Journal of Adhesion Science and Technology | Year: 2013
Coatings are one of the most used protection methods for metals. Metallic coatings, such as zinc and its alloys, are used to protect steel in mild corrosive environments. In aggressive environments, on the other hand, organic coatings must be employed in the so-called duplex systems. However, the galvanized steel/organic coating adhesion is a problem and many attempts had been done to solve it with the incorporation of a chromate-based or phosphate-based interlayer. Nowadays, the use of these compounds is questioned due to their environmental impact and new adhesion promoters, like silanes, are being investigated. The aim of this paper was to study the adhesion and the anticorrosive behavior of a duplex system with a layer of glycidoxypropyltrimethoxysilane (γ-GPS) between the zinc and the coating. Polarization tests and corrosion potential measurements were done on the γ-GPS/galvanized steel to select the better anticorrosive pretreatment conditions for the application of an organic traditional paint. Dried and wet adhesion of the coating to the pretreated substrate was studied by the standard tape test. Salt spray test and electrochemical noise technique were employed to study the corrosion behavior of the duplex systems. Results showed that the films of γ-GPS formed on galvanized steel diminished the corrosion current of the metal, but they do not protect the substrate by a barrier effect. The incorporation of the pretreatment in the duplex system increased the adhesion of the paint, especially when the pretreated substrate was cured 1 h at 200 °C. © 2013 Copyright Taylor and Francis Group, LLC.
Giudice C.A.,CIDEPINT |
Pereyra A.M.,National University of Costa Rica
Fire and Materials | Year: 2010
The objective of this paper is to know the fire performance of wooden panels (Pinus radiata) impregnated with silica nanoparticles added to silica/alkali colloidal solutions. Two series of impregnated panels were prepared with diverse penetrations and retentions (a) after drying/curing the impregnants at laboratory conditions until reaching constant weight and (b) after finishing this stage with prior distiller water immersion for seven days and a later air exposition for attaining moisture balance. Panels were tested in a limiting oxygen chamber and in a two-foot tunnel. Some results displayed a high fire-retardant efficiency. Copyright © 2009 John Wiley & Sons, Ltd.
Progress in Organic Coatings | Year: 2016
Silanes have been studied as adhesion promoters between metals (aluminum, galvanized steel and steel) and paints such as polyurethanes. The objective of this work was to study γ-glycidoxypropyltrimethoxysilano (glymo) as adhesion promoter between sandblasted steel and one water-based epoxy paint formulated in the laboratory. In some cases, the silane film was doped with sodium phosphate or sodium benzoate, and in other cases, glymo or extra epoxy resin were incorporated as part of the paint formulation. The performance of the metal-glymo-paint system was studied by electrochemical noise technique and accelerated tests (salt spray cabinet and humidity chamber). Dry and wet adhesions were also determined. The results showed that the incorporation of γ-glycidoxypropyltrimethoxysilane as pretreatment or in paint formulation does not enhance paint adhesion in undamaged areas. However, when the painted area was damaged, the incorporation of silane in the paint or doped silane in the pretreatment enhances paint performance in these areas. © 2015 Elsevier B.V. All rights reserved.
Rosales B.M.,CIDEPINT |
Vera R.M.,Pontifical Catholic University of Valparaiso |
Hidalgo J.P.,Pontifical Catholic University of Valparaiso
Corrosion Science | Year: 2010
Copper-based statuary alloys were submitted to accelerated patina formation and degradation in well-defined laboratory conditions. Analogies and differences between these patinas and patinas developed on monuments during long-term outdoor exposure are discussed. A very simple patina growth and degradation technique is proposed to better understand the electrochemical processes involved. Patinas were analysed in many replica samples and using destructive techniques not applicable to monuments due to their historic and cultural value. The best quantitative information obtained by "in situ" open circuit potential and current density measurements demonstrated the significant contribution of these electrochemical tools to Cultural Heritage maintenance. © 2010 Elsevier Ltd.
Journal of Materials Engineering and Performance | Year: 2015
Traditionally, chromates and phosphates were used as pretreatments for metals to protect them from corrosion during a temporary period. Nowadays, due to their toxicity, replacements are being study. The most studied compounds are based on silanes and, among them, glicidoxypropyltrimethoxysilane, aminopropyltrimethoxysilane, and mercaptopropyltrimethoxysilane are the most important ones. The objective of this research work was to study the anticorrosive protection afforded by films of γ-mercaptopropyltrimethoxysilane deposited on SAE 1010 steel in order to select the optimum preparation conditions. The films were applied on sandblasted steel after 24 or 48 h of hydrolysis of the silane in a water/methanol solution (1.5/1, by volume) and cured for 10 min at 80 °C or for 1 h at 100 °C. In order to evaluate the characteristics of the films, Fourier transformed infrared spectroscopy was done on the films and the coated surfaces were observed by scanning electron microscopy. The anticorrosive protection afforded by the films was studied by electrochemical tests employing polarization curves (Tafel mode) in 0.5 M NaCl solution and corrosion potential measurements in NaCl 0.05 M. The best results were obtained with silane hydrolyzed for 48 h cured at 80 °C for 10 min. © 2015, ASM International.