Fundamentals of Glass-to-Metal Bonding: I, Wettability of Some Group I and Group VIII Metals by Sodium Silicate Glass

The degree of wetting of Cu, Ag, Au, Pd, Pt, and Ni by three sodium silicate glasses having 30.8, 33.6, and 36.9% Na2O was observed in vacuum, helium, hydrogen, oxygen, and air atmospheres. No apparent correlation of the contact angles of the three sodium silicate glasses with the metals studied in the various atmospheres was observed with the position of the metals in the periodic system of elements. It was found that within the range of glass compositions studied, there is no appreciable difference in contact angle for identical conditions. In pure helium no chemical effect of atmosphere itself is possible. The observed variations in contact angle from metal to metal may be related to the polarizing power of the metal, which may be presumed to have the effect of lowering the interfacial tension. At present it is felt that no reaction between pure metal and glass occurs in an inert atmosphere. In oxygen and hydrogen atmospheres chemical reactions are possible, and these reactions result in phenomena that favor spreading. Results are reviewed on a theoretical basis.