Influence of surface treatment on PEDOT coatings: surface and electrochemical corrosion aspects of newly developed Ti alloy

Performance and Durability of Non-Stick Coatings Applied to Stainless Steel: Subtractive vs. Additive Manufacturing

This study compares subtractive manufacturing (SM) and additive manufacturing (AM) techniques in the production of stainless-steel parts with non-stick coatings. While subtractive manufacturing involves the machining of rolled products, additive manufacturing employs the FFF (fused filament fabrication) technique with metal filament and sintering. The applied non-stick coatings are commercially available and are manually sprayed with a spray gun, followed by a curing process. They are an FEP (fluorinated ethylene propylene)-based coating and a sol-gel ceramic coating. Key properties such as surface roughness, water droplet sliding angle, adhesion to the substrate and wear resistance were examined using abrasive blasting techniques. In the additive manufacturing process, a higher roughness of the samples was detected. In terms of sliding angle, variations were observed in the FEP-based coatings and no variations were observed in the ceramic coatings, with a slight increase for FEP in AM. In terms of adhesion to the substrate, the ceramic coatings applied in the additive process showed a superior behavior to that of subtractive manufacturing. On the other hand, FEP coatings showed comparable results for both techniques. In the wear resistance test, ceramic coatings outperformed FEP coatings for both techniques. In summary, additive manufacturing of non-stick coatings on stainless steel showed remarkable advantages in terms of roughness, adhesion and wear resistance compared to the conventional manufacturing approach. These results are of relevance in fields such as medicine, food industry, chemical industry and marine applications.

Surface Properties and In Vitro Corrosion Studies of Blasted and Thermally Treated Ti6Al4V Alloy for Bioimplant Applications

The biomedical Ti6Al4V alloy was thermally treated under sandblasting and mirror finish surface preparation conditions. The surface morphology, structure, roughness, wettability, and energy were characterized. Microhardness and in vitro corrosion studies were carried out. X-ray diffraction results showed a formation of rutile TiO₂ phase for thermally treated samples under different pretreated conditions. The thermally oxidized samples exhibited an increase in microhardness compared to the untreated mirror finish and sandblasted samples by 22 and 33%, respectively. The wettability study revealed enhanced hydrophilicity of blasted and thermally treated samples. The surface energy of the thermal treatment samples increased by 26 and 32.6% for mirror surface and blasted preconditions, respectively. The acquired in vitro corrosion results using potentiodynamic polarization measurement and electrochemical impedance spectroscopy confirmed the surface protective performance against corrosion in Hank's medium. The enhanced surface characteristics and corrosion protection of treated Ti6Al4V alloy give it potential for bio-implant applications.

In Vitro Corrosion and Bioactivity Performance of Surface-Treated Ti-20Nb-13Zr Alloys for Orthopedic Applications

The influence of surface treatments on the microstructure, in vitro bioactivity and corrosion protection performance of newly fabricated Ti-20Nb-13Zr (TNZ) alloys was evaluated in simulated body fluid (SBF). The TNZ alloy specimens were treated with separate aqueous solutions of NaOH and H2O2 and with a mixture of both, followed by thermal treatment. The nanoporous network surface structure observed in H2O2-treated and alkali-treated specimens was entirely different from the rod-like morphology observed in alkali hydrogen peroxide-treated specimens. XRD results revealed the formation of TiO2 and sodium titanate layers on the TNZ specimens during surface treatments. The water contact angle results implied that the surface-treated specimens exhibited improved surface hydrophilicity, which probably improved the bioactivity of the TNZ specimens. The in vitro corrosion protection performance of the surface-treated TNZ specimens was analyzed using electrochemical corrosion testing in SBF, and the obtained results indicated that the surface-treated specimens exhibited improved corrosion resistance performance compared to that of the bare TNZ specimen. The in vitro bioactivity of the treated TNZ specimens was assessed by soaking in SBF, and all the investigated treated specimens showed numerous apatite nucleation spheres within 3 days of immersion in SBF.

Electrochemical Strategies for Titanium Implant Polymeric Coatings: The Why and How

Among the several strategies aimed at polymeric coatings deposition on titanium (Ti) and its alloys, metals commonly used in orthopaedic and orthodontic prosthesis, electrochemical approaches have gained growing interest, thanks to their high versatility. In this review, we will present two main electrochemical procedures to obtain stable, low cost and reliable polymeric coatings: electrochemical polymerization and electrophoretic deposition. Distinction should be made between bioinert films—having mainly the purpose of hindering corrosive processes of the underlying metal—and bioactive films—capable of improving biological compatibility, avoiding inflammation or implant-associated infection processes, and so forth. However, very often, these two objectives have been pursued and achieved contemporaneously. Indeed, the ideal coating is a system in which anti-corrosion, anti-infection and osseointegration can be obtained simultaneously. The ultimate goal of all these coatings is the better control of properties and processes occurring at the titanium interface, with a special emphasis on the cell-coating interactions. Finally, advantages and drawbacks of these electrochemical strategies have been highlighted in the concluding remarks.

PEDOT/FHA nanocomposite coatings on newly developed Ti-Nb-Zr implants: Biocompatibility and surface protection against corrosion and bacterial infections

The fabrication of bioactive polymer nanocomposite coatings with enhanced biocompatibility and surface protection has been a topic of abundant concern in orthopaedic implant applications. Herein, we electrochemically prepared a novel poly (3,4-ethylenedioxythiophene) (PEDOT) based nanocomposite coatings with different contents of fluoro hydroxyapatite (FHA) nanoparticles on a newly developed Ti-Nb-Zr (TNZ) alloy; an appropriate approach to advance the surface features of TNZ implants. FTIR, XRD, and Raman analyses of the coating confirm the successful preparation of PEDOT/FHA nanocomposite, and XPS validate the chemical interaction between FHA and PEDOT matrix. SEM and TEM examination show the uniform distribution of spherical FHA nanoparticles inside the PEDOT matrix. Hardness and contact angle measurement results showed improving in the hardness and surface wettability of the coated samples respectively. Electrochemical corrosion tests specified that the PEDOT/FHA coatings exhibit higher corrosion protection than the pure PEDOT coatings. The fabricated nanocomposite coating supports the cell adsorption and proliferation of MG-63 cells. Moreover, antibacterial studies against Gram positive and negative bacteria reveal the enhanced antibacterial performance of the coated TNZ substrates. Our results show the potential applications of PEDOT/FHA nanocomposite as a most viable coating for the orthopaedic implants.

Fabrication of Bilayer Coating of Poly(3,4-ethylenedioxythiophene)-Halloysite/Chitosan and Mg2+/Sr2+-Doped HAP on Titanium Alloy for Biomedical Implant Applications: Physicochemical and In Vitro Biological Performances Studies

The prime objective of the present work is to develop biocompatible overlayer-deposited titanium alloys to replace already available titanium alloy-based biomaterials for implantation applications. Here, we prefer to use a bilayer coating on titanium alloys instead of single coating. The adhesion and biocompatibility of titanium alloy is improved by coating with a bilayer, for example, PEDOT-HNT/CS-MHA composite using the electrochemical deposition method. Corrosion behavior of the PEDOT-HNT/CS-MHA bilayer composite coating was investigated in the PBS medium by polarization studies. The functional groups, phase purity, surface morphology, and wettability of the PEDOT-HNT/CS-MHA were characterized by various instrumental techniques like FTIR, XRD, SEM, and contact angle techniques. From the above studies, it is proved that PEDOT-HNT/CS-MHA-coated Ti alloy showing a better biocompatibility and corrosion resistance than the PEDOT-HNT-deposited Ti alloy. In addition, the in vitro bactericidal and cell viability studies were also carried out to further confirm the biocompatibility of the protective coating. Hence, the bilayer deposition has shown excellent stability and biocompatibility and can be used for the potential biomaterials for orthopedics applications.