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SHARAGOV, Vasile; RAIFURA, Svetlana; LYSENKO, Galina. Analysis of homogeneity of surface layers of sheet glass produced by different manufacturing plants using the method of section etching by HF solution. In: Materials Science and Condensed Matter Physics. Ediția a 9-a, 25-28 septembrie 2018, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2018, p. 271.
|Materials Science and Condensed Matter Physics
Ediția a 9-a, 2018
Conferința "International Conference on Materials Science and Condensed Matter Physics" |
Chișinău, Moldova, 25-28 septembrie 2018
In the process of molding, glasses of industrial purpose form a stratified structure. The character and parameters of their stratified structure can be estimated by determining the index of glass homogeneity. Glass inhomogeneity index is established for the entire amount of sample with the help of existing methods. To ensure the specified physicochemical properties of glass (mechanical strength, thermal resistance, chemical resistance, etc.), the parameters and the character of inhomogeneous structure of its surface layers have to be known. The aim of the undertaken experiments was to study the inhomogeneous structure of surface layers of sheet glass produced at different plants using the method of section etching by HF solution. The object of the study is sheet glass produced by vertical drawing. Samples of glass, selected from several manufacturing plants, have been used for this study. To analyze the composition and structure of the surface layers of samples, the method of section etching by HF solution was used, which consists in successive layer-by-layer dissolution of glass with a weak concentration of HF solution, followed by an analysis of the extracts formed. At the same time, not less than three samples with dimensions of approximately 3x3 cm were subject to etching. The samples were rotated in the solution, or kept in a stationary position. The thickness of the dissolved layer of glass and the rate of its dissolution in HF solution were calculated based on sample‘s mass losses before and after etching. The concentration of Na+, K+ Ca2+ and Mg2+ was measured in extracts before and after etching with the help of flame photometry method. Graphs demonstrating the dependence of the rate of glass dissolution on the thickness of the stratified layer were built to analyze the data obtained. When analyzing the surface layers of glass, the thickness of the glass layer dissolved in one etching ranged from 0.05 to 2 μm, and the duration of one etching varied from 2.5 to 60 minutes. The thickness of the dissolved glass layer was verified by changing only the duration of one etching. All the other parameters of section etching by HF solution (volume, concentration and temperature of the solution, hydrodynamic conditions, etc.) remained unchanged. The experiments showed that the rates of dissolution of glass samples produced by various manufacturing plants are not stable. The following regularity was determined: the shorter the duration of one etching, the greater the results scattering. Increasing the duration of one etching from 2.5 to 20 min, the ratio of maximum value of the dissolution rate to its minimum value decreases to 5 times, that is, the result scattering significantly reduces. Considerable scattering of data for the rate of surface layers‘ dissolution can be explained only by its inhomogeneous structure. Data on section etching by HF solution allow us to roughly estimate the nature and thickness of separate layers of glass, as well as the degree of inhomogeneity of its structure. The experiment revealed strips with thickness ranging from fractions to several microns drawn in the longitudinal direction of the glass ribbon. To determine the nature of inhomogeneous structure of sheet glass the optimum duration of one etching is 20 minutes. In general, glass samples produced by different manufacturing plants have approximately the same degree of structure inhomogeneity.