Comparison of corrosion behaviour of thermal sprayed and diffusion-coated materials

C., S.; Gudenau, Heinrich Wilhelm; Bayer, George T.

doi:10.1002/1521-4176(200203)53:3<195::aid-maco195>3.0.co;2-g

Cited by 15 publications

(8 citation statements)

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“…With regards to the briefly described problems occurring with steels, the reliable protection of steel components, including of long size tubing, is highly important.Different surface engineering methods, particularly those based on coatings, are used in industry to protect steels and alloys against corrosion. They include painting, dipping, sol-gel processes, cold and thermal spraying, chemical and electrochemical methods (anodizing, electroplating, electroless plating, and electrophoretic deposition), plasma-assisted technologies, physical vapor deposition (PVD), and chemical vapor deposition (CVD), among others [16][17][18][19][20][21][22][23][24][25]. However, most of these methods cannot be widely utilized in industry, especially for processing of large complex shape components and long tubing when the inner surface needs to be protected.…”

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Corrosion Resistance of Boronized, Aluminized, and Chromized Thermal Diffusion-Coated Steels in Simulated High-Temperature Recovery Boiler Conditions

et al. 2018

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In this study, the high-temperature molten salt corrosion resistance of bare steels and steels with protective coatings, fabricated by thermal diffusion processes (boronizing, aluminizing and chromizing), were investigated and compared. Surface engineering through thermal diffusion can be used to fabricate protective coatings against corrosion, while alleviating issues around possible cracking and spallation that is typical for conventional thermal-sprayed coatings. In this regard, samples of low carbon steel and 316 stainless steel substrates were boronized, chromized, and aluminized through a proprietary thermal diffusion process, while some of the samples were further coated with additional thin oxide and non-oxide layers to create new surface architectures. In order to simulate the actual corrosion conditions in recovery boilers (e.g., from black liquor combustion), the surfaces of the samples sprayed with a modeling salt solution, were exposed to low-temperature (220 • C) and high-temperature (600 • C) environments. According to microstructural and X-ray diffraction (XRD) studies and results of hardness determination, the coatings with multilayered architectures, with and without additional oxide layers, showed successful resistance to corrosive attack over bare steels. In particular, the samples with boronized and chromized coatings successfully withstood low-temperature corrosive attack, and the samples with aluminized coatings successfully resisted both low-and high-temperature molten salt corrosive attacks. The results of this study conducted for the first time for the thermal diffusion coatings suggest that these coatings with the obtained architectures may be suitable for surface engineering of large-sized steel components and tubing required for recovery boilers and other production units for pulp and paper processing and power generation.2 of 36 materials and process features, low-melting temperature ash or smelt is produced. The produced smelt mainly consists of different salts, e.g., sodium and potassium chlorides, sulfates, and carbonates. At elevated temperatures, mostly greater than 500 • C, the aforementioned salts in certain combination likely become molten. In the presence of oxygen, the molten salts can be highly corrosive [2,3]. Combustion of the black liquor fuel also results in the formation of hot corrosive gases, such as SO 2 , CO 2 , Cl 2 , and some others [5].Generally, high-temperature black liquor corrosion occurs according to two main mechanisms, namely (i) high-temperature active oxidation and (ii) corrosion due to the formation of sulfidic and chlorine gasses and residual deposits of molten salts and their interaction with the steel surface [6]. In the former mechanism, which generally occurs in high temperatures (above 450 • C), the anions of the molten salt, such as chlorides (Cl − ), sulfates (SO 4 2− ) and sulfides (S 2− ), continuously diffuse into the oxide-metal interface and actively sustain the oxidation. On the other hand, in the latter mechanism, the presence of the an...

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Corrosion Resistance of Boronized, Aluminized, and Chromized Thermal Diffusion-Coated Steels in Simulated High-Temperature Recovery Boiler Conditions

et al. 2018

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“…But compared to the corrosion behaviours of NiCr (APS, HVOF), NiCrBSi (APS, HVOF) and Cr 3 C 2 /NiCr (APS, HVOF) in the same atmosphere, described by Cha et al [7], the coating materials investigated in this test series are not suitable for the application on boiler tubes. High temperature corrosion is the main strain in waste incinerator plants and power plants.…”

Section: Resultsmentioning

confidence: 70%

“…The equipment and the conditions of the high temperature corrosion tests are described in details by Cha et al [7]. The gravimetric changes of the specimen are registered continuously as a function of time with a microbalance, which has a resolution of 0.1 mg.…”

Section: Test Materials and Test Conditionsmentioning

confidence: 99%

“…thermal spraying and diffusion coating of metallic materials, may provide alternatives to high cost stainless steels and super alloys against corrosive strain [7,8]. thermal spraying and diffusion coating of metallic materials, may provide alternatives to high cost stainless steels and super alloys against corrosive strain [7,8].…”

Section: Introductionmentioning

confidence: 99%

“…Earlier investigations and their various test conditions are described and summarised by Cha et al [7] in detail. The corrosion resistance test results are evaluated by the determination of the maximum mass gain on the surface of the sample and by the determination of the scale constant k. The scale constant k is calculated from the maximum mass gain, the surface of sample and the time [11].…”

Section: Introductionmentioning

confidence: 99%

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Corrosion of coating materials in oxidizing and hydrogen chloride containing atmospheres

Cha¹,

Wölpert²

2002

Materials & Corrosion

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The boiler tubes in waste incinerator plants and power plants are mainly corrosive strained. This paper presents the corrosion behaviour of various coating materials in two corrosive atmospheres at 500 8C. In a first test, Ni-based materials applied by High Velocity Oxygen Fuel Flame (HVOF)-spraying and Atmospheric Plasma Spraying (APS) as well as Cr-based materials obtained by diffusion coating process are tested in oxidizing atmosphere with water saturation. The results of the corrosion test in this H 2 O-O 2 -N 2 -atmosphere show that NiCr applied by HVOF is less oxidized than that applied by APS-coating, whereas NiCrBSi coating by APS shows higher resistance than that applied by HVOF-spraying. The diffusion coating of Cr/Si is better than that of pure Cr. In a second test, metallic Mo and W-based materials applied by thermal spraying are tested to verify their corrosion resistance in HCl-It is shown that pure Mo applied by APS on 13 CrMo 44 and WCrNi sprayed on 15 Mo 3 by HVOF as well as on 13 CrMo 44 show relatively high corrosion resistance, whereas Mo sprayed by APS on 15 Mo 3 is not resistant. Both tungsten-cobalt-chromium mixtures show extremely high oxidation rates. Base materials in both tests were the standard boiler tube materials 15 Mo 3 and 13 CrMo 44. But even the low corrosion rates of the best materials in these tests are higher compared to those of materials already presented by Cha et al. in an earlier paper. Die Wa Èrmetauscherrohre von Mu Èllverbrennungsanlagen und Kraftwerken sind hauptsa Èchlich korrosiv beansprucht. Die vorliegende Vero Èffentlichung stellt das Korrosionsverhalten von verschiedenen Beschichtungswerkstoffen in zwei korrosiven Atmospha Èren bei einer Temperatur von 500 8C vor. Zuerst wurden die durch Hochgeschwindigkeitsflammspritzen (HVOF) und atmospha Èrisches Plasmaspritzen (APS) aufgetragenen Ni-Basiswerkstoffe und die diffusionsbeschichteten Cr-Basiswerkstoffe in oxidierender Atmospha Ère mit Wassersa Èttigung getestet. Die Ergebnisse der Korrosionsversuche in der H 2 O-O 2 -N 2 -Atmospha Ère zeigen, dass NiCr (HVOF) resistenter ist als durch APS Beschichtung, wobei die Beschichtung mit NiCrBSi durch APS ho Èhere Besta Èndigkeit als die durch HVOF zeigt. Eine diffusionsbeschichtete Cr/Si-Schicht zeigt ho Èhere Besta Èndigkeit als eine reine Cr-Schicht. In einer zweiten Versuchsreihe wurden metallisches Mo und W-Basiswerkstoffe auf Korrosionsbesta Èndigkeit in HCl-H 2 O-O 2 -N 2 -Atmospha Ère untersucht. Dabei zeigt sich, dass die Proben mit Mo (APS) auf 13 CrMo 44, sowie WCrNi (HVOF) auf 15 Mo 3 und 13 CrMo 44 relativ hohe Korrosionsbesta Èndigkeiten besitzen. Dagegen ist Mo (APS) auf 15 Mo 3 nicht besta Èndig. Beide W-Co-Verbindungen zeigen extrem hohe Oxidationsraten. Als Basiswerkstoffe wurden die Standard Kesselrohr-Werkstoffe 15 Mo 3 und 13 CrMo 44 gewa Èhlt. Aber auch die niedrigsten Korrosionsraten der besten Werkstoffe in dieser Untersuchung sind ho Èher als diejenigen der in einer fru Èheren Arbeit von Cha et al. vorgestellten Werkstoffe.

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Protective Coatings

2018

High Temperature Corrosion

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Comparison of corrosion behaviour of thermal sprayed and diffusion-coated materials

Cited by 15 publications

References 2 publications

Corrosion Resistance of Boronized, Aluminized, and Chromized Thermal Diffusion-Coated Steels in Simulated High-Temperature Recovery Boiler Conditions

Corrosion Resistance of Boronized, Aluminized, and Chromized Thermal Diffusion-Coated Steels in Simulated High-Temperature Recovery Boiler Conditions

Corrosion of coating materials in oxidizing and hydrogen chloride containing atmospheres

Protective Coatings

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