Surface Metallization and Ceramic Deposition on Thermoplastic-Polymer and Thermosetting-Polymer Composite Via Atmospheri

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Surface Metallization and Ceramic Deposition on Thermoplastic‑Polymer and Thermosetting‑Polymer Composite Via Atmospheric Plasma Spraying Hansol Kwon1 · Jaeick Kim1 · Changhee Lee1  Received: 22 June 2020 / Accepted: 18 August 2020 © The Korean Institute of Metals and Materials 2020

Abstract  A spray coating technique is an excellent method for surface metallization and ceramic deposition to widen the application fields of irreplaceable engineering polymers. In this study, Al metallization and ­Al2O3 deposition on thermoplastic-polymers (polycarbonate, polyimide) and a thermosetting-polymer composite (carbon fiber reinforced epoxy) were conducted via atmospheric plasma spray (APS). Due to the susceptibility of polymers to thermal or mechanical damage, precise process control is required. It was shown that the engineering temperature range critically determines the process window of thermoplastic-polymers. An A ­ l2O3 coating can be fabricated on polymers via an Al bond coat. Like a heat sink, the Al buffer layer enables polymers to endure process heating. In low thermally resistant polycarbonate (PC), only a low plasma energy source could be applied. Additionally, vaporization induced by Al droplet contact was a clear reason of the unstable weak interface between the coating and substrate. The coatings fabricated on polyimide (PI) substrates generally showed a continuous and clean interface with a moderate adhesion property. In the case of carbon fiber reinforced epoxy (CFRP), it is believed that carbon fibers acted as a heat sink such that considerable thermal damage of CFRP was not observed and there was not delamination of the coatings. However, fracturing of carbon fibers and epoxy resin by grit-blasting (surface pre-treatment) made the surface unstable. This led to the worst adhesion characteristics between the coating and CFRP substrate. It was demonstrated that because the available temperature range and surface condition are very sensitive compared to conventional metal substrates, advanced surface pre-treatment, precise process optimization, and additional cooling are required for successful deposition. Keywords  Atmospheric plasma spray (APS) · Polymer substrate · Process parameter · Microstructure · Adhesion strength

1 Introduction Recently, engineering polymers have replaced conventional structure metals in various industrial products (aircrafts, automobiles, production facilities, home appliances, electric devices, etc.…). Due to their high strength to weight ratio, transparency, flexibility, formability at relatively low temperatures, machinability, and low manufacturing cost, polymers are irreplaceable in many industries [1–3]. It is well known that engineering polymers can be

* Changhee Lee [email protected] 1



Kinetic Spray Coating Laboratory (NRL), Division of Materials Science and Engineering, Hanyang University, Seoul 04763, Republic of Korea

separated into two main categories based on their response to heat: thermoplastic- and thermosetting-polymers [1, 3]. A thermoplastic-polymer beha