Fundamentals of Glass‐to‐Metal Bonding: IV, Wettability of Gold and Platinum by Molten Sodium DisiIicate

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Abstract
Further studies were made on the effect of the nature of the atmosphere on the wetting of gold and platinum by sodium disilicate at 1000°C. The gases were oxygen, nitrogen, carbon dioxide, helium, argon, water vapor, carbon monoxide, hydrogen, and several mixtures of some of these gases. Data reported were obtained in the pressure range 10 ‐5 mm. of Hg to approximately 1 mm. of Hg. A special experimental apparatus was constructed for this purpose. In this pressure range the results showed that the wetting of gold was unaffected by these atmospheres. The platinum‐sodium disilicate contact angle, on the other hand, depended on the nature and pressure of the gas. This angle was affected most by atmospheres of water vapor, carbon monoxide, hydrogen, and oxygen. Water vapor was found to be easily displaced from the metal by oxygen. The results were interpreted on the basis of selective adsorption of the gases at the various metal interfaces and of absorption of oxygen and hydrogen by platinum.