Definição da metodologia da caracterização da temperabilidade de vidros planos finos

AUTOR(ES)

Maria Elisa Philippsen

DATA DE PUBLICAÇÃO

2007

RESUMO

The tempering of glass can substantially increase its resistance to mechanical shock. Tempered thin glass, compared to tempered thick glass, is more susceptible to spontaneous fracturing. During the tempering process, the glass is heated above the transition temperature (Tg) and below its melting point (melting temperature for silica vitrea is 1750 C). The surface is then rapidly cooled. The cooling at the surface is quicker than at the center of the glass since (Tg) is greater at the surface. In thin glass, there are more contractions, which increase the possibility of spontaneous fracturing. Tempered glass can be characterized by its shape and size when it fractures. During this research, the glass fragment sizes, Vickers hardness, and glass temper at 620 C to 690 C were studied. These temperatures were chosen because of the 650 C standard temper temperature in the glass industry. Temperatures above and below the industry standard were chosen to produce a better characterization of tempered glass. For this research, some characterization techniques were applied to obtain information about glass temperability: fragmentation technical, Vickers Hardness, flection test, sphere technique, fracture KIc through Vickers hardness and mechanical shock resistance to tempered thickness. Through the use of diverse techniques of characterization, it is possible to demonstrate the traits of tempered glass. The study revealed that glass tempered at 620 C had good resistance to impact (minimum energy 4,64 kgm/s) and resulted in a significant reduction in fracturing probability. However, in the fragmentation test, glass tempered at 640 C showed that the glass fragments were more homogeneous, which is preferred. Overall, better glass tempered temperature evaluated were between 620 C and 640 C. The objective of this research was to define a methodology to characterizar temperability of thin flat glass.

ASSUNTO(S)

dureza vidro ceramica temperabilidade caracterização temperatura

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