Plasma-Sprayed Al Alloy Coating with Enhanced Lamellar Bonding Through Novel Self-Bonding Strategy
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https://doi.org/10.1007/s11837-020-04394-z Ó 2020 The Minerals, Metals & Materials Society
SURFACE ENGINEERING: APPLICATIONS FOR ADVANCED MANUFACTURING
Plasma-Sprayed Al Alloy Coating with Enhanced Lamellar Bonding Through Novel Self-Bonding Strategy HAROON RASHID,1 XIN-YUAN DONG,1 JUN WANG,1 XIAN-JIN LIAO,1 YING-KANG WEI,1 XIAO-TAO LUO,1 and CHANG-JIU LI1,2 1.—State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an, China. 2.—e-mail: [email protected]
Plasma spraying was employed to deposit an Al coating in order to create a self-metallurgical bonding effect through impact-induced melting with highly overheated molten droplets. Numerical simulation was employed to estimate the interface temperature between the molten Al splat and the Al substrate. The interface bonding was examined from cross sections of the Al splat and the etched coatings. The results show that, with Al droplets higher than 1800°C, impact-induced Al substrate melting occurs. The measurements showed that, during spraying, most Al particles were heated to temperatures theoretically causing an impact-induced melting effect, which subsequently produces a metallurgical self-bonding effect. The observed results confirm the metallurgical bonding in plasma-sprayed Al coating.
INTRODUCTION Since aluminium has many useful characteristics, such as corrosion resistance, light weight, high ductility,1–3electromagnetic shielding ability,4 decorative ability,5 a non-toxic nature,6 and selective absorption ability,7 it is widely applied as a coating in the oil and gas sector, the chemical and petrochemical industry, marine environments, the automotive and aerospace industry, structural applications, electronic components, cosmetics, packaging applications, and astronomical mirrors.8 The methods available for Al coating deposition include thermal spraying, hot dipping, calorizing, vacuum deposition, thermal diffusion, vapor deposition and cladding.9–11 Although Al cannot be electrodeposited from aqueous solutions because it reacts with water to form Al hydroxide on the electrode instead of pure Al, the electrodeposition of Al from non-aqueous solutions, e.g., molten salts, has been investigated by various researchers.12 Among all coating processes, thermal spraying of Al coatings has often been employed to prevent steel infrastructures such as highways and bridges from corrosion owing to reduced life cycle costs and the
(Received June 25, 2020; accepted September 16, 2020)
availability of on-site coating as compared to other methods such as hot dipping.13 Zinc and Al coatings have been used to protect steel structures from corrosion since the early 1900 s, e.g., thermally sprayed metal coatings on bridge structures in the 1930.14 Al coatings on offshore steel structures have been found to be very beneficial for protection against corrosion.15 Bullard et al.,16,17 have carried out extensive work which highlights the importance of thermally sprayed Al protective coatings for
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