Primary investigation of corrosion resistance of Ni-P/TiO2 composite film on sintered NdFeB permanent magnet

✍ Scribed by Laizhou Song; Yanan Wang; Wanzhou Lin; Qian Liu

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 717 KB
• Volume: 202
• Category: Article
• ISSN: 0257-8972
• DOI: 10.1016/j.surfcoat.2008.05.025

✦ Synopsis

In this paper, an electroless nickel plating and sol-gel combined technique used to prepare the Ni-P/TiO 2 composite film on sintered NdFeB permanent magnet is described and the composite film was characterized by X-ray diffraction (XRD), environmental scanning electron microscopy (ESEM), and energy dispersive X-ray spectrometer (EDX). The corrosion resistance of Ni-P/TiO 2 film was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The self-corrosion current density (i corr ) of Ni-P/TiO 2 composite film is 2.38μA/cm 2 in 0.5mol/L H 2 SO 4 solution about 33% of that of Ni-P coating and 0.22μA/cm 2 in 0.5mol/L NaCl solution about 14% of that of Ni-P coating, respectively. In 0.5mol/L H 2 SO 4 and 0.5mol/L NaCl solutions, the polarization resistance (Rp) of the composite film is 12.5kΩ cm 2 and 120kΩ cm 2 , about 1.6 and 2 times that of Ni-P coating, respectively. The results indicate that Ni-P/TiO 2 composite film has a better corrosion resistance than Ni-P coating.