Alloy In Simulated Body Fluid Research Articles

Crevice corrosion behavior of a biodegradable Zn-Mn-Mg alloy in simulated body fluid.

Crevice corrosion at the implantation sites cannot be neglected in clinical applications of biodegradable zinc alloys as implants. In this study, a crevice corrosion protocol was designed to investigate the crevice corrosion behavior of the Zn-0.45Mn-0.2Mg (ZMM42) alloy for the first time, by varying crevice thicknesses in simulated body fluid (SBF) through immersion and electrochemical analysis. The results indicated that the ZMM42 alloy was susceptible to crevice corrosion in the range from 0.03 mm to 0.2 mm. When the crevice thickness was 0.05 mm, the crevice corrosion of the specimen became more severe compared to other thicknesses.

The effect of solid solution treatment with coating on corrosion properties of AZ91 Mg alloy in simulated body fluid

The current study involves an attempt to reduce the corrosion rate of AZ91 Mg alloy that is used in biomedical applications, where it is known as biodegradable material and needs to increase its lifetime until healing can occur. Firstly, solid solution treatment at 450 °C for 8 hr. was worked to reduce the second phase represented by Mg17Al12 and then reduce the galvanic cells on the alloy’s surface. Secondly, coating with indium and titanium metals was done by DC sputtering. The characterization of treated and treated/coated specimens was accomplished by XRD, SEM/EDS, and AFM confirming the improvement of solid solution treated/In coated alloy surface compared with the treated uncoated and solid solution treated/Ti coated alloy. Corrosion properties were investigated by potentiostatic measurement indicating that the solid solution treated/In coated alloy gave lower corrosion current density (i.e., lower corrosion rate), protection efficiency equal to 38.31%, polarization resistance increased from 33.482 × 102 to 36.876 × 102 Ω.cm2 and lower porosity compared with coated specimen by Ti. The reason for this improvement comes from the full coverage of the surface by a compact regular layer of indium as well as the formation of the Mg3In phase. The porosity percentage PP% showed the high porosity for treated/Ti coated specimen which reached to 2104.1%.

Influence of Mechanical Torsion on MgCa1 Corrosion Behavior in Simulated Body Fluid

In this paper, the influence of mechanical torsion on the corrosion of MgCa1 alloy in simulated body fluid (SBF) is presented. The corrosion behavior is examined by microstructural observations, including a scanning electron microscope equipped with an energy dispersive spectroscopy detector and electrochemical studies, mainly impedance spectroscopy measurements and polarization curves. The experiments were performed for different time durations (4 h to 8 h) with and without torsion applied (within elastic deformation range in the form of rotary movements) to assign the differences between the corrosion behavior of the samples. It is shown that mechanical torsion (rotations) promotes the leaching of calcium from the grain boundaries in the samples, which decreases the overall alloy corrosion rate. On the other hand, grain boundaries leached out of calcium compounds influence the sample microstructure by enabling cracks formation and propagation. Therefore, rotated samples corroded at a lower rate but were more susceptible to catastrophic failure. It was then concluded that MgCa1 alloy may be a promising biodegradable material for medical implants, however, its durability in SBF with torsion applied is far from being satisfactory.

Morphological, microstructural, mechanical, and electrochemical optimization of a novel Mg–2Ca–1Mn–1 Sr alloy by P ion implantation for orthopedic implants

This study investigates the influence of phosphorous (P) ion implantation on the morphological, microstructural, mechanical, and electrochemical properties of a novel bioresorbable Mg–2Ca–1Mn–1 Sr (XMJ211) quaternary alloy in simulated body fluid (SBF) post-implantation for potential orthopedic implants. The novelty lies in both the unique alloy composition and systematically optimizing the alloy's performance through P ion implantation at varying fluences. XRD analysis revealed the increased volume fractions of secondary binary phases, such as Mg3P2, and a fractional decrease in grain size from approximately 71 µm to 39 µm with gradually increased P implantation. Mechanical hardness improved from approximately 60 HV to 75 HV with P addition due to grain refinement and increased second-phase binary particles. The EIS analysis confirmed an improvement in the bio-corrosion resistance of the alloy from 48 kΩ to 87 kΩ as P addition increased up to fluence 4, with diminishing effects at higher fluences. The study results successfully demonstrate a balance between the mechanical and electrochemical properties of the alloy with moderate amounts of P addition, positioning it as a promising bioresorbable biomaterial for orthopedic implants and eliminating the need for secondary implant removal surgery post-patient recovery. This research bridges the knowledge gap in the literature and introduces a novel approach to optimizing the performance of Mg-based alloys for biomedical applications.

Improvement in corrosion resistance of biocompatible Ti1.5Al0.3ZrNb refractory high entropy alloy in simulated body fluid by nanosecond laser shock processing

A biocompatible Ti1.5Al0.3ZrNb refractory high-entropy alloy (RHEA) with high specific strength and superior tensile ductility is developed. The activation of multiple slip systems and dislocations cross-slip facilitate dislocation interactions, improving the plastic deformability and continuous strain hardening ability of the Ti1.5Al0.3ZrNb RHEA. After laser shock processing (LSP), the surface roughness of the RHEA increases and significant grain refinement occurs on the surface, from micron-grains to nano-grains. Meanwhile, abundant dislocations and dislocation debris are generated. This surface morphology significantly improves the corrosion resistance of the RHEA in simulated body fluid. The corrosion current density of the LSP-Ti1.5Al0.3ZrNb is only ∼1/3 of the Ti1.5Al0.3ZrNb, and the resistance Rct is 2.29 × 105 Ω·cm2 in the LSP-Ti1.5Al0.3ZrNb, which is an order of magnitude higher than that of the Ti1.5Al0.3ZrNb. The improved corrosion resistance of LSP-Ti1.5Al0.3ZrNb is ascribed to multiple LSP-induced compressive residual stress, grain refinement and high-density dislocations. Combining the RHEAs with LSP techniques could offer the opportunity to break existing corrosion limitation, and obtain substantial performance improvement.

Evaluation of tribocorrosion performance of Ti6Al4V alloy in simulated inflammatory and hyperglycemic microenvironments

The poor tribocorrosion resistance of the Ti6Al4V alloy limits its wide applications in orthopedics. In addition, the tribocorrosion performance and mechanism of the Ti6Al4V alloy are not clear in some clinically specific pathological settings, such as peri-implantitis and diabetes. In this work, the tribocorrosion performances of the Ti6Al4V alloy in simulated body fluids (SBF) containing H2O2 and glucose were investigated to analyze the degradation behavior in the simulated inflammatory and hyperglycemic microenvironment. The tribocorrosion tests were carried out on a tribometer equipped with a three-electrode system electrochemical workstation. The material volume loss of the Ti6Al4V alloy in the high glucose environment (6 g/L) is 3.1 times more than that in the glucose-free environment, while H2O2 does not increase the material volume loss. The continuous corrosion product film on the Ti6Al4V surface in the SBF with H2O2 acts as a lubricant in mechanical wear, while the Ca and Mg-containing mineralized film formed in the high glucose environment increases the coefficient of friction (COF) during sliding. These results suggest that diabetic patients may be at a higher risk of the implant failure due to the tribocorrosion. This finding also provides a valuable reference for the placement of titanium-based implants in specific pathological settings in orthopedics.

Effect of MgF2 coating on stress corrosion cracking behavior of Mg−Zn−Ca alloy in simulated body fluid

The stress corrosion cracking behavior of Mg−3wt.%Zn−0.2wt.%Ca (MZC) alloy and fluoride (MgF2) coated Mg−3wt.%Zn−0.2wt.%Ca alloy (MZC-MF) for bone implant applications was investigated using slow strain- rate tensile (SSRT) tests in simulated body fluid (SBF). The results show that MgF2 coating could significantly improve the corrosion resistance and prolonged fracture failure time of MZC alloy. MgF2 coating also greatly reduced the stress corrosion cracking sensitivity of MZC alloy in SBF. Compared to MZC alloy, stress corrosion cracking sensitivity index (Iscc) of MZC-MF alloy decreased by 21% (ultimate tensile strength, UTS), 22% (time to failure, tf), 23% (elongation after fracture, δ), 7% (reduction ratio of cross-sectional area after fracture, ϕ) and 15% (inner product work, A), respectively.

Corrosion Performance of Ti6Al7Nb Alloy in Simulated Body Fluid for Implant Application Characterized Using Macro- and Microelectrochemical Techniques

In this paper, the applicability of Ti6Al7Nb as a more biocompatible alternative for bone and dental implants than Ti6Al4V and pure titanium in terms of corrosion resistance and electrochemical inertness is investigated. The chemical inertness and corrosion resistance of the Ti6Al7Nb biomaterial were characterized by a multi-scale electrochemical approach during immersion in simulated physiological environments at 37 °C comparing its behavior to that of c.p. Ti, Ti6Al4V, and stainless steel. The establishment of a passive regime for Ti6Al7Nb results from the formation of a thin layer of metal oxide on the surface of the material which prevents the action of aggressive species in the physiological medium from direct reaction with the bulk of the alloy. Conventional electrochemical methods such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) provide quantified information on the surface film resistance and its stability domain that encompasses the potential range experienced in the human body; unfortunately, these methods only provide an average estimate of the exposed surface because they lack spatial resolution. Although local physiological environments of the human body are usually simulated using different artificial physiological solutions, and changes in the electrochemical response of a metallic material are observed in each case, similar corrosion resistances have been obtained for Ti6Al7Nb in Hank’s and Ringer’s solutions after one week of immersion (with a corrosion resistance of the order of MΩ cm2). Additionally, scanning electrochemical microscopy (SECM) provides in situ chemical images of reactive metal and passive dielectric surfaces to assess localized corrosion phenomena. In this way, it was observed that Ti6Al7Nb exhibits a high corrosion resistance consistent with a fairly stable passive regime that prevents the electron transfer reactions necessary to sustain the metal dissolution of the bulk biomaterial. Our results support the proposition of this alloy as an efficient alternative to Ti6Al4V for biomaterial applications.

Investigating Effect of ECAP Process on Corrosion Behavior of WE43 Magnesium Alloy in Simulated Body Fluid

Investigating Effect of ECAP Process on Corrosion Behavior of WE43 Magnesium Alloy in Simulated Body Fluid

Evaluation of the Influence of Eggshell (ES) Concentration on the Degradation Behavior of Mg-2.5Zn Biodegradable Alloy in Simulated Body Fluid.

Currently, permanent vascular stents are fabricated using titanium and stainless steel implants that are nondegradable and offer high stability, but they have certain disadvantages. For example, the prolonged exposition of aggressive ions in the physiological media and the existence of defects in the oxide film create conditions for corrosion to occur, thus triggering unwanted biological events and compromising the mechanical integrity of the implants. Moreover, when the implant does not need to be permanent, there is the need to submit the patient for a second surgery for implant removal. As a solution for nonpermanent implants, biodegradable magnesium alloys have been deemed a promising substitute, for example, for cardiovascular-related applications and the construction of orthopedic devices. A biodegradable magnesium alloy (Mg-2.5Zn) reinforced by zinc and eggshell was employed in this study as an environment-conscious magnesium (eco) composite (Mg-2.5Zn-xES). Disintegrated melt deposition (DMD) was used to fabricate the composite. Experimental studies were conducted to investigate the biodegradation performance of Mg-Zn alloys containing 3 and 7 wt % eggshell (ES) in simulated body fluid (SBF) at 37 °C. Different corrosion techniques were used to study the corrosion behavior of the Mg-2.5Zn-xES composites, including weight loss measurements, hydrogen evolution, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and scanning vibrating electrode technique (SVET). Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) were employed to scrutinize the corroded surfaces' morphology and composition. The outcomes indicated that Mg-2.5Zn-3ES possesses the lowest degradation activity.

Influence of the Alloying Elements on the Corrosion Behavior of As-Cast Magnesium–Gallium–Zinc Alloys in Simulated Body Fluid

The in vitro corrosion rate of as-cast ternary Mg-Ga-Zn alloys in simulated body fluid (SBF) was evaluated. The effects of Ga3+ and Zn2+ on the formation, growth and stability of Ca, P-rich compounds on the surface of the ternary alloys, and the effect of these compounds on corrosion rate, were studied. Ternary Mg-Ga-Zn alloys (Ga from 0.375 to 1.5 wt% and Zn from 1.5 to 6 wt%) were obtained and then immersed in SBF to evaluate the corrosion rate using the weight loss method. The species formed on the alloys surface were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FT-IR). The formation of amorphous Ca, P-rich compounds on the alloys was observed. The species formed are related to the corrosion rate and the ions released into the SBF. The Mg, Ga and Zn ions released into the SBF during the corrosion process of the studied alloys play an important role in the growth of the Posner’s clusters, propitiating the reduction in size of the Ca, P-rich agglomerates. The corrosion rate of these as-cast ternary alloys increased as the intermetallics formed increased. The amount and size of the intermetallics formed depend on the Ga and Zn concentration in the alloys.

Corrosion Behavior of Micro-arc Oxidation-Coated AZ80 Magnesium Alloy in Simulated Body Fluid at Different Flow Rates

Corrosion Behavior of Micro-arc Oxidation-Coated AZ80 Magnesium Alloy in Simulated Body Fluid at Different Flow Rates

Microstructure-dependent corrosion fatigue crack growth behavior of Ti-6Al-4V alloy in simulated body fluid

The fatigue crack growth rate (FCGR) of Ti-6Al-4V alloys in simulated body fluid (SBF) was first determined by direct current potential drop (DCPD) method. The results show that the acceleration effect of SBF corrosion environment on FCGR of lamellar structure is far greater than that of equiaxed and bimodal structures, especially in Paris region, which is mainly due to the high corrosion sensitivity of the lamellar α/β phase boundary to SBF under fatigue loading.

Effect of the Combination of Torsional and Tensile Stress on Corrosion Behaviors of Biodegradable WE43 Alloy in Simulated Body Fluid.

The real physiological environment of the human body is complicated, with different degrees and forms of loads applied to biomedical implants caused by the daily life of the patients, which will definitely influence the degradation behaviors of Mg-based biodegradable implants. In the present study, the degradation behaviors of modified WE43 alloys under the combination of torsional and tensile stress were systematically investigated. Slow strain rate tensile tests revealed that the simulated body fluid (SBF) solution could deteriorate the ultimate tensile stress of WE43 alloy from 210.1 MPa to 169.2 MPa. In the meantime, the fracture surface of the specimens tested in the SBF showed an intergranular corrosion morphology in the marginal region, while the central area appeared not to have been affected by the corrosive media. The bio-degradation performances under the combination of torsional and tensile stressed conditions were much more severe than those under unstressed conditions or single tensile stressed situations. The combination of 40 MPa tensile and 40 MPa torsional stress resulted in a degradation rate over 20 mm/y, which was much higher than those under 80 MPa single tensile stress (4.5 mm/y) or 80 MPa single torsional stress (13.1 mm/y). The dynamic formation and destruction mechanism of the protective corrosion products film on the modified WE43 alloy could attribute to the exacerbated degradation performance and the unique corrosion morphology. The dynamic environment and multi-directional loading could severely accelerate the degradation process of modified WE43 alloy. Therefore, the SCC susceptibility derived from a single directional test may be not suitable for practical purposes. Complex external stress was necessary to simulate the in vivo environment for the development of biodegradable Mg-based implants for clinical applications.

Study of Microstructure and Corrosion Behavior of Cast Zn–Al–Mg Alloys

Zn-based alloys have found increasing interest as orthopedic biodegradable implantable materials, hence it was the aim of this work to investigate the microstructure and corrosion behavior of Zn–0.5Al–xMg cast alloys with different Mg additions in simulated body fluid (SBF). The cast samples were prepared using a simple stir casting method and the molten alloys were poured in a cast iron mold. The SEM results showed that adding Mg greatly influenced the microstructure of the Zn-based alloys where the degree of fineness of the microstructure increased with a rise in the Mg content. Moreover, polarization measurements revealed that the Zn–0.5Al–0.6Mg alloy attained the lowest degradation rate of 0.33 mm/year as compared to the other investigated alloys which complies the requirements of ideal corrosion rates for biodegradable bone implants. This corrosion rate helps the implantable metal alloy to last in the body until healing of the bone tissue proceeds. The fine structure and uniform distribution of Aluminum oxide and MgZn2 intermetallic phases along the grain boundaries were most likely the main factors in the superior corrosion stability of the Zn–0.5Al–0.6Mg alloy in SBF. However, higher concentrations of Mg (1 wt%) lowered the corrosion resistance of the Zn–Al–Mg alloy which was attributed to the accelerated galvanic corrosion between Zn and Mg2 Zn11 phases and the inhomogeneous distribution of corrosion products on the alloy surface due to the increased grain size and the coarse structure of the Zn alloy.

Tribocorrosion Behaviour of a Ti–25Nb–3Zr–2Sn–3Mo Alloys Induction Nitride Layer in a Simulated Body Fluid Solution

Ti–25Nb–3Zr–2Sn–3Mo (TLM) alloys have been used in orthopaedics due to their excellent biocompatibility. However, the poor tribological performance caused by the low shear strength limits the applicability of TLM alloy. Herein, the surface of the TLM alloy was strengthened by induction nitriding technology, and the microstructure of the formed nitride layer as well as its corrosion property were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical workstation. The results showed that a gradient nitride layer with a thickness of ~30 μm was obtained on the surface of the TLM alloy after induction nitriding and the surface microhardness of the TLM alloy also increased from approximately 230 HV to 1253 HV. Meanwhile, the corrosion resistance of the TLM alloy in simulated body fluids (SBFs), was significantly improved by the nitride layer, which was supported by the corrosion potential value increasing from −665.77 (the raw sample) to −241.00 mV (the nitrided sample). Triborrosion behaviour is also characterized by a reciprocating sliding wear tester connected to an electrochemical workstation with different electrochemical conditions. The results evidenced that the TLM alloy has excellent tribocorrosion resistance after induction nitriding, who’s the mechanical material loss (WA) was only 0.23% of that of the raw sample under a 10 N load, and the total material loss (WT) was 15% of that of the raw sample.

In-vitro degradation behavior of hybrid epoxy-alkyl sol–gel/anodized composite coating on AZ31B Mg alloy

AbstractMg alloys are considered a promising alternative to use as biodegradable implants. However, the main limitations of these alloys are the high susceptibility to hydrogen evolution and corrosion. Consequently, it is necessary to control the corrosion rate through surface treatment techniques. In this regard, a double layer system, based on the first deposition of a MgO coating and the subsequent deposition of an organo-silane sol-gel coating (anodized/SGMI) was proposed to increase the biocompatibility and reduce the corrosion rate of Mg alloy. Sol-gel coatings were prepared using methyltriethoxysilane (MTES), (glycidyloxypropyl) trimethoxysilane (GPTMS), SiO2 nanoparticles, and 1-methyl imidazole (1-MI). 29Si and 13C NMR measurements were performed to investigate the inorganic-organic network formation during the sol-gel synthesis, and to characterize the structure of the cured silane coating. According to the results, the addition of 1-MI mainly promotes the condensation reaction of GPTMS and MTES. After sol-gel deposition, a higher cross-linking coating network was obtained and the degradation of AZ31B Mg alloy in simulated body fluid (SBF) was slowed down. The control of the hydrogen and pH evolution over 450 h suggest that the anodized/SGMI coating system may be suitable for short-term implants applications; particularly for applications that are expected to degrade after 10-12 days such as surgical skin staples. Graphical Abstract

Influence of Tantalum Addition on the Corrosion Passivation of Titanium-Zirconium Alloy in Simulated Body Fluid.

Ti-15%Zr alloy and Ti-15%Zr-2%Ta alloy were fabricated to be used in biomedical applications. The corrosion of these two alloys after being immersed in simulated body fluid for 1 h and 72 h was investigated. Different electrochemical methods, including polarization, impedance, and chronoamperometric current with time at 400 mV were employed. Also, the surface morphology and the compositions of its formed film were reported by the use of scanning electron microscope and energy dispersive X-ray. Based on the collected results, the presence of 2%Ta in the Ti-Zr alloy passivated its corrosion by minimizing its corrosion rate. The polarization curves revealed that adding Ta within the alloy increases the corrosion resistance as was confirmed by the impedance spectroscopy and current time data. The change of current versus time proved that the addition of Ta reduces the absolute current even at high anodic potential, 400 mV. The results of both electrochemical and spectroscopic methods indicated that pitting corrosion does not occur for both Ti-Zr and Ti-Zr-Ta alloys, even after their immersion in SBF solutions for 72 h.

Evaluation of corrosion behaviour of turmeric-coated AZ51 alloy in simulated body fluid for biomedical applications

ABSTRACT In this study, the corrosion behavior of turmeric-coated AZ51 alloy is studied in a simulated bodily fluid (SBF) and then correlated using different characterization techniques. Optical microstructures of all the samples reveal the presence of grains of the α-Mg alloy and precipitates of β-Mg17Al12. Two well-defined peaks were obtained from the XRD patterns -Mg and Mg17Al12, correlating with the optical microscopy results. The potentiodynamic polarisation investigation illustrates the corrosion behavior of uncoated (UC) and turmeric-coated magnesium samples dipped for 24 (DC-24), 48 (DC-48), and 96 hours (DC-96). Results confirmed that the DC-48 sample shows the maximum corrosion resistance among all the samples, and the EIS study correlates well with the study. The mineralization study confirms that the DC-48 sample has the maximum corrosion resistance due to the uniformity and compact nature of the coating.

Insight into synergetic effects of serum albumin and glucose on the biodegradation behavior of WE43 alloy in simulated body fluid

The biodegradation rate of Mg alloy medical devices, such as screws and plates for temporary bone fracture fixation or coronary angioplasty stents, is an increasingly important area of study. In vitro models of the corrosion behavior of these devices use revised simulated body fluid (m-SBF) based on a healthy individual’s blood chemistry. Therefore, model outputs have limited application to patients with altered blood plasma glucose or protein concentrations. This work studies the biodegradation behavior of Mg alloy WE43 in m-SBF modified with varying concentrations of glucose and bovine serum albumin (BSA) to (1) mimic a range of disease states and (2) determine the contributions of each biomolecule to corrosion. Measurements include the Mg ion release rate, electrolyte pH, the extent of hydrogen evolution (as a proxy for corrosion rate), surface morphology, and corrosion product composition and effects. BSA (0.1 g l–1) suppresses the rate of hydrogen evolution (about 30%) after 24 h and—to a lesser degree—Mg2+ release in both the presence and absence of glucose. This effect gets more pronounced with time, possibly due to BSA adsorption on the Mg surface. Electrochemical studies confirm that adding glucose (2 g l–1) to the solution containing BSA (0.1 g l–1) caused a decrease in corrosion resistance (by around 40%), and concomitant increase in the hydrogen evolution rate (from 10.32 to 11.04 mg cm–2 d–1) to levels far beyond the tolerance limits of live tissues.