1,720,981 research outputs found
In vitro corrosion and bio-tribocorrosion performance of electron beam powder bed fusion Ti6Al4V specimens with lapping and superfinishing treatments
No full textLapping and superfinishing treatments were adopted to enhance the corrosion performance of electron beam powder bed fusion (EB-PBF)–Ti6Al4V alloys, and the results were compared with those of the wrought counterparts. The effect of the lapping and superfinishing on the electrochemical behaviour of the samples was scrutinized in a phosphate-buffered saline (PBS) + H2O2 solution with and without bovine serum albumin (BSA) employing potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Profilometer data revealed an impressive 80% and 95% reduction in surface roughness for lapping and superfinishing, respectively, compared to the grinding process. Following a wettability test, smoother surfaces exhibited increased hydrophilicity, with contact angles for the wrought samples ranging from 73.13° (lapped) to 87.59° (grinded) and for the EB-PBF–Ti6Al4V samples from 72.87° (superfinished) to 89.15° (grinded). The electrochemical findings indicated that EB-PBF–Ti6Al4V alloys manifest higher corrosion resistance relative to wrought counterparts, owing to an increased presence of the β phase in the microstructure. Considering that the EB-PBF samples were optimized from the corrosion point of view, tribocorrosion tests were focused on them. Lapping and superfinishing treatments significantly bolstered bio-tribocorrosion resistance of EB-PBF–Ti6Al4V specimens, leading to a noteworthy 50% positive shift in the corrosion potential of EB-PBF–Ti6Al4V alloy during bio-tribocorrosion testing. Although BSA demonstrated a corrosion-mitigating effect in all conditions, its impact on tribocorrosion properties was negligible
Evaluation of layer-by-layer assembly systems for drug delivery and antimicrobial properties in orthopaedic application
Full text linkLayer-by-layer self-assembly systems were developed using monolayer and multilayer carriers to prevent infections and improve bone regeneration of porous Ti-6Al-4V scaffolds. These polymeric carriers incorporated (Gel/Alg-IGF-1 + Chi-Cef) and (4Gel/Alg-IGF-1 + Chi-Cef) on the surface of porous implants produced via electron beam melting (EBM). The results showed that the drug release from multilayer carriers was higher than that of monolayers after 14 days. However, the carrier containing Gel/Alg-IGF-1 + Chi-Cef exhibited more sustained behavior. Cell morphology was characterized, revealing that multilayer carriers had higher cell adhesion than monolayers. Additionally, cell differentiation was significantly greater for (Gel/Alg-IGF-1) + Chi-Cef, and (4Gel/Alg-IGF-1) + Chi-Cef multilayer carriers than for the monolayer groups after 7 days. Notably, the drug dosage was effective and did not interfere, and the cell viability assay showed safe results. Antibacterial evaluations demonstrated that both multilayer carriers had a greater effect on Staphylococcus aureus during treatment. The carriers containing lower alginate had notably less effect than the other studied carriers. This study aimed to test systems for controlling drug release, which will be applied to improve MG63 cell behavior and prevent bacterial accumulation during orthopaedic applications
Surface modification of additive manufactured Ti6Al4V scaffolds with gelatin/alginate- IGF-1 carrier: An effective approach for healing bone defects
No full textThe study investigates the potential of porous scaffolds with Gel/Alg-IGF-1 coatings as a viable candidate for orthopaedic implants. The scaffolds are composed of additively manufactured Ti6Al4V lattices, which were treated in an alkali solution to obtain the anatase and rutile phases. The treated surface exhibited hydrophilicity of <11.5°. A biopolymer carrier containing Insulin-like growth factor 1 was coated on the samples using immersion treatment. This study showed that the surface-modified porous Ti6Al4V scaffolds increased cell viability and proliferation, indicating potential for bone regeneration. The results demonstrate that surface modifications can enhance the osteoconduction and osteoinduction of Ti6Al4V implants, leading to improved bone regeneration and faster recovery. The porous Ti6Al4V scaffolds modified with surface coating of Gel/Alg-IGF-1 exhibited a noteworthy increase in cell viability (from 80.7 to 104.1%viability) and proliferation. These results suggest that the surface modified scaffolds have potential for use in treating bone defects
Hybrid Additive Manufacturing of a Ti–6Al–4 V (Electron Beam‐Powder Bed Fusion) and a AISI 316 L (Laser Beam‐Powder Bed Fusion) via Dissimilar Transient Liquid Phase Bonding
No full textPresent study investigates a hybrid additive manufacturing strategy using transient liquid phase bonding (TLP) to join a laser beam powder bed–fused AISI 316 L with an electron beam powder bed–fused Ti–6Al–4 V utilizing a copper interlayer. TLP is performed in a vacuum furnace for 1 h at 890, 930, and 970 °C. Joint zones (JZs) are analyzed by scanning electron microscopy and X-ray diffraction; mechanical properties by microhardness and shear tests; corrosion resistance by electrochemical impedance spectroscopy, cyclic potentiodynamic polarization, and immersion in phosphate-buffered saline solution. The findings indicate that raising the bonding temperature to 970 C leads to an expansion of the isothermal solidification region, effectively eliminating Ti–Cu intermetallic compounds at the joint center. However, this temperature also promotes titanium and iron diffusion, resulting in the development of brittle Ti–Fe phases. Consequently, joint hardness increases, while shear strength declines—from 301.6 MPa (TLP 890) to 262 MPa (TLP 930) and 174 MPa (TLP 970). Corrosion resistance rises from an R1 value of 241.5 kΩ cm2 (TLP-890) to 314.4 kΩ cm2 (TLP-970), while corrosion current density (Icorr) decreases from 1.91 × 10−3 μA cm−2 (TLP-890) to 6.55 × 10−4 μA cm2 (TLP-970)
Tailoring surface characteristics of laser powder bed fusioned AISI 316L stainless steel for biomedical applications
No full textAISI 316L stainless steel, manufactured using laser powder bed fusion (L-PBF) technology, is renowned for its low carbon content, biocompatibility, excellent mechanical properties, and corrosion resistance, making it suitable for biomedical applications. This research focuses on the vibro finishing and laser polishing of L-PBF AISI 316L stainless steel to improve its surface characteristics. The quality of the treatments was evaluated using various techniques, including X-ray diffraction, scanning electron microscopy, surface roughness analysis, electrochemical tests, wettability assessment, cytotoxicity analysis, and cell adhesion promotion assessment. The results indicate that both surface treatments effectively reduced surface roughness under optimal conditions. Laser-polishing treatment significantly improved wettability and demonstrated higher corrosion resistance during experiments conducted in phosphate-buffered saline. Electrochemical outcomes indicate that the vibro-finished and laser-polished samples possess superior corrosion resistance compared to the as-built L-PBF, which can be attributed to the improvement in surface properties. Moreover, the treated samples exhibited favorable surface energy, positively influencing cell adhesion. Furthermore, analysis of cell morphology reveals that when MG63 cells are cultured on laser-polished surfaces, they exhibit better adhesion compared to the as-built samples. These findings highlight the potential of vibro-finishing and laser-polishing techniques in enhancing the surface quality and biocompatibility of L-PBF AISI 316L stainless steel, offering promising prospects for its application in biomedical devices
A novel titanium alloy for load-bearing biomedical implants: Evaluating the antibacterial and biocompatibility of Ti536 produced via electron beam powder bed fusion additive manufacturing process
No full textAdditive manufacturing (AM) of Ti-based biomedical implants is a pivotal research topic because of its ability to produce implants with complicated geometries. Despite desirable mechanical properties and biocompatibility of Ti alloys, one major drawback is their lack of inherent antibacterial properties, increasing the risk of postoperative infections. Hence, this research focuses on the Ti536 (Ti5Al3V6Cu) alloy, developed through Electron Beam Powder Bed Fusion (EB-PBF), exploring bio-corrosion, antibacterial features, and cell biocompatibility. The microstructural characterization revealed grain refinement and the formation of Ti2Cu precipitates with different morphologies and sizes in the Ti matrix. Electrochemical tests showed that Cu content minimally influenced the corrosion current density, while it slightly affected the stability, defect density, and chemical composition of the passive film. According to the findings, the Ti536 alloy demonstrated enhanced antibacterial properties without compromising its cell biocompatibility and corrosion behavior, thanks to Ti2Cu precipitates. This can be attributed to both the release of Cu ions and the Ti2Cu precipitates. The current study suggests that the EB-PBF fabricated Ti536 sample is well-suited for use in load-bearing applications within the medical industry. This research also offers an alloy design roadmap for novel biomedical Ti-based alloys with superior biological performance using AM methods
Surface functionalization of additively manufactured Ti6Al4V scaffolds with CaP/ZnO coatings
No full textA biologically active coating with strong adhesion can improve the inherent bioinert nature of the additively manufactured Ti6Al4V scaffolds. In this research, a calcium phosphate coating containing antibacterial zinc oxide nanoparticles was applied onto the lattice-structured Ti6Al4V scaffolds using the plasma electrolytic oxidation (PEO) method, and its corrosion resistance and in vitro bioactivity were analyzed. The results revealed that the thickness of the CSh (Coat-Short: Scaffold with an approximate porosity size of 2.23 mm and coated) sample coating was approximately 1.8 times thicker that of the coating created on the CL (Coat-Long: Scaffold with an approximate porosity size of 3.74 mm and coated) sample. Zinc oxide nanoparticles in the coating were found to be uniformly dispersed, resulting in a 5.5% reduction in the hydrophilic behavior of the coatings. Moreover, both types of samples, with the reinforcement of the barrier layer, successfully improved the long-term corrosion behavior of the substrate, with a more pronounced effect on the CSh samples. After 14 days of immersion in simulated body fluid, cauliflower-shaped hydroxyapatite deposits were observed across the entire surface of the coatings. MG63 cells on the CSh sample demonstrated a wider spread and greater adhesion compared to other samples. Additionally, the cell viability increased from 83.3 +/- 4.1 (% control) in the uncoated sample to 94.9 +/- 1.1 (% control). These results suggest that coatings fabricated on scaffold surfaces with smaller porosity (CSh) exhibit more favorable corrosion and biological behavior, highlighting their potential applications in orthopedics
Electrochemical Behavior of Electron Beam Powder Bed Fused Ti536 Alloy under Simulated Inflammatory Conditions
Full text linkMechanical, electrochemical and permeability behaviour of Ti6Al–4V scaffolds fabricated by electron beam powder bed fusion for orthopedic implant applications: The role of cell type and cell size
Full text linkTi–6Al–4V scaffolds have attracted much attention for biomedical applications owing to their bone-mimicking mechanical properties and better bone tissue in-growth and additive manufacturing can be employed to fabricate complex geometry scaffolds. The present study aimed to investigate the effects of scaffold architecture on the mechanical, electrochemical, and permeability behaviour of Ti–6Al–4V scaffolds fabricated by electron beam powder bed fusion (EB-PBF). For this, scaffolds with diamond and rhombic dodecahedron cell types, having various cell sizes, were designed and successfully fabricated. Chemical etching minimized the surface defects and improved the geometric fidelity of the scaffolds compared to the original designs. The larger the cell size, the coarser the dual α/β phase microstructure due to the higher heat accumulation in thicker struts. The scaffold architecture proved significant effects on the mechanical properties, where all scaffolds were mechanically comparable with human bone. Short/long-term electrochemical corrosion tests indicated that the corrosion performance significantly improved with an increase in cell size, irrespective of the cell type; this was attributed to the lower exposure of surface area to the electrolyte, coarse microstructure and a higher fraction of β phase. This study recommended that the EB-PBF Ti–6Al–4V scaffolds are promising candidates for orthopaedic implant applications from mechanical and electrochemical points of view
Surface modified Ti6Al4V for enhanced bone bonding ability – Effects of silver and corrosivity at simulated physiological conditions from a corrosion and metal release perspective
Full text linkDifferent surface treatments, with and without silver (Ag), of a Ti6Al4V alloy for increased bone bonding ability were investigated and compared with non-treated surfaces. Studies were conducted at 37 degrees C in phosphate buffered saline (PBS, pH 7.4) of varying hydrogen peroxide (H2O2) and bovine serum albumin (BSA) concentrations. Increased levels of metal release and corrosion were observed in the presence of both H2O2 and BSA due to complexation with Ti and Al in the surface oxide, respectively. Ag release was enhanced by the presence of BSA. Galvanic effects by Ag were minor, but possibly observed in the most corrosive environment.</p
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