The use of Physical Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD) thin coatings has become a widespread practice in the design of components subject to an aggressive environment. Corrosion in an aggressive environment can be critical for the design of structural components under constant and fatigue loads, due to the presence of Stress Corrosion Cracking (SCC) and fatigue corrosion. The protection from aggressive environments granted by the use of thin coatings is desired also in nonstructural, electrochemically active components, such as medical implants and fuel cells. In the present work, a review of the most recent industrial patents related to the application of PVD and CVD coatings developed in the last decade for the reduction of the detrimental effects of corrosion is presented. The article illustrates some selected patents which deal with the corrosion protection of components subject to fatigue loads and to static corrosion. Regarding dynamically loaded parts the reviewed papers describe thin coatings adopted to screen out turbine blades and disks from pitting corrosion, erosion and oxidation. A method to protect sliding parts of compressors using Hydrofluoroolefin refrigerant is also reported. In the latter part of the work, technical solutions for components under static corrosion are investigated, by presenting patents related to the coating of Implanted Medical Devices (IMD) and fuel cells, thus providing shielding from the external aggressive environment. Finally, a patent which proposes a multilayer finishing to improve the corrosion protection of common PVD treatments is presented. Keywords: Corrosion fatigue, erosion, fuel cells, implanted medical devices, oxidation, pitting corrosion, thin coatings, turbines.
The electrochemical corrosion properties of bulk nanocrystalline 304 stainless steel produced by severe rolling technique and its conventional polycrystalline 304 stainless steel were studied by immersion test for 20 days in 0.5 mol/L HCl solution at room temperature. The corrosion rate of bulk nanocrystalline 304 stainless steel was less than that of conventional polycrystalline 304 stainless steel. The electronic structures and compositions of the two oxide films on bulk nanocrystalline 304 stainless steel and conventional polycrystalline 304 stainless steel in 0.5 mol/L HCl solution for 20 days’ immersion at room temperature were also studied by X-Ray Photoelectron Spectroscopy (XPS). The pitting corrosion resistance of bulk nanocrystalline 304 stainless steel was also simultaneously enhanced in comparison to conventional polycrystalline 304 stainless steel. These results were attributed to the better chemically stable, more compact and thicker oxide film on bulk nanocrystalline 304 stainless steel. The better chemical stability of oxide film on bulk nanocrystalline 304 stainless steel was due to the larger binding energies of Fe3+2p3/2, Fe2+2p3/2 and Cr3+2p3/2 in the oxide film on bulk nanocrystalline 304 stainless steel. Keywords: Electronic structures, oxide film, pitting corrosion, stainless steel, X-Ray photoelectron spectroscopy.
Corrosion affects the quality of the environment, the durability of the infrastructure assets and industrial equipments. Therefore, it is crucial using corrosion engineering control methods and techniques, in particular safe "green" e.g. environmental friendly corrosion inhibitors that will extend the life of the infrastructure saving large expenses in materials equipment and structures. This review presents an analysis of patents on corrosion inhibitors developed for aqueous systems, steel reinforced concrete, acid pickling operations, oil industry and additives in the formulation of protection coatings. Keywords: Corrosion inhibitor, patents, water systems.
Ferrous based-metals, e.g., iron metal and metal alloys containing iron (mild steel), and steels are routinely used in the construction of cooling systems and in other fields due to their low cost and availability. Environmental considerations have been of paramount importance. Corrosion resistant stainless steel or “super alloys” have been used in applications where prevention of corrosion of steel structures or pipes was absolutely essential. These materials are expensive and more difficult to produce than conventional steel materials. Iron and steels undergo inhibition, passivation and corrosion protection treatments to make these materials economical and durable for variety of applications. Numerous techniques are available in the literature to provide these treatments. Heavy metals, chromates, phosphates and fluorides are employed as effective materials for inhibition, passivation and corrosion prevention. A lot of research is underway to remove these materials due to their toxicity. In Europe rules have been established to limit the Chromium content (due to its toxicity) for easy and safe recycling of the materials. There still exists a need for finding out economical, efficient processes and materials which will reliably adhere to the surface being treated in chemically adverse or saline environment and can provide protection against corrosion. For these reasons tremendous efforts are being made to develop/invent new processes for inhibition, passivation and corrosion protection. Keywords: Corrosion, hindering, inhibition, passivation, steels.
This paper intends to review the main systems of monitoring the degradation of reinforced concrete structures with steel that have been patented in the last 10 years. Given that the degradation process in the large majority of cases is an electrochemical corrosion process of the reinforcement caused by chemical actions on the structure, the systems are generally systems that determine electrochemical greatnesses. The systems are essentially sets of electrodes with different arrays that allow the implementation of different electrochemical techniques such as linear polarization resistance, electrochemical impedance spectroscopy, electrochemical noise, ionic conductivity, in order to obtain information about reinforcement potentials and corrosion rates and penetration speeds of aggressive agents. Keywords: Electrochemical monitoring, monitoring, reinforced concrete degradation.
Elaborations in the field of chemical and abrasion resistant coatings and composite polymer materials by company Polymate LTD.-INRC (Israel) and its employees are reviewed. The main fields of advanced corrosion resistance materials are liquid and water based rubber compositions, hybrid nonisocyanate polyurethane coatings, nanostructured organic-mineral coatings. The review includes patents used by the industry of several countries of Europe, USA, Canada and Asia.Chemical resistant materials, abrasion resistant materials, polymeric materials for coatings, hybrid nonisocyanate urethane-epoxides, nanostructured hybrid oligomer composition, rubber-based compositions, organic-mineral coatings.
The discovery of the first petroleum off-shore fields 30 meters below sea level in the Brazilian coast in 1968 stimulated the development of new technology for oil extraction and production in increasing water deepness. Outstanding levels such as 6000 meters were expected for oil extraction in the offshore pre-salt reservoirs in the 2010s, which demanded a large amount of material, raising costs to extremely high levels. So, considerable new research efforts are being directed towards the development of new martensitic steels, with improved properties as a lower cost option for such application. In the present work information is gathered about recent developments on new martensitic stainless steels capable of withstanding severe conditions of operation and exploration of petroleum in marine platforms. These materials must present adequate mechanical strength and corrosion resistance in these conditions. With this purpose such information, based on articles and patents published in international databases since the onset of the 21st century (2001) until 2012, is compiled and analyzed in this review article. Keywords: Stainless steels, corrosion, microstructure, mechanical properties, oil and gas, seawater, marine environment.
The development of hybrid materials is desirable given that combinations of polymers and inorganic materials can be self-assembled forming pre-ordered complex structures with precise mechanical, chemical and electrical programmable properties. These new materials possess new and/or enhanced properties. For instance, polymeric materials are widely used in industry because of their superior properties such as flexibility, resistance to biochemical attack, good biocompatibility, lightweight, and inertness. In this work, synthesis, characterization and electrochemical noise evaluation of hybrid materials casted from nylon 6-6 and titanium are carried out for a patent application. Synthesis was carried out with different % weight of titanium functionalized with APTES. The materials obtained here were characterized through scanning electron microscopy (SEM), thermal analysis (TA), infrared spectroscopy (IR) and electrochemical noise technique in Hank solution to simulate the internal fluids of the human body, looking forward to biomaterial applications. SEM shows a homogenous material. Concentration of titanium was verified with TA. IR spectra show differences between Ny-Ti at different concentrations. Results also showed that hybrid materials made with 50%wt titanium present the lower resistance and the 40% wt the highest, as was confirmed by electrochemical noise resistance. Keywords: Hybrid materials, nylon, titanium, electrochemical noiseHybrid materials, nylon, titanium, electrochemical noise
A simultaneous in situ optical microscopy and simultaneous electrochemical analysis method is presented for studying 316L stainless steel in hydrometallurgical process solutions. The electrochemical method involved potentiodynamic analysis of the 316L stainless steel surface in aerated and deaerated experimental hydrometallurgy process fluids. This technique is reviewed along with other potentiodynamic methods used in stainless steels, recent patents on stainless steel technologies, and the results are discussed in conjunction with various theories and applications. The results illustrate a wide variety of corrosion behaviors (active, passive, anodic knee) and parameters (corrosion rate, pitting potential, mixed potential, pH) possible for 316L stainless steel under potentiodynamic test conditions. Analysis of these samples provides both a detailed visual account of the corrosion process in addition to standard electrochemical analysis regarding pitting potential, corrosion potential and corrosion rate. Polarization data and analysis with respect to the corrosion patterns observed is presented including in situ images of surface layer changes, etching, pitting and microstructure. Analysis of copper sulfide inclusions and metal surface film behaviors in solution were performed showing the tendency of inclusions and film to dissolve and act as nucleation sites for pits. The proprietary experimental hydrometallurgical process fluids tested further support the ability of in situ optical microscopy to successfully image and provide valuable insights into the corrosion processes taking place. Keywords: In situ, optical, potentiodynamic, polarization, SEM-EDS, etching, pitting, inclusions, grain boundaries, aerated, deaerated, 316L, hydrometallurgical process solutions.
This article deals with the effective attributes of friction material application out of aluminum matrix composites (AMC) containing disperse ceramic phase, particularly SiC particles, via literature survey and result analyzing of the relevant research works. These properties include thermal expansion coefficient, wear, friction coefficient, mechanical and thermal strength, durability, etc. The wear mechanism of braking in brake pads is discussed to perceive the material behavior of the friction pad constituents and phases to ameliorate the vehicle’s brake pad performance considering its main tasks. The discussion elaborates the advantages and the disadvantages of AMC as friction material based on the essential brake pad properties defined by automotive standards parameters and the vehicle industries requirements. Analysis of the results presented in this paper suggests that the optimized reinforced AMC may result in a new patent for friction material applied in the vehicle brake pad. Keywords: Brake pad, cermet, aluminum matrix composite, SiC particles, wear mechanism, wear rate.
The phenomenon of corrosion of metals including Fe, Al, Cu, Zn, Mg and their alloys is controlled to a great extent by selection of highly corrosion resistant inhibitors. The associated cost factor favors the use of cheap metallic materials along with efficient corrosion prevention methods in many industrial applications. In this aspect, corrosion inhibitors have a significant role in the protection of metals from corrosion. These inhibitors are either hazardous chemicals or environmentally friendly chemicals. Many authors reported that the use of plants extracts from mango, cashew, passion-fruit, orange, khillah seeds, African bush pepper, neem leaves and papaya as corrosion inhibitors in an acid medium for protection of metals such as steel, copper, and copper alloys gave high inhibition efficiency. Some environmentally friendly chemicals namely, octanoic acid, 2-ethylhexanoic acid and their alkali salts, sodium borates, triazoles, hydrocarbyl, and benzotriazoles were used as corrosion inhibitors. Polymeric compounds such as polyacrylic, polymaleic, and polyaspartic acid and its salts were also used as corrosion inhibitors for acidic ferrous metal surfaces in contact with acidic corrosive aqueous saline environment saturated with carbon dioxide. Published patents related to the corrosion inhibition using green corrosion inhibitors are discussed. Keywords: Corrosion inhibitor, acidic corrosion, adsorption isotherm, Langmuir, weight loss, polarization, impedance, synthetic inhibitors, environmentally friendly inhibitors, biodegradation.
The poor corrosion resistance of magnesium alloys is limiting their widespread applications. Some patents and literatures have reported corrosion-resistant magnesium alloys and surface treatment techniques to improve the corrosion resistance. However, these acknowledges are not enough for well understanding the corrosion behavior of magnesium alloys in actual application environments. In this paper, the influence of Cl- on the corrosion rate of AM50 alloy in simulated acid rain (SAR) was studied using electrochemical tests and scanning electronic microscopy (SEM) observation, and then the corrosion mechanism of magnesium alloys in the acid solution was established. The results show that Cl- can accelerate the corrosion of Mg matrix around the AlMn phases in the initial stage of corrosion. The predominant corrosion type of the AM50 alloy is the uniform type of corrosion in SAR. The coverage fraction of Mg(OH)2, MgH2, and the concentration of Mg+ are three key factors influencing the corrosion processes of magnesium alloys in SAR. Keywords: Acid solutions, Mg alloys, corrosion mechanism, negative difference effect, simulated acid rain (SAR).
This paper aims to study the influence of secondary air swirling flow on the non-premixed turbulent combustion fed with fuel oil n°2 injected within a combustor of a drying furnace. First, our attention was focused on the effects that could have this configuration on the phenomenon of walls corrosion caused by water vapor (H2O) and oxygen (O2). Preliminary results showed the possibility to reduce both temperature and water vapor near walls and at the same time to control the humidity which accompanies pollutants in the environment. Keywords: Walls corrosion, swirl number, non-premix turbulent combustion, CO2 emission, NO pollution
Flow Accelerated Corrosion (FAC), also known as Erosion-Corrosion (EC), is a serious safety and reliability problem facing carbon-steel pipes in power generation plants. It is also a serious problem in the oil and gas industry when oil, gas and solids flow together through piping systems. This phenomenon results in wear and thinning of large areas of pipes and fittings which could compromise their structural integrity and thereby could lead to sudden and sometimes to catastrophic failures. Such failures may require shutdowns which result in production losses, and impose potential threats to human safety and the environment. The existing technology of pipe thickness measurements depends mainly on ultrasonic, radiation and electromagnetic inductions techniques. This paper presents an overview of the patents developed for pipe thickness measurements and introduces a new potential technique for non-intrusive thickness measurements of industrial piping systems while in operation. The technique is based on analyzing the vibration response of the piping system and it provides both the magnitude and the location of the wear due to flow-accelerated corrosion. The magnitude of the wear is determined by examining the vibration frequency of the piping system and the location of the wear is determined by examining its mode shapes. The proposed sensor can also be used for the quality inspection of newly manufactured pipes.
The methanol electro-oxidation in alkaline solution was studied on titanium electrode carrying Ni-P and Ni deposits. The phosphorus in Ni-P makes the Ni-P deposits fine and fine, and leads to the Ni-P deposits with a high specific surface area. Meanwhile, the weak binding between hydrogen and the Ni-P makes adsorbed hydrogen from methanol dehydrogenation on Ni-P deposits more easily cleaned up and makes Ni-P deposits to release fresh surface for the adsorption of other methanol molecules. The methanol electro-oxidation on Ni-P deposits just starts at the potential that coincided with that; at which Ni(OH)2 on the surface of electrodes becomes NiOOH. However, on Ni deposits, methanol oxidation is delayed behind the potential at which Ni(OH)2 is oxidized to NiOOH due to the hindrance of strongly-absorbed hydrogen, which is thought to be desorbed at a bit more positive potential. Patents relevant o the topic have been discussed. Keywords: Alkaline, electrocatalysis, methanol oxidation, Ni-P.
Corrosion played a significant role in the catastrophic collapse of many aged steel bridge infrastructures around the world. Those damages and many reviewed patents intensified the importance of careful evaluation of existing structures for the feasibility of current usage and strengthening them by retrofitting some selected corroded members to ensure the public safety. Only experimental approach is not enough to estimate the remaining strength of corroded members as actual corroded surfaces are different from each other. However in modern practices, numerical simulation is being used to replace the time-consuming and expensive experimental work and to comprehend on the lack of knowledge on mechanical behavior, stress distribution, ultimate behavior and so on. This paper comprises the non-linear FEM analysis results of many actual corroded plates with different corrosion conditions and a simple and comprehensive analytical method is developed by measuring the maximum corroded depth (tc,max) only, for the utilization of recently developed numerical techniques in assessment of the state of corrosion and consequences for the safety of old steel bridges. Keywords: Bridge maintenance, corrosion, FEM analysis, maximum corroded depth, residual strength, steel bridges, tensile test.
In situ phosphatizing coating (ISPC) was invented and patented in 1994, where in situ phosphatizing reagent (ISPR) was shown to form a dense interfacial phosphate layer on and bond strongly with metal substrates, and simultaneously link with covalent bonds to the polymer top-layer. In this paper, we report the synthesis of ISPR-catalyzed polysilsesquioxane (PSSQ) oligomers by the sol-gel method. Using different amounts of ISPR, the well-defined nanonetwork structures of PSSQ were characterized by SEM. The dispersion of ISPR-catalyzed PSSQ in ISPC to form a stable and compatible organic-inorganic hybrid (ISPC/PSSQ) nanocoating was carried out. The nanocoating was applied on AlMg alloys (AZ31A, AZ31B and AZ91D), and the corrosion performance was characterized by salt spray test (ASTM B117) and electrochemical impedance spectroscopy (EIS). The cross-section of dry film nanocoating layer on AZ91D was characterized by TEM EDS elemental mapping analysis. It was shown that the ISPR-catalyzed PSSQ forms a dense and uniform interfacial passivation layer sited tightly on top of metal surface and beneath the polymer layer. A 400 nm thick interfacial passivation layer of PSSQ in the nanocoating on AZ91D was shown to pass 360 hours of salt spray test ( 0.5% corrosion area). The current and future development on self-healing of corrosion protection, Li as anodic protection for Mg in LiMg alloys and encapsulation and release of ISPC/PSSQ corrosion inhibitor in nanocontainer has been illustrated. The excellent corrosion protection performance of ISPC/PSSQ nanocoating on AlMg alloys will be discussed.
This work presents the application of artificial intelligence for the assessment on the corrosion conditions diagnosis of electric transmission line tower foundations. A literature and patents review and background in relation to corrosion monitoring and application of artificial intelligence relevant to this problem, along with an example of a novel corrosion monitoring of tower legs in the field, based in the close remote procedure are presented. A predictive computational model was developed, under the criteria of artificial neural networks, to obtain and propose a degree of corrosion index in tower leg foundations of electric transmission lines, for the purpose of establishing a decision making process for predictive maintenance programs. Information was gathered in the field, through electrochemical corrosion monitoring of eighty tower legs belonging to twenty transmission line towers under different environmental conditions. A data base was elaborated and with it, the neural network was developed, trained and its performance proved. The configuration 6-5-2 (6 Input, 5 hidden, 2 output neurons) used, presented an excellent agreement (R2=0.9998) between experimental and simulated corrosion data. The sensitivity analysis showed that all studied input variables (soil resistivity, free corrosion potential and electrochemical measurements) have an effect on the estimation of the corrosion level, with the strongest being the corrosion potential and resistance. With the results obtained and presented, an assessment on the corrosion conditions diagnosis for transmission line tower foundations, predictive maintenance programs and actions can be proposed and established. Keywords: Artificial intelligence, expert systems, neural networks, corrosion monitoring, transmission lines, tower foundations
An in situ optical microscopy and simultaneous electrochemical analysis method is presented for studying 316L stainless steel in sulfuric acid based solutions. The electrochemical methods involved potentiostatic and potentiodynamic analysis of 316L stainless steel surface in aerated and deaerated 1M-3.39M H2SO4 while varying Ni+ and Cl-. This technique is reviewed along with several other in situ surface analytical probes and patents such as scanning tunneling microscopy (STM), scanning electrochemical microscopy (SECM) and variations on SECM (near fieldalternating current) and the results are discussed in conjunction with various theories and applications. The results when compared to SECM data indicate that the SECM resolution, control and performance are improved. The results also illustrate the wide variety of corrosion behaviors possible for 316L stainless steel under potentiostatic and potentiodynamic test conditions. Analysis of these samples provides both a detailed visual account of the corrosion process in addition to standard electrochemical analysis regarding pitting potentials, corrosion potential and corrosion rate. Polarization data and analysis regarding the corrosion patterns observed is presented including in situ images of etching, surface layer changes and pitting. Images and analysis of chromium carbide and sulfide inclusion behaviors in sulfuric acid were performed showing the tendency of inclusions to dissolve and act as nucleation sites for pits. Keywords: Aerated, dearated, etching, grain boundaries, inclusions, in situ, optical, pitting, potentiostatic, potentiodynamic, polarization, SEM-EDS, 316L, 1M-3.39M H2SO4
