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Structural and stress relaxation kinetics at temperatures significantly lower than the glass transition

Grant number: 15/21573-4
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): December 01, 2015
Effective date (End): November 30, 2016
Field of knowledge:Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials
Principal Investigator:Edgar Dutra Zanotto
Grantee:Rodrigo Cardoso dos Passos
Home Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
Associated research grant:13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass, AP.CEPID

Abstract

Relaxation is an inherent process in vitreous materials, however it is not fully understood. The purpose of this project is to study two relaxation processes: structural and residual tension at temperatures significantly than the glass transition temperature (Tg). The structural relaxation is going to be studied in a diopside glass (CaO‡MgO‡2SiO2) at 40 K below its Tg¬¬. In order to proceed with this study, structural relaxation will be quantified from the measurement of the variation in the refractive index after several heat treatments. The kinetics of residual tensions relaxation will be studied in a commercial soda-lime glass, utilizing a polarized light microscopy technique. The understanding of the residual tensions has utmost technological relevance in the annealing processes of vitreous materials. Also, we are going to correlate the relaxation kinetics with those of the viscous flow for the cited materials. The kinetics of relaxation significantly below Tg is a field of study yet to be explored, therefore, its comprehension is necessary for the development of the vitreous materials science. (AU)