Properties of a glass surface modified by a new frosting paste. Surface morphology

Abstract

A new paste is proposed for frosting glass surfaces. The action of the paste is based on the physical-chemical process of surface chemical ion exchange. The paste does not contain hydrofluoric acid or its derivatives. The frosting process occurs at 300°C and differs substantially from the existing frosting processes -chemical etching and sandblasting. The morphology of the surface layer of the frosted glass is characterized by a system of microblocks (linear dimensions 50 -150 mm) and microcracks (width 100 -200 nm). The microblocks have even faces and a smooth frontal surface. The surface morphology of the glass is the same after frosting and subsequent deposition of a metal by chemical reduction.It is well-known that an important factor in the deposition of organic or inorganic coatings on a glass surface is the adhesion power of the glass, which acts as a substrate. Modification of the structure of the surface layer of glass by, specifically, frosting can change the surface roughness substantially and, in consequence, increase the adhesion power of the glass as a substrate per unit area of the geometric surface.Sandblasting with solid abrasive particles and chemical etching of a glass surface by solutions containing hydrofluoric acid or its derivatives are now widely used for frosting glass.A new method of frosting glass is applying a paste (RF Patent No. 2238919) [1, 2], which does not contain hydrofluoric acid or its derivatives and acts on the basis of surface ion exchange processes [3,4]. The present article gives the results of a comparative investigation, by the method of electron scanning microscopy, of the morphological structural properties of the surface layer of glass modified by sandblasting, chemical etching, and treatment with the new frosting paste (NFP) which contains no hydrofluoric acid. The structure of the surface layer of glass after frosting by chemical etching and by using the NFP followed by deposition of a thin layer of silver by chemical reduction was also investigated.Samples of sodium-calcium-silicate glass (GOST 111-2001) were used. Chemical etching was performed by fluorine-containing paste for frosting glass, prepared following the recommendations presented in USSR Inventor's Certificate No. 948926A. The duration of the chemical etching of the glass samples was 5 -10 min.The glass surface modification process NFP consisted of the following stages [1, 2]: degreasing the surface and washing with warm flowing water;depositing a layer of paste on the glass surface with an appropriate tool using a stencil consisting of a film manufactured by the ORACAL Company and prepared by plotter cutting, or using a silkscreen form;removing the stencil, if it was used at the preceding stage;heat-treatment of the glass sample at approximately 300°C for 15 -20 min;removing the dry layer of paste by washing in warm flowing water.A doctor was used to deposit the paste layer on the surface of the glass. The thickness of the paste layer deposited on the glass when using a stencil consisting of an ORACAL...