Between 1999 and 2001, corrosion-related costs accounted for 3.1% of the Gross Domestic Product (or $276 billion a year) in the US. To minimize the economical loss requires accurately predicting and effectively preventing corrosion. Generally, corrosion is the deterioration of metal by its interaction with a combination of physical and chemical environments. Therefore, corrosion detection can be indirectly achieved by monitoring the accumulation of corrosion products or the physical or chemical changes they cause, e.g. appearance, acoustic and electromagnetic transmission, pH, etc. On the other hand, corrosion can be directly monitored by its electrochemical characteristics such as corrosion current, electrochemical noise, corrosion potential. Each of these corrosion monitoring techniques is worth its own fulfilled discussion. Instead of go through each techniques exhaustively, we will just give a general review of the major corrosion monitoring techniques across different research areas, with the intention of a contribution to the interdisciplinary research of corrosion monitoring techniques.
Nickel is the primary determinant of contact sensitization, therefore there is now a tendency to take nickel out of goods that could be in contact with human body. However this needs careful evaluation of the corrosion properties of nickel substitution especially in the fashion and jewellery industry where aesthetical defects are not acceptable. This paper analyses the corrosion behaviour of a recently patented Cu-Sn-Zn-In alloy, named “Quatro®”. The alloy is substantially nickel-free and can be obtained as thin coatings by electrodeposition from aqueous solutions. The obtained coatings show mechanical and aesthetical properties similar to the nickel ones constituting a potentially inexpensive alternative to this one. In this paper the corrosion properties of Quatro® coatings, electrochemically deposited on brass substrates, were evaluated by free corrosion tests and analysis of electrochemical parameters such as open circuit potential, corrosion current, breakdown potential and potentiodynamic polarization curves. In NaCl solution the corrosion properties of this alloy result to be similar to the traditional nickel coatings. In view of possible applications of this alloy as “Ni-free” solution for jewellery application, the corrosion properties in artificial sweat were also tested. In this environment, the investigations evidenced higher corrosion activity, assessing this solution not suitable for top finishing goods designed to be in contact with skin.
The corrosion inhibition of 304L stainless steel in physiological serum (PS) in the presence of poly (vinyl) alcohol (PVA) is discussed according to electrochemical measurements. The layer composition formed on stainless steel surface was estimated using Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS) techniques. Electrochemical measurements indicated that PVA presence in PS solution decreases the corrosion current and increases the polarization resistance. XPS analysis showed that the surface layer consisting of PVA contains small amounts of other elements, such as: Na, Cl. The surface characterization of electro polished 316L stainless steel by using poly (O-2-hydroxyethyl) starch (PETA) in physiological serum (PS) is discussed according to electrochemical measurements, Scanning Electron Microscopy and Mossbauer Spectroscopy. The results obtained through polarization curves indicate that PETA reduces anodic dissolution and also decreases the corrosion current (icorr). Scanning Electron Microscopy (SEM) showed no evidence of corrosion pits on the surfaces of electro polished 316L stainless steel, but the formation of a thick film on the steel surface was observed. The Mossbauer spectrometry proves uniformity, compactness and stability of the passive films. More patents detailed the methods for producing a corrosion- inhibiting coating on the implants made of biocorrodable materials.
In this work, modification and application of Poly (ethylene terephthalate) (PET) waste as organic coating were reported. A potential application of PET coating is to provide protection against corrosion in automobile fuel tanks. PET powder was obtained from post-consumer beverage bottles. The corrosion resistance of the coating was evaluated by total and partial immersion tests in gasoline, diesel oil and alcohol. PET waste was depolymerized in the presence of glycols or ethanol amines and manganese acetate as a catalyst. The produced oligoesters were used to prepare epoxy, alkyd, vinyl ester and polyurethane organic coatings. The cured epoxy, alkyd, polyurethane and unsaturated polyester resins were evaluated as corrosion protective coating application of steel. The recent advances in manipulating patterned recycled PET arrays and patents are reviewed with a focus on the progress of the recycled products and applications.
The paper presents the mechanism of obtaining polychrome layers by microcrystalline phosphatation of iron objects. These ornamental layers must be aesthetic and must offer protection against corrosion induced by various climatic conditions. Chemical and physical-structural, analyses were carried out by OM and SEM-EDX, in order to verify the obtaining processes. The procedure described by the patent can be applied to new objects but also to ancient artifacts, that must be chromatically reintegrated, after restoration.
An in situ optical microscopy and electrochemical analysis method is presented for studying corrosion processes of metals and alloys (316L SS, Al 6061, Mg) in aerated and deaerated solutions (0.5 M and 6M NaCl, 1M H2SO4). Real time optical images were recorded for various in situ physical surface changes (etching, pitting, surface discoloration, gas bubbles), microstructure (inclusions, grain boundaries, dislocation slip traces, twins) and correlated to the electrochemical (potentiostatic, potentiodynamic, polarization) data measured simultaneously. This technique is reviewed along with other in situ surface analytical probes including recent advances in optical microscopy methods involving higher resolution imaging and the results are discussed in terms of theories and current applications in the field of study. This super-resolution patent review highlights developments in optical microscopy , phototransformable optical labels [14, 17, 19], and double confocal microscopy , and corrosion results from near-field scanning optical microscopy, and in situ confocal laser scanning microscopy compared to our in situ optical microscopy plus electrochemical analysis.
Nowadays organic compounds corrosion inhibitors are receiving more and more attention due to their wide applications in acidic rinsing and pickling of metals in industry and laboratory, how to build a kinetic model to quantitatively describe corrosion behavior in the absence and presence of organic corrosion inhibitors is of great importance to corrosion research, the recent progresses in corrosion inhibitors researches and patents are reviewed with a focus on metal corrosion and inhibition in acidic solutions. The effect of 4-(2-Pyridylazo) resorcin (PAR) on the corrosion inhibition of steel in a concentration range of hydrochloric acid has been investigated by using weight loss method, in order to study the concentration of acid and experimental temperature on the steel corrosion in the absence and presence of corrosion inhibitor, a general kinetic model has been proposed, to verify its correctness, temperature dependent and acid concentration dependent experiments have been carried out. It is found that for each experimental temperature inhibition efficiency monotonously decreases with an increase in concentration of hydrochloric acid, there is a “critical concentration” in this system, when concentration of hydrochloric acid is lower than this “critical concentration”, effect of experimental temperature on inhibition efficiency is unobvious. In point of the application of PAR as steel inhibitor in hydrochloric acid, it is safe for PAR to be used at a relatively low temperature; the logarithm of corrosion rate is directly proportional to the concentration of hydrochloric acid, i.e., lnv ∞ c; the logarithm of N is reciprocally proportional to the 1/T, i.e., lnN ∞ -1/T; the logarithm of corrosion rate is reciprocally proportional to 1/T, i.e., lnv ∞ -1/T; A “peak” value of apparent activation energy appears with increasing concentration of hydrochloric acid when fixing inhibitor concentration. For the uninhibited specimen, the “peak” value appears at 1.0 M HCl, for the inhibited specimen, however, the “peak” value appears at 1.5 M HCl. The experimental data accords well with the proposed theoretical kinetic model. Furthermore, the recent advances in corrosion inhibitions and inhibitors are reviewed with a focus on the progress of corrosion inhibition for metals in acidic solutions.
Selection of an appropriate corrosion inhibitor, inhibitor combination or package is an exceptionally cost effective and materials saving measure in various industries. The article reviews recent (2008-2010) patents reported on corrosion inhibitors. Up-to-date developments in the inhibition technology are presented in accordance with the areas of application of inhibitors - industrial cooling water systems, oil and gas fields, coatings, acid pickling, lubricants, vapor phase inhibition, concrete corrosion etc. Nanotechnological advancements in inhibitor technology (in coatings) and novel products employing vapor phase corrosion inhibitors were discussed.
A review is provided about the current research and the relevant patents on magnesium/magnesium alloys corrosion in the industry and bioapplication. Except for reviewing the kinds of corrosion on galvanic corrosion, stress corrosion, corrosion fatigue, and biocorrosion, its corresponding mechanisms are also explained, such as the influence of metallurgical factors, environmental factors and simulated body fluid (SBF). Furthermore, the protection of magnesium/magnesium alloys corrosion is also expressed, for instance, surface treatment/modification, alloying, coating etc. In addition, due to the continuing challenges associated with the use of magnesium alloys, more considerations about future applications and research directions are given according to the properties improvement of magnesium alloys for the eco-friendly requirements.