Recent Patents on Corrosion Science - Volume 2, Issue 1, 2012

Recent Patents on Corrosion Science was launched in June 2011 and now we are publishing 2nd volume of the Journal. This Journal publishes review and research articles and guest edited thematic issues on recent patents in the field of Corrosion Science. In this issue seven papers have been included. The first paper entitled “Techniques for In Situ Corrosion Studies of 316L Stainless Steel in Sulfuric Acid Solutions” is written by Shirokoff et al. This article describes an interesting topic on in-situ corrosion response of 316LSS in sulfuric acid. This paper uses in situ optical microscopy techniques and electrochemical measurements for 316L stainless steel in various sulfuric acid solutions. The second paper entitled “Protective Coatings for Porcelain Insulators” is written by Dachamir Hotza. The topic is very important for improving the performance of outdoor insulators. The third paper entitled “Enhanced Method of Predicting Tensile Strength Degradation of Steel Bridge Members Due to Corrosion” is written by Appuhamy et al. This paper describes an interesting method for predicting tensile strength degradation of steel bridge members due to corrosion. The fourth paper entitled “Methanol Electro-Oxidation in Alkaline on a Titanium Electrode Supporting Ni-P or Ni Deposits” is written by Wei et al. The manuscript describe the catalytic activity of Ni-P/Ti towards methanol electrooxidation in alkaline solution. The fifth paper entitled “Interfacial Passivation of Nanocoatings for Corrosion Inhibition of Magnesium Alloys” is written by Lin et al. In this paper synthesis of ISPR-catalyzed polysilsesquioxane (PSSQ) oligomers by the sol-gel method has been reported. The sixth paper entitled “An Innovative Vibration Sensor for Flow Accelerated Corrosion Measurement”is given by Ahmed et al. This paper presents an overview of the patents developed for pipe thickness measurements and introduces a new potential technique for nonintrusive thickness measurements of industrial piping systems while in operation. The last paper entitled “A review of recently patented work on thermal sprayed coatings used for wear and corrosion protection” is written by Cooke et al. This review covers significant patented progress in the field of wear- and corrosion-resistant thermal spray coatings achieved during the past five years....

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.

This review presents a selection of patents reported on coatings for high-voltage porcelain insulators. An insulator is subject to surface corrosion due to air pollution or salt deposition, which may form a conductive electrolytic solution. This may cause a flashover and shut down the transmission and distribution electrical energy line, particularly in high polluted or coastal regions. The main goal of protective coatings has been to produce flashover-free high-voltage insulators. Coating porcelain insulators with specific inorganic or organic may prevent the leakage current. Major approaches are based either on semiconducting glazes or hydrophobic coatings.

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.

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.

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.

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 application of thermally sprayed ceramic or metallic coatings has become an important part of surface coating technology. Over the last two decades, the industry has seen extensive development of sophisticated equipment that has simplified the application of thermal spray coating to complex surfaces. The availability of a broad range of tailored feedstock materials, and sensitive characterization and quality assurance methods has made surface coatings and their improved deposition techniques increasingly attractive. The drive for new and improved materials and characterization methods has forced engineers and designers to modify old techniques and invented new ones to satisfy the growing demand for thermal spray materials. These materials are used for wear and corrosion protection of engineered components and structures. This review will cover significant patented progress in the field of wear- and corrosionresistant thermal spray coatings achieved during the past five years.

The patents annotated in this section have been selected from various patent databases. These recent patents are relevant to the articles published in this journal issue, categorized by the processes and technologies related to various disciplines of corrosion science.