Alloy In Simulated Body Fluid Research Articles

Corrosion Behavior of Mg-Zn-Y-Nd Alloy in Simulated Body Fluid

Corrosion Behavior of Mg-Zn-Y-Nd Alloy in Simulated Body Fluid

Role of porosity on electrochemical corrosion behavior of porous Ti-20Nb-5Ag alloy in simulated body fluid

Porous titanium alloys are presently well-considered materials for orthopedic applications owing to their superior mechanical properties, excellent biocompatibility and high resistance to corrosion. Also, porous alloys are potentially minimizing the risk of stress-shielding effect as compared to bulk implant materials. In this present work focused to examine electrochemical corrosion behavior of porous Ti-20Nb-5Ag alloy (wt%) with different porosity levels. This designed alloy composition of elemental powders was mixed through mechanically alloying. The mechanically alloyed powder blended with four different amounts of NH4HCO3 (wt%), use to prepare the porous Ti-20Nb-5Ag alloy with porosity ranging from 22% to 68%. After the successful development of porous samples, we investigated the effect of porosity levels on electrochemical corrosion behavior of porous Ti-20Nb-5Ag alloys by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in simulated body fluid (SBF) at 37 °C. The results show that an increasing the trend of porosity level causes a reduction of corrosion resistance. With increasing porosity, the corrosion current density increased and decreases the electrochemical polarization resistance in the SBF solution.

Effect of melting method on the bio-corrosion resistance of Mg67Zn28Ca5 cast magnesium alloy in simulated body fluid

In recent years, biodegradable magnesium alloys have attracted considerable attention in medical devices, such as permanent implants and stents. However, poor corrosion resistance is a major problem limiting the practical application of magnesium alloys. In this study, Mg67Zn28Ca5 alloys were prepared via two different methods, namely, vacuum induction melting and ulfur hexafluoride shielded melting. The effect of melting method on the bio-corrosion resistance of MgZnCa cast magnesium alloy was also studied. The microstructure and phase composition of Mg67Zn28Ca5 alloys were investigated by optical microscopy and X-ray diffraction. The element distribution and surface morphology of Mg67Zn28Ca5 alloys were examined by scanning electron microscopy and energy-dispersive spectroscopy. The corrosion resistance of Mg67Zn28Ca5 alloys was measured via electrochemical and immersion tests. Results showed uniform composition of the Mg67Zn28Ca5 alloy melted by vacuum induction. Immersed in the simulated body fluid, the corrosion rate of Mg67Zn28Ca5 by vacuum induction melting (0.2618 mm/a) was lower than that by ulfur hexafluoride shielded melting (0.9686 mm/a); the corrosion potential of Mg67Zn28Ca5 melted by vacuum induction (−1313 mV) was nobler than that by ulfur hexafluoride shielded melting (−1483 mV); the corrosion current of Mg67Zn28Ca5 by vacuum induction melting (1.202 × 10−5 A) was lower than that by ulfur hexafluoride shielded melting (4.332 × 10−5 A). The Mg67Zn28Ca5 by vacuum induction melting showed uniform corrosion behavior.

Stress corrosion cracking behavior of zirconia ALD–coated AZ31 alloy in simulated body fluid

Stress corrosion cracking behavior of zirconia ALD–coated AZ31 alloy in simulated body fluid

Effect of immersion time on corrosion behavior of Mg-2Nd-0.5Zn-0.4Zr-1Y alloy in simulated body fluid

The purpose of this paper is to investigate the corrosion behavior of biodegradable Mg-2Nd-0.5Zn-0.4Zr-1Y alloy immersed in simulated body fluid (SBF) with different immersion times. The corrosion behavior of the materials in SBF was determined by optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), electrochemical test and immersion tests. The results indicated that the Mg-2Nd-0.5Zn-0.4Zr-1Y alloy was comprised of α-Mg matrix, Mg12Nd, Mg24Y5 and MgZn phases and the average grain size was about 60 μm. The corrosion started from the weak region between the eutectic phase/Zr-rich region and α-Mg matrix. The corrosion products were mainly composed of Mg(OH)2, CaCO3 and Ca5(PO4)3(OH). The corrosion form of Mg-2Nd-0.5Zn-0.4Zr-1Y alloy was mainly pitting corrosion. With the prolongation of immersion time, the pitting began to grow and eventually developed into filiform corrosion. The degradation behavior of the alloy in SBF included main four stages: (a) stage 1: galvanic corrosion; (b) stage 2: pitting corrosion; (c) stage 3: accumulated hydrogen bursting the corrosion layer and (d) stage 4: lateral and longitudinal growth of pitting.

The influence of the crosslinking degree on the corrosion protection properties of chitosan coatings in simulated body fluid

This paper describes the protection of magnesium AZ31 alloy sheets in a simulated body fluid (SBF) medium provided by chitosan coatings. It demonstrates, by means of potentiodynamic polarization curves and electrochemical impedance spectroscopy, that chitosan coatings with a crosslinking degree of up to 42% are efficient in protecting the alloy in SBF, with a performance superior to similar coatings reported in the literature. With higher crosslinking degrees the coating becomes brittle and susceptible to cracks, decreasing its protective properties. The hydrogen evolution rate observed for the best coating complies with the acceptance level and further demonstrates its potential to control the degradation of magnesium alloy implants.

Elucidating the role of microstructural modification on stress corrosion cracking of biodegradable Mg4Zn alloy in simulated body fluid.

This paper investigates the effect of microstructure modification by heat treatment on stress corrosion cracking (SCC) behavior of Mg4Zn alloy in simulated body fluid (SBF). Mg4Zn alloy in as cast, solution heat treated and peak aged conditions was susceptible to SCC in SBF when strained at 3.6 × 10-6 s-1. SCC index based on fracture energy is least for solutionized alloy (0.84), while 0.88 for as cast and peak aged alloys. Fractographic analysis indicates predominantly intergranular SCC for solution treated alloy initiated by anodic dissolution near grain boundaries. As cast and peak aged alloy shows mainly transgranular failure due to hydrogen embrittlement adjacent to secondary phase particles.

Improved corrosion performance of biodegradable magnesium in simulated inflammatory condition via drug-loaded plasma electrolytic oxidation coatings

Magnesium and its alloys are nowadays one of the most common biodegradable materials for orthopedic applications. Following the implantation of an orthopedic device, near the implant hydrogen peroxide and acidic environment are generated by an inflammatory reaction. In this study, a betamethasone sodium phosphate (BSP) layer as an anti-inflammatory drug was prepared on plasma electrolytic oxidation (PEO) coatings by a dip-coating process on magnesium alloys. X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), field emission scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (FESEM-EDX) and atomic force microscopy (AFM) were utilized for characterization studies. The results showed that the BSP layer successfully sealed the PEO coating. The corrosion resistance of the uncoated and coated samples was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests in normal and simulated inflammatory conditions. During the simulated inflammation, the samples indicated an enhanced corrosion rate compared to that of normal condition. The results in the inflammatory environment showed that the corrosion resistance of the PEO/BSP coating was remarkably improved by two or three orders of magnitude, compared with uncoated Mg alloy and the PEO coating. Immersion tests show that the BSP layer significantly improves the bioactivity of PEO-coated Mg alloy in simulated body fluid (SBF). Moreover, the in vitro release behavior of drug loaded PEO coating was evaluated.

The corrosion behaviour of as-welded and post-weld heat treated Ti6Al4V alloy in simulated body fluid

In this study, the corrosion behavior of Ti6Al4V alloy base metal, laser welded and post-weld heat treated (PWHT) samples in simulated body fluid was investigated. The potentiodynamic polarization curves of the as-welded and PWHT samples were compared with each other and with the base metal. Surface morphologies of samples were evaluated. The polarization curves indicate that, the lower corrosion resistance obtained for as-welded samples as compared to base metal. The corrosion resistance of welded joints improved with increasing welding speed. PWHT process has positively affected to the corrosion properties of the laser welded Ti6Al4V joints.

Wear Behavior of Biodegradable Mg–5Zn–1Y–(0–1)Ca Magnesium Alloy in Simulated Body Fluid

In this study, wear behavior of biodegradable Mg–5Zn–1Y–(0–1)Ca alloys is investigated in simulated body fluid. Wear test is performed using a pin-on-disc system, under three different loads of 10, 20 and 40 N, at ambient temperature; and the whole configuration is exposed to simulated body fluid. The volumetric wear rate and friction coefficient of each alloy are determined. The worn surfaces are analyzed using a scanning electron microscope, equipped with an energy dispersive spectrometer to determine the involved main wear mechanism. The Ca-free alloy contains α-Mg and intermetallic Mg3YZn6, and Ca addition produces another intermetallic Ca2Mg6Zn3. Results show that different wear mechanisms and rates, as well as friction coefficients, are achieved due to the effect of simulated body fluid on the alloys with regards to the different Ca content and the presence of corrosion products. Microscopic studies reveal that abrasion is the dominant wear mechanism taken place in all alloys under all loads. Increasing Ca content leads to wear resistance deterioration while increasing wear load results in decreasing wear rate and friction coefficient of the alloys. The results of the wear rate and friction coefficient of Mg–5Zn–1Y–1Ca alloy exhibit greater instability compared to the other alloys due to its more enhanced corrosion caused by the formation of the intermetallic Ca2Mg6Zn3 particles. In total, Ca-free alloy provides the best wear resistance, especially at the higher wear load.

Effect of Zn content and heat treatment on tribological behavior of biodegradable Mg-xZn alloys in simulated body fluid

In this study, magnesium alloys with different weight fractions of zinc were fabricated and heat treatment was performed. Microstructure of specimens was characterized by Light Optical Microscope (LOM). Wear tests were applied under different loads in simulated body fluid. Results show that aging process effects tribological behavior of Mg–Zn alloys positively. Mg-3Zn alloy exhibits best wear performance under 2 N load among the samples. Simulated body fluid possesses lubricant properties during wear tests. 16 h heat treated alloys show better wear characteristic than non-heat treatment samples due to decreasing of internal stress. Abrasive and oxidative wear mechanisms are observed by Scanning Electron Microscope (SEM).

Biodegradation Behavior of Coated As-Extruded Mg–Sr Alloy in Simulated Body Fluid

As-extruded Mg–Sr alloy, a kind of promising biodegradable biomedical material, was coated using micro-arc oxidation and also using a phosphate conversion coating. The corrosion behaviors were investigated using Hanks’ solution. The corrosion of the as-extruded Mg–Sr alloy became more serious with increasing immersion time; that is, the corrosion pits became more numerous, larger and deeper. The micro-arc oxidation coating and the phosphate conversion coating were effective in improving the corrosion resistance of the as-extruded Mg–Sr alloy. The micro-arc oxidation coating was much more effective. Moreover, the as-extruded Mg–Sr alloy and the coated as-extruded Mg–Sr alloy exhibited lower corrosion rates than the as-cast Mg–Sr alloy and the corresponding coated as-cast Mg–Sr alloy, indicating that the corrosion properties of the coated samples are dependent on their substrates. The finer microstructure of the substrate of the as-extruded condition corroded much slower. The corrosion resistance of the coated Mg–Sr alloy depended on the coating itself and on the microstructure of the substrate.

3D printing of Zr-based bulk metallic glasses and components for potential biomedical applications

In this work, the 3D printing technique based on selective laser melting (SLM) was applied to fabricate a Ni-free and Ag-bearing Zr-based bulk metallic glass (BMG) and porous architectures with complex geometries and various functions. The 3D-printed Zr-based BMG was systematically examined by a set of experiments, including microstructure characterizations, mechanical testing, wear and corrosion resistance measurements, in vitro biocompatibility and antibacterial capability assessments. We revealed that the 3D-printed BMG presents almost fully amorphous structure with a high strength (>1700 MPa) and relatively low Young's modulus (∼80 GPa). The wear resistance was comparable to the commercial Ti6Al4V medical alloy in simulated body fluid (SBF), and the corrosion resistance surpassed Ti6Al4V due to lower corrosion rate as well as smaller passive current density. In addition, the 3D-printed BMG showed excellent biocompatibility, as indicated by superior cell proliferation support and ppb level of ion release. More importantly, the 3D printed BMG also exhibited excellent antibacterial ability against E. coli due to the inclusion of a trace amount of Ag. Furthermore, for application purposes, porous BMG components with pore size of 500 μm were printed by SLM technique, which displayed an interconnected porosity of 70% and extremely low Young's modulus of 13 GPa (being comparable to the human bone tissue), while maintaining a high yield strength of 350 MPa. The findings in this work suggested that the SLM-based 3D printing technique could be promising for manufacturing Zr-based BMGs with complex geometries in a wide range of biomedical applications.

In vitro bioactivity of laser surface-treated Ti6Al4V alloy.

The effects of lasing parameters on the precipitation of hydroxyapatite (HA) on the commercial Ti6Al4V alloy in simulated body fluid (SBF) were investigated. Ti6Al4V plates were polished and ultrasonically cleaned in acetone and ethyl alcohol, respectively. The specimen surfaces were treated with Er:YAG laser using super short pulse (SSP, 50μs) and very short pulse (VSP, 100μs) modes. Surface roughness was measured before and after laser treatment. The specimens were immersed in simulated body fluid (SBF) for 1, 3, and 7days and, then the amount of Ca and P precipitation on specimens was determined using SEM/EDS analysis. An average roughness varying between 0.19 and 0.81μm in surface roughness was detected in all laser-treated specimens depending on the lasing parameters. The highest surface roughness and Ca precipitation were found in VSP group (20Hz and 5W). Laser treatment of specimen surfaces has dramatically increased the HA precipitation due to the increasing surface roughness. It is also concluded that the immersion time was effective on the HA precipitation as well.

Corrosion Behavior of Hydrotalcite Film on AZ31 Alloy in Simulated Body Fluid

The hydrotalcite (HT) film is a promising bioactive coating for magnesium alloys. In the present study, we investigate the corrosion behavior of HT film in the simulated body fluid (SBF), and compare with which in NaCl solution. The HT film can provide a very plummy initial protection to the AZ31 alloy in SBF. The corrosion behavior of the HT film in the two solutions is quite different. When in 0.1 mol·L−1 NaCl solution, the film is dissolved gradually, and filiform corrosion is predominant after 3 days immersion. While in Hank’s solution, the thickness and composition of the film are changed. A corrosion products layer mainly consisted of Mg/Ca–PO43−/HPO42−, and minor of CaCO3 is deposited on the top of HT film, which enhances the barrier effect of the HT film. As a result, except for local pit corrosion at several active places, most of the area of the coated sample still remains integral even after immersion for 15 days. It is demonstrated that the HT film has better corrosion protection effect in SBF than in NaCl solution.

Advancement of the artificial amorphous-crystalline structure of laser cladded FeCrMoCB on nickel-free stainless-steel for bone-implants

Abstract This research proposes the development of amorphous-crystalline FeCrMoCB layer as a promising biomaterial for bone-implant applications. The FeCrMoCB amorphous powder was laser cladded on nickel-free stainless-steel (Cronidur30) using three laser specific energies (Es) levels (31.8, 27.5 and 23.4 J/mm2) to attain different amorphous contents. The amorphous-crystalline structure and the microstructure were investigated using X-ray diffraction and scanning electron microscope, respectively. Later, the corrosion rate and the wear rate in simulated body fluids (SBF) were evaluated to investigate the advancement of the artificial amorphous-crystalline structure of laser cladded FeCrMoCB metallic glass (MG) composite via electrochemical corrosion test and pin-on-disc test, respectively. The hardness and Young's modulus (E) were acquired using nanoindentation measurement while the cytocompatibility was evaluated by MTT assay using MC3T3 cell-lines. The material characterization showed that increasing of Es resulted in decreasing the amorphous phase and increasing the crystalline phase. The laser cladded FeCrMoCB MG composite showed significant enhancement of the corrosion and wear resistance in SBF implying longer implant service time. This advancement behavior is not only superior to the uncoated substrate, but also compared to other biomaterials including Zr-based MG, Ti6Al4V, and CoCrMo alloys in SBF. Finally, the FeCrMoCB MG composite showed an acceptable cytocompatibility behavior bringing promising enhanced characteristics for bone-implant material.

Effect of Zirconia ALD coating on stress corrosion cracking of AZ31 alloy in simulated body fluid

In the last years, magnesium (Mg) and its alloys have been widely studied as materials for temporary implant devices. However, one of the main limitations that hampers its use in these applications is the occurrence of corrosion-assisted cracking phenomena, such as stress corrosion cracking (SCC) and corrosion fatigue (CF), in presence of the simultaneous action of corrosive human-body-fluid and mechanical loadings. This work aims to provide some improvements in the field, assessing the effect of a 100nm thick zirconia coating produced by means of atomic layer deposition (ALD) on the SCC susceptibility of AZ31 alloy. Slow strain rate tests (SSRT) have been carried out with an applied strain rate equal to 2.6 10-6 s-1, and the samples were immersed in simulated body fluid at 37 °C for the whole duration of the tests. The presence of the coating has revealed to provide a reduction in the SCC susceptibility, measured by means of the ISCC indexes. In addition, to provide an explanation of the observed behavior, corrosion experiments (potentiodynamic polarization curves and hydrogen evolution experiments) have been carried out.

Scanning Electrochemical Microscopy (SECM) Study of the Electrochemical Behavior of Anodized AZ31B Magnesium Alloy in Simulated Body Fluid

In this work, scanning electrochemical microscopy (SECM) was employed to study the corrosion behavior of anodized AZ31B magnesium alloy exposed to simulated body fluid. SECM measurements were carried out in surface generation/tip collection mode. The hydrogen evolution flux caused during corrosion of the magnesium alloy was oxidized at the ultra-microelectrode (UME). Thus, this experimental procedure allowed evaluating the effect of the anodic protection in this alloy from the SECM analysis of Z- approximation curves, cyclic voltammograms and topographic maps. The results evidence differences in the local electrochemical response of magnesium alloy in the anodized and pristine conditions. The main sites of H2 evolution were verified in the magnesium alloy without anodizing at short exposure times.

Surface Nanocrystallization Induced by Ultrasonic Shot Peening and Its Effect on Corrosion Resistance of Ti–6Al–4V Alloy

Alloy Ti–6Al–4V was subjected to ultrasonic shot peening (USP) for 1 min (min) and 5 min to examine the effect of surface nanostructure on corrosion resistance of this alloy in simulated body fluid (SBF). USPed samples were also subjected to stress relieving (SR) treatment at 400 °C for 1 h in the argon atmosphere (AR). The surface nanostructure and constituted phases were characterized by TEM, and the effect of USP was examined on electrochemical corrosion resistance in SBF solution. It has been observed that corrosion resistance is enhanced due to USP. The development of the resistance to corrosion is attributed to the quick formation of protective oxide scale due to extensive increase in number of grain boundaries and the associated compressive residual stress induced by USP. The relatively lower corrosion resistance and higher tendency of pitting following SR treatment of the USPed specimens are due to decreasing the associated residual stress.

Effects of laser shock peening on the corrosion behavior and biocompatibility of a nickel–titanium alloy

Nickel-titanium (NiTi) alloy is an attractive material for biomedical implant applications. In this study, the effects of laser shock peening (LSP) on the biocompatibility, corrosion resistance, ion release rate and hardness of NiTi were characterized. The cell culture study indicated that the LSP-treated NiTi samples had lower cytotoxicity and higher cell survival rate than the untreated samples. Specifically, the cell survival rate increased from 88 ± 1.3% to 93 ± 1.1% due to LSP treatment. LSP treatment was shown to significantly decrease the initial Ni ion release rate compared with that of the untreated samples. Electrochemical tests indicated that LSP improved the corrosion resistance of the NiTi alloy in simulated body fluid, with a decrease in the corrosion current density from 1.41 ± 0.20 μA/cm2 to 0.67 ± 0.24 μA/cm2 . Immersion tests showed that calcium deposition was significantly enhanced by LSP. In addition, the hardness of NiTi alloy increased from 226 ± 3 HV before LSP to 261 ± 3 HV after LSP. These results demonstrated that LSP is a promising surface modification method that can be used to improve the mechanical properties, corrosion resistance and biocompatibility of NiTi alloy for biomedical applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1854-1863, 2019.