Synthesis of electrodeposited Co–P–ZrO2–CeO2 nanocomposite coating: Effect of heat treatment on corrosion and mechanical properties

Abstract

Electrodeposited cobalt coatings have been considered a suitable replacement for hard chromium coatings due to their promising properties. In this research, electrochemical methods through the direct current technique have been applied to synthesize a novel Co–P–ZrO2–CeO2 nanocomposite coating. The addition of different phosphorous contents as a determinant of the crystalline or amorphous structure was investigated using X-ray diffraction (XRD). The needle-like or cauliflower morphologies and related elemental compositions were surveyed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), respectively. The XRD, microhardness, wear, and corrosion resistance tests were conducted on heat-treated samples. The results illustrate that heat treatment significantly increases the microhardness of the amorphous nanocomposite layer (up to 1323 HV0.1). Additionally, it causes the best wear behavior for the nanocrystalline Co–P–ZrO2–CeO2 (0.2), while leading to a lower wear resistance for the amorphous coatings (0.65). Furthermore, applying heat treatment diminishes the corrosion behavior of the coating. Tafel polarization and electrochemical impedance spectroscopy (EIS) tests reveal that the best corrosion resistance has been achieved for an amorphous nanocomposite coating 11929 Ω cm2. These findings demonstrate that this coating has desirable properties for industrial applications.