Coating Qualities Deposited Using Three Different Thermal Spray Technologies in Relation with Temperatures and Velocities of Spray Droplets

Kawaguchi, Y.; Miyazaki, Fumihiro; Yamasaki, Masafumi; Yamagata, Yuriko; Kobayashi, Nozomi; Muraoka, Katsunori

doi:10.3390/coatings7020027

Cited by 21 publications

(20 citation statements)

References 7 publications

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“…The impact of these particles allows them to deform and form on the topography of the substrate before the solidification of a denser coating, with greater union between splats and the growth of a less porous structure. Similar results were reported by Y. Kawaguchi [15], who indicated that high porosity is due to a low velocity of the drops, resulting from their poor acceleration by the compressed air during the thermal spraying. Figure 8 shows the potentiodynamic polarization curves for the coatings deposited at various working pressures.…”

Section: Microstructural Characterization Of Al-cu-fe Coatingssupporting

confidence: 89%

The Corrosion Resistance of Aluminum–Bronze Coatings as a Function of Gas Pressure Used in the Thermal Spraying Process

2019

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We report the results of the influence of acetylene and oxygen gas pressure on the corrosion resistance of bronze-aluminum coatings deposited on a naval brass substrate by means of the thermal (flame) deposition process. The coatings were characterized by means of scanning electronic microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), X-ray fluorescence (XRF), and transmission electron microscopy (TEM). The corrosion tests were carried out via Tafel and electrochemical impedance spectroscopy (EIS). In addition, some samples were selected in order to investigate heat treatment and its effects on corrosion resistance. The results indicate that changes in the pressure and flow of the gas affects the composition, morphology, and physical properties of the coatings, and these effects have consequences for the behavior of the coatings when they are immersed in corrosion environments. The collision speed of the particles was identified as the most significant factor that influences the properties and the performance of the coating. The gas pressure modified the oxides and the porosity level, which improved the corrosion resistance.Coatings 2019, 9, 507 2 of 17 coatings in terms of adherence, mechanical properties, and corrosion resistance [2]. In order to optimize the results, the coatings have been deposited while changing the work distance and substrate roughness, and the effect of the pretreatment of the surface using different physical and chemical methods has been studied [3]. However, a combination of parameters relating to the combustion and gas projection pressure for producing better strength and good adhesion has not been found. Aluminum-bronze coatings have good wear and corrosion resistance properties because a copper oxide layer is formed on the surface. They are recommended for the protection and dimensional restoration of parts that are subject to harsh operating conditions [1].In the process of thermal projection by combustion, the chemical energy of combustible and combustion gases is used for the generation of the flame responsible for melting the projected particles. Oxyacetylene torches use a mixture of acetylene (C 2 H 2 ) and oxygen (O 2 ), which in a stoichiometric ratio produces a flame that reaches a temperature of up to 3386 K at 1 atmosphere of pressure [4]. An oxidant or highly oxidizing flame is when an excess of oxidizer is applied, and as a result, a primary reaction zone (cone of the flame) is obtained that is much longer than in a reductive flame or a stoichiometric flame. The particles stay longer in the hottest area of the flame, and therefore they can achieve better heating.The axial and radial temperature distribution and the changes in the velocity of the flame gases significantly affect the temperature of the particles and their behavior in flight, which influences the quality of the coating. The hot gases generated by combustion undergo complex events that involve heat and mass transfer phenomena in the boundary layers of the particle [5]. In ord...

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Section: Microstructural Characterization Of Al-cu-fe Coatingssupporting

confidence: 89%

The Corrosion Resistance of Aluminum–Bronze Coatings as a Function of Gas Pressure Used in the Thermal Spraying Process

2019

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“…Likewise, microcracks, similar to pores, can induce macroscopic failures when a sufficiently high load is applied. It was also observed that small cracks around the scratch path may decrease cohesive resistance in the test [18,33]. In the present investigation, a direct relationship between porosity and resistance to cohesion was not found, probably because hardness had a more important effect, due to the fact that it was an abrasion test.…”

Section: Resultscontrasting

confidence: 62%

“…The impact of these particles allows their deformation on the topography of substrate before its solidification, which produces a denser coating with greater bonding between splats and a less porous structure. Kawaguchi [33] indicates that the high porosity is due to the low velocity of the drops resulting from its poor acceleration by compressed air in the thermal projection process. Figure 4a shows the results of the microhardness vs. the particle collision speeds.…”

Section: Resultsmentioning

confidence: 99%

Influence of Gas Pressure on the Mechanical and Tribological Properties of Cu-Al Coatings Deposited via Thermal Spray

2019

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We report the results of the influence of the acetylene and oxygen gas pressure on the wear resistance of aluminum–bronze coatings deposited on naval brass substrate by means of the thermal (flame) deposition process. The coatings were characterized by means of scanning electronic microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), and X-ray fluorescence (XRF). The adhesion was determined with cross-hatching tests, and the mechanical response was assessed by measuring the nanohardness and by three-body and ball-on-disk abrasive wear tests. The results indicate that changes in the pressure and flow of the gas affect the morphology and the mechanical properties of the coatings, and these effects have consequences for the wear behavior of the coatings. Before the projection of the coatings, numerical simulations were carried out using Jets & Poudres software, where the collision speed of the particles was identified as the most significant factor that influences the mechanical properties and the performance of the coating. The gas pressure modified the hardness and the porosity level, which allowed improving the wear resistance.

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“…However, due to the high process temperature of these techniques, the thermal-sprayed coatings inevitably have problems such as oxidation, phase transition, porosity and residual thermal stresses. For example, the porosity of arc spraying and flame spraying is generally higher than 10%, while plasma spraying and HVOF technologies usually results in 3-8% and <3% porosity, respectively [21,22]. Consequently, the quality of coatings is degraded due to the high porosity [23,24].…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Corrosion Behavior of Cold-Sprayed Zn-Al Composite Coating

et al. 2020

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A Zn–Al composite coating was successfully deposited on Q235 steel by cold spray technology for the corrosion protection in the marine atmosphere. The microstructure and corrosion behavior of the prepared coating was studied byScanning Electron Microscope (SEM), X-ray Diffraction (XRD), salt spray test and electrochemical experiments. A 2400-h neutral salt spray corrosion test (with a corrosion medium of 3.5% sodium chloride solution) showed that the prepared cold-sprayed Zn-Al composite coating has excellent anti-corrosion properties. Based on the microstructure evolution and corrosion products analysis, droplets’ flow-driven ‘synergistic corrosion effect’ was proposed to explain the co-corrosion behavior of Zn and Al particles in the composite coating.

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Coating Qualities Deposited Using Three Different Thermal Spray Technologies in Relation with Temperatures and Velocities of Spray Droplets

Cited by 21 publications

References 7 publications

The Corrosion Resistance of Aluminum–Bronze Coatings as a Function of Gas Pressure Used in the Thermal Spraying Process

The Corrosion Resistance of Aluminum–Bronze Coatings as a Function of Gas Pressure Used in the Thermal Spraying Process

Influence of Gas Pressure on the Mechanical and Tribological Properties of Cu-Al Coatings Deposited via Thermal Spray

Microstructure and Corrosion Behavior of Cold-Sprayed Zn-Al Composite Coating

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