Spread Of Corrosion Research Articles

Investigation of the Corrosion and Tribological Properties of WC-Co Tools Hardened with PVD Coatings in Solid Oak Wood Processing

Corrosion and friction coefficient tests were performed on solid oak wood machined with hard-metal woodworking tools coated with PVD coatings (AlCrN, AlTiN, TiAlN, TiCN and CrN). The tannic acid attacks the carbide more intensively than the PVD coatings. During cutting, corrosion spreads on the cutting edge of the cutter due to mechanical action, which dissolves the cobalt binder of the hard-metal and causes the carbide grains to flake off. After 80 min of contact with the wood, the cobalt content decreases from 3.53 to 1.74%. Depending on the PVD coating material, cracks of 4 to 40 µm in width appear after 120 min (9000 m cutting path). After 120 min of machining, wear, corrosion effects and the influence of corrosion on the coefficients of friction were evaluated for tools with and without PVD coatings. TiCN is the most sensitive to corrosion, while AlCrN and CrN coatings are the least sensitive, with the AlTiN coating being the most affected under real cutting conditions (with mechanical + thermal + corrosion effects) and the tools with CrN and AlCrN coatings being the least affected. Corrosion affects the hard-metal and PVD coatings and reduces the coefficient of friction. The angle between the directions of sliding and sharpening of the cutting edge sharpening significantly influences this parameter. The coefficient of friction of hard-metal WC-Co and PVD coatings is higher in the parallel machining direction than in the perpendicular machining direction and ranges from 16.03% (WC-Co) to 44.8% (AlTiN). The coefficient of friction of hard-metal WC-Co decreases by 5.13% before and after exposure to tannic acid, while the corrosion of PVD coatings reduces it by 4.13% (CrN) to 26.7% (TiAlN).

Effect of multipass submerged friction stir processing on the microstructure, mechanical properties and corrosion resistance of 5383Al alloy

The 5383Al alloy is commonly used as a hull material because of its excellent mechanical properties, corrosion resistance and weldability. Nevertheless, the presence of coarse Al6(Fe, Mn) particles and the aggregation of the β phase at the grain boundaries noticeably diminish the corrosion resistance of 5383Al, even though they improve its mechanical properties somewhat. In the present study, multipass submerged friction stir processing (M-SFSP) was conducted on 5383Al alloy to precisely control the microstructure while maintaining a balance between mechanical performance and corrosion resistance. The effects of M-SFSP on the microstructure, mechanical properties and corrosion resistance of the 5383Al were investigated. The results show that homogenous ultrafine equiaxed grains of around 0.65 μm in size was acquired in the M-SFSPed zone through dynamic recrystallization. In the M-SFSPed zone, the dislocation density decreased and the proportion of high-angle grain boundaries increased. As a result, the M-SFSPed 5383Al alloy exhibited excellent and homogeneous mechanical properties, including an ultimate tensile strength of up to 400 MPa, comparable to that of the base material (BM). In addition, many fine Al6(Fe, Mn) particles were uniformly distributed in the M-SFSPed zone, and no β-Al3Mg2 phase was detected at the grain boundaries in the M-SFSPed zone. The M-SFSPed samples showed considerably lower mass loss to corrosion than the BM (1.8 mg/cm2 vs. 42.8 mg/cm2), indicating that M-SFSP increased the corrosion resistance of the 5383Al alloy through microstructure control. This improvement was attributed to the refinement of the Al6(Fe, Mn) phase and the redissolution of the β-Al3Mg2 phase, which effectively inhibited the spread of corrosion. Thus, M-SFSP is considered as a promising method for the manufacturing of 5383Al with high strength and outstanding corrosion resistance.

A Review of Oxide Layer Formation and Corrosion Dynamics in Reinforced Concrete

Corrosion is a natural phenomenon that threatens the durability of steel reinforcement in reinforced concrete. Initially, the reinforcement is protected by a layer of iron oxides known as the passivation layer, formed due to the high alkalinity of the concrete medium. This passivation layer acts as a barrier, preventing the progression of corrosion by isolating the steel from corrosive elements. However, the incorporation of corrosion catalysts such as chlorides or carbon dioxide can destroy this protective layer. Once the passivation layer is compromised, reinforcement corrosion begins, leading to the formation of more complex iron oxides, such as rust (Fe2O3). These corrosion products influence the characteristics of the environment around the reinforcement, creating cracks in the concrete and facilitating the penetration of water and other corrosive agents. This process promotes the spread of corrosion within the reinforced concrete structure, accelerating its deterioration. An extensive analysis of the development of the oxide layer on steel reinforcement is given in this article, and its impact on the interface between reinforcement and concrete. It explores the mechanisms by which the passivation layer is formed and the conditions that lead to its failure.

Study on the Microstructure and Properties of Mg-Gd-Ni-Y Alloy Containing LPSO Phase

The long-period stacking ordered (LPSO) structure, functioning as a strengthening phase in magnesium alloys, plays a pivotal role in compensating for inherent performance limitations. In this study, an as-cast Mg-Gd-Ni-Y alloy, including the LPSO phase, was initially obtained through an ingot metallurgy process. Subsequently, the alloy underwent distinct thermal treatments: annealing at 500 °C for 10 h, and extrusion using an extrusion ratio of 10 at a speed of 5 mm/s. Comparative analysis of the microstructure and corrosion characteristics was performed across these three alloy states. Comprising primarily of α-Mg, LPSO phase, and eutectic structures (ES), the alloy exhibited distinctive microstructural features. Immersion experiments conducted in a 3.5% NaCl solution revealed that the as-cast alloy displayed the highest dissolution rate at various temperatures, from room temperature, to 50 °C, and 70 °C. Following annealing, a reduction in the second phase content within the alloy significantly contributed to the observed decrease in its dissolution rate. Extrusion processes resulted in a denser network structure within the microarchitecture, to some extent impeding the spread of corrosion to some extent. By emloying scanning Kelvin probe force microscopy (SKPFM) and micro-electrochemical testing, it was discerned that predominantly the electrochemical system involving α-Mg and the second phases predominantly dictated the heightened dissolution rate of the alloy. This study presents valuable insights into understanding the dissolution mechanisms and potential strategies for controlling the dissolution performance of magnesium alloys containing the LPSO phase.

Insight into the Corrosion Inhibition Mechanism of Sodium Silicate on the Magnesium Alloy Surface: Experimental and Theoretical Calculations.

The corrosion inhibition mechanism of sodium silicate (SS) for WE43 magnesium alloy in NaCl solution was investigated by in situ observation, electron probe microanalysis (EPMA), electrochemical test, and theoretical calculations. In situ observation showed that local corrosion was markedly inhibited after the addition of the SS inhibitor. Electrochemical data revealed that a protective layer was formed on the metal/solution interface and an optimum inhibition efficiency of 98.3% in the case of 2.5 g/L SS. A uniform magnesium silicate layer with a thickness of ∼2 μm formed on the uncorroded area was confirmed. Quantum chemical calculations revealed that SiO32- could absorb on the MgO (1 0 0) surface in a parallel orientation through the coordinate bonds between the O and Mg atoms. The distances of Mg-O bonds are 2.052 and 2.249 Å, suggesting that they are coordinated. The adsorption/interaction mechanisms of SiO32- were also analyzed through charge density distribution and atomic densities. Molecular dynamics simulations further confirmed that a uniform SiO32- layer was absorbed on the MgO surface. In the local corroded area, free SiO32- would react with Mg2+ and OH- produced by corrosion to form the insoluble magnesium silicate compound, which hindered the spread of corrosion.

Scanning and transmission electron microscopy examinations of composite hybrid chromate and chromate phosphate conversion coatings exposed in hot 100% relative humidity environments

Conversion coatings are sine qua non in the finishing of aluminium alloys. They may be put into service without coating of paints. However, for aesthetics in architectural applications, paint overcoat is common. Chromate phosphate coatings are relatively less toxic than chromate which gained the pride of place until recently. Thus, aluminium specimens coated with hybrid chromate/phosphate conversion coatings have been subjected to 100% relative humidity for 480 h at 313K in comparison to chromate coatings and bare aluminium. Scanning electron microscopy examination revealed that initial dried river bed morphologies on coated specimens were obliterated. The friable outer coatings collapsed into the cracks/environment leaving a relatively smooth surface after exposure. Additionally, transmission electron microscopy of sections before and after exposure revealed similar texture and morphological striations nearly parallel to each other throughout the length of the coatings to the metal/coating interface. These were not disrupted as well as the metal/coating interface which remained relatively smooth with no visible corrosion products after exposure. Thus, the coatings formed effective barrier between the substrate and the relatively harsh environment. From EDS, elemental compositions were the same albeit, spectral intensities remained relatively constant after humidity exposure regimes. The coatings are made up of either Cr, O and Al for chromate and Cr, P, O and Al for chromate/phosphate. At deliberately breached regions, the coatings prevented spread of corrosion and paint delamination over the substrates. On the other hand, bare aluminium was decorated with mounds of hydrated aluminium oxide/hydroxide after exposure as revealed in the SEM/TEM.

Research of Dynamic Corrosion Behavior, Microstructure, and Biocompatibility of Mg–Zn–Ca–Zr Alloys in Simulated Body Fluid Solution Induced by Zn Element Addition

Herein, the effect of Zn (2,3,4 and 5 wt%) addition on the microstructure, corrosion behavior, and biocompatibility of Mg‐xZn‐0.5Ca‐0.4Zr alloys is discussed by micromorphology, immersion/electrochemical, and cytotoxicity experiments. The results reveal that all as‐cast samples with a duplex morphology consist of Mg7Zn3 phase and α‐Mg matrix. With the addition of Zn element, the quantities of Mg7Zn3 phase increase gradually; while its micromorphology obviously changes from dot‐like to network shape, the average grain size decreases gradually. In addition, corrosion mechanism demonstrates that all as‐cast alloys suffer from microgalvanic corrosion between eutectic Mg7Zn3 and α‐Mg substrate due to potential difference of |ΔE| = 180 mV. However, the strip‐shape Mg7Zn3 contained in the Mg–4Zn–0.5Ca–0.4Zr alloy and compared with dot‐like\network shape phase can effectively hinder the spreading of corrosion from one grain to another, which causes Mg–4Zn–0.5Ca–0.4Zr to exhibit superior corrosion resistance. In addition, the biocompatibility conducted by methyl‐thiazolyl‐tetrazolium method via L929 cells reveals that as‐cast Mg–4Zn–0.5Ca–0.4Zr alloy is confirmed with low hemolysis rate (H% = 2.5%) and excellent proliferation capability (P% > 100%), which suggest that Mg–4Zn–0.5Ca–0.4Zr may be a good candidate for implant application.

Investigation on Wear and Corrosion Behavior of Cu, Zn, and Ni Coated Corten Steel

Corten steel is a low-carbon alloy steel. It is widely used in architecture, the transport sector, and industrial applications, where the steel is exposed to harsh environments. It is very much sought after due to its auto protection from corrosive environments through the formation of patina (rust). The specialty of patina formed on the corten steel is that it can self-heal itself and stop the spreading of corrosion. Generally, steels are given protective coatings to enhance resistance to corrosion, wear, abrasion, etc. One of the popular protective coating techniques is electroplating. In this study, the effect of electroplating of copper (Cu), zinc (Zn), and nickel (Ni) on the wear and corrosion behavior of Corten ASTM A242 grade steel is investigated. It was observed that the Cu coating yielded poor corrosion and wear protection performance. The Zn coating exhibited a moderate improvement. The Ni electroplating produced excellent results and, the wear and corrosion resistance was improved in the corten steel. Thus, when compared with Cu, Zn, and Ni coatings, the Ni-coated corten steel is an ideal candidate in applications where there is a need for good resistance to wear, abrasion, and corrosion.

Monitoring saltwater corrosion of steel using ultrasonic coda wave interferometry with temperature control

Assessing corrosion is crucial in the petrochemical and marine industries. Usual ultrasonic methods based on pulse-echo and guided waves to detect corrosion lack of precision and struggle in structures with a complex shape. In this paper, a complementary and sensitive ultrasonic method based on coda wave interferometry is presented to detect and quantify thickness loss caused by saltwater corrosion of a steel sample. The method consists in exciting the sample and measuring periodically the scattered coda signal. Correlation of the coda signal with a reference taken for the sample initial state permits the monitoring of corrosion spread with a high accuracy. A laboratory experiment is conducted with two steel samples immersed in saltwater with coda and temperature measured simultaneously. One of the samples is protected from corrosion and is used as a control sample to determine the influence of temperature on the coda signals. It is shown that the coda signals on the corroded sample can be temperature-corrected using the temperature measurement only. A control sample is not needed. A good correlation is found between a parameter quantifying the stretching of the coda over time and the corrosion surface, which is monitored with a camera. Finally, a simple theoretical model of coda signal is proposed to quantify the real-time average corrosion rate during the experiment with a sub-micrometric precision. The estimated final average corrosion depth is validated by independent depth profile measurements. The uncertainties and sensitivity of the presented method are investigated.

Effect of trace copper on the microstructure, corrosion behavior and biological properties of biodegradable Mg–2Zn-1Gd-0.5Zr alloy

The biodegradable Mg–2Zn-1Gd-0.5Zr-xCu (x = 0, 0.1, 0.3, 0.5 wt.%) alloys are prepared to evaluate their microstructures, corrosion behavior, biocompatibility and antimicrobial properties. When the Cu element adds to the alloys, the new MgZnCu phase generates in the alloys in addition to the MgZn2 phase, W–Mg3Gd2Zn3 phase and I–Mg3Gd6Zn phase. With the Cu content increases, the grains become finer. Meanwhile, the shape of the MgZnCu phase transforms from spherical and elongated into the reticular. The grain boundary, the reticular W–Mg3Gd2Zn3 phase and the MgZnCu phase act as physical barriers to hinder the spread of corrosion. The generation of Ca–P compounds and the formation of dense oxides further improve the corrosion resistance of the alloys. Meanwhile, an increase in the content of the second phase and a change in the morphology of the MgZnCu phase also enhance galvanic corrosion, which reduces the corrosion resistance of the alloys. The corrosion rate of the Mg–2Zn-1Gd-0.5Zr-0.1Cu alloy is 0.47 ± 0.05 mm/year, and its degradation rate is much lower than that of the other Cu-containing alloys. Mg–2Zn-1Gd-0.5Zr-0.1Cu alloy has no cytotoxicity to MC3T3-E1 in the biocompatibility tests and shows good antibacterial properties in the antimicrobial experiments. In general, the Mg–2Zn-1Gd-0.5Zr-0.1Cu alloy is considered as the potential biodegradable antimicrobial biomaterial for bone implants.

A Comparative Study on the Anti-Corrosive Performance of Zinc Phosphate in Powder Coatings

Powder coatings are gaining popularity for their economic and environmental benefits. Additives (pigments) such as zinc phosphate enhance the anti-corrosive properties of coatings, but their behavior in powder coatings has not been extensively studied. In this study, zinc phosphate was incorporated into three powder coating systems: polyester clearcoat, polyester and epoxy coatings with filler BaSO4. Neutral salt spray and electrochemical tests (OCP, LPR, and EIS) confirmed that the anti-corrosive performance improved with the addition of zinc phosphate. The optimal additive dosage was determined to be 2% for all of the coating systems studied here, based on salt spray tests. Here, the time until failure increased by 1.5 to 2 times. Using electrochemical tests, an optimal additive dosage of 8% was found for the polyester clearcoat, while the other coating systems maintained an optimal additive dosage of 2%. Performance increased by as much as one order of magnitude based on resistance/impedance measurements. This suggested a synergistic effect between the additive and the filler. The passivation layer was confirmed by both X-ray diffraction and Raman spectroscopy. Based on the results and discussion presented in this article, the discrepancy was caused by different features of the two tests, such that the electrochemical tests probe the function of intact coatings, whereas salt spray measures only the corrosion spreading from the scribe. It is proposed that the two test methods characterize different aspects of the coatings, corresponding to their service conditions. This has theoretical and practical significance in the evaluation of anti-corrosive coatings. Other properties of the coatings, including adhesion, gloss, distinctness-of-image, and pencil hardness, were measured as per applicable standards and the conformance was verified.

Study on properties of porous SiO2/GO modified polyurethane coatings loaded with corrosion inhibitor

Polyurethane (PU) coating can provide physical barrier for metal surface, but the penetration of corrosive ions will affect the long-term corrosion resistance of the coating. In order to improve the corrosion resistance of the coating, it is necessary to modify the coating to reduce the internal defects of the coating and improve the corrosion resistance of the coating. Using mesoporous silica (SiO2) as the carrier to support the corrosion inhibitor 2- mercaptobenzimidazole (MBI), and using the silane coupling agent GPTS as the bridging agent to compound with graphene oxide (GO) to prepare f-GO-MBI @SiO2 composite nano-materials, f-GO-MBI @SiO2 composite nano-materials are added to the polyurethane varnish in different proportions, and the f-GO-MBI @SiO2 modified PU coating is obtained on the surface of carbon steel by spraying method to improve the carbon corrosion resistance of steel substrate. The composition and loading conditions of drug-loaded composite nanomaterials were characterized by fourier infrared spectroscopy (FTIR) and laser particle size analyzer; electrochemical impedance spectroscopy (EIS) and neutral salt spray test were used to study the properties of different coatings corrosion resistance. The results shows that the addition of f-GO-MBI @SiO2 composite nano-materials significantly improves the corrosion resistance of the coating, the low addition amount will reduce the anti-corrosion effect, and the addition of too high can easily lead to agglomeration of composite nano-materials and produce paint film defects. When the addition amount of f-GO-MBI @SiO2 is 5 wt%, the low-frequency impedance of the coating is two orders of magnitude higher than that of the pure polyurethane coating, the corrosion spread width at the neutral salt spray scratches is reduced to 1.5 mm, and the coating has the best corrosion resistance.

EVIDENCES OF WEATHERING OF IRON-NICKEL AND TROILITE IN THE GRUZ'KE Н4-TYPE CHONDRITE

Terrestrial weathering of the Gruz'ke chondrite was investigated by considering its initial chemical, structural, and mineralogical characteristics. The spread of corrosion and degree of alteration were related to the high content of Fe-Ni metal, the phase inhomogeneity and the different concentration of Ni in the metal, as well as, the shock metamorphism features, and the residence time of the meteorite sample in a soil environment. The formation of secondary oxide veins and oxide rims, consisting of iron hydroxide pseudomorphs was caused by the selective corrosion of kamacite α-(Fe,Ni), compared to taenite γ-(Fe,Ni) and troilite FeS. A spatial relationship between shock metamorphism features, namely areas of plastic deformation, shock heating and weathering of the meteorite matter, has been confirmed. A secondary Ni-enriched phase, which contains 71.34 to 72.94 wt.% Ni, probably corresponds to awaruite (Ni2Fe to Ni3Fe) or native nickel. This phase is described for the first time as corrosion product of Fe-Ni grains in the Gruz'ke chondrite. We assume that this phase was formed during the alteration of Fe-Ni metal. Fe was removed from the meteorite metal during the corrosion process, while sulfur was introduced. The formation of iron hydroxide pseudomorphs caused changes in primary chemical and structural properties of some crystals of nickel-iron metal and troilite. Thus, the use of weathered mineral grains to interpret the pre-terrestrial conditions of the chondrite matter formation and evolution is limited. In spite of the changes in chemical and mineral composition, the corrosion products of nickel iron and troilite have consistent low chlorine content.Therefore we assume that the akaganeite β-FeO(OH,Cl) secondary phase is unlikely to form. It will prevent further alteration of the Fe-Ni metal and ensure long-term storage and preservation of the meteorite sample for further laboratory research and storage in the museum collection.

The Spread of Corrosion of the Deposited Material Using the Cold Spray Method

A layer of copper was applied to the base aluminum material using the cold spray method (cold kinetic deposition). The samples were exposed to corrosion in a salt chamber for 100, 200 and 300 hours. The change in the size of the internal and surface resistance of the samples was monitored. The corrosion results were also examined using an electron microscope.

(Corrosion Division Morris Cohen Graduate Student Award Address) Galvanic Corrosion of Copper-Coated Carbon Steel for Used Nuclear Fuel Containers

Carbon steel vessels coated with ∼3 mm of Cu have been proposed for the permanent disposal of used nuclear fuel in a deep geological repository (DGR) in Canada. In the event that a container is emplaced in the DGR with an undetected defect in the Cu coating that exposes the steel substrate, galvanically accelerated corrosion of steel is, in principle, possible. To investigate this scenario, the progression of steel corrosion at the base of novel simulated through-coating defects was monitored electrochemically and imaged non-destructively using X-ray micro-computed tomography (micro-CT) as a function of time, O2 availability (including anoxic conditions), and coating method (cold spray deposition (with and without heat treatment) and electrodeposition). The corrosion products and surface damage were analyzed using Raman spectroscopy and scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDX). These analyses showed how the corrosion damage to steel evolved over time and how it was affected by the method used to coat steel with Cu and the amount of O2 available. The results showed that steel exposed at the base of a through-Cu coating defect corroded and became covered by corrosion products, while there was no visible loss of Cu. The supply of O2 to the sample surface governed the corrosion rate, while the distribution of damage to steel at the base of the defect depended on the Cu coating method and the resulting quality of the Cu/steel interface. Cold spray Cu-coated steel specimens exhibited a radial spread of corrosion along the Cu/steel interface, while electrodeposited Cu/steel specimens experienced preferential interfacial corrosion in the direction in which the steel substrate was machined prior to the electrodeposition of Cu. An example of the progression of corrosion observed by micro-CT is shown in Figure 1. Less extensive corrosion along the Cu/steel interface was observed on samples that were shown by electron backscatter diffraction (EBSD) and adhesion tests to have a less stressed, more uniform, and more well-adhered interface. However, less extensive corrosion was typically at the expense of deeper penetration into the steel. In the absence of O2, the quality of the Cu/steel interface greatly affected both the overall amount of corrosion damage to steel and the distribution of damage. The corrosion rates were significantly lower under anoxic conditions than under oxic conditions, and tended to decrease over time. The influence of a wide range of cathode:anode area ratios and Cl− concentrations, and the availability of O2, was evaluated by monitoring the galvanic current passing between separate Cu and steel electrodes, connected through a zero-resistance ammeter (ZRA), and the galvanic potential of the couple. The galvanic corrosion of steel was most severe when it was exposed to air-sparged solution with a moderate [Cl−] as part of the couple with the largest Cu:steel area ratio. Figure 1

GaAs Microisland Anodes Protected by Amorphous TiO2 Films Mitigate Corrosion Spreading During Water Oxidation in Alkaline Electrolytes

GaAs Microisland Anodes Protected by Amorphous TiO₂ Films Mitigate Corrosion Spreading During Water Oxidation in Alkaline Electrolytes

Micro-galvanic corrosion behavior and mechanical properties of extruded Mg–2Y–1Zn-0.4Zr-0.3Sr alloys with different extrusion temperament immersed in simulated body fluids

The Mg–2Y–1Zn-0.4Zr-0.3Sr alloy is a new kind of degradable material for biomedical application. In order to optimize its corrosion resistance and mechanical properties, the plastic extrusion deformation was implemented to improve its properties. The results indicated that the alloy's grains were refined significantly due to dynamic recrystallization (DRX), and the W-phase (Mg3Zn3Y2) was crashed into particles distributed along extrusion direction; meanwhile, the elongated un-complete dynamic recrystallization (un-DRX) grains decreased with the increase of extrusion temperature. The micro-galvanic corrosion cell was easily formed between the W-phase (2.9 V) and the Mg matrix (2.2 V) due to the large potential difference, the corrosion tendency, however, of micro-galvanic was weakened owing to the part of W-phase dissolved into Mg matrix with the temperature enhancement. In addition, the grain boundary, potential higher than adjacent grains, also acted as a barrier role to prevent the spread of corrosion and improve the corrosion resistance. In a nutshell, the extruded Mg–2Y–1Zn-0.4Zr-0.3Sr alloy at 400 °C (UTS = 254Mpa, YS = 195Mpa, EL = 27% and CR = 0.47 ± 0.099 mm/y) meet the basic requirements as biomedical implant materials.

Technological Innovation on Conveyor Idlers

Purpose of research: • Traditionally conveyor idlers are made of steel or rubber lagged steel or PVC sleeved. • Fertiliser & Chemicals are hygroscopic and tends to absorb moisture from the atmosphere • This absorption accelerates corrosion of Steel components of the conveyors affecting the life of the idlers and the conveyor belt. Frequent replacement of idlers and the conveyor belt affects the productivity • Most of the bulk material transportation is through sea where the humidity is very high. • Steel idlers are heavier consuming more energy Innovation: • Corrosive surface damages the belt covers • Finely finished surfaces of ball bearings are subjected to corrosion spreading from steel shaft resulting in premature failure of the bearings • Lower energy required for rotation of lighter idlers These gave birth to “HPPE Polymer Idlers” which is light in weight, non-corrosive and non-metallic. Benefits in energy saving, costs saving, increased belt life and improved productivity.

Non-Destructive X-Ray Microprobe Characterization of Corrosion at the Polymer/Steel Interface

This work used the unique capability of synchrotron x-rays to probe a buried polymer/metal interface with high energy resolution and spatial resolution on the micron scale. X-rays of sufficient energy can penetrate the organic polymer coating and interrogate heavier elements found at the interface. X-ray fluorescence (XRF) spectra can be collected provided the element specific energy of the fluoresced photon is sufficient to penetrate through the polymer coating. We characterized the interface beneath several polymer coatings on steel reinforcing bar after exposure to alkaline potash brine using the Soft X-ray Microcharacterization Beamline (SXRMB) at the Canadian Light Source. Characterization included correlated XRF maps for Fe, Mn, K and Cl as well as micro x-ray absorption near edge spectroscopy (µ-XANES) to analyze Fe corrosion products at certain areas of interest. By collecting Fe XRF maps with an incident beam energy of 7115 eV, we exploited the differences in absorption cross section between Fe metal and oxidized Fe species at this energy. The result is a map with excellent contrast between corroded and non-corroded regions of the interface. This provides a relatively quick means to locate localized anodic zones beneath opaque polymer coatings without a visual indicator (i.e. a blistered region of polymer). XRF maps for K and Cl showed these elements were segregated at the interface with K hotspots providing a surrogate measurement for cathodic activity at the interface. µ-XANES analysis showed evidence of Fe corrosion products that varied somewhat from those reported in previous studies, owing to our efforts to perform sample handling in an inert atmosphere after the exposure to potash brine. The speciation of Fe combined with the spatial distribution of Mn, K, Cl provided evidence to support previous literature models pertaining to mechanisms of coating delamination and the spread of corrosion at the polymer/metal interface.

Масс-спектрометрическая визуализация для исследования поверхности стали

Визуализация масс-спектрометрическими методами исследования поверхности широко используется для построения карт распределения различных соединений. В настоящей работе данныйинструмент впервые применён для исследования морфологии и состояния различных промышленных сталей. Ранее метод применялся только для визуализации с тонких поверхностей. Авторами показана принципиальная возможность оценки состояния поверхности стали и скорости протекания на ней коррозионных процессов. Показано, что при образовании продуктов коррозии последние легко и на низком уровне обнаруживаются в виде кластерных ионов, что позволяет легко определять начинающуюся коррозию. Визуализация наглядно показывает степень локализации и распространения коррозии, которая на сталях проходит сразу почти по всей поверхности. Также на поверхности стали обнаружены следы адсорбции хлора, который является потенциальным активатором коррозии и показана его локализация. Также возможно обнаружить продукты коррозии и адсорбированные на поверхности соединения, построить диаграмму распределения по широкой области поверхности любого обнаруженного соединения, провести локализацию исследуемой области для изучения её в сочетании с классическими методами исследования поверхности, проводить общий контроль состояния поверхности сплава во времени при его эксплуатации. Метод является уникальным, не имеет аналогов в мире и может быть распространён на любые другие поверхности и материалы