LAUSR

Abstract The electrical contact resistance of a Ag/carbon nanotube (CNT) composite plating film prepared using a cyanide-free bath was evaluated against a H2S gas corrosion test. After the corrosion test, the Ag/CNT composite plating film exhibited a lower electrical contact resistance than a Ag plating film evaluated for comparison. The mechanism of the superior electrical contact characteristics of the Ag/CNT composite plating film was investigated using various methods. Scanning electron microscopy observations and X-ray diffraction analyses revealed that the amount of silver sulfide (Ag2S) generated on the Ag/CNT composite film was smaller than that on the Ag film. Electrochemical measurements clarified that the sulfidation resistances of the Ag/CNT composite film and the Ag film were approximately the same. However, the contact angle of the Ag/CNT composite film against water was remarkably greater than that of the Ag film. This high hydrophobicity of the Ag/CNT film likely suppressed Ag2S production by corrosion, resulting in the observed superior electrical contact characteristics after the H2S gas corrosion test.