An investigation on effects of heat treatment on corrosion properties of Ni–P electroless nano-coatings

✍ Scribed by Taher Rabizadeh; Saeed Reza Allahkaram; Arman Zarebidaki

• Publisher: Elsevier Science
• Year: 2010
• Weight: 631 KB
• Volume: 31
• Category: Article
• ISSN: 0261-3069
• DOI: 10.1016/j.matdes.2010.02.027

✦ Synopsis

Electroless Ni–P coatings are recognized for their excellent properties. In the present investigation electroless Ni–P nano-crystalline coatings were prepared. X-ray diffraction technique (XRD), scanning electron microscopy (SEM), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were utilized to study prior and post-deposition vacuum heat treatment effects on corrosion resistance together with the physical properties of the applied coatings.
X-ray diffraction (XRD) results indicated that the As-plated had nano-crystalline structure. Heat treatment of the coatings produced a mixture of polycrystalline phases. The highest micro-hardness was achieved for the samples annealed at 600°C for 15min due to the formation of an inter-diffusional layer at the substrate/coating interface.
Lower corrosion current density values were obtained for the coatings heat treated at 400°C for 1h. EIS results showed that proper heat treatments also enhanced the corrosion resistance, which was attributed to the coatings’ structure improvement.