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Earth construction technologies are outstanding for their alignment with environmental sustainability. Earth plasters are essential in this type of construction, providing protection against exposure to open sky. However, in light earth walls (LEM, Light Earth Method), where parts of the structural timber are exposed, some challenges affect the adhesion of plaster. This can lead to cracking and detachment, threatening the structure's durability against environmental factors. This research work assessed the adhesion of plasters on LEM walls, considering rain, wind, solar radiation, and the orientation and type of protective paint. The work proposes the use of bonding layers of natural material before thick plasters on areas of exposed wood and samples must be subjected to pull-out tests after two rainy periods of time. The results support the effectiveness of natural materials as plasters and protectors for light earth walls. The choice between natural or synthetic paint does not significantly affect adhesion during the evaluated period. However, dry preparation of samples for pull-out testing reduced adhesion and generated unfocused data.

Several inorganic materials such as bioactive glasses, glass–ceramics and calcium phosphates have been shown to be bioactive and resorbable which make them suitable for coating bone implants. This study focuses only on bioactive glasses. These biomaterials are highly biocompatible and can form a strong chemical bond with the tissues. This review comprehensively covers bibliographic reports that have investigated bioactive glass deposition using different thermal spray techniques.The main drawback for the glass coating deposition is the low adherence with the substrate. Some strategies can favour a good bond such as using bond coats, blends, pre-heating the substrate or modifying the glass composition.The characteristics of the feedstock powders are determinant for the properties of the coatings obtained. Porosity and thickness of the coatings can be modulated by using different thermal spray techniques and varying parameters of the process.The degradation rate of some bioactive glasses can achieve kinetics similar to the new bone formation. Taking advantage of its dissolution capacity, glasses can be doped with functional elements.While several biological studies have been performed with bioactive glass materials, there has been relatively little research on the biological response of coated glasses by thermal spray techniques. Research studies have demonstrated the opportunities of this promising material to enhance the bioactivity of the implants.

The e-coat process is the first step in automotive painting and consists of immersing the part in a conductive water-based paint bath, followed by several rinse tanks and preceded by a rinse tank with demineralized water after pre-treatment. In this process, microbiological contamination is common, which is prevented or eliminated by adding isothiazolone based biocides combined with other active components. The objective of this study was to evaluate the efficiency of two commercial biocides containing the active components, 5-Chloro-2-methyl-2H-isothiazol-3-one (CIT) and 2-Methyl-2H-isothiazol-3-one (MIT), in the inactivation of two Staphylococcus warneri strains, isolated from contaminated water from tanks of an e-coat paint applicator company. The Minimum Inhibitory Concentration (MIC) was 5 mg/L and the Minimum Bactericide Concentration (MBC) was 10 mg/L for both biocides. Survival curves were obtained and the Weibull model was adjusted. The models obtained indicated lower resistance of S. warneri strain isolated from the demineralized water tank and higher inactivation rate of the biocide containing the association of isothiazolinone and ethylenedioxy (dimethanol).

A review of the state of the art is presented regarding metal coatings based on zinc-aluminium-magnesium alloys, for protection against corrosion in metallic trunking systems, as an alternative to traditional zinc-based metal coatings. This revision covers its evolution over time, the different qualities and designations existing in the market, its structure and composition, the international standards that regulate them, the main commercialized brands and their characteristics, the main metallic trunking manufacturers that offer said alloys, and finally, an analysis of the resistance to corrosion based on field tests and accelerated corrosion tests which have been part of this investigation. From this analysis, a mathematical model has been determined for the estimation of long-term corrosion, in which the logarithmic behavior of the corrosion-time function is evidenced. All in all, the article pretends, on one hand, to be a compendium of the key aspects to consider in this type of alloys and on the other hand, to give support to the project engineer in the decision makingprocess, which supposes the election of this type of coating versus zinc-based coatings, providing the most relevant aspects to be considered, in such a way as to ensure compliance with the specifications of the project, in terms of resistance to corrosion

The study presents a methodology for the optimum selection of the most suitable zinc-based coatings in metallic trunking systems to fulfill the requirements related to atmospheric corrosion resistance. The current methodologies are based on heuristic procedures that do not consider the influence of the in situ atmospheric conditions, which are the main cause of most of the corrosion problems. The effect of corrosion over time is generally estimated using a logarithmic function, which depends on corrosion during the first year of exposure, as well as on environmental parameters (e.g. temperature, humidity, pollutants, etc.). Different mathematical models for the prediction of corrosion during the first year of exposure were analyzed. Ten of these models were selected and compared with actual tests determining the model that best fitted the actual values. From this first-year corrosion value, the long-term corrosion function was calculated for each relevant commercial coating. Finally, a case study was analyzed by means of the proposed methodology. The results show the importance of the corrosion function and its influence in the selection of the coating to minimize costs.

Nowadays the growth of technological materials in the form of thin lms, layers, or coatings, still remains like one of the topics of greatest vitality, in both the scientic and technological environment. These technological materials already are in various applications of the dierent products that we use on our daily basis. However, how technology on coatings can help the country's productive sector?. We briey describe this hidden potential of coatings through this communication to help close the gap between the knowledge production in the academy and the work tools that the Peruvian industry sector needs to improve the quality of its nal products.

The use of edible coatings (EC) has played an important role in the food industry, proving effective in fruit conservation. The objective of this work was to evaluate the effect of edible coatings on a set of physicochemical, microbiological, and sensory parameters of strawberry by using chitosan, calcium caseinate, and low-methoxyl pectin combined with glycerol as plasticizer, ascorbic acid and citric acid as antioxidant agents; uncoated strawberries were used as control. Analyses were performed on days 0, 3, 6, 9, and 12 of storage at 5 °C, evaluating physicochemical and microbiological properties. It was found that the samples with edible coatings differed significantly from the control in the parameters evaluated. The EC1 (chitosan) was effective in prolonging the shelf life of strawberry for up to 14 days, conserving physical and chemical attributes during storage.

Se seleccionaron, caracterizaron, procesaron y depositaron sobre ladrillos refractarios, dos residuos industriales provenientes de procesos de la industria petroquímica y termoeléctrica, así como un mineral de cromita. La composición química y las fases cristalográficas de cada uno de estos polvos fueron determinadas mediante Fluorescencia y Difracción de Rayos X, mientras que la morfología y tamaño de partícula fueron analizados mediante Microscopía Electrónica de Barrido. Estos polvos fueron depositados mediante proyección térmica oxiacetilénica sobre ladrillos refractarios silico-aluminosos y concretos de alta alúmina de bajo cemento, cuyas referencias comerciales de la empresa Erecos S.A.S. son ER-40 y CBC-50 respectivamente. Los parámetros utilizados para la elaboración de los recubrimientos fueron optimizados a partir de recubrimientos elaborados previamente y de los resultados de simulaciones realizadas con el software Jets&poudres. De los recubrimientos obtenidos el que presentó mayor homogeneidad en su estructura fue el elaborado con el mineral de cromita, los demás evidenciaron gran cantidad de partículas sin fundir y mayor porosidad. Sin embargo, por la composición química, su buena adherencia y las fases presentes en los recubrimientos todos son potenciales candidatos para ser usados como medio protector contra el deterioro de refractarios expuestos a altas temperaturas.

Conservation environment with high humidity content or exposure to liquid water are directly linked to degradation of cellulosic materials, such as paper and fabrics. This research had as main objective the development of formulations based on two water-repellent products commercially available: a fluoroacrylic co-polymer and a polydimethylsiloxane. The purpose was to test their applicability to paper and textiles, both ancient and modern. Different analytical techniques have been used: FTIR-ATR spectroscopy, colorimetric analysis, observations by SEM-EDX and light microscopy, contact angle measurement and mechanical strength. Applications were carried out by spray and immersion achieving a systematization of the method and the choice of non-toxic solvents. Two of the four formulations tested were prepared with the addition also of silica nanoparticles. The results highlighted the compatibility and effectiveness of fluoroacrylic polymer with low nanosilica percentages applied by immersion.

The history of calcium phosphates in the medicine field starts in 1769 when the first evidence of its existence in the bone tissue is discovered. Since then, the interest for calcium phosphates has increased among the scientific community. Their study has been developed in parallel with new advances in materials sciences, medicine or tissue engineering areas. Bone tissue engineering is the field where calcium phosphates have had a great importance. While the first bioceramics are selected according to bioinert, biocompatibility and mechanical properties with the aim to replace bone tissue damaged, calcium phosphates open the way to the bone tissue regeneration challenge. Nowadays, they are present in the majority of commercial products directed to repair or regenerate damaged bone tissue. Finally, in the last few decades, they have been suggested and studied as drug delivering devices and as vehicles of DNA and RNA for the future generation therapies.

The objective of this work was to evaluate the performance of various edible coatings for preserving the quality of walnut kernels (W) during storage. Three edible coatings based on carboxymethyl cellulose (CMC), methyl cellulose (MC) and whey protein isolates (WP) were prepared. Coated and uncoated walnuts (WC) were stored for 210 days at room temperature (23±2 °C). After 210 days, WC presented the highest peroxide value (PV = 3.06 meqO2/kg), conjugated dienes (CD = 3.01) and trienes (CT = 0.31), pentanal, nonanal, hexanal, and decane, 5,6-bis (2,2-dimethylpropylidene) contents. Meanwhile, WMC showed the lowest PV (1.20 meqO2/kg), CD (2.26) and CT (0.17) and the lowest decrease in carotenoid content (0.60 mg/kg). The L* value measured in walnut oil decreased in all samples. MC, CMC and WP coatings showed protection on walnuts against the deterioration process. MC coating displayed the best performance.

In this work, alumina-coated YTZP materials are proposed as means to combine the mechanical reliability of YTZP with the stiffness and hardness of alumina. Additionally, compressive stresses are developed in the alumina coating when cooling from the sintering temperature due to the thermal expansion mismatch between alumina and YTZP. The proposed processing method involves dipping of pre-sintered YTZP specimens in stable alumina suspensions and co-sintering of the dipped specimens. The influence of the processing parameters on the macro and microstructure of the materials has been established. Berkovich indentation has been performed to determine the Young's modulus of the substrates and coatings. The structural integrity of the coatings has been analysed using scratch tests. The Young's modulus. The optimised specimens present high resistance to scratch up to loads of 150 N.

Galvannealed (GA) coatings are composed of Fe-Zn phases, being its quality greatly affected by the phase’s distribution, making it important to be characterized. Glow Discharge Optical Emission Spectroscopy (GDOES) technique allows a quick and accurate evaluation of the chemical composition profile along the coating thickness. In this study, GA coatings were produced varying the temperature (530°C, 550°C, 580°C) and times (0 s, 5 s, 15 s, 60 s) of galvannealing treatment, in order to change the Fe-Zn phases distribution. The coatings were characterized by SEM and XRD. GDOES analyses were performed to identify the distributions of Fe and Al and correlate them with the η, ζ, δ and Γ phases. It was found that variations in temperature and treatment time influenced the distribution of Fe and Al. For short times, Fe and Al were concentrated near the coating/substrate interface and as the time increase concentrations became more uniform along the coating. The characterization of GA coatings from the Fe and Al distribution were effective for checking the distribution of Zn-Fe phases

The sol-gel process is widely used to obtain coatings on glass-ceramic substrates in order to improve the scratch and abrasion resistance, also providing a bright and homogeneous appearance of a glaze avoiding expensive final polishing treatments. This paper describes the preparation of silica and silica / zirconia coatings by sol-gel method on Li2O-Al2O3-SiO2 (LAS) glassceramic substrates produced by sintering. The coatings were deposited by dip-coating on LAS substrates and characterized by optical microscopy and spectral ellipsometry. On the other hand, hardness and elastic modulus, coefficient of friction and abrasion and scratch resistance of the coatings were determined and compared with the substrate properties. Coatings deposited on LAS glass-ceramic confere the substrate a bright and homogeneous aspect, similar to a glaze, improving the appearance and avoiding the final polishing. However these coatings do not increase the scratch resistance of the substrate only equaling the properties of the glass-ceramic.El proceso sol-gel es un método interesante para la producción de recubrimientos vítreos sobre sustratos vitrocerámicos con el fin de mejorar su resistencia al rayado y al desgaste, y proporcionando además un aspecto homogéneo, vidriado y brillante que evite los costosos tratamientos finales de pulido. Este trabajo describe la preparación de recubrimientos de sílice y sílice/ circona por el método sol-gel sobre sustratos vitrocerámicos del sistema Li2O-Al2O3-SiO2 (LAS) producidos por sinterización. Los recubrimientos se depositaron por la técnica de inmersión y se caracterizaron mediante microscopía óptica de luz reflejada y elipsometría espectral. Por otro lado, se determinó la dureza y el módulo de elasticidad, además del coeficiente de fricción, la resistencia al desgaste y al rayado de los recubrimientos. Estos resultados se compararon con las propiedades del sustrato sin recubrir. Las capas depositadas confieren al sustrato un aspecto homogéneo, vidriado y brillante, mejorando el aspecto final y evitando el pulido. Sin embargo, estas capas no aumentan la resistencia al desgaste del sustrato, aunque igualan sus características.

Magnesium alloys are reaching special interest due to their good specific properties, low cost and good manufacturing properties. However, their low hardness, wear and corrosion resistance limit their applications in certain sectors of industry. These drawbacks can be solved by applying hard ceramic coatings, such as nitrides or metal carbides. TiN is one of the most used coatings due to its high adhesion, hardness, low coefficient of friction and chemical stability. Physical vapor deposition by cathodic arc CAPVD, is a versatile technique, which uses low temperatures and high ionization energies, generating homogeneous coatings. To achieve coatings with high quality, a careful control of the manufacturing parameters is required, such as bias voltage, gas flow or intensity. This paper focuses on magnesium alloys, AM60, coated with TiN using physical vapor deposition cathodic arc technique (CAPVD) at different intensity values (40A and 100A) and surface preparation (grinding up to 4000 grit and polished to 3μm). It was included a final condition with an intermediate Al film. The samples were characterized by X-ray diffraction, roughness, optical microscopy and scanning electron.Las aleaciones de magnesio están alcanzando especial interés gracias a sus buenas propiedades específicas, bajo coste y buenas propiedades de moldeabilidad. No obstante su baja dureza, resistencia a desgaste y corrosión, limita sus aplicaciones en ciertos campos de la industria. Estos inconvenientes se pueden solucionar aplicando recubrimientos duros cerámicos, como nitruros o carburos metálicos. El TiN es uno de los más utilizados debido a su alta adherencia, dureza, bajo coeficiente de fricción y estabilidad química. La deposición física en fase vapor mediante arco catódico, ACPVD, es una técnica muy versátil, que emplea bajas temperaturas y altas energías de ionización, generando recubrimientos de bajo espesor, homogéneos y de calidad. Para alcanzar una alta calidad en los recubrimientos es necesario un exhaustivo control de los parámetros de fabricación, como son la tensión de polarización, el flujo de gas, la intensidad, etc. El presente artículo estudia la aleación de magnesio, AM60, recubierta con TiN mediante, ACPVD a diferentes valores de intensidad (40A y 100A) y diferente preparación superficial (desbaste hasta grano 4000 y pulido hasta 3μm). Se incluye una condición final donde se introduce una capa de Al intermedia. Las muestras se caracterizaron mediante difracción de rayos X, rugosidad, microscopía óptica y electrónica de barrido.

Using Density Functional Theory (DFT) SiN and TiN structures were simulated, in order to study the influence of the silicon atoms insertion in the TiN lattice placed on interstitial and substitutional positions in a face centered cubic (FCC) crystalline lattice. Results showed that the SiN - FCC structure is pseudo-stable; meanwhile the tetragonal structure is stable with ceramic behavior. The TiN - FCC structure is stable with ceramic behavior similar to SiN - Tetragonal. 21% silicon atoms insertion in interstitial positions showed high induced deformation, high polarization and Si - N bond formation, indication an amorphous transition that could lead to the production of a material composed from TiN grains or nano-grains embedded in a Si - N amorphous matrix. When including 21% of silicon atoms, substituting titanium atoms, the distribution showed higher stability that could lead to the formation of different phases of the stoichiometric Ti1 -x SixNy compound.

Friction and wear control can be achieved primarily by considering the nature of the counter faces, together with the environmental conditions. In most cases, a transfer film is found on the sliding surfaces. Environment plays a crucial role on the kinetics of formation and on the composition of the transfer film, and thus strongly influences friction levels and wear rates. In this paper, the effect of the actual environment (refrigerant) present in hermetic compressors on the tribological behaviour of a Si rich multifunctional DLC coating deposited on 1020 steel is analyzed. Unlubricated reciprocating pin-on- disk tests are performed using a High Pressure Tribometer under different atmospheres (Air, CO2 and R600a). Samples tested in R600a environment present the lowest friction coefficient and the lowest wear rate for both body and counter-body

Hydroxyapatite (HAp: Ca10(PO4)6OH2) is a biocompatible and bioactive ceramic material widely used as a coating on metal surfaces (dental implants, hip replacements ...), but the low adhesion between HAp and the substrate, due to differences in thermal expansion coefficients of both (very important in thermal spraying because of the fast cooling of the coating, which can produce a lost of adherence), and the degradation of HAp, have been tried to be improved through the incorporation of TiO2 to get a good combination of mechanical properties. Therefore, the objective of this project is to produce coatings of HAp 80% TiO2 and 20% (by weight) on Ti6Al4V by High-Speed Thermal Spray (HVOF). The study of the microstructure has been carried out using scanning electron microscopy and characterization of the crystalline phases by X-ray diffraction and Raman spectrometry. The coatings adhesion has been measured by tensile tests according to ASTM C633-01 (2008), and their bioactivity also has been evaluated through its immersion in simulated body fluid (SBF), in order to measure their capacity to form an apatite layer on their surface.La Hidroxiapatita (HAp: Ca10(PO4)6OH2), es un material cerámico biocompatible y bioactivo muy empleado como recubrimiento sobre superficies metálicas (implantes dentales, prótesis de cadera…); sin embargo, la baja adherencia entre la HAp y el sustrato, debida a las diferencias entre los coeficientes de expansión térmica de ambos (a tener en cuenta en recubrimientos por proyección térmica ya que el enfriamiento posterior a la proyección puede producir una pérdida de adherencia o incluso la descohesión del recubrimiento) y a la degradación de la HAp, se está intentado mejorar mediante la incorporación de TiO2, para obtener una buena combinación de propiedades mecánicas y biológicas. Por tanto, el objetivo de este trabajo es la obtención de recubrimientos de 80% de HAp y 20% de TiO2 (en peso) sobre Ti6Al4V mediante Proyección Térmica de Alta Velocidad (HVOF -High-Velocity Oxy-Fuel-). El estudio de la microestructura se ha llevado a cabo mediante microscopía electrónica de barrido y la caracterización de las fases presentes a través de difracción de rayos X y espectrometría Raman. La adherencia de los recubrimientos ha sido medida mediante ensayos de tracción, según la norma ASTM C633-01 (2008); asimismo, se ha evaluado su bioactividad a través de su inmersión en Fluido Fisiológico Simulado (SBF), midiendo así la capacidad que presentan para formar una capa de apatita en superficie.

In the design phase of a glazing system, multiple laminated glass configurations may be conceived for various architectural purposes (mainly related to aesthetical issues, energy efficiency, safety and security and/or acoustic insulation). Therefore, the availability of computational simulations of optical and thermal properties of laminated glass as a function of the properties of its constituents (glass panes, polymeric films, selective coatings) may be of great utility. Standardised procedures for this kind of calculations are still being prepared by CEN (European Committee for Standardization). The theoretical study of laminated glass with internal selective coatings is especially relevant due to the introduction of reflectivity within the multilayer optical system. Here, a theoretical model based on transfer matrix method and applied to multilayer glazing with external and internal coatings is presented. Simulation results are compared with UV-VIS-NIR spectrophotometric measurements.En el caso del vidrio laminado, dadas las múltiples configuraciones que pueden concebirse con propósitos arquitectónicos varios en la fase de diseño (estéticos, de eficiencia energética, seguridad o aislamiento acústico, principalmente), resulta de gran utilidad poder disponer de simulaciones computacionales de las propiedades ópticas en función de las propias de sus constituyentes (sustratos vítreos, láminas poliméricas y capas selectivas a la radiación solar). Los procedimientos para la determinación por cálculo de las magnitudes de caracterización óptica de este tipo de vidrios se encuentran actualmente en proceso de normalización por el CEN (Comité Europeo de Normalización). El estudio de vidrios laminados con capa selectiva interna, en contacto con la lámina polimérica, tiene un valor teórico especialmente significativo, al introducir reflectividad en el interior del sistema óptico multicapa. En este trabajo se presenta un modelo teórico basado en el método de matrices de transferencia particularizado para el cálculo de las propiedades ópticas del vidrio laminado con capas externas e internas. Los resultados de la simulación se comparan con datos experimentales obtenidos mediante espectrofotometría UV-VIS-NIR.

Fly ash samples were characterized by atomic absorption, plasma spectroscopy, DTA/TGA, SEM/EDS, XRD and laser diffraction in order to obtain fly ash coatings on stainless steel substrates by electrophoretic deposition. Fly ash was milled and residual carbon and Fe2O3 were eliminated by calcination and magnetic separation, respectively. Fly ash suspensions were prepared with several organic media such as water, ethanol, isopropanol and acetone. The pH of the suspensions was controlled by the addition of NaOH and HCl aqueous solutions. The results of dynamic mobility and zeta potential in a range of pH from 4 to 12 showed that fly ash has better stability in acetone-NaOH aqueous solution. The greatest value of zeta potential in this medium was -50 mV. The electrophoretic coatings were carried out at 100, 200 and 300 V during 1 to 5 minutes. The coatings characterized by SEM/EDS, showed an excellent particle packing and a homogenous surface without cracking. Additionally, the coatings thermal treatment at 1050ºC allowed their partial sintering.Muestras de ceniza volante fueron caracterizadas por medio de absorción atómica, espectroscopía de plasma, ATD/ATG, MEB/EDXS, DRX y difracción láser con el propósito de realizar recubrimientos de ceniza volante sobre substratos de acero inoxidable por medio de la técnica de deposición electroforética. Los polvos de ceniza fueron molidos y el carbón residual y el Fe2O3 fueron eliminados por medio de calcinación y separación magnética, respectivamente. Se realizaron suspensiones de ceniza volante molida en los siguientes medios polares: agua, etanol, isopropanol y acetona. El pH fue controlado por medio de adición de soluciones acuosas de NaOH y HCl. Los resultados de movilidad dinámica y potencial zeta efectuados a estas suspensiones por medio de la técnica electroacústica en un intervalo de pH de 4 a 12, mostraron que la ceniza volante presenta mejor estabilidad en acetona-solución acuosa de NaOH. El valor más elevado de potencial zeta en este medio fue de -50 mV. Los recubrimientos electroforéticos fueron realizados a 100, 200 y 300 V durante 1 a 5 minutos. Los recubrimientos caracterizados por MEB/EDX mostraron un excelente empaquetamiento de partículas y una superficie homogénea sin agrietamiento. Además el tratamiento térmico de los recubrimientos a 1050ºC permitió una sinterización parcial de los mismos.

Photodegradation effect is widely used for water purification this contributes to preservation and protection of environment. Titanium oxide, (TiO2), is a compound that shows up this phenomenon. TiO2 is a semiconductor which may degradate pollutants through of a oxidation process. It permit the treatment of the residual water. It this work we has conformed coatings of TiO2 y TiO2-SiO2, utilized Sol-Gel method and investigated the degradation of the blue Methylene. For this, we introduced these coatings in the blue methylene solution which was illuminated with radiation of λ=365nm to activate its photocatilist properties. The structures of the coatings were characterized using Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS).El efecto de fotodegradación es ampliamente utilizado para la purificación del agua, acción que contribuye a la conservación y protección del medio ambiente; el óxido de titanio (TiO2) es uno de los semiconductores que pueden degradar contaminantes mediante procesos de oxidación, lo que lo hace apto para el tratamiento de aguas residuales. En este trabajo se conformaron recubrimientos de TiO2 y TiO2-SiO2, por el método Sol-Gel, y se estudio la degradación que experimentaba una solución de azul de metileno al introducirle estos recubrimientos e iluminarlos con una radiación de λ=365nm para activar su propiedad fotocatalítica. Los recubrimientos fueron caracterizados microestructuralmente utilizando Microscopía de Fuerza Atómica (MFA) y Espectroscopía de Fotoelectrones de rayos X (XPS). Los resultados obtenidos de los ensayos de fotodegradación indican que los recubrimientos con una cantidad pequeña de silicio presentan un mayor efecto de fotodegradación indicando que el silicio puede generar puntos de anclaje que facilitan las reacciones de fotocatálisis. Por otro lado, la formación de centros activos, constituidos principalmente por carbono, también contribuyeron al desarrollo de estas reacciones.

En este trabajo se seleccionaron nueve esquemas de diferentes empresas del mercado nacional, de reconocida trayectoria, para realizar la evaluación en ambientes muy severos, marinos tropicales. A tal efecto se utilizaron perfiles de acero galvanizado nuevo y ya expuesto (con corrosión del sustrato), a las mismas condiciones de evaluación. Se seleccionaron dos estaciones de campo: La Voz y El Cruce del Lago de Maracaibo, ambos climas marinos tropicales de elevada agresividad. Adicionalmente, se efectuaron ensayos acelerados en una estación en el Centro de Estudios de Corrosión (CEC), utilizando la norma ISO 11474, y en el laboratorio (Cámara climática/PROHESION). Cabe destacar que luego de mas de 36 meses de exposición en las estaciones de campo, el desempeño de los diferentes esquemas sobre galvanizado ya expuesto se observa claramente definido, pudiendo seleccionar fácilmente el que muestra un mejor comportamiento. No obstante, para el caso del galvanizado nuevo, luego de este tiempo de evaluación, no se aprecia tan evidente la diferencia en el comportamiento; ya que esquemas de recubrimiento con un pobre desempeño en el galvanizado expuesto presentan un buen comportamiento en ese sustrato, demostrando la eficiencia de los sistemas Duplex.In this work nine different coating systems, from national suppliers, were selected to perform the evaluation in two severe tropical marine environments. New galvanized profiles as well as pre-exposed to the same environmental conditions were used as the test probes. Two different field stations were selected: La Voz and The Cross of Maracaibo Lake. Additionally, accelerated test were carried out in a station located at Centro de Estudios de Corrosión (CEC) by using the standard ISO 11474, and in the laboratory (PROHESION chamber). It is important to emphasize that after more than 36 month-exposure the behavior of the different coating systems on pre-exposed galvanized was clear, permitting to select the coating system with the best performance. Nevertheless in the case of new galvanized probes, after the evaluation period, most of the duplex systems had a very good performance.

The chemical and thermal stability of zircon under low PO2 environments at different temperatures and absolute pressures have been studied. The experiments performed out in a graphite furnace at atmospheric pressure and under vacuum (1•10-3 atm) in the temperature range 1300-1500ºC up to 5 hours. Both experimental conditions and reaction mechanism were inferred from the zircon volatility diagrams, constructed as part of this work. As a result of the thermal treatments, the SiO2 was removed from the zircon, resulting in a porous layer of monoclinic zirconia with a variable thickness as a function of temperature, time and absolute pressure. A specific surface area up to 5m2/g.was obtained. This kind of materials can be used as catalyst supports in applications such as catalytic combustion and fuel cells.Se ha estudiado el comportamiento del circón en atmósferas de baja PO2 a distintas temperaturas y presiones absolutas. Los tratamientos se han realizado en un horno de grafito a presión atmosférica y en vacío (1x10-3 atm), a temperaturas entre 1300-1500ºC, durante tiempos de hasta 5 horas. Tanto el diseño de los experimentos como la interpretación de los resultados se realizaron a partir del diagrama de volatilidad del circón, construido como parte de este trabajo. Los resultados obtenidos demuestran que en estas condiciones el circón es inestable y se reduce, perdiendo su sílice como SiO(g) y dando lugar a la formación de un recubrimiento superficial poroso de circona monoclínica, de espesor variable en función de la temperatura, tiempo y presión absoluta del tratamiento, y superficie específica comprendida entre 4 y 5m2/g. Por su microestructura y propiedades, este tipo de materiales pueden tener aplicaciones como soporte de catalizadores para combustión catalítica o en células de combustible.

The anti-skid resistance of six coatings (Alfa, Beta, Gamma, Lambda, Mu and Theta) designed for outdoor wood flooring were tested in chestnut (Castanea sativa Mill.) and pine (Pinus pinaster Ait.) using a Portable Skid Resistance Tester according to standard ENV 12633. Film thickness, coating retention level, and presence of mineral particles were determined for each coating. Furthermore, the liquid water absorption coefficient of chestnut was determined in accordance with standard UNE-EN 1609, to relate all parameters. The highest value of skid resistance in both chestnut and pine was obtained with coating Mu (49.75) and coating Gamma (53.16), respectively. Film thickness and coating retention level were consistently higher for pine than for chestnut. Gamma presented the highest presence of minerals. For chestnut the absorption coefficient of liquid water in the tangential direction was 0.0056 ± 0.0010 kg·m-2·s-0.5, considerably lower than the value found for pine: 0.011 kg·m-2·s-0.5. The different performance of the system wood-coating, and consequently the anti-skid resistance, was attributed to the absorption properties of the different species.

Objective of the present paper has been the development of a new pressing dye concept in the field of ceramic tiles. The use of metal-ceramic composite coatings has allowed multiplying the dies life time for a factor between 2 and 3 (1.000.000 – 1.500.000 pressing cycles), the use of lower price steels; avoid some high energy consuming processing steps. This process doesn’t provoke a great increasing in the direct cost of the classical manufacturing route. In order to coat the dies HVOF (Hyper Velocity Oxi-Fuel spraying) has been selected. This technique combines the high temperatures of Hydrogen or Acetylene flame with the very high kinetic energy due to the supersonic speed of the particles (700 – 1100 m/s). As coating material a WC-Co composite (80-20 weight %) was selected. These characteristics have allowed to obtain coatings without porosity (less than 1%) and very high wear resistance.El objetivo del presente trabajo ha sido el desarrollo de una nueva concepción de moldes de prensado para la industria del pavimento y revestimiento cerámicos. El empleo de recubrimientos con materiales compuestos metal-cerámica ha permitido, además de multiplicar la vida útil de los moldes por un factor entre 2 y 3 (1.000.000 – 1.500.000 ciclos de prensado), emplear aceros más económicos en la producción del molde, su reutilización, eliminar etapas de alto consumo energético, como el templado, que además provocan gran número de rechazos en el proceso, todo ello sin un incremento desmesurado en los costes directos respecto a los del procedimiento tradicional. Como método para la obtención del recubrimiento se ha empleado la proyección a alta velocidad, conocida por sus siglas en ingles HVOF (Hiper Velocity Oxi-Fuel spraying). Esta técnica combina las temperaturas relativamente elevadas de la llama de Hidrógeno o Acetileno con la energía cinética muy elevada que proporcionan las velocidades supersónicas de proyección (700 – 1100 m/s). Como material de recubrimiento se ha empleado un compuesto WC-Co en relación 80-20 (% en peso). Estas características han permitido obtener recubrimientos con porosidad casi nula, con una elevada resistencia al desgaste.