Effect of Magnetron Sputtering Transition Layer on the Bonding Properties of Electroplated Ni Metal Coatings on the Inner Wall of CFRP Cylinders

The surface of the inner wall of the carbon fiber reinforced resin matrix composite cylinder is metallized, and a metal coating with large thickness and high bonding strength is prepared on the inner wall of the cylinder of the carbon fiber composite through three steps of radio frequency plasma activation, magnetron sputtering deposition of the transition layer metal, and plating deposition of nickel. The bonding strength between the coating and the substrate was tested by the pulling method to investigate the effects of different transition layer types and thicknesses on the bonding strength of the metal coating. A scanning electron microscope (SEM) and an accompanying energy spectrometer were used to observe the surface microscopic morphology and cross-section elemental composition of the metal coatings, and an X-ray diffractometer was used to analyze the crystal structure of the metal coatings. The results show that magnetron sputtering of the Ti-Cu transition layer can significantly improve the bonding strength between the electroplated Ni metal coating and the substrate, and the thickness of the titanium film layer has a great influence on the film-based bonding strength, while the thickness of the copper film layer has a relatively small influence on the bonding strength, and the film-based bonding strength decreases with the thickening of the copper film layer. A transition layer of 0.2 μm Ti + 1 μm Cu was magnetron sputtered on the inner wall of the CFRP cylinder, followed by electroplating of about 17 μm Ni metal, and the bonding strength of the prepared metal coating reached 2.05 MPa, which endowed the metallic characteristics of the inner wall of the carbon fiber composite cylinder.