Reinforcement Fibers in Zinc-Rich Nano Lithiun Silicate Anticorrosive Coatings

Well-known the electrochemical nature of most processes of corrosion, the technology of anticorrosive coatings is oriented in the direction of making products that control the development of electrode reactions and that generate the isolating of metal surface by applying films with very low permeability and high adhesion (Sorensen et al., 2011). The zinc-rich coatings and those modified with extenders and/or metal corrosion inhibitors display higher efficiency than other coatings. A problem that presents this type of primers is the extremely reactive characteristic of metallic zinc; consequently, the manufacturers formulate these coatings in two packages, which imply that the zinc must be incorporated to the vehicle in previous form to coating application (Jianjun et al., 2008 & Lei-lei & De-liang, 2010). Considering the concept of sacrificial anode (cathodic protection), coatings that consist of high purity zinc dust dispersed in organic and inorganic vehicles have been designed; in these materials, when applied in film form, there are close contacts of the particles among themselves and with the base or metallic substrate to be protected. The anodic reaction corresponds to the oxidation of zinc particles (loss of electrons) while the cathodic one usually involves oxygen reduction (gain of electrons) on the surface of iron or steel; the ?pressure? of electrons released by zinc prevents or controls the oxidation of the metal substrate. Theoretically, the protective mechanism is similar to a continuous layer of zinc applied by galvanizing with some differences because the differences because the coating film initially presents in general a considerable porosity (Jegannathan et al.,2006). The problems previously mentioned led to study other shapes and sizes of zinc particles. The physical and chemical properties as well as the behaviour against the corrosion of these primers are remarkably affected by quoted variables and in addition, by the PVC; thus, for example, it is possible to mention the laminar zinc, which was intensely studied by the authors in other manuscripts (Giudice et al., 2009 & Pereyra et al., 2007).The objective of this paper was study the influence of the content and of the nature of reinforcement fibers as well as the type of inorganic film-forming material, the average diameter of spherical zinc dust and the pigment volume concentration on performance of Environmentally friendly, inorganic coatings suitable for the protection of metal substrates. The formulation variables included: (i) two binders, one of them based on a laboratoryprepared nano solution lithium silicate of 7.5/1.0 silica/alkali molar and the other one a pure tetraethyl silicate conformed by 99% w/w monomer with an appropriate hydrolysis degree; (ii) two pigments based on spherical microzinc (D 50/50 4 and 8 µm); (iii) three types of reinforcement fibers used to improve the electric contact between two adjacent spherical zinc particles (graphite and silicon nitride that behave like semiconductor, and quartz that is a non-conductor as reference); (iv) three levels of reinforcement fibers (1.0, 1.5 and 2.0% w/w on coating solids) and finally, (v) six values of pigment volume concentration (from 57.5 to 70.0%)Fil: Giudice, Carlos Alberto. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; Argentina. Universidad Tecnologica Nacional. Facultad Regional La Plata; Argentin

Introductory Chapter: Protection of Materials

The science and technology of materials have as objective provided access to specific knowledgein this field and besides generated matters of interest for the development of originalresearches leading to new materials and, as a consequence, to proper protection methods toachieve high economic impact.Since iron and steels constitute a group of widely used materials in civil and industrialconstruction, this chapter describes firstly the fundamental concepts of metal corrosion andthe most frequent failures originating on service. Besides, in this chapter, it was considered ofinterest to include aspects inherent to the physicochemistry of fire and its mechanism ofspreading because of the significant human and material losses produced year after year byaction of the fire.It is appropriate to mention that the different chapters of this book describe innovativemethods of surface treatment to control the kinetics of metallic corrosion and the action of fireon several materials.Fil: Canosa, Guadalupe. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; ArgentinaFil: Giudice, Carlos Alberto. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Shaped for performance: the combination of lamellar zinc and mica improves the efficiency of zinc-rich primers

Lamellar zinc was investigated as a partial or complete replacement for spherical zinc in potassium-silicate based zinc-rich primers. Additionally, mica was examined as an extender for lamellar zinc. The best corrosion and blister resistance was obtained by using lamellar zinc combined with mica, at zinc addition levels well below those normally required in such primers.Fil: Pereyra, A. M.. No especifíca;Fil: Giudice, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Silicatos de etilo con diferente grado de hidrólisis como material impregnante ignífugo para maderas

La madera, al igual que el resto de los materiales, no puede resistir indefinidamente la acción del fuego sin sufrir deterioro. En este trabajo se estudió el comportamiento de paneles de madera de baja densidad impregnadas con silicatos de etilo parcialmente hidrolizados. Los resultados obtenidos en laboratorio, con diferentes grados de penetración y retención del impregnante, mostraron a través de ensayos en una Cabina Horizontal-Vertical, en una Cámara LOI y en un Túnel Inclinado una alta eficiencia retardante del fuego.The wood, like other materials, cannot indefi nitely resist the action of the fi re without undergoing deterioration. In this work, low-density wood panels were impregnated with partially hydrolyzed ethyl silicates The results obtained in laboratory, with different degree of penetration and retention of the impregnant material, showed through tests in a Horizontal-Vertical Cabinet, a LOI Chamber and an Inclined Tunnel a high fi re retardant effi ciency.Fil: Pereyra, Andrea Marisa. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; ArgentinaFil: Giudice, Carlos Alberto. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; Argentin

Fire resistance of wood impregnated with soluble alkaline silicates

The aim of this paper is to determine the fire performance of wood panels (Araucaria angustifolia) impregnated with soluble alkaline silicates. Commercial silicates based on sodium and potassium with 2.5/1.0 and 3.0/1.0 silica/alkali molar ratios were selected; solutions and glasses were previously characterized. Experimental panels were tested in a limiting oxygen chamber and in a twofoot tunnel. Results displayed a high fire-retardant efficiency using some soluble silicates. Experimental panels were tested in a Limiting Oxygen Chamber (LOI values) and in a Two-Foot Tunnel (Flame-spread index, Panel consumption, After-flaming time and After-glow time). Testing results displayed a high fire retardant efficiency and a minimum thermal expansion of some soluble silicates.Fil: Giudice, Carlos Alberto. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; Argentina. Universidad Tecnológica Nacional; ArgentinaFil: Pereyra, Andrea Marisa. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; Argentina. Universidad Tecnológica Nacional; Argentin

Silica nanoparticles in high silica/alkali molar ratio solutions as fire-retardant impregnants for woods

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.Fil: Giudice, Carlos Alberto. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; Argentina. Universidad Tecnologica Nacional. Facultad Regional La Plata; ArgentinaFil: Pereyra, Andrea Marisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentina. Universidad Tecnologica Nacional. Facultad Regional La Plata; Argentin

Shaped for performance: the combination of lamellar zinc and mica improves the efficiency of zinc-rich primers

Lamellar zinc was investigated as a partial or complete replacement for spherical zinc in potassium-silicate based zinc-rich primers. Additionally, mica was examined as an extender for lamellar zinc. The best corrosion and blister resistance was obtained by using lamellar zinc combined with mica, at zinc addition levels well below those normally required in such primers.Fil: Pereyra, A. M.. No especifíca;Fil: Giudice, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Dimensional stability, fire performance and decay resistance in wood impregnated with Alkylalkoxysilanes

The wood, very heterogeneous and complex material, changes its volume by water absorption or desorption causing swelling or shrinkage and also it can be degraded both by action of microorganisms and fire; the above-mentioned is a great inconvenient for most commercial uses. In this research, wood specimens of Pinus radiata were previously pretreated in a Soxhlet extractor for 2 hours with a solution of sodium hydroxide (activation of the cellulose) and then impregnated with alkylalkoxysilanes hydrolyzed and condensed "in situ" by the sol-gel process. Silanes selected were triethoxysilane, methyltriethoxysilane, n-propyltriethoxysilane, n-buthyltriethoxysilane and n-octhyltriethoxysilane. Impregnation process was carried out under controlled operating conditions to achieve similar weight gains of the chemical modifier. The pH was adjusted to alkaline value for controlling kinetic of hydrolysis and condensation reactions. Results indicated that dimensional stability increased with the increase of the length of the hydrocarbon chain of the alkoxydes, which would be based essentially on their enhanced hydrophobicity but without discarding the partial occupation of the pores by polymerized siloxanes and the interaction of alkoxides with cell wall components. In addition, wood specimens impregnated with mentioned alkylalkoxysilanes also showed an excellent fire performance and decay resistance.Fil: Canosa, Guadalupe. Universidad Tecnologica Nacional. Facultad Regional la Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alfieri, Paula Vanesa. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; ArgentinaFil: Giudice, Carlos Alberto. Universidad Tecnologica Nacional. Facultad Regional la Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Tecnología de pinturas y recubrimientos: Componentes, formulación, manufactura y control de calidad

Se presenta un libro actualizado sobre la tecnología de pinturas y recubrimientos que combina los conocimientos provenientes de la investigación científica con la experiencia práctica derivada de servicios especializados y tareas de asesoría a la industria de ambos autores. La obra ofrece así un adecuado equilibrio entre los conocimientos fisicoquímicos de los materiales empleados en la formulación de pinturas y recubrimientos y la moderna tecnología hacia la cual debe tender la industria. La formulación de pinturas y los procesos involucrados en la manufactura presentaron cambios sustanciales en los últimos años, debido fundamentalmente al desarrollo de modernos materiales y a los procesos de alta tecnología disponibles para la producción. Así, este libro aborda todos los componentes de una pintura, es decir los materiales poliméricos formadores de película, los pigmentos y extendedores, los aditivos con diferentes funciones específicas y los solventes. Además se desarrollan los principios de formulación de productos base solvente orgánico y de látices como así también los aspectos básicos de la fisicoquímica de la dispersión de los pigmentos y su estabilización y los fundamentos característicos de la operaciones involucradas en los diferentes molinos continuos y discontinuos empleados en la producción. Paralelamente se considera el control y la preservación del medio ambiente en la producción de pinturas, describiendo los tipos de residuos y las etapas de su generación durante el proceso y algunas tecnologías para el reciclado y tratamiento de los contaminantes. Luego, se describen fallas de la película en servicio atribuibles a la formulación, a la falta de adhesión y a aquellas relacionadas con el tipo de sustrato y la aplicación. En cada caso se define el aspecto de la falla, sus posibles causas y las soluciones más adecuadas. Por otro lado, se detallan los controles de calidad más frecuentes de la pintura y de la película seca como así también el instrumental y equipamiento necesarios para su implementación. Finalmente, se citan referencias bibliográficas para aquellos lectores que desean obtener información más detallada. El libro cumple el objetivo de constituirse en una obra de referencia que ofrezca una respuesta satisfactoria a las cuestiones relacionadas con la tecnología de pinturas tanto para los investigadores, los docentes de posgrado y los especialistas del sector productivo.Fil: Giudice, Carlos Alberto. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Pereyra, Andrea Marisa. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin

Effectiveness and Safety of Biosimilars in Pediatric Non-infectious Uveitis: Real-Life Data from the International AIDA Network Uveitis Registry

IntroductionSince many biological drug patents have expired, biosimilar agents (BIOs) have been developed; however, there are still some reservations in their use, especially in childhood. The aim of the current study is to evaluate the efficacy and safety of tumor necrosis factor (TNF) inhibitors BIOs as treatment for pediatric non-infectious uveitis (NIU).MethodsData from pediatric patients with NIU treated with TNF inhibitors BIOs were drawn from the international AutoInflammatory Disease Alliance (AIDA) registries dedicated to uveitis and Behcet's disease. The effectiveness and safety of BIOs were assessed in terms of frequency of relapses, risk for developing ocular flares, best-corrected visual acuity (BCVA), glucocorticoids (GCs)-sparing effect, drug survival, frequency of ocular complications, and adverse drug event (AE).ResultsForty-seven patients (77 affected eyes) were enrolled. The BIOs employed were adalimumab (ADA) (89.4%), etanercept (ETA) (5.3%), and infliximab (IFX) (5.3%). The number of relapses 12 months prior to BIOs and at last follow-up was 282.14 and 52.43 per 100 patients/year. The relative risk of developing ocular flares before BIOs introduction compared to the period following the start of BIOs was 4.49 (95% confidence interval [CI] 3.38-5.98, p = 0.004). The number needed to treat (NNT) for ocular flares was 3.53. Median BCVA was maintained during the whole BIOs treatment (p = 0.92). A significant GCs-sparing effect was observed throughout the treatment period (p = 0.002). The estimated drug retention rate (DRR) at 12-, 24-, and 36-month follow-up were 92.7, 83.3, and 70.8%, respectively. The risk rate for developing structural ocular complications was 89.9/100 patients/year before starting BIOs and 12.7/100 patients/year during BIOs treatment, with a risk ratio of new ocular complications without BIOs of 7.1 (CI 3.4-14.9, p = 0.0003). Three minor AEs were reported.ConclusionsTNF inhibitors BIOs are effective in reducing the number of ocular uveitis relapses, preserving visual acuity, allowing a significant GCs-sparing effect, and preventing structural ocular complications.Trial RegistrationClinicalTrials.gov ID NCT05200715