Generación de un anticorrosivo derivado de la extracción de las colillas de cigarrillo como alternativa para mejorar la resistencia a la corrosión en las estructuras metálicas

Trabajo de investigaciónLa presente investigación se plantea el desarrollo de un recubrimiento anticorrosivo a partir de las colillas de cigarrillo como principal fuente de preparación que garantice protección y funcionalidad en el acero que se implementa en la industria de la ingeniería civil, lo cual brindara una solución al manejo de los grandes problemas que estas implican en el medio ambiente, y de este modo optar por una nueva alternativa de anticorrosión.1. INTRODUCCIÓN 2. PLANTEAMIENTO Y FORMULACIÓN DEL PROBLEMA 3. METODOLOGÍA 4. ANÁLISIS DE RESULTADOS 5. CONCLUSIONES 6. RECOMENDACIÓNES ANEXOSPregradoIngeniero Civi

Analiza struktury nawijanej rury kompozytowej na bazie włókien ciągłych

In this paper, we have presented the problem of composites manufacture and microstructure analysis. The specimens were made of continuous glass and carbon fibers on a polymer matrix (epoxy resin). Eight special rings were designed for project needs. They were made of carbon (five of them) and glass (the rest) fibers. The same amount of material was used for the production of each sample. An analysed rings were made by circumferential fibres wound on a rigid core. Each sample was wound with a different tensile force of fibers to verify the distributions changes and the packing density of the fibers in the composite material. In the next stage, samples were cut to obtain small pieces, which were mounted in epoxy resin. Next, prepared elements were grind on sand papers and polished. After these procedures, prepared areas were analysis by microscope images. The volume fraction of voids, fibers and discontinuities holes in the matrix were analyzed. To verify obtained results method of the image analysis was used, the histogram of structure phase distribution was determined. In both composite materials: fiber volume friction is very high and there was no observable effect of fiber tension during the winding procedure on fiber packing density in the obtained structures

Functionalizable Sol-Gel Silica Coatings for Corrosion Mitigation

Corrosion is constantly a major problem of the world economy in the field of metal products, metal processing and other areas that utilise metals. Previously used compounds utilizing hexavalent chromium were amongst the most effective materials for corrosion protection but regulations have been recently introduced that forbid their use. Consequently, there is a huge drive by engineers, technologists and scientists from different disciplines focused on searching a new, more effective and environmentally-friendly means of corrosion protection. One novel group of materials with the potential to solve metal protection problems are sol-gel thin films, which are increasingly interesting as mitigation corrosion barriers. These environmentally-friendly and easy-to-obtain coatings have the promise to be an effective alternative to hexavalent chromium compounds using for anti-corrosion industrial coatings. In this review the authors present a range of different solutions for slow down the corrosion processes of metallic substrates by using the oxides and doped oxides obtained by the sol-gel method. Examples of techniques used to the sol-gel coating examinations, in terms of anti-corrosion protection, are also presented

Improvement of Interaction in a Composite Structure by Using a Sol-Gel Functional Coating on Carbon Fibers

The modification of carbon fibers for improving adhesion between fibers and an epoxy resin in composite materials has become the focus of attention. In this work the carbon fiber coating process has been devised in a way preventing the stiffening and clumping of fibers. To improve interactions between coated fibers and a resin in composites, four types of silica coatings with different organic functional groups (3-aminopropyl–coating 1, 3-mercaptopropyl–coating 2, 2-(3,4-epoxycyclohexyl) ethyl–coating 3, methyl–coating 4) were obtained. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to distinguish the changes of a carbon fibers surface after coating deposition. The thickness of the obtained coatings, including the diversity of thickness, was determined by transmission electron microscopy (TEM). The increase in surface free energy (SFE) of modified fibers, including the distinction between the polar and dispersive parts, was examined by wettability measurements using a tensometric test. The developed coating preparation process allowed to cover fibers separately with nanoscale silica layers, which changed their morphology. The introduction of organic functional groups resulted in surface free energy changes, especially an increase in specific polar surface energy components

Surface Evaluation of Aligners after Immersion in Coca-Cola and Orange Juice

Orthodontic removable appliances made of transparent thermoplastic materials—aligners—are becoming increasingly popular in contemporary orthodontic practice. It is important for the clinician to fully understand the mechanical properties and behavior of the appliance used. Because of that, the aim of our study was to investigate the changes in aligner surface after immersion in Coca-Cola and orange juice. For surface evaluation, fractal analysis, texture analysis, and wetting angle measurement were performed. Statistically significant changes were found between some of the groups in the fractal dimension analysis. In texture analysis, all but one intergroup comparison showed statistically significant differences. For wetting angle assessment, statistically significant differences were found. These were, however, more numerous when assessing glycol droplets, rather than water droplets. Fractal dimension analysis confirmed a correlation between the intensity of changes in the aligner surface with immersion time in the liquids assessed. Texture analysis showed a high sensitivity to the changes in aligner surface. It failed, however, to reveal changes relative to immersion time. Wetting angle analysis revealed aligner surface degradation for Coca-Cola. It did not, however, prove the dependence of the intensity of this degradation as a function of time. Both Coca-Cola and orange juice can cause aligner surface degradation

The Effect of Flame Retardant—Aluminum Trihydroxide on Mixed Mode I/II Fracture Toughness of Epoxy Resin

Fire resistance is a major issue concerning composite materials for safe operation in many industrial sectors. The design process needs to meet safety requirements for buildings and vehicles, where the use of composites has increased. There are several solutions to increasing the flame resistance of polymeric materials, based on either chemical modification or physical additions to the material’s composition. Generally, the used flame retardants affect mechanical properties either in a positive or negative way. The presented research shows the influence of the mixed-mode behavior of epoxy resin. Fracture toughness tests on epoxy resin samples were carried out, to investigate the changes resulting from different inorganic filler contents of aluminum trihydroxide (ATH). Three-point bending and asymmetric four-point bending tests, with different loading modes, were performed, to check the fracture behavior in a complex state of loading. The results showed that the fracture toughness of mode I and mode II was reduced by over 50%, compared to neat resin. The experimental outcomes were compared with theoretical predictions, demonstrating that the crack initiation angle for higher values of KI/KII factor had a reasonable correlation with the MTS prediction. On the other hand, for small values of the factor KI/KII, the results of the crack initiation angle had significant divergences. Additionally, based on scanning electron microscopy images, the fracturing of the samples was presented

Analysis of the Deceleration Methods of Fatigue Crack Growth Rates under Mode I Loading Type in Pearlitic Rail Steel

The paper presents a comparison of the results of the fatigue crack growth rate for raw rail steel, steel reinforced with composite material—CFRP—and also in the case of counteracting crack growth using the stop-hole technique, as well as with an application of an “anti-crack growth fluid”. All specimens were tested using constant load amplitude methods with a maximum loading of Fmax = 8 kN and stress ratio R = σmin/σmax = 0.1 in order to analyze the efficiency of different strategies of fatigue crack growth rate deceleration. It has been shown that the fatigue crack grows fastest in the case of the raw material and slowest in the case of “anti-crack growth fluid” application. Additionally, the study on fatigue fracture surfaces using light and scanning electron (SEM) microscopy to analyze the crack growth mechanism was carried out. As a result of fluid activity, the fatigue crack closure occurred and significantly decreased crack driving force and finally resulted in fatigue crack growth decrease

Synthesis and corrosion resistance of SiO2-TiO2-ZrO2-Bi2O3 coatings spin-coated on Ti6Al4V alloy

This report shows the synthesis and corrosion resistance of SiO2-TiO2-ZrO2-Bi2O3 coatings deposited by means of spin-coating on Ti6Al4V alloy. The sols were prepared from a mixture of organic precursors, tetraethoxysilane (TEOS) 98%, titanium tetrabutoxide (TBT) 97%, Zirconium (IV) butoxide (TBZ) 80% in 1-butanol solution, and bismuth nitrate pentahydrate Bi (NO3)3 * 5H2O. The coatings were evaluated via potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests in an electrolytic solution of 3.5% wt NaCl + 0.5 M H2SO4. The rheology and pH of the prepared sols were studied through rheology, pH as a function of time, Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) analysis. The coatings were characterized via X-ray diffraction (XRD), scanning electron microscopy equipped with dispersive energy spectroscopy (SEMEDX), X-ray fluorescence (XRF), and adhesion measurements. The results showed that the films add good corrosion resistance to the metal substrate, decreasing current densities up to one order of magnitude

Preparation of sol-gel SiO 2

A protective SiO2 coating was prepared by sol-gel method on stainless steel plates, using precursor solutions having 2 different concentrations: low (0.5M) and high (2M) concentration. The dip coating-drying cycles have been repeated three times, after that the coatings were thermally treated at 300°C or 500°C in air. Scanning electron microscopy (SEM), AFM and X-ray diffraction analyses have been applied. The corrosion resistances of SiO2 coated steels were examined in NaCl medium for 346 hours. Many microcracks and craters in the samples, prepared from solution of high concentration appear after corrosion attack. The coatings obtained from solution of low concentrations reveals almost unchanged surface structure without visible cracks and pits. The evaluated corrosion rate of this coating is lower than those of uncoated steel