THE WETTING OF GOLD AND PLATINUM BY WATER.
NAVAL RESEARCH LAB WASHINGTON D C
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When a sessile drop of pure water is placed on a clean surface of pure polished gold or platinum, it will spread spontaneously over the metal and exhibit a zero contact angle. However, in order to rid surfaces of these metals of adsorbed hydrophobic contaminants, it is necessary to heat them to white-hot temperatures in flowing streams of high-purity hydrogen, nitrogen, argon, krypton, or air. Such a treatment gives surfaces which are completely wetted by pure water and exhibit zero contact angles in gases freed from trace contaminants by an adsorbent cold trap. However, prolonged exposure of the metals to these gases renders them nonwetting because of the gradual adsorption of trace hydrophobic contaminants present in the gas streams. Author