Some peculiarities in the structures of vertically drawn plate glass

Abstract

In measuring the strengths of glass by methods normally satisfactory for ordinary purposes (tensile, bending, compressive) there is always a large spread in the results which, as is well known, is associated with the different states of the surface of the specimens. Hair crack, cracks and other defects on the glass surface are one of the most important factors determining strength. However, experimental data on the relationship between the strength of glass and the surface state, are extremely rare. Moreover, a knowledge of the nature and distribution of the surface defects which reduce the strength of the glass is necessary in developing methods of strengthening the glass. This article deals with the results of several investigations of the structure of the surface and strength of plate glass. Plate glass drawn by the vertical method (Furko) made at the Gusev Dzerzhinskii Factory was studied together with glass produced by nonfloat working at the L'vov Glass Factory. Specimens were cut from different parts of the ribbon. Fig.i. Surface of vertically Unaided visual examination of the vertically drawn glass revealed no surface drawn plate glass, etched defects not belonging to glass faults. Under the microscope ( x 600) amidst some with 4%hydrofluoric acid for ten visual fields was seen only one defect in the form of a fine furrow located in 3 rain. ( x 600). the drawing direction. After etching the surface with 4% HF for 3 minutes, there developed a large number of fine, mattefurrows located parallel to each other in the drawing direction of the glass ribbon. These furrows were quite visible with the unaided eye. Microscopic and electron-microscopic investigations * of the etched surface of the specimens were made to explain the structure of the furrows. The microscopic studies were made with microscope M-9 and the interference microscope MII-4.