“…As a result, more heat accumulates on the surface of particles facing the flame, and atomic diffusion is more active. Since the oxides on the surface are in the form of Fe and Cr oxides [15], more Cr diffuses to the surface from the amorphous particles near the upper surface, resulting in Cr-deficient areas near the surface. Liu [16] also considered that a Cr-depleted zone about 100 nm wide existed in the area close to the intersplats, because Cr diffused to the particle surface due to the oxidation effect in the spraying process.…”
Fe-based amorphous coatings are typically fabricated by high-velocity oxygen-fuel spraying using industrial raw materials. The bonding mode between the coating particles and the corrosion mechanism of the coating in the chloride-rich environment were studied. The results indicate that some fine crystallites such as α-Fe and Fe3C tend to precipitate from the amorphous matrix as the kerosene flow rate increases or the travel speed of spraying gun decreases. Moreover, some precipitates of the (Cr, Fe)2O3 nanocrystal were detected in the metallurgical interfaces of the amorphous coating. The relationship among the amorphous volume fraction, porosity, and spraying parameters, such as the kerosene flow rate and the travel speed of the spray gun, were established. Due to an oxidation effect during spraying process, atomic diffusion, crystallite precipitation and regional depletion of Cr occur in the area along the pre-deposited side near the metallurgical bonding interface, leading to the initiation of pitting. A model of pitting initiation and expansion of Fe-based amorphous coatings is proposed in this paper.
“…As a result, more heat accumulates on the surface of particles facing the flame, and atomic diffusion is more active. Since the oxides on the surface are in the form of Fe and Cr oxides [15], more Cr diffuses to the surface from the amorphous particles near the upper surface, resulting in Cr-deficient areas near the surface. Liu [16] also considered that a Cr-depleted zone about 100 nm wide existed in the area close to the intersplats, because Cr diffused to the particle surface due to the oxidation effect in the spraying process.…”
Fe-based amorphous coatings are typically fabricated by high-velocity oxygen-fuel spraying using industrial raw materials. The bonding mode between the coating particles and the corrosion mechanism of the coating in the chloride-rich environment were studied. The results indicate that some fine crystallites such as α-Fe and Fe3C tend to precipitate from the amorphous matrix as the kerosene flow rate increases or the travel speed of spraying gun decreases. Moreover, some precipitates of the (Cr, Fe)2O3 nanocrystal were detected in the metallurgical interfaces of the amorphous coating. The relationship among the amorphous volume fraction, porosity, and spraying parameters, such as the kerosene flow rate and the travel speed of the spray gun, were established. Due to an oxidation effect during spraying process, atomic diffusion, crystallite precipitation and regional depletion of Cr occur in the area along the pre-deposited side near the metallurgical bonding interface, leading to the initiation of pitting. A model of pitting initiation and expansion of Fe-based amorphous coatings is proposed in this paper.
“…Moreover, the evolution of a film having higher concentration of defects and low compactness led to deteriorated corrosion properties in HCl solution compared to NaCl solution. Besides, Wang et al [292] examined the influence of Cl − and S 2− rich environments on passivation characteristics for Febased MGC, and observed Cl − as the major influential factor for passivity breakdown in a mixed environment of NaCl and Na 2 S (Figure 38c-e).…”
Section: Duration Of Immersionmentioning
confidence: 99%
“…Moreover, the evolution of a film having higher concentration of defects and low compactness led to deteriorated corrosion properties in HCl solution compared to NaCl solution. Besides, Wang et al [292] examined the influence of Cl − and S 2− rich environments on passivation characteristics for Fe-based MGC, and observed Cl − as the major influential factor for passivity breakdown in a mixed environment of NaCl and Na 2 S (Figure 38c–e). Figure 38. Importance of corrosive environment on passivation behaviour of Fe-based MGC: schematic illustration for anion adsorption along with attributes of passive film for Fe-based (Fe 54.2 Cr 18.3 Mo 13.7 Mn 2.0 W 6.0 B 3.3 C 1.1 Si 1.4 , wt.-%) MG in (a) sulphate and (b) chloride solutions [291], and MGC in (c) NaCl, (d) Na 2 S and (e) NaCl + Na 2 S solutions [292]. Cited images have been reproduced with due permission from the publisher.…”
Section: Corrosion Properties Of Fe-based Metallic Glass Coatingsmentioning
confidence: 99%
“…Importance of corrosive environment on passivation behaviour of Fe-based MGC: schematic illustration for anion adsorption along with attributes of passive film for Fe-based (Fe 54.2 Cr 18.3 Mo 13.7 Mn 2.0 W 6.0 B 3.3 C 1.1 Si 1.4 , wt.-%) MG in (a) sulphate and (b) chloride solutions [291], and MGC in (c) NaCl, (d) Na 2 S and (e) NaCl + Na 2 S solutions [292]. Cited images have been reproduced with due permission from the publisher.…”
Section: Corrosion Properties Of Fe-based Metallic Glass Coatingsmentioning
Among various materials available for alleviating the corrosion-related degradation, thermal sprayed Fe-based metallic glass coatings (MGCs) have received huge attention from the scientific community due to the exceptional combination of mechanical and corrosion properties, along with commercially attractive low material cost of this particular alloy system. Emerging reports on the thermal sprayed Fe-based MGCs outperforming conventional corrosion-resistant materials and coatings have accelerated further exploration of this domain, resulting in an immense increase of research activities over the last few decades producing fascinating results. This review takes a holistic approach encompassing an in-depth assessment of all the relevant salient work till date, including corrosion properties, corresponding degradation mechanisms, metallurgical and environmental factors with reference to passive film dynamics and/or formation of corrosion products. Moreover, various strategies for improved corrosion properties and recent research progress have been reviewed with an attempt to identify the present knowledge gaps and the future research directions.
Corrosion of metals induces enormous loss of material performance and increase of cost, which has been a common and intractable issue that needs to be addressed urgently. Coating technology has been acknowledged to be the most economic and efficient approach to retard the metal corrosion. For several decades, polymers have been recognized as an effective anticorrosion coating material in both industries and scientific communities, as they demonstrate good barrier properties, ease of altering properties and massive production. Nanomaterials show distinctively different physical and chemical properties compared with their bulk counterparts, which have been considered as highly promising functional materials in various applications, impacting virtually all the fields of science and technologies. Recently, the introduction of nanomaterials with various properties into polymer matrix to form a polymer nanocomposite has been devoted to improve anticorrosive ability of polymer coatings. In this review article, we highlight the recent advances and synopsis of these high-performance polymer nanocomposites as anticorrosive coating materials. We expect that this work could be helpful for the researchers who are interested in the development of functional nanomaterials and advanced corrosion protection technology.
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