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Corrosion Protection (corrosion + protection)
Selected AbstractsSurface-Modified Mesoporous SiO2 Containers for Corrosion ProtectionADVANCED FUNCTIONAL MATERIALS, Issue 15 2009Ekaterina V. Skorb Abstract The development of active corrosion protection systems for metallic substrates is an issue of prime importance for many industrial applications. The present work shows a new contribution to the design of a new protective system based on surface modified mesoporous silica containers. Incorporation of silica-based containers into special sol,gel matrix allows for a self-healing effect to be achieved during the corrosion process. The self-healing ability occurs due to release of entrapped corrosion inhibitors in response to pH changes caused by the corrosion process. A silica,zirconia-based hybrid film is used in this work as a coating matrix deposited on AA2024 aluminum alloy. Mesoporous silica nano-particles are covered layer-by-layer with polyelectrolyte layers and loaded with inhibitor [2-(benzothiazol-2-ylsulfanyl)-succinic acid]. The hybrid film with nanocontainers reveals enhanced long-term corrosion protection in comparison with the individual sol,gel films. The scanning vibrating electrode technique also shows an effective healing ability of containers to cure the corrosion defects. This effect is due to the release of the corrosion inhibitor triggered by the corrosion processes started in the cavities. The approach described herein can be used in many applications where active corrosion protection of materials is required. [source] Plasma Polymerization of HMDSO with an Atmospheric Pressure Plasma Jet for Corrosion Protection of Aluminum and Low-Adhesion SurfacesPLASMA PROCESSES AND POLYMERS, Issue 10 2009Uwe Lommatzsch Abstract Thin functional films were deposited on aluminum with an atmospheric pressure plasma jet using hexamethyldisiloxane (HMDSO) as precursor. A high dynamic deposition rate on the order of 450,nm,·,m,·,min,1 was achieved. Composition and structure of the thin films show a strong dependence on the downstream location of the precursor injection. A 4,mm downstream shift of the precursor injection increases the carbon content in the thin film by a factor of 2.5, as indicated by XPS analysis and alters the degree of cross-linking according to the FTIR spectra. The coating with the low carbon content (17 at.-%) provides corrosion resistance for aluminum 2024 unclad exposed for 96,h to a neutral salt spray test. The coating with the high carbon content reduces the adhesion of an epoxy resin to the surface and may be used as a release coating. [source] Surface-Modified Mesoporous SiO2 Containers for Corrosion ProtectionADVANCED FUNCTIONAL MATERIALS, Issue 15 2009Ekaterina V. Skorb Abstract The development of active corrosion protection systems for metallic substrates is an issue of prime importance for many industrial applications. The present work shows a new contribution to the design of a new protective system based on surface modified mesoporous silica containers. Incorporation of silica-based containers into special sol,gel matrix allows for a self-healing effect to be achieved during the corrosion process. The self-healing ability occurs due to release of entrapped corrosion inhibitors in response to pH changes caused by the corrosion process. A silica,zirconia-based hybrid film is used in this work as a coating matrix deposited on AA2024 aluminum alloy. Mesoporous silica nano-particles are covered layer-by-layer with polyelectrolyte layers and loaded with inhibitor [2-(benzothiazol-2-ylsulfanyl)-succinic acid]. The hybrid film with nanocontainers reveals enhanced long-term corrosion protection in comparison with the individual sol,gel films. The scanning vibrating electrode technique also shows an effective healing ability of containers to cure the corrosion defects. This effect is due to the release of the corrosion inhibitor triggered by the corrosion processes started in the cavities. The approach described herein can be used in many applications where active corrosion protection of materials is required. [source] Poly(O -anisidine) coatings electrodeposited onto AL-2024: Synthesis, characterization, and corrosion protection evaluationADVANCES IN POLYMER TECHNOLOGY, Issue 4 2004Kunal Shah Abstract Poly(O -anisidine) coating was successfully electrodeposited onto Al-2024. Cyclic voltammetry and reflection absorption infrared spectroscopy (RAIR) analysis were carried out in order to fully understand the formation and structure of the resulting polymer coating. RAIR spectrum showed the characteristics peaks of poly(O -anisidine). As the reaction time was varied, the CV peak shifted from 0.75 to 0.81 V vs. SCE suggesting that a change in structure of the polymer from a reduced state to a partially oxidized form has occurred. UV spectrum showed two peaks at 320 and 620 nm suggesting the presence of conjugation on the polymer backbone. The deposition of the poly(O -anisidine) onto the substrate was controlled by nucleation and growth mechanism. DC polarization technique was used to evaluate the corrosion protection offered by poly(O -anisidine) coatings. Preliminarily data shows that these coatings help to ennoble the surface of the substrate. © 2004 Wiley Periodicals, Inc. Adv Polym Techn 23: 291,297, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20024 [source] Comparison of the corrosion protection of mild steel by polypyrrole,phosphate and polypyrrole,tungstenate coatingsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008M. G. Hosseini Abstract The electrodeposition of polypyrrole,phosphate (PPy,P) and polypyrrole,tungstenate (PPy,W) on mild steel (MS) were achieved in an oxalic acid medium with cyclic voltammetry techniques. Adherent and homogeneous PPy,P and PPy,W films were obtained. The corrosion behavior of mild steel with phosphate (PPy,P) and tungstenate (PPy,W) composite coatings in 3.5% NaCl solutions were investigated through a potentiodynamic polarization technique, open-circuit potential,time curves, and electrochemical impedance spectroscopy (EIS). On the basis of a physical model for corrosion of mild steel composites, Zview (II) software was applied to the EIS to estimate the parameters of the proposed equivalent circuit. It was found that the PPy,W coatings could provide much better protection than the PPy,P and polypyrrole coatings. The effects of the phosphate and tungstenate process parameters on the morphology and structure of the passive films were investigated by scanning electron microscopy and electron dispersion X-ray analyses. The results reveal that the PPy,P and PPy,W coated electrodes offered a noticeable enhancement in protection against corrosion processes. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Infrared stealth and anticorrosion performances of organically modified silicate-NiZn ferrite/polyaniline hybrid coatingsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 3 2008K. H. Wu Abstract Hybrid coatings based on organically modified silicate-Ni0.5Zn0.5Fe2O4/polyaniline were synthesized through a sol,gel technique with different NiZn ferrite/polyaniline weight ratio (1/1, 1/2, 1/5). These hybrid films were deposited via spin coating onto an aluminum alloy to improve the corrosion protection and to act as infrared stealth coatings. The effects induced by the NiZn ferrite/polyaniline hybrids on the chain dynamic, ferromagnetic behavior, infrared stealth, and anticorrosion performances of the coated samples were investigated. The rotating-frame spin-lattice relaxation times and scale of the spin-diffusion path length indicated that the configuration of the hybrid films was highly cross-linked and dense. The thermal extinction of the hybrid coatings increased with the increase in the polyaniline content. Potentio-dynamic and salt-spray analysis revealed that the hybrid films provided an exceptional barrier and corrosion protection in comparison with untreated aluminum alloy substrates. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 926,935, 2008 [source] Impeding corrosion of sintered NdFeB magnets with titanium nitride coatingMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 2 2010A. Ali Abstract Sintered NdFeB magnets have poor corrosion resistance that renders them susceptible to corrosion in industrial and marine environments. This paper evaluates the properties of cathodic arc physical vapour deposited (CAPVD) titanium nitride coating for corrosion protection of sintered NdFeB permanent magnets. The performance of titanium nitride coating has been compared to the electrodeposited nickel,copper,nickel multilayer coating. The rates of coatings degradation in simulated marine environment were estimated with electrochemical impedance spectroscopy (EIS). Cyclic polarization was carried out to assess the pitting potential. The surface chemistry and coating morphologies were studied with scanning electron microscope (SEM). X-ray diffraction (XRD) was used for qualitative phase analyses of coatings and the substrate. It was figured out that the charge transfer resistance of CAPVD titanium nitride coating increased with exposure time. The negative rate of Rp-degradation for titanium nitride coating compared to the nickel,copper,nickel multilayer for equivalent exposure time is a unique and valuable result. Polarization results showed that ,pits re-passivation' of titanium nitride coating could be responsible for the extended corrosion protection of the NdFeB substrate. The magnetic properties remained comparable for both types of coatings. [source] Progress in corrosion protection as a requirement for technical progress,MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 7 2009W. Fürbeth Abstract In many of the more recent technologies, corrosion plays a crucial role in determining their successful application. The present paper identifies such important corrosion issues in a number of technologies, which are currently under development or have been recently discussed. In this sense, CO2 sequestration, fuel cells, offshore wind energy and other offshore technologies, geothermal energy, advanced coal conversion technologies, nuclear energy, light weight construction in transport, ionic liquids as well as medical technologies are discussed with respect to corrosion problems and existing research needs. In this way, this paper intends to show the complexity and the variety of corrosion topics of today and at the same time, point at the economic aspects and the impact on daily life. In the end, this leads to an introduction of the World Corrosion Organization and its study on future needs for research and development in materials degradation and corrosion control. [source] Evaluation of different sealing methods for anodized aluminum-silicon carbide (Al/SiC) composites using EIS and SEM techniquesMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 11 2007H. Herrera-Hernandez Electrochemical impedance spectroscopy (EIS) and the scanning electron microscope (SEM) have been used in an investigation of the effectiveness of various sealing methods that can be used to improve the corrosion resistance of an anodized aluminum-silicon carbide (Al/SiC) composite. Anodic oxide films were grown on Al7075-T6 and the Al/SiC composite by sulfuric acid anodizing and sealing in a cold saturated solution of nickel acetate. Other samples were sealed using the traditional method of boiling water or hot nickel acetate for comparison. The results revealed a uniform anodized layer on Al7075-T6 that resisted pitting corrosion for more than 2,weeks exposure to NaCl, whereas a cracked oxide film with variations in thickness was observed on the composite material. Pit initiation occurred in less than 5,days on the anodized Al/SiC that was sealed in the hot solutions. This study suggests that the traditional hot sealing methods did not provide sufficient corrosion protection for aluminum metal,matrix composites (MMCs) because the reinforcing SiC particles deteriorated the surface film structure. However, this defective film can be repaired by nickel hydrate precipitation during cold sealing or by applying a thick polyurethane coating. [source] Capability of thermodynamic calculation in the development of alloys for deposition of corrosion-protection coatings via thermal sprayingMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 9 2007M. Born The capability of thermodynamic calculations for the development of materials for corrosion protection of steels via thermal spraying is illustrated in several practical examples. Although the thermodynamic calculations are usually performed for the equilibrium state, they can yield important information even about fast chemical reactions that are far from the equilibrium conditions. The relevance and reliability of thermodynamic calculations can be improved significantly if their results are complemented by chemical and microstructural analyses. In this contribution, details on the melting and alloying processes in technically relevant nickel-based alloys were obtained from the combination of the thermodynamic calculations, differential thermal analysis, local chemical analysis using scanning electron microscopy with energy dispersive spectroscopy of characteristic X-rays and X-ray diffraction analysis. Furthermore, the results of the thermodynamic calculations performed on nickel-based alloys clarified the role of individual chemical elements dissolved in the alloys for the corrosion resistance of the alloys and thus they contributed to the improvement of the chemical stability of these alloys during the chemical reaction with gaseous substances containing chlorine. [source] Abrasive wear mechanisms of VPS- and HVOF-sprayed TiC-Ni based nanocrystalline coatingsMATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 10-11 2004X. Qi Verschleißmechanismen; nanokristalline Schichten; TiC-Ni; thermisches Spritzen Abstract Nanocrystalline coatings have a high potential for various engineering applications, e.g. against wear of rolls in the paper fabrication and as corrosion protection. Using vacuum plasma spray (VPS) and high velocity oxy-fuel (HVOF) spray techniques, coating materials are exposed to high flame temperatures only for less than a millisecond. Therefore, high-energy milled powders can be used as feedstock material without losing its nanocrystalline microstructure during the thermal spray process. In this way, homogeneous, dense nanocrystalline coatings can be produced, which show enhanced hardness, thus obtaining promising superior wear resistance. In the present study, (Ti,Mo)(C,N)-45vol.%NiCo nanocrystalline coatings were prepared by VPS- and HVOF-spraying of high-energy milled powders. Abrasive wear tests JIS H 8615 with varying number of strokes and scratch tests with a Vickers indenter were applied to produce wear traces on the polished surfaces of the nanocrystalline coatings. Abrasive wear behaviour was analyzed by investigating the surface morphologies with optical microscopy (OM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Experimental results indicate that the VPS-coating has higher abrasive wear resistance than the HVOF-coating according to the JIS H8615 test. The abrasive wear mechanism of VPS-sprayed nanocrystalline coatings can be delineated as cutting plus ploughing. For HVOF-sprayed nanocrystalline coatings the abrasive wear mechanism can be described as cutting plus material delamination. Abrasive Verschleißmechanismen von VPS- und HVOF-gespritzten nanokristallinen TiC-Ni-Schichten Nanokristalline Schichten haben ein hohes technisches Anwendungspotenzial, z.,B. für Papierwalzen zum Schutz gegen Verschleiß und Korrosion. Während des thermischen Spritzens mit der Vakuumplasmaspritz (VPS)- und der hochgeschwindigkeits-Flammspritz (HVOF)-Technik werden die Beschichtungsmaterialien nur für weniger als eine Millisekunde den hohen Temperaturen ausgesetzt. Daher können hochenenergiegemahlene Pulver als Beschichtungswerkstoff genutzt werden, ohne dass diese während des Spritzprozesses ihre nanokristalline Mikrostruktur verlieren. Dadurch können homogene, dichte nanokristalline Schichten produziert werden, die hohe Härte aufweisen und damit auch eine hohe Verschleißfestigkeit zeigen sollten. In der vorliegenden Arbeit werden nanokristalline Schichten auf der Basis von (Ti, Mo)(C, N)-45Vol.%NiCo durch die VPS- und HVOF-Technik hergestellt. Verschleißtests nach JIS H 8615 mit unterschiedlicher Hubzahl und Ritztests mit dem Vickers-Indenter werden durchgeführt, um Verschleißspuren auf den polierten Oberflächen der nanokristallinen Schichten zu erzeugen. Die Verschleißmechanismen werden aufgrund der Oberflächenmorphologien von verschleißbeanspruchten Schichten durch optische Mikroskopie (OM), Raster-Elektronenmikroskopie (REM) und Rasterkraftmikroskopie (AFM) analysiert. Die experimentellen Ergebnisse zeigen, dass die VPS-gespritzte Schicht eine höhere Verschleißfestigkeit aufweist als die HVOF-gespritzte Schicht. Der Verschleißmechanismus der VPS-gespritzten nanokristallinen Schicht kann als Kombination von Spanen und Pflügen charakterisiert werden. Für HVOF-gespritzte nanokristalline Schichten stellt sich der Verschleißmechanismus dagegen als Spanen mit partiellen Schichtablösungen dar. [source] On Some Characteristics of Ti Oxynitrides Obtained by Pulsed Magnetron SputteringPLASMA PROCESSES AND POLYMERS, Issue S1 2007Mariana Braic Abstract TiOxNy coatings were investigated as possible candidates for ion diffusion barrier layers. The elemental and phase composition, texture, hardness, adhesion, and corrosion resistance of the coatings were analyzed. The ion release in Ringer solution for uncoated and coated samples were also determined. The film properties were found to significantly depend on the reactive gas composition (O2/N2 ratio). The coatings proved to enhance the corrosion protection and to reduce the ion release of the uncoated specimens. [source] Economical Advantages of Low-Pressure Plasma Polymerization CoatingPLASMA PROCESSES AND POLYMERS, Issue 6 2005Hirotsugu Yasuda Abstract Summary: Low-pressure plasma polymerization coating, as described in this paper, is an ultimately green process that uses a minimum amount of substances and produces a minimum amount of effluent and hence does not require an environmental remediation process. The super-green aspect of the processing entirely changes the equation for the viability of the process in industrial applications. The main hampering factors for the low-pressure processes are 1) psychological fear of vacuum processes, 2) relatively high initial equipment costs, and 3) a lack of adequate cost estimate for the entire process. In many cases, the first two factors are enough for planners to shy away from this promising technology. However, when one examines the overall cost of processing as a whole, the cost of initial equipment often is not the decisive factor. Such cases are presented in the nano-film coating applied in corrosion protection of aluminum alloys, steel, and surface-state modification of contact lenses. The benefits of environmental friendliness, non-hazardous processing and superior performance of products that can be achieved only by low-pressure plasma polymerization coatings are more than enough to compensate the initial cost of the equipment. For nanofilm (20 nm) coatings, the most expensive annual operation cost is for wastewater treatment, which is much more than the initial cost of vacuum plasma polymerization reactor. [source] Beton unter hohen Temperaturen , eine Frage der TunnelsicherheitBETON- UND STAHLBETONBAU, Issue 2 2006Konrad Bergmeister Prof. Dipl.-Ing. Die Sicherheit in den Tunnels wird einerseits durch das Verhalten der Benützer und andererseits durch die Konstruktion und Ausstattung bestimmt. Neben der Modellierung des Verhaltens und der Anwendung von Sicherheitstheorien in Tunnel gilt es, organisatorische und erzieherische Maßnahmen in der Planungs-, Ausführungs- und Betriebsphase zu setzen. Durch die extreme Hitzeentwicklung können die Einbauten und das Tunneltragwerk beschädigt werden. Dabei kann es zu Betonabplatzungen (spalling) und zum Ablösen von Betonstücken bzw. Verankerungen kommen. In diesem Beitrag werden unterschiedliche Spritzbetone -experimentell unter hohen Temperaturen untersucht. Dabei zeigt sich, daß die Dichte und die Porenverteilung sowie die Zugkapazität der Betonformulierung von ausschlaggebender Bedeutung sind. Concrete exposed to high Temperatures , a safety Issue of tunnels The safety of tunnels is related to the behaviour of the users as well as to the construction and the equipment, which may be damaged due to heat impact. Concrete spalling decreases the effects of corrosion protection and the bonding of the reinforcement, and the load capacity is also diminished. Predictions about possible concrete spalling and failure mechanism often are based on experimental research. The crucial parameters for concrete spalling are the gas pressure in the pores, the physical properties e. g. water absorption at 20 °C and after 1000 °C and the mechanical resistance. In a full scale fire test in a highway tunnel there have been investigated various shotcrete mixtures. Pore size and distribution have been determined with the Mercury Intrusion (MIP) Porosimeter, whereas the permeability was calculated using the results of the MIP at different temperatures. It could be shown, that the moisture in the pore system and the physical and chemical adsorpted water in the matrix as well as in the aggregates evaporates under external increase of temperature and thus leading to higher pressure. Fire resistant shotcrete for use in tunnel shells should exhibit a certain volume of open pores in order to equalize the vapour pressure. [source] | ||||||||||||||||||||||