Corrosion mechanism of NiCrBSi coatings deposited by HVOF

Wei-min, Zhao; Wang, Yong; Dong, Li; Wu, Kaiyuan; Xue, Jie

doi:10.1016/j.surfcoat.2004.04.057

Cited by 92 publications

(42 citation statements)

References 9 publications

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“…The porous coatings can do harm to the persisancy of corrosion resistance during testing [8][9]. Very good dense coatings with few porosity had been deposited that provided better corrosion resistance.…”

Section: Discussionmentioning

confidence: 99%

Investigation of Hot Corrosion Behaviour of Uncoated and WC-17CO Coated Samples in Aggressive Molten Salt Environment

Singh¹,

Singh²,

Choudhary³

2017

IJMPERD

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Hot corrosion is usually a significant issue in power plant's boilers. The alloys and metals get corroded, once exposed to high temperature corrosion in air, or in actual boiler environment in power plants. In order to protect materials; thermal spraying is a newly developed technology that enhances high temperature corrosion resistance of boiler steels. In the present study, WC-17Co coating were deposited by HVOF technique on substrate ASTM-SA213-T91.

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Section: Discussionmentioning

confidence: 99%

Investigation of Hot Corrosion Behaviour of Uncoated and WC-17CO Coated Samples in Aggressive Molten Salt Environment

Singh¹,

Singh²,

Choudhary³

2017

IJMPERD

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“…The morphology of the coatings shows some degree of lamellar microstructures, with the elongated axis of the impacted splats aligned with the substrate surface. The pore content is an important factor that can affect the corrosion behavior of the thermal-spray coatings [32][33][34][35][36][37]. The porosity level was around 2.6 ± 0.2, 3.3 ± 0.5 and 3.0 ± 0.3 vol % for Fe-based 1, Fe-based 2 and Fe-based 3, respectively, confirming that the coatings were slightly porous for a typical HVAF coating.…”

Section: As-sprayed and Corroded Cr3c2-nicrmentioning

confidence: 99%

Electrochemical Behavior of Bilayer Thermal-Spray Coatings in Low-Temperature Corrosion Protection

Sadeghimeresht

Markocsan

2017

Coatings

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Cr 3 C 2 -NiCr coatings are greatly used to protect critical components in corrosive environments and to extend their lifetime and/or improve functional performance. However, the pores formed during spraying restrict the coating's applicability area for many corrosion protection applications. To overcome this technical challenge, bilayer coatings have been developed, in which an additional layer (the so-called "intermediate layer") is deposited on the substrate before spraying the Cr 3 C 2 -NiCr coating (the so-called "top layer"). The corrosion behavior of the bilayer coating depends on the composition and microstructure of each layer. In the present work, different single-layer coatings (i.e., Cr 3 C 2 -NiCr, Fe-and Ni-based coatings) were initially sprayed by a high-velocity air fuel (HVAF) process. Microstructure analysis, as well as electrochemical tests, for example, open-circuit potential (OCP) and polarization tests, were performed. The potential difference (∆E) had a great influence on galvanic corrosion between the top and intermediate layers, and thus, the coatings were ranked based on the OCP values (from high to low) as follows: NiCoCrAlY > NiCr > Cr 3 C 2 -NiCr > NiAl > Fe-based coatings (alloyed with Cr) > pure Ni. The Ni-based coatings were chosen to be further used as intermediate layers with the Cr 3 C 2 -NiCr top layer due to their capabilities to show high OCP. The corrosion resistance (R p ) of the bilayer coatings was ranked (from high to low) as follows: NiCoCrAlY/Cr 3 C 2 -NiCr > NiCr/Cr 3 C 2 -NiCr > NiAl/Cr 3 C 2 -NiCr > Ni/Cr 3 C 2 -NiCr. It was shown that splat boundaries and interconnected pores are detrimental for corrosion resistance, however, a sufficient reservoir of protective scale-forming elements (such as Cr or/and Al) in the intermediate layer can significantly improve the corrosion resistance.

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“…The self-fluxing alloys of Ni-Cr-Si-B system possess high wear resistance [1][2][3][4][5][6][7] and corrosion resistance [2][3][4][5][8][9][10] at room and higher temperatures and also high heat resistance [1,3]. Due to these properties, machine details made of these materials are widely used in aerospace industry and aircraft construction [11], atomic [3,12,13], oil and chemical industry, and metallurgy [14].…”

Section: Introductionmentioning

confidence: 99%

“…There are many techniques of coatings deposition stating from the self-fluxing alloys, for example CVD and DVD [1], different kind of welding (laser cladding [15,16], vacuum-arc deposition [17]) and thermal spraying (plasma spraying [6,10,18], flame spraying [1,6,7], high velocity oxy-fuel spraying [8,9]). The technology of plasma spraying is widely used [6,10,[18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

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Structural features of Ni-Cr-Si-B materials obtained by different technologies

Kornienko

Никулина

Belousova

et al. 2016

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. This study considers the structural features of Ni-Cr-Si-B (Ni -base; 15.1 % Сr; 2 % Si; 2 % В; 0.4 % С) materials obtained by different methods. The self-fluxing coatings were deposited by plasma spraying on the tubes from low carbon steel. Bulk cylinder specimens of 20 mm diameter and 15 mm height were obtained by spark plasma sintering (SPS). The structure and phase composition of these materials were investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffractometry (XRD). The major phases of coatings and sintered materials are γ-Ni, Ni3B, CrB and Сr7С3. We demonstrate that the particle unmelted in the process of plasma spraying or SPS consist of γ-Ni-Ni3B eutectic and also CrB and Сr7С3 inclusions. The prolonged exposure of powder to high temperatures as well as slow cooling rates by SPS provide for the growth of the structural components as compared to those of plasma coatings materials. High cooling rates at the plasma spraying by melted particles contribute to the formation of supersaturated solid solution of Cr, Si and Fe in γ-Ni. The structure of the melted particles in sintering material has gradient composition: the core constituted of Ni grains of 10 μm with γ-Ni-Ni3B eutectic on the edges. The results of the experiment demonstrate that the sintering material has a smaller microhardness in comparison with plasma coatings (650 and 850 MPa, respectively), but at the same time the material has higher density (porosity less than 1 %) than plasma coatings (porosity about 2…3 %).

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Corrosion mechanism of NiCrBSi coatings deposited by HVOF

Cited by 92 publications

References 9 publications

Investigation of Hot Corrosion Behaviour of Uncoated and WC-17CO Coated Samples in Aggressive Molten Salt Environment

Investigation of Hot Corrosion Behaviour of Uncoated and WC-17CO Coated Samples in Aggressive Molten Salt Environment

Electrochemical Behavior of Bilayer Thermal-Spray Coatings in Low-Temperature Corrosion Protection

Structural features of Ni-Cr-Si-B materials obtained by different technologies

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