Accession Number:

AD0671180

Title:

EFFECT OF ADSORBED WATER ON WETTING PROPERTIES OF BOROSILICATE GLASS, QUARTZ, AND SAPPHIRE,

Descriptive Note:

Corporate Author:

NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s):

Report Date:

1968-05-06

Pagination or Media Count:

20.0

Abstract:

Contact angles of a variety of hydrophobic liquids were measured on clean surfaces of borosilicate glass, quartz, and sapphire at 20C with the RH at 0.6 and 95. The adsorption of water molecules at 0.6 RH resulted in the formation of only a fraction of a monolayer yet, this fraction converted each high-energy solid surface to one having a low critical surface tension of wetting, gamma sub c. The increased amount of water adsorbed at 95 RH to form a film comprising little more than a condensed monolayer further lowered gamma sub c to a value somewhat above that of bulk water. At each RH investigated the value of gamma sub c was the same for each of these three solids hence, gamma sub c was dependent upon the surface concentration of adsorbed water but was independent of the chemical nature of the solid substrate. The somewhat different values of gamma sub c obtained on using several different homologous series of hydrophobic liquids are explained in terms of differences in the contribution from nondispersion interfacial forces acting between the water film and the contacting organic-liquid molecules. These results reveal clearly the important influence of only a monolayer of adsorbed water upon the spreading, adhesion, and contact angles of organic liquids resting upon high-energy, hydrophilic, solid surfaces. To illustrate the effect of the baking pretreatment temperature on the removal of physically adsorbed water, the three specimens were dried at three temperatures 65C, 120C, and 215C. No significant differences were found on the specimens following baking treatment at the different temperatures. Author

Subject Categories:

  • Physical Chemistry
  • Ceramics, Refractories and Glass
  • Solvents, Cleaners and Abrasives

Distribution Statement:

APPROVED FOR PUBLIC RELEASE