Direct sputtering- and electro-deposition of gold coating onto the closed surface of ultralow-density carbon-hydrogen foam cylinder

This work aimed to fabricate a gold coating on the surface of ultralow-density carbon-hydrogen foam cylinder without electroless plating. Poly (divinylbenzene/styrene) foam cylinder was synthetized by high internal phase emulsion, and chemical vapor deposition polymerization approach was used to form a compact poly- p -xylylene film on the foam cylinder. Conducting gold thin films were directly deposited onto the poly- p -xylylene-modified foam cylinder by magnetron sputtering, and electrochemical deposition was adopted to thicken the gold coatings. The micro-structures and morphologies of poly (divinylbenzene/styrene) foam cylinder and gold coating were observed by field-emission scanning electron microscopy. The gold coating content was investigated by energy-dispersive X-ray. The thicknesses of poly- p -xylylene coating and sputtered gold thin-film were approximately 500 and 100   nm, respectively. After electrochemical deposition, the thickness of gold coating increased to 522   nm, and the gold coating achieved a compact and uniform structure.