Advanced Materials Research Vols. 79-82

Abstract: Catalytic crystalline waterproof coatings (CCWC) can penetrate into pores and cracks of concrete and catalyze reaction to increase the impermeability of concrete. This paper reported the results of a study conducted to evaluate the effect of CCWC on corrosion of concrete. The test results of water impermeability, chloride permeability and potential clearly showed that CCWC could stop water and any soluble salts from penetrating the concrete to cause corrosion. Moreover, results of the secondary impermeability test and SEM micrographs indicated that the active compound could work for a longer term and endow the cement-based materials with self-healing function, which make concrete more compacted. Therefore, it was concluded that CCWC is very effective to protect the steel from corrosion in concrete.

Abstract: With an aim to investigate erosion properties, TiC/Fe composites fabricated by self -propagating high-temperature synthesis and pseudo heat isostatic pressing (SHS/PHIP) technique were studied experimentally. Phase composition, microstructure, composition and microhardness of the products are analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and microhardness tester, respectively. The elevated temperature erosion tests of the TiC/Fe composites were tested with the help of a GW/CS-MS type tester using SiO2 quartz and Al2O3 corundum as the abrasive. The influences of the different parameters such as impact angle, environment temperature, abrasive, on the erosion property of the TiC/Fe composites were studied. The morphology of the worn surface was analyzed with SEM to determine the erosion mechanisms.

Abstract: The present work aims at studying the corrosion resistance of carbon steel substrates pre-treated with bis-[triethoxysilylpropyl] tetrasulfide (BTESPT) solutions. The corrosion behavior of the pre-treated substrates during immersion in seawater was assessed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The analytical characterization of the silane films was performed by scanning electron microscopy (SEM). The results show that the pre-treatments based on silanes provide good corrosion protection of carbon steel substrates and the bis-silane film has good adhesion properties.

Abstract: Structural health monitoring (SHM) is an emerging research area with multiple applications. Lamb waves are ultrasonic elastic waves that travel inside and along thin plates and is frequently used as diagnostic tools to detect damage in plate-like structures. In this paper, a transient dynamic finite element simulation of Lamb wave with piezoelectric transducers for damage detection in a composite plate is carried out. The embedded cross-shaped piezoelectric active sensor arrays were used to generate and receive guided Lamb waves propagating in the plate structure. A full-scale FEM model for the laminate was created using three-dimensional eight-node layered structural solid element and piezoelectric active sensors were created using coupled field elements on the commercial finite element code ANSYS platform. The beam forming technique of Lamb waves is used to locate damage in the plate .The results of the numerical simulation demonstrate the effectiveness of the approach.

Abstract: A comparative study of the corrosion behavior of the copper-nickel-tin alloy in a nutrient–rich simulated seawater-based nutrient-rich medium in the presence and the absence of the marine bacteria was carried out by electrochemical experiments, microscopic methods. Comparing to the corresponding control samples, the electrochemical data demonstrated that the presence of the bacteria accelerated the corrosion of the alloy. Scanning electron microscopy (SEM) images revealed the occurrence of micro-pitting and intergranular corrosion underneath the biofilm on the alloy surface.

Abstract: Sol-gel TiO2 thin films undoped and doped with Ag-ions have been formed on 304ss by dip-coating method respectively. The Ag/TiO2 films are compact and have anatase phase with stable crystal structure and have a thickness of 50 nm approximately. The bactericidal rate of the Ag/TiO2 film against sulfate-reducing bacteria (SRB) strains reaches 97.1% when doping Ag+ with a percentage of 3%. The analysis of potentiodynamic polarization curves illustrates Ag/TiO2 film decreases the corrosion rate obviously.

Abstract: Microbiologically Influenced Corrosion behavior of copper manganese aluminum alloy (CMA) were studied in the environment of sulfate-reducing bacteria (SRB). Surface topography of microorganism films were observed by using atomic force microscopy (AFM) and Scanning Electron Microscope (SEM), The result showed that number of SRB were a little, so that microorganism films can’t form in the surface of CAM; Microscopic structure was analyzed in the process corrosion, with increase of exposure time, selective corrosion occurred mainly on containing Al at a high level of β-phase and κ-phase. X-ray Photoelectron Spectroscopy (XPS) showed the main component of corrosion product was Sulphide. The change of Ecorr and corrosion current density in culture medium containing SRB was greater than it in 3.5% NaCl. It showed that the selective corrosion of the copper was accelerated by the metabolism substance. The content of sulfide was increasing with exposure time increasing.

Abstract: The microbially influenced corrosion of copper by marine bacterium Vibrio natriegens (V. natriegens) was investigated using surface analysis (atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS). AFM images corroborated the results from the EIS models which show biofilm attachment over time. The electrochemical results showed that the corrosion of copper was accelerated in the presence of V. natriegens based on the decrease in the resistance of the charge transfer resistance (Rct) obtained from EIS.

Abstract: “Underwater super-hydrophobic” surface applied in the corrosion protection was prepared by melting myristic acid (CH3(CH2)12COOH) adsorbed onto the anodized aluminum. The static contact angle for seawater on the surface was measured to be 154°. The surface structure and composition were then characterized by means of scanning electron microscopy (SEM) with energy dispersive X-ray spectrum (EDX) and atomic force microscope (AFM). The electrochemical measurements showed that the super-hydrophobic surface significantly improved the corrosion resistance of aluminum in sterile seawater.

Abstract: Pitting resistance of air cold plasma-oxidation 316L stainless steel was evaluated by exposing the specimens into a ferric chloride solution. The results indicate that the pitting resistance of plasma-oxidized specimens improved obviously. Potentiodynamic polarization curves were measured to study its corrosion behavior. The corrosion mechanism was also interpreted by electrochemical impedance spectroscopy (EIS) and Auger electron spectroscopy (AES).The results reveal that the oxide layer formed by the plasma treatment is much thicker than that without treatment and is double-deck structure, which leads to the change of EIS characteristic of sample surface.