The Confocal Scanning Laser Microscopic Study of the Pitting Corrosion on Sputter-Deposited W-Ti Alloys in 1 M NaOH Solution

Abstract

The pitting corrosion of the passive films formed on the surface of sputter-deposited W-30Ti and W-53Ti alloys after immersion for 24 hours in alkaline 1 M NaOH soution at 25°C was studied by using the surface sensitive technique of the confocal scanning laser microscopic (CSLM) technique including corrosion tests and electrochemical measurements. The higher corrosion rate of the W-30Ti alloy (i.e., about 3x 10^-2 mm/y) than those of the W-53Ti and W-90Ti alloys (i.e., about 4-5 x 10^-3 mm/y) was mostly due to the deep type of pitting corrosion observed on the surface of the passive film formed on the W-30Ti alloy in 1 M NaOH solution. The shallow type of pits was developed on the surface of the passive film formed on the W-53Ti alloy, whereas no pitting corrosion on the titanium-rich W-90Ti alloy.

Keywords: Pitting corrosion; Open circuit corrosion potential; Corrosion test; CSLM study

Tribhuvan University Journal Vol. XXVI, No. 1, 2009 Page: 17-26