Accession Number : AD0762767

Title :   The Rate of Dissolution of Amorphous Silica in Water. Inaccessibility of Crack Tips in Glass.

Descriptive Note : Technical rept.,

Corporate Author : RENSSELAER POLYTECHNIC INST TROY N Y MATERIALS DIV

Personal Author(s) : Doremus,Robert H. ; Alim-Marvasti,F. ; Pavelchek,Edward K. ; Doremus,Robert H.

Report Date : JUN 1973

Pagination or Media Count : 43

Abstract : The report discusses two research projects. In the first, the rate of dissolution of finely divided amorphous silica in water was determined by molybdate analysis of the dissolved monomeric silicic acid. Effects of pH, temperature, addition of salt, and stirring were studied. It was concluded from the results and those of earlier investigators that the dissolution rate was not controlled by a simple reaction of silica with water at the silica surface. The second report discusses the strengthening of soda-lime glass which results when it is etched with hydrofluoric acid. It was found much smaller than expected for etching of the crack tip. Thus little or no etchant reaches the tip, and perhaps it is protected from the surroundings by a layer of hydrated glass. Etching experiments indicate that the etching acid does penetrate part way down the crack, giving rounded pits and lines on the glass surface. (Modified author abstract)

Descriptors :   (*SILICON DIOXIDE, SOLUBILITY), (*GLASS, CRACKS), WATER, PH FACTOR, TEMPERATURE, ETCHING

Subject Categories : Physical Chemistry
      Ceramics, Refractories and Glass

Distribution Statement : APPROVED FOR PUBLIC RELEASE