Fiber Corrosion Research Articles

Corrosion and tribological properties of basalt fiber reinforced composite materials

This experiment has examined the corrosion and tribological properties of basalt fiber reinforced composite materials. There were slight changes of weight after the occurring of corrosion based on time and H 2 SO 4 concentration, but in general, the weight increased. It is assumed that this happens due to the basalt fiber precipitate. Prior to the corrosion, friction-wear behavior showed irregular patterns compared to metallic materials, and when it was compared with the behavior after the corrosion, the coefficient of friction was 2 to 3 times greater. The coefficient of friction of all test specimen ranged from 0.1 to 0.2. Such a result has proven that the basalt fiber, similar to the resin rubber, shows regular patterns regardless of time and H 2 SO 4 concentration because of the space made between resins and reinforced materials.

Effect of the Aggressive Environment on the Damage of a Glass Polyester Composite Developed by Hand Layup Process

This work treats the behavior of a glass fibre/unsaturated polyester (UP) composite with structural defects subjected to the attack of two corrosive solutions: H2SO4and NaOH. The gravimetric analysis, the uptake mass of the resin, and the interfaces in the composite are established according to the proportion of the matrix/composite. The obtained results showed that, in the acidic solution, the glass fibre and the fibre/matrix interface absorption share is more significant than the alkaline solution. While the Fourier transform infrared analysis (FT-IR) of the UP resin revealed the presence of chemical degradation phenomenon (hydrolysis), the fibre corrosion was characterized by the atomic absorption analysis (AAS). The fibres/matrix interfaces degradation was confirmed by microscopic observations (SEM). The diffusion kinetics of the both acid and alkaline solutions and chemical and mechanical degradation are affected by the presence of the pores in elaborated material.

Optical corrosion sensor based on fiber Bragg grating electroplated with Fe-C film

An optical fiber corrosion sensor (OFCS) based on iron-carbon (Fe-C) film was researched. OFCS was formed byelectroplating a Fe-Cfilmon fiber Bragggrating (FBG)metalized with silver film by magnetron sputtering. There was a more than 430-pm change of FBG wavelength when Fe-C film was seriously corroded. Compared to electrochemical method, the optical fiber sensor shows dominance in long-lasting monitoring of corrosion. The electric signal was broken off after the 20-h corrosion of Fe-C film, while the optical fiber sensor's monitoring lasted more than 40 days. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of

Alkali resistance, microstructural and mechanical performance of zirconia-coated basalt fibers

Sol–gel approach was developed to apply zirconia coatings on basalt fibers. Dense or porous ZrO2 coatings were obtained, depending on the process parameters. The alkali resistance of uncoated and ZrO2-coated basalt fibers in alkali solution was studied. The morphology, elemental and phase composition of etched fibers as a function of etching time were studied by means of a set of analytical methods. A scheme of etching of as-received and coated basalt fiber was proposed. Zirconia coating slows down the corrosion of basalt fiber in alkali solution. The denser zirconia coating slows down the corrosion to a higher extent than the porous coating. The uncoated and coated basalt fibers were tested in mini composites with cement matrix. It was shown that the surface of the coated fiber is affected by the alkaline medium of the cement matrix to a smaller extent than the surface of as-received basalt fiber.

Corrosion Resistance of E-Glass Fiber in Simulated Oilfield Environment

Corrosion behavior and mechanism of E-glass fiber in simulated oilfield environment including CO2, H2S and Cl- were firstly studied. After simulated corrosion test, morphology of E-glass fiber was gathered using SEM. Chemical bonding status and elemental analysis were systematically investigated by XPS, FT-IR and EDS. The results revealed that corrosion of E-glass fiber in simulated oilfield acidic medium was primarily attributed to ion exchange mechanism, which was not only controlled by acid concentration, but also dominated by formation of complex ions or insoluble salts. The depletion of cations on E-glass fiber surface can disrupt the continuity of glass network, therefore reducing the strength of fiber.

Description to Fe-C Alloy Film Fiber Corrosion Sensors by Fractal Corrosion Images

In this paper, the fractal dimensions are proposed for characterizing the optical fiber corrosion sensors, which is applied to measure the steel corrosion based on Fe-C alloy film. Because corrosion was a complex random phenomenon and the corrosion surface of Fe-C alloy film of the optical fiber corrosion sensor possessed fractal characteristics, the image fractal dimensions is as a quantitative index of the sensor corrosion degree. The experimental results showed that the complexity level of the sensor surface morphology increased and the optical output power increased along with the increase of fractal dimensions. And the sensing law of the thicker Fe-C alloy film is better than that of the thinner film. Therefore, it is feasible that the fractal dimension is used to characterize the Fe-C alloy film optical fiber corrosion sensors and it is also optimistic to the future prospect of the Fe-C alloy film optical fiber corrosion sensors.

Long-term durability prediction models for GFRP bars in concrete environment

This article presents a durability study of glass fiber reinforced polymer (GFRP) bars within concrete environment and provides recommendations for effective accelerated ageing methods, data reduction and validation, and formulation of master curves for long-term predictions. Concrete beams reinforced with GFRP bars were immersed in tap water inside temperature-controlled tanks. Sustained load was applied to beam samples, and elevated temperatures were used to accelerate the ageing of GFRP bars. After exposure, GFRP bars were tested for residual tensile strength, which was considered as a measure of the durability performance of the specimens. Scanning electron microscopy (SEM) images were used to evaluate the microstructural changes of conditioned specimens. Short-term (up to 270 days) results showed that compared to alkalinity and low sustained load, moisture and elevated temperature played much more important roles in accelerating environmental attack to GFRP bars. Based on the short-term test results, the dominant degradation mechanism for GFRP bars in concrete was found as the deterioration of fiber/matrix interface. A degradation model based on Arrhenius concept and prediction procedures are given, and correlations with other studies and field data are provided. The tensile strength retentions for GFRP bars in saturated concrete subjected to sustained load were predicted. It was found that degradation rates decreased rapidly, but tensile strength retentions at different exposure temperatures converge to a constant value with the increase of exposure time. Beyond fiber-matrix debonding, there is a possibility that other degradation mechanisms such as fiber corrosion may start to dominate the deterioration process of GFRP bars with time.

Strength behavior and crack-formation mechanisms of E-glass fiber exposed to sulfuric acid environment

In this study, strength behavior and crack-formation mechanism of E-glass fiber exposed to sulfuric acid environment for different immersion times were investigated. In order to study the strength degradation, E-glass fibers were immersed in sulfuric acid. Strength reduction, stiffness, and fracture strain of fibers vs. immersion times were studied. The corrosion mechanism of E-glass fiber exposed to acid, were examined by quantitative X-ray fluorescence method. The results showed that corrosion of E-glass fiber was accompanied by removal of Al, Ca, and Fe ions from the fibers. Moreover, intact and degraded fibers were examined by scanning electron microscope and energy dispersive X-ray (EDX) microanalysis methods to show the relation between the reaction of E-glass fiber elements and acid environment. The ion-depletion-depth model was used to study the fracture process. The results showed that by increasing the immersion time in acid, spiral stress induced due to the shrinkage of E-glass fiber surface caused axial cracks in fibers. Different points of fibers, in which cracks were generated, were examined by EDX method. The results were used to explain the role of Al, Ca, and Fe ions in creation of surface cracks on E-glass fibers subjected to sulfuric acid for different immersion times.

The Study on Accelerated Life Mechanism of Glass Fiber Reinforced Magnesium Oxychloride Cement

Accelerated aging procedure and SIC test method have been used to determine the mechanical property of glass fiber reinforced magnesium oxychloride cement (GRMC). Hydration product, microstructure and corrosion degree of glass fibers have been analyzed by XRD and SEM in the oxychloride magnesium cement matrix. The mechanism of mechanical property degradation has been concluded based on the analysis of testing data. For ordinary GRMC sample, the main hydration product 5Mg(OH)2·MgCl2·8H2O (5·1·8) hydrolyzed to Mg(OH)2 easily in water. Mechanical property degraded because of the formation of leptophyllous Mg(OH)2, the looseness of interface region of matrix and glass fiber and corrosion of glass fiber. However, the extended mechanical performance was excellent due to the steadily exsit of 5·1·8 in high performance GRMC sample. It could be concluded that the 5·1·8 existing steadily in oxychloride magnesium cement matrix was the basilic premise for glass fiber which could not be corrupted easily.

Optical fiber corrosion sensor based on laser light reflection

The development of an optical fiber corrosion sensor based on the principle of lightreflection is presented in this paper. The sensor consists of an optical fiber reflection sensorand a tube/film subassembly formed by welding a sacrificial metallic film to a steel tube.One side of the sacrificial metallic film is finely polished and is isolated from theenvironment while the other side is exposed to the corrosive environment. The corrosionpits initiated at the exposed film surface slowly penetrate the sacrificial film as theexposure time increases. The corrosion pits that reach the polished surface reducethe surface reflectivity of the polished surface. This decrease in reflectivity isdetected by the optical fiber reflectivity sensor. To interrogate multiple sensorsat one time, a sensor multiplexing scheme was implemented. The principles ofoperation, packaging, and characterization of the corrosion sensors are presented.

Corrosion of E-glass fiber in simulated oilfield environments

In order to have a better understanding of corrosion behaviors and mechanisms of E-glass fibers in oilfield environments, three different oilfield atmospheres including CO 2, H 2S and Cl − were firstly given. After different simulated corrosion tests, morphologies of E-glass fibers were gathered using SEM. Chemical bonding status and elemental analysis were systematically investigated by XPS, FT-IR and EDS. The results revealed that corrosion of E-glass fibers in simulated oilfield acidic media was primarily attributed to ion exchange mechanism, which was not only controlled by acid concentration, but also dominated by formation of complex ions or insoluble salts. The depletion of cations on E-glass fiber surface can disrupt the continuity of glass network, thus disturb the glass structure, therefore reducing the strength of fibers.

Characterization of Fe-C Alloy Film Optical Fiber Corrosion Sensors by Fractal

The optical fiber corrosion sensor was applied to measure the steel corrosion based on Fe-C corrosion-sensitive metal film, the sensing principle of which was introduced. Because corrosion was a complex random phenomenon and the corrosion surface of Fe-C alloy film of the optical fiber corrosion sensor possessed fractal characteristics, the image fractal dimensions was as a quantitative index of the sensor corrosion degree. The experimental results showed that the complexity level of the sensor surface morphology increased and the optical output power increased along with the increase of fractal dimensions. Therefore, a new method was provided for the research of the optical fiber corrosion sensor.

Increased wear of aqueous lubricated short carbon fiber reinforced polyetheretherketone (PEEK/SCF) composites due to galvanic fiber corrosion

It was previously reported that under certain conditions an electric current that transgresses the interface of a short carbon fiber (SCF)/polyetheretherketone (PEEK) composite vs. a X10CrNiMoTi1810 steel pairing causes extensive galvanic corrosion of the composite's short carbon fibers [1]. In order to elucidate the influence of this phenomenon on the wear resistance of PEEK/SCF, different PEEK/SCF composites were exposed to unidirectional sliding wear under the same environmental conditions that led to fiber corrosion. Our results indicate that there is a mutual amplification of wear and fiber corrosion. Comparing different fiber types, we found the pitch based carbon fiber investigated is much more susceptible to galvanic corrosion than the polyacrylnitrile (PAN) based one. The pitch based carbon fiber corroded so severely that one of the PEEK/pitch SCF composites exhibited even a higher specific wear rate than neat PEEK.

Galvanic corrosion of polyacrylnitrile (PAN) and pitch based short carbon fibres in polyetheretherketone (PEEK) composites

When an electric current is conducted through a short fibre reinforced polyetheretherketone composite, being in contact with a stainless steel electrode, carbon fibre corrosion occurs. Surface analysis shows that structural defects range from debonding events and fibre cracking in the early stage of the corrosion process to the final disintegration of the fibre. The extent of fibre corrosion is quantified by atomic force microscopy, and the influence of fibre type, fibre volume content and the aqueous medium on the fibre corrosion is reported. Overall, polyacrylnitrile based fibres have a higher corrosion resistance than pitch based ones.

Design of Photonic Bandgap Fibre with Novel Air-Hole Structure

We introduce PBGFs with the cladding made of our newly designed quasi-hexagonal air holes and demonstrate how it actually operates. This cladding structure is introduced for the first time to the best of our knowledge, and is realized by making use of the hydrofluoric acid's corrosive properties. The fibre corrosion can be accurately controlled, thus opening us the gate for the design and fabrication of new PBGFs with more complex and more efficient cladding structures. Numerical results and actual simulations indicate that PBGFs built with this cladding structure have improved bandgap properties and guiding bands as wide as 500 nm have been theoretically reached. Using the same method, we have also been able to design two other types of PBGFs with improved cladding structure.

Mechanical and chemical characteristics of hermetically coated silica optical fibre

The mechanical strength of carbon hermetically coated fibres, compared to standard single mode silica optical fibre, has been investigated through chemical exposure to fluorinated vapour reagents, known as the harshest reagents for silica. Two reagents were used: ammonium hydrogenofluoride and hydrofluoric acid. Dynamic fatigue tests for different stress rates were implemented using a two-point bending testing device in order to determine n-stress corrosion parameter from Weibull statistics. As-received and chemically etched fibres were compared. Hermetically coated fibres appeared extremely durable in harsh chemical conditions. No significant change in the Weibull distribution and the mean fibre strength was observed after 6 days of chemical exposure to hydrofluoric vapours. In the same conditions, the mechanical strength of the epoxy-acrylate polymer coated standard fibres has decreased to nearly 50% of the initial strength value. SEM observations revealed crystal deposition on the chemical exposed fibres. Chemical analysis provides partial information on the complex mechanisms of fibre corrosion.

Development of stripped-cladding optical fiber sensors for continuous monitoring: II: Referencing method for spectral sensing of environmental corrosion

Corrosion affects a variety of metallic structures. Methodologies for sensing corrosion have involved indirect measurements of environment corrosiveness in which the degradation of test probes or components is evaluated. Optical fiber corrosion transducers consisting of metal coated glass waveguide have been proposed in the past. Here, we propose a multi-wavelength optical fiber corrosion sensor. As the metal (nickel) corrodes and separates from the fiber, the light transmission of the waveguide changes due to a large difference in the refractive indices of nickel and air. In order to create a sensor capable of long-term measurements, a self-referencing method was developed that is based on observations of spectral signals ratios. The proposed approach differs from other procedures in that the optical signal shows a frequency dependence as the waveguide coating corrodes. The sensor requires only relatively inexpensive light sources and spectral detectors. A first-principles algorithm was used to model laboratory measurements. Good qualitative agreement between theoretical calculations and experimental results, suggests that theoretical models can be used to quantitatively interpret spectral signals in terms of cumulative corrosion. The sensor design is well suited for autonomous operation.

Experimental study of micro-cracks in stress corrosion of fiber reinforced composites

Micro-cracks with a depth of 30–40 μm are formed on the surface of glass-fiber reinforced plastics (GFRP) rod, which could lead to the stress corrosion crack propagation along the original direction and developing dominant influence on the stress corrosion cracking (SCC) performance of the composite material. Micro-cracks with different depth and angles were simulated on the surface of GFRP rod. The strain response histories around the micro-crack during the whole stress corrosion test of the GFRP rod were obtained. The effects of depth and angle of micro-crack on SCC of GFRP rod were analyzed. The stress corrosion fracture times of GFRP rod with micro-cracks of different depth and angle were obtained.

Optical and electrochemical measurements for optical fibre corrosion sensing techniques

The feasibility of an optical fibre corrosion sensor (OFCS) was studied. A multi-mode fibre was metallised by physical vacuum deposition and electroplating of a Fe–C alloy film on a 1–2 cm uncladded section of an optical fibre. The shift of light power transmitted through the fibre was registered with corrosion. Microanalysis was carried out to show the formation of metallised film. The electrochemical process of the corrosion on the fibre was researched by continuously monitoring open potential E corr, linear polarized resistance R p and electrochemical impedance spectra.

Hot Corrosion, Oxidation and Their Effects on the Tensile Strength of SiC Fiber in Alkaline Melts

An experimental study on the behavior of hot corrosion and oxidation of SiC fiber (Hi-NicalonTM) coated with the film of varied alkaline melts was investigated at 1000°C. The hot corrosion and oxidation of SiC fiber were characterized by specific mass loss. The tensile properties on the fibers before and after hot corrosion were evaluated by room temperature single filament test technique. The specific mass loss and strength retention after hot corrosion indicated that the corrosion effect of Hi-NicalonTM fiber in sodium carbonate was more severe than in sodium sulfate. The corrosion effects of Na2SO4 could be enhanced by addition of small amount of Na2CO3/NaNO3. Scanning electron microscopy (SEM) and X-ray diffractometer (XRD) revealed that the degradation of SiC fiber in corrosive and oxidative environment was mainly related to the interaction between the alkaline melts and silica scale. Furthermore, the excess carbon in Hi-NicalonTM fiber must enhance the hot corrosion and oxidation leading to the degradation in microstructure and mechanical properties.