3.5 wt. % NaCl and Harrison’s solutions. Severe localized corrosion in Harrison’s solution led to higher degradation of elongation at fracture (Af) throughout immersion duration; EXCO exposure led to higher corrosion attack rate for the short exposure times (≤ 6 hours). Correlation between the different electrolytes regarding tensile ductility decrease was attempted through a linear coefficient for the initial, small exposure times; 1-hour EXCO exposure of AA2198-T8 was found to be equivalent to 107 hours exposure to 3.5 wt. % NaCl solution, while the respective correlation with Harrison’s solution showed that 1-hour EXCO exposure is equivalent to 27 hours Harrison exposure.

Impact of scandium and terbium on the mechanical properties, corrosion behavior, and biocompatibility of biodegradable Mg-Zn-Zr-Mn alloys

Magnesium (Mg)-based bone implants degrade rapidly in the physiological environment of the human body which affects their structural integrity and biocompatibility before adequate bone repair. Rare earth elements (REEs) have demonstrated their effectiveness in tailoring the corrosion and mechanical behavior of Mg alloys. This study methodically investigated the impacts of scandium (Sc) and terbium (Tb) in tailoring the corrosion resistance, mechanical properties, and biocompatibility of Mg–0.5Zn–0.35Zr–0.15Mn (MZZM) alloys fabricated via casting and hot extrusion. Results indicate that addition of Sc and Tb improved the strength of MZZM alloys via grain size reduction and solid solution strengthening mechanisms. The extruded MZZM–(1–2)Sc–(1–2)Tb (wt.%) alloys exhibit compressive strengths within the range of 336–405 MPa, surpassing the minimum required strength of 200 MPa for bone implants by a significant margin. Potentiodynamic polarization tests revealed low corrosion rates of as–cast MZZM (0.25 mm/y), MZZM–2Tb (0.45 mm/y), MZZM–1Sc–1Tb (0.18 mm/y), and MZZM–1Sc–2Tb (0.64 mm/y), and extruded MZZM (0.17 mm/y), MZZM–1Sc (0.15 mm/y), MZZM-2Sc (0.45 mm/y), MZZM-1Tb (0.17 mm/y), MZZM-2Tb (0.10 mm/y), MZZM–1Sc-1Tb (0.14 mm/y), MZZM-1Sc-2Tb (0.40 mm/y), and MZZM–2Sc–2Tb (0.51 mm/y) alloys, which were found lower compared to corrosion rate of high-purity Mg (∼1.0 mm/y) reported in the literature. Furthermore, addition of Sc, or Tb, or Sc and Tb to MZZM alloys did not adversely affect the viability of SaOS2 cells, but enhanced their initial cell attachment, proliferation, and spreading shown via polygonal shapes and filipodia. This study emphasizes the benefits of incorporating Sc and Tb elements in MZZM alloys, as they effectively enhance corrosion resistance, mechanical properties, and biocompatibility simultaneously.

Effect of silicon content on the corrosion behaviors of CrAlSiN thin films deposited by magnetron co-sputtering

One CrAlN and four CrAlSiN thin films containing 0.8–7.3 at. % Si were grown by a magnetron co-sputtering process using pure Cr, Al, and Si targets. The microstructure of the CrAlSiN coating changed from a coarse columnar structure to a dense and compact morphology as Si content increased from 0.8 to 7.3 at. % due to the formation of more amounts of amorphous silicon nitride phase to block the growth of columnar grains. Pitting corrosion was the main corrosion failure mechanism for each coating. According to the potentiodynamic polarization test, the lowest corrosion current density, the highest pitting potential, and the widest passivation range were obtained on the 7.3 at. % Si contained CrAlSiN coating. After the electrochemical impedance spectroscopy study of CrAlN and CrAlSiN thin films in 3.5 wt. % NaCl aqueous solution for 100 h immersion, the corrosion resistance of CrAlSiN thin films was 14 times higher than the CrAlN film due to its fine nanocolumnar microstructure to effectively retard the attack of corrosive electrolyte through the defects of coating.

Inhibitory effects of 1-butylpyridin-1-ium bromide in 0.1 M sulphamic acid for mild steel

ABSTRACT In recent years, there has been a consistent development in the introduction of novel corrosion inhibitors due to their potential to reduce the dissolution of metal surfaces under various corrosive environments. The current study investigates the inhibitory effect of the surfactant 1-butylpyridin-1-ium bromide (BPB) on mild steel (MS) in 0.1 M sulphamic acid. The electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation (PDP) studies were used to analyse the inhibition investigations. In addition, atomic force microscopy (AFM), scanning electron microscopy (SEM) and contact angle (CA) measurements were also used to analyse the inhibition investigations. The PDP studies showed a maximum inhibition efficiency of 63.3% at 400 ppm concentration, demonstrating the inhibitor’s efficacy. The investigated compound was found to comply with the Temkin adsorption isotherm with an R 2 value of 0.99954. The results of PDP tests firmly suggest that the inhibitor is of mixed type. ΔG ads values of −9.659 kJ mol−1 suggested that the inhibitor adhered to the metal surface by physical adsorption. Based on the findings it appears that the molecules adhere to the surface of MS forming partial hydrophobic films that act as a barrier for the metal surface.

Inherent Antibacterial Properties of Biodegradable FeMnC(Cu) Alloys for Implant Application.

Implant-related infections or inflammation are one of the main reasons for implant failure. Therefore, different concepts for prevention are needed, which strongly promote the development and validation of improved material designs. Besides modifying the implant surface by, for example, antibacterial coatings (also implying drugs) for deterring or eliminating harmful bacteria, it is a highly promising strategy to prevent such implant infections by antibacterial substrate materials. In this work, the inherent antibacterial behavior of the as-cast biodegradable Fe69Mn30C1 (FeMnC) alloy against Gram-negative Pseudomonas aeruginosa and Escherichia coli as well as Gram-positive Staphylococcus aureus is presented for the first time in comparison to the clinically applied, corrosion-resistant AISI 316L stainless steel. In the second step, 3.5 wt % Cu was added to the FeMnC reference alloy, and the microbial corrosion as well as the proliferation of the investigated bacterial strains is further strongly influenced. This leads for instance to enhanced antibacterial activity of the Cu-modified FeMnC-based alloy against the very aggressive, wild-type bacteria P. aeruginosa. For clarification of the bacterial test results, additional analyses were applied regarding the microstructure and elemental distribution as well as the initial corrosion behavior of the alloys. This was electrochemically investigated by a potentiodynamic polarization test. The initial degraded surface after immersion were analyzed by glow discharge optical emission spectrometry and transmission electron microscopy combined with energy-dispersive X-ray analysis, revealing an increase of degradation due to Cu alloying. Due to their antibacterial behavior, both investigated FeMnC-based alloys in this study are attractive as a temporary implant material.