Biofunctionalization of titanium surfaces for dental implants: osteogenic, anti-microbial and tribocorrosion resistant surfaces

PhD thesis in Biomedical Engineering

Organic-inorganic hybrid sol-gelcoatings for metal corrosion protection: a review of recent progress

This paper is a review of the most recent and relevant achievements (from 2001 to 2013) on the development of organic–inorganic hybrid (OIH) coatings produced by sol–gel-derivedmethods to improve resistance to oxidation/corrosion of different metallic substrates and their alloys. This review is focused on the research of OIH coatings based on siloxanes using the sol–gel process conducted at an academic level and aims to summarize the materials developed and identify perspectives for further research. The fundamentals of sol–gel are described, including OIH classification, the interaction with the substrate, their advantages, and limitations. The main precursors used in the synthesis ofOIHsol–gel coatings for corrosion protection are also discussed, according to the metallic substrate used. Finally, a multilayer system to improve the resistance to corrosion is proposed, based on OIH coatings produced by the sol–gel process, and the future research challenges are debated.

Seismic-resistant building practices resulting from local seismic culture

Considering that vernacular architecture may bear important lessons on hazard mitigation, this chapter focuses on the European Mediterranean countries and studies traditional seismic-resistant architectural elements and techniques that local populations developed to prevent or repair earthquake damage. This area was selected as a case study because, as a highly seismic region, it has suffered the effect of many earthquakes along the history and, thus, regions within this area are prone to have developed a Local Seismic Culture. After reviewing seismic resistant construction concepts, a wide range of traditional construction solutions that, in many cases, have shown to improve the seismic performance of vernacular constructions of these regions is presented, as a contribution to the general overview of retrofitting building systems provided in this book. The main motivation is that most of these techniques can be successfully applied to preserve and to retrofit surviving examples without prejudice for their identity.

Hot-dip galvanized steel dip-coatedwith ureasilicate hybrid in simulated concrete pore solution: Assessment of coating morphology and corrosion protection efficiency

The barrier effect and the performance of an organic–inorganic hybrid (OIH) sol–gel coating are highlydependent on the coating deposition method as well as processing conditions. In this work, studies onthe influence of experimental parameters using the dip coating method were performed. Factors suchas residence time (Rt), a curing step between each dip step and the number of layers of sol–gel OIHfilms deposited on HDGS to prevent corrosion in highly alkaline environments were studied. These OIHcoatings were obtained using a functionalized siloxane, 3-isociantepropyltriethoxysilane that reactedwith a diamino-functionalized oligopolymer (Jeffamine®D-230). The barrier efficiency of OIH coatings insimulated concrete pore solutions (SCPS) was assessed in the first moments of contact, by electrochemicalimpedance spectroscopy and potentiodynamic methods. The durability and stability of the OIH coatings inSCPS was monitored during eight days by macrocell current density. The morphological characterizationof the surface was performed by scanning electronic microscopy before and after exposure to SCPS.Glow discharge optical emission spectroscopy was used to obtain quantitative composition profiles toinvestigate the thickness of the OIH coatings as a function of the number of layers deposited and theinfluence of the Rt in the coating thickness.

Ureasilicate hybrid coatings for corrosion protection of galvanized steel in chloride-contaminated simulated concrete pore solution

Organic-inorganic hybrid (OIH) sol-gel coatings based on ureasilicates (U(X)) have promising properties for use as eco-friendly coatings on hot dip galvanized steel (HDGS) and may be considered potential substitutes for pre-treatment systems containing Cr(VI). These OIH coatings reduce corrosion activity during the initial stages of contact of the HDGS samples with highly alkaline environments (cementitious media) and allow the mitigation of harmful effects of an initial excessive reaction between cement pastes and the zinc layer. However, the behavior of HDGS coated with U(X) in the presence of chloride ions has never been reported. In this paper, the performance of HDGS coated with five different U(X) coatings was assessed by electrochemical measurements in chloride-contaminated simulated concrete pore solution (SCPS). U(X) sol-gel coatings were produced and deposited on HDGS by a dip coating method. The coatings performance was evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization curves measurements, macrocell current density and polarization resistance in contact with chloride-contaminated SCPS. The SEM/EDS analyses of the coatings before and after the tests were also performed. The results showed that the HDGS samples coated with the OIH coatings exhibited enhanced corrosion resistance to chloride ions when compared to uncoated galvanized steel.

Erratum: Ureasilicate hybrid coatings for corrosion protection of galvanized steel in cementitious media

Artigo completo publicado na revista "Journal of The Electrochemical Society" 160:10 (2013) 467-479 e disponível no RepositóriUM em: http://hdl.handle.net/1822/33855

Erratum: Alcohol-aminosilicate hybrid coatings for corrosion protection of galvanized steel in mortar

Artigo completo publicado na revista "Journal of The Electrochemical Society" 161:6 (2014) C349-C362 e disponível no RepositóriUM em: http://hdl.handle.net/1822/33784

Erratum: Erratum: Alcohol-aminosilicate hybrid coatings for corrosion protection of galvanized steel in mortar

Artigo completo publicado na revista "Journal of The Electrochemical Society" 161:6 (2014) C349-C362 e disponível no RepositóriUM em: http://hdl.handle.net/1822/33784. Errata disponível no RepositóriUM em: http://hdl.handle.net/1822/40064. (Publisher’s note: An erratum that addressed the errors in Figure 9 was originally published on Dec. 10, 2014, however the graphs in that erratum were not correct.)