Behavior In Simulated Body Fluid Research Articles

Electrochemical Study and Mechanical Properties of Ti-Zr Alloy for Biomedical Applications

In response to concerns of potential cytotoxicity and adverse tissue reactions caused by vanadium and aluminum in the currently used biomaterial Ti-6Al-4V, the Ti–20Zr alloy was evaluated in this study because it has been suggested as a candidate for human body implant material. The Ti-20Zr alloy was obtained by vacuum-melting, followed by heat treatment at 1000 °C for 1 h, and then air-cooled. Optical and scanning electron microscopy revealed that the sample had an α and β lamellar microstructure. Analysis showed that the mechanical properties, in terms of hardness measurements performed at low loads, were significantly different between the two phases. Thus, it was found out that the α phase is softer by about 30% compared to the β phase. The Electrochemical Impedance Spectroscopy technique (EIS) was employed to study the electrochemical behavior in simulated body fluid (SBF). The electrochemical behavior demonstrated that Ti-20Zr alloy exhibits excellent corrosion resistance due to the stable oxide layer formed on its surface. SEM and EDS investigations showed that the surface topography, after electrochemical studies, is characterized by a porous film with increased oxygen content, which might be suitable for the osteoinductive growth of bone.

Laser surface structuring of titanium alloy (Ti-6Al-4V) for improved tribocorrosion resistance for bio-implant applications

In this study, laser surface structuring (LSS) of titanium alloy (Ti-6Al-4 V) using pulsed Nd: YLF laser with 100 ns pulse duration at various laser powers, scan speeds, and line-spacings has been undertaken for improving the tribocorrosion property. Due to LSS, there is an increment in nano hardness (4.9 GPa - 6.3 GPa) and Young's modulus (140 GPa − 153 GPa) when compared to untreated Ti-6Al-4 V (3.9 GPa, 123 GPa). The tribocorrosion behavior in simulated body fluid against the ZrO2 ball in fretting mode shows that due to LSS, the degradation rate was significantly reduced (5.3–67.2%) when compared to the untreated one. With an increase in load, the coefficient of friction and material removal rate increases. The mechanism of tribocorrosion is established.

Enhancing the degradation rate and biomineralization nature of antiferromagnetic Fe-20Mn alloy by groove pressing.

The Fe-Mn alloys are potential candidates for biodegradable implant applications. However, the very low degradation rates of Fe-Mn alloys in the physiological environment are a major disadvantage. In this study, the degradation rate of a Fe-20Mn alloy was improved using the groove pressing (GP) technique. Hot rolled sheets of 2 mm thickness were subjected to GP operation at 1000°C. Uniform fine-grained (UFG) Fe-Mn alloys were obtained using the GP technique. The influence of GP on the microstructure, mechanical properties, degradation behavior in simulated body fluid (SBF), surface wettability, biomineralization, and cytocompatibility was investigated and compared to the annealed (A Fe-Mn) and rolled (R Fe-Mn) sample. The groove-pressed Fe-Mn (G Fe-Mn) alloy had a grain size of approximately 40 ± 16 μm whereas the A Fe-Mn and R Fe-Mn samples had grain sizes of 303 ± 81 and 117 ± 14.5 μm, respectively. Enhanced strength and elongation were also observed with the G Fe-Mn sample. The potentiodynamic polarization test showed the highest Icorr, lowest polarization resistance, and lowest Ecorr for the G Fe-Mn sample among all other samples indicating its higher degradation rate. The weight loss data from immersion tests also shows that the percentage of weight loss increases with time indicating the accelerated degradation behavior of the sample. The static immersion test showed an enhancement in weight loss of 0.46 ± 0.02% and 1.02 ± 0.05% for R Fe-Mn and G Fe-Mn samples, respectively, than A Fe-Mn sample (0.31 ± 0.03%) after 56 days in immersion in SBF. The greater biomineralization tendency in UFG materials is confirmed by the G Fe-Mn sample's stronger hydroxyapatite deposition. When compared to the A Fe-Mn and R Fe-Mn samples, the G Fe-Mn sample has a better wettability, which promotes higher cell adhesion and vitality, showing higher biocompatibility. This study demonstrates that Fe-20Mn processed by GP has potential applications for the manufacture of biodegradable metallic implants.

Structural Parameters and Behavior in Simulated Body Fluid of High Entropy Alloy Thin Films.

The structure, composition and corrosion properties of thin films synthesized using the Pulsed Laser Deposition (PLD) technique starting from a three high entropy alloy (HEA) AlCoCrFeNix produced by vacuum arc remelting (VAR) method were investigated. The depositions were performed at room temperature on Si and mirror-like polished Ti substrates either under residual vacuum (low 10-7 mbar, films denoted HEA2, HEA6, and HEA10, which were grown from targets with Ni concentration molar ratio, x, equal to 0.4, 1.2, and 2.0, respectively) or under N2 (10-4 mbar, films denoted HEN2, HEN6, and HEN10 for the same Ni concentration molar ratios). The deposited films' structures, investigated using Grazing Incidence X-ray Diffraction, showed the presence of face-centered cubic and body-centered cubic phases, while their surface morphology, investigated using scanning electron microscopy, exhibited a smooth surface with micrometer size droplets. The mass density and thickness were obtained from simulations of acquired X-ray reflectivity curves. The films' elemental composition, estimated using the energy dispersion X-ray spectroscopy, was quite close to that of the targets used. X-ray Photoelectron Spectroscopy investigation showed that films deposited under a N2 atmosphere contained several percentages of N atoms in metallic nitride compounds. The electrochemical behavior of films under simulated body fluid (SBF) conditions was investigated by Open Circuit Potential (OCP) and Electrochemical Impedance Spectroscopy measurements. The measured OCP values increased over time, implying that a passive layer was formed on the surface of the films. It was observed that all films started to passivate in SBF solution, with the HEN6 film exhibiting the highest increase. The highest repassivation potential was exhibited by the same film, implying that it had the highest stability range of all analyzed films. Impedance measurements indicated high corrosion resistance values for HEA2, HEA6, and HEN6 samples. Much lower resistances were found for HEN10 and HEN2. Overall, HEN6 films exhibited the best corrosion behavior among the investigated films. It was noticed that for 24 h of immersion in SBF solution, this film was also a physical barrier to the corrosion process, not only a chemical one.

On the formation of porosity in hydroxyapatite/polyester high-velocity oxygen-fuel sprayed coatings and their electrochemical behavior in simulated body fluid

On the formation of porosity in hydroxyapatite/polyester high-velocity oxygen-fuel sprayed coatings and their electrochemical behavior in simulated body fluid

Spray-dried calcium phosphate—gelatin composites and their behavior in simulated body fluid with the presence of cross-linking agent

Spray-dried calcium phosphate—gelatin composites and their behavior in simulated body fluid with the presence of cross-linking agent

Metastable FeMg particles for controlling degradation rate, mechanical properties, and biocompatibility of Poly(l-lactic) acid (PLLA) for orthopedic applications

Poly(l-lactic) acid (PLLA) is commonly used in bioabsorbable medical implants, but it suffers from slow degradation rate and rapid decline in mechanical properties for orthopedic applications. To address this drawback, recent research has explored the use of Mg as a filler for PLLA, resulting in composites with improved degradation rate and cytocompatibility compared to neat PLLA. In this study, FeMg powder particles were proposed as fillers for PLLA to investigate the potential of PLLA/FeMg composites for bioabsorbable implants. Cylinder specimens of PLLA, PLLA/Fe, PLLA/Mg and PLLA/FeMg were prepared using solvent casting followed by thermo-molding. The microstructure, thermal behavior, in vitro degradation behavior in simulated body fluid, mechanical properties and cytocompatibility of these composites were examined. The results indicate that the presence of FeMg particles prevents the deterioration of the composite mechanical properties, at least up to 14 days. Once a certain amount of degradation of the composite is reached, the degradation is faster than that of PLLA. Direct cytotoxicity assays revealed that pre-osteoblast MC3T3-E1 cells successfully adhered to and proliferated on the PLLA/FeMg surface. The inclusion of a low percentage of Mg into the Fe lattice not only accelerated the degradation rate of Fe but also improved its cytocompatibility. The enhanced degradation rate, mechanical properties, and osteoconductive properties of this composite make it a promising option for temporary orthopedic biomedical devices.

Electrochemical Corrosion Behavior in Simulated Body Fluid of a Metastable β‐Type Ti29Nb13Ta4.6Zr Biomedical Alloy with Improved Mechanical Properties

Herein, the mechanical properties and corrosion behavior in simulated body fluid of the β‐type Ti29Nb13Ta4.6Zr alloy (TNTZ) are investigated and compared to Ti6Al4V alloy. The samples are obtained from the solution‐treated (ST) and water‐quenched TNTZ bars. Following quenching, the bars are cold rolled aged (CRA) at 673 K for 20 min in order to reach a desired combination of high yield strength and low elastic modulus. The corrosion tests are conducted using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) during a long period of immersion in physiological Ringer's solution (up to 144 h), and the mechanical behaviors are assessed through uniaxial tensile tests. The results show that both TNTZ ST and CRA conditions have lower Young's moduli than Ti6Al4V. However, with CRA treatment, the alloy is significantly strengthened due to a homogeneous precipitation of nanometer‐sized α‐phase with lenticular morphology in the β‐matrix. Potentiodynamic polarization and EIS results reveal that both TNTZ CRA and Ti6Al4V passivate under testing conditions, and the passive current density is very low, providing corrosion resistance in the potential range studied. The EIS results also reveal that the passive film formed on the surface of both materials is highly corrosion resistant.

Accelerated corrosion of zinc, erbium and cerium co-doped Mg-alloys prepared by spark plasma sintering for bioresorbable implant applications

Magnesium (Mg) alloys have become attractive as bioresorbable implants in recent times as they possess compatible mechanical properties with that of the cortical bone. Mechanical properties of Mg alloys can be tailored using suitable alloying elements. Bioresorption, the corrosion in the physiological condition, on the other hand, can be tailored using a variety of techniques such as alloying, melting and thermo-mechanical and cold working as well as and functionally graded coating. Powder metallurgy processes such as spark plasma sintering have gained interest for rapid consolidation of metals which were generally difficult to sinter due to excessive grain growth. In this study, we investigate the potential of a newly designed Mg alloy that is prepared by Spark Plasma Sintering (SPS). We selected the alloying elements zinc (Zn), erbium (Er) and cerium (Ce) depending on their solid solubility in Mg and the potential mechanical properties and expected biocompatibility. We carried out surface analysis using microscopy, microhardness and accelerated corrosion behaviour in simulated body fluid. A possible reason for strengthening and corrosion behaviour has been discussed in light of reduced porosity and grain size. Accelerated corrosion test and microhardness test revealed maximum corrosion rate (39%) and minimum hardness (93.87Hv) for the samples sintered at relatively lower temperature of 400 ᵒC suggesting tunability of both bioresorption and strength of these alloys by controlling density during sintering.

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.

Corrosion behavior, mechanical properties, and in-vitro biocompatibility of cast Mg–3Zn–xSi biodegradable alloys for bone regeneration

In this research, Mg–3Zn–xSi (x = 0, 0.1, 0.3, and 0.6 wt%) biodegradable alloys were produced by simple stir casting method, their microstructure and phase changes were evaluated using X-ray diffraction (XRD), optical microscope (OM) and scanning electron microscope coupled with energy dispersive x-ray analysis (SEM–EDS). Potentiodynamic polarization was conducted to measure the alloys’ corrosion behavior in simulated body fluid (SBF). Tensile strength test and in-vitro biocompatibility evaluation regarding MTT cytotoxicity, ALP osseointegration assay and MG-63 cell growth pattern were conducted. Electrochemical investigations showed that Mg–3Zn alloys enclosing Si attained degradation rates suitable for structural support until bone healing, while the Mg–3Zn alloy without Si had a corrosion rate of 0.128 mm/year which is much lower than the required value. None of the inspected alloys exhibited a significant cytotoxic effect, meanwhile, Mg–Zn base alloy and the alloy with 0.3 wt% Si demonstrated the highest ALP level. The optimum cell growth pattern was demonstrated for Mg–Zn base alloy and the alloy with 0.1 wt% Si. Evidence of calcium phosphate precipitation was observed in the four investigated Mg–3Zn alloys. Therefore, based on the fore mentioned results, Mg–3Zn–xSi alloys were suggested as viable biodegradable materials due to their compatible degradation rates, proved cytocompatibility, high cell viability and excellent osseointegration potential.

Increased body fluid repellency and electrochemical corrosion resistance of intravascular stent materials by ICP-CVD-based DLC thin-film deposition

Intravascular stents face adhesion- and corrosion-based challenges causing In-stent Restenosis (ISR). This study analyzes the influences of thin-film Diamond-Like-Carbon (DLC) deposition on body fluid repellency and corrosion behavior in Simulated Body Fluid (SBF) at 37 °C for intravascular stent materials. The stent specimens of 316 L and 316 LVM stainless steel, Ti-Alloy, and CoCr-Alloy were coated with DLC thin-films by Inductively Coupled Plasma Chemical Vapor Deposition (ICP-CVD). The repellencies of bare and DLC-coated specimens to body fluids, including the blood, plasma, glycerol, and distilled water (DIW) were analyzed by their Contact Angles (CA). Electrochemical impedance spectroscopy (EIS) and corrosion analysis in simulated body fluid were conducted using a potentiostat system. Bare specimens exhibited hydrophilic behavior with 51° CA for distilled water and lower body fluid repellencies with 69°, 64°, and 57° CAs for total blood, blood plasma, and glycerol, respectively. DLC coating improved blood repellency to 88° CA and hydrophobic feature to 81° CA. The electrochemical corrosion analysis exhibited that ICP-CVD based DLC thin-film deposition increased the electrochemical polarization resistance of BMS specimens from 22.02 kΩ.cm2 to 386.6 kΩ.cm2 for 316 L SS, 408.8 kΩ.cm2 for 316 LVM SS, 1703.0 kΩ.cm2 for CoCr-Alloy, and 1748 kΩ.cm2 for Ti-Alloy. The obtained values reduced the corrosion rate from 447.1 μm/year to 0.241 μm/year and the mass loss rate from 357.1 mg/cm2year to 0.165 mg/cm2year. This study concludes that DLC thin-film structures can lower the risk of ISR by adhesion and corrosion inhibition in BMS specimens, and they have a potential application in fluid-repellent and anti-corrosive drug-free stents.

Effect of the electrical discharge machining on Ti6Al4V corrosion behaviour in simulated body fluid

Titanium alloys, such as Ti6Al4V, are widely employed in the biomedical industry for implant applications due to their favourable properties. However, these alloys can experience long-term corrosion in the presence of bodily fluids, which is a critical concern for implants as it affects their timespan. Therefore, this study aimed to examine the corrosion resistance of Ti6Al4V in body fluid. Highly desirable electrical discharge machining (EDM) techniques used for Ti6Al4V sample preparation with three different conditions (oil, deionized water, and hydroxyapatite mixed in deionized water). Corrosion was assessed using electrochemical analyses, with microstructural analysis. Results indicated that the samples produced using water and oil had the best and lowest corrosion resistance, respectively. Protective oxide layer formed during the EDM in water while heterogeneous surface was produced for EDM in oil. The increase in capacitance leads to the thickening of the oxide layer, thereby enhancing the corrosion resistance.

Fabrication of tailored Ti6Al4V-based materials by conventional powder metallurgy for bone implant applications

ABSTRACT This works proposes a methodology for fabricating materials with specific characteristics mimicking human bones. A Ti64 alloy powder was used as the base material and it was mixed with Ag, Ta, TiN and salt particles to obtain different features. A hip-bone like component was fabricated, including a highly porous core of Ti64/25Ta/5Ag and a compact outer shell of Ti64/5Ag that is supposed to improve corrosion and osseointegration. Besides, a harder cover surface in Ti64/10TiN composite should increase the wear resistance. The green component was sintered at 1260°C in argon. Its Young’s modulus was close to the one of bones due to the added porosity, which also provided a permeability close to the one reported for trabecular bones. Tribocorrosion behaviour in simulated body fluid was improved by TiN addition. In conclusion, the proposed processing route was able to produce complex components fulfilling specific features required for human bone replacement.

Fretting corrosion behavior of Ti6Al4V alloy against zirconia-toughened alumina ceramic in simulated body fluid

The fretting corrosion at the head-neck interface of artificial hip joints is an important reason for the failure of prostheses. The Ti6Al4V alloy-zirconia-toughened alumina (ZTA) ceramic combination has been widely used to make the head and neck of artificial hip joints. In this study, its fretting corrosion behavior in simulated body fluid was studied by electrochemical monitoring, surface morphology characterization, and chemical composition analysis. A running condition fretting map (RCFM) of load and displacement was established, including three regimes, namely partial slip regime (PSR), mixed fretting regime (MFR), and gross slip regime (GSR). The friction dissipation energy increased gradually from the PSR to MFR and GSR. In the PSR, the damage mechanisms were slight abrasive wear and tribocorrosion at the edge of contact area, as well as extremely slight adhesive wear at the center. In the MFR, the damage mechanisms were mainly adhesive wear, abrasive wear, and corrosive wear. In the GSR, the damage mechanism was serious abrasive wear, fatigue wear, and corrosive wear combined with slight adhesive wear. Finally, an ion-concentration map was created, displaying the material-loss transition of different displacements and loads. The material loss increased with the increased displacement, and increased first and then decreased with the increased load.

Microstructure and Mechanical Characteristics of Ti-Ta Alloys before and after NaOH Treatment and Their Behavior in Simulated Body Fluid

In the present study, the microstructure and mechanical properties of Ti-xTa (x = 5%, 15%, and 25% wt. Ta) alloys produced by using an induced furnace by the cold crucible levitation fusion technique were investigated and compared. The microstructure was examined by scanning electron microscopy and X-ray diffraction. The alloys present a microstructure characterized by the α' lamellar structure in a matrix of the transformed β phase. From the bulk materials, the samples for the tensile tests were prepared and based on the results and the elastic modulus was calculated by deducting the lowest values for the Ti-25Ta alloy. Moreover, a surface alkali treatment functionalization was performed using 10 M NaOH. The microstructure of the new developed films on the surface of the Ti-xTa alloys was investigated by scanning electron microscopy and the chemical analysis revealed the formation of sodium titanate and sodium tantanate along with titanium and tantalum oxides. Using low loads, the Vickers hardness test revealed increased hardness values for the alkali-treated samples. After exposure to simulated body fluid, phosphorus and calcium were identified on the surface of the new developed film, indicating the development of apatite. The corrosion resistance was evaluated by open cell potential measurements in simulated body fluid before and after NaOH treatment. The tests were performed at 22 °C as well as at 40 °C, simulating fever. The results show that the Ta content has a detrimental effect on the investigated alloys' microstructure, hardness, elastic modulus, and corrosion behavior.

Surface Modified β-Ti-18Mo-6Nb-5Ta (wt%) Alloy for Bone Implant Applications: Composite Characterization and Cytocompatibility Assessment.

Commercially available titanium alloys such as Ti-6Al-4V are established in clinical use as load-bearing bone implant materials. However, concerns about the toxic effects of vanadium and aluminum have prompted the development of Al- and V-free β-Ti alloys. Herein, a new alloy composed of non-toxic elements, namely Ti-18Mo-6Nb-5Ta (wt%), has been fabricated by arc melting. The resulting single β-phase alloy shows improved mechanical properties (Young's modulus and hardness) and similar corrosion behavior in simulated body fluid when compared with commercial Ti-6Al-4V. To increase the cell proliferation capability of the new biomaterial, the surface of Ti-18Mo-6Nb-5Ta was modified by electrodepositing calcium phosphate (CaP) ceramic layers. Coatings with a Ca/P ratio of 1.47 were obtained at pulse current densities, -jc, of 1.8-8.2 mA/cm2, followed by 48 h of NaOH post-treatment. The thickness of the coatings has been measured by scanning electron microscopy from an ion beam cut, resulting in an average thickness of about 5 μm. Finally, cytocompatibility and cell adhesion have been evaluated using the osteosarcoma cell line Saos-2, demonstrating good biocompatibility and enhanced cell proliferation on the CaP-modified Ti-18Mo-6Nb-5Ta material compared with the bare alloy, even outperforming their CaP-modified Ti-6-Al-4V counterparts.

Plasma Electrolytic Oxidation (PEO) Coating on γ-TiAl Alloy: Investigation of Bioactivity and Corrosion Behavior in Simulated Body Fluid

The effect of applied voltage (400, 450, and 500 V) on the microstructure, bioactivity, and corrosion rate of plasma electrolytic oxidation (PEO) coatings on γ-TiAl alloy was investigated. The microstructure and chemical composition of the achieved coatings were studied, along with their corrosion and bioactivity behaviors in simulated body fluid (SBF). The results demonstrated that the higher the coating′s surface pore, the greater the number of suitable sites for the formation of hydroxyapatite with a spherical structure. The coatings applied utilizing 400, 450, and 500 V displayed 59.4, 96.6, and 145 Ω.cm2 as their inner layer electrical resistances, respectively. The findings of the biological examination revealed that Mesenchymal stem cells (MSCs) displayed more cytocompatibility and had a higher capacity for cell attachment in the PEO-coated sample than in γ-TiAl, as a result of better initial cell attachment made possible by the topography of the 500 V PEO coatings. The latter has significant potential to be employed in orthopedic applications.

Characteristics and Morphological Studies of Nd Doped Titanium Thin Film Coating on SS 316L by DC Sputtering

Nd doped Titanium coating was applied on stainless steel 316L by DC sputtering method to investigate the corrosion behavior in simulated body fluid at 37°C. The characterization of coated surface was done by XRD analysis that shows the incorporation of coating peaks within peaks of substrate (SS 316L), SEM/EDS also used to identify the structure and elemental composition of coating layer and the results indicated the formation of titanium carbide with neodymium particles which distributed on the titanium thin film and the EDS analysis showed the presence of Ti, Nd, O and high percent of C. AFM analysis indicated the increasing in surface roughness from 52.20 nm to 176.7 nm after coating with more valleys and peaks in two and three dimensions images, as well as more resistant for wear after coating from Abbott-Firestone results. The results of corrosion measurement showed the more positive corrosion potential for coated surface and decreasing in corrosion current density to obtain protection efficiency equal to 97.11% due to ability of the coating layer to isolate the substrate from corrosive environment.

Biodegradable WE43 Magnesium Alloy Produced by Selective Laser Melting: Mechanical Properties, Corrosion Behavior, and In-Vitro Cytotoxicity

In this work, selective laser melting (SLM) technology was used to prepare Mg-4Y-3Nd-Zr (WE43) alloy. This alloy and production method are promising for the design of biodegradable implants. The aim of this study was to investigate the chemical composition, microstructure, mechanical properties, corrosion behavior in simulated body fluid (SBF), and cytotoxicity of the alloy produced by SLM method and to compare it with conventionally gravity cast reference alloy. Analysis of the surface of the revealed an oxygen content of 7 wt.%. Undesirable unmelted and only partially adhered spherical particles of the starting powder were also found. The microstructure of the material was very fine and consisted of α-Mg dendritic matrix, β-Mg41(Nd, Y)5 intermetallic phase, Y2O3 inclusions, and 0.6 vol.% of residual porosity. The Vickers hardness, compressive yield strength, compressive strength, and maximum compressive strain were 88 HV0.1, 201 MPa, 394 MPa, and 14%, respectively, which are close to the reference values in as-cast. The in vitro corrosion rates determined by immersion and potentiodynamic tests were 2.6 mm/year and 1.3 mm/year, respectively. Cytotoxicity tests indicated good biocompatibility of the 3D-printed alloy.