| Texto completo | |
| Autor(es): |
Lancelotti, Ricardo Felipe
[1, 2]
;
Cassar, Daniel Roberto
[2]
;
Nalin, Marcelo
[3]
;
Peitl, Oscar
[2]
;
Zanotto, Edgar Dutra
[2]
Número total de Autores: 5
|
| Afiliação do(s) autor(es): | [1] Univ Fed Sao Carlos, Grad Program Mat Sci & Engn, Sao Carlos, SP - Brazil
[2] Univ Fed Sao Carlos, Dept Mat Engn Ctr Res Technol & Educ Vitreous Mat, Sao Carlos, SP - Brazil
[3] Sao Paulo State Univ, UNESP, Inst Chem, Araraquara, SP - Brazil
Número total de Afiliações: 3
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Journal of the American Ceramic Society; v. 104, n. 5 JAN 2021. |
| Citações Web of Science: | 1 |
| Resumo | |
Knowledge of relaxation processes is fundamental in glass science and technology because relaxation is intrinsically related to vitrification, tempering as well as to annealing and several applications of glasses. However, there are conflicting reports-summarized here for different glasses-on whether the structural relaxation time of glass can be calculated using the Maxwell equation, which relates relaxation time with shear viscosity and shear modulus. Hence, this study aimed to verify whether these two relaxation times are comparable. The structural relaxation kinetics of a lead metasilicate glass were studied by measuring the refractive index variation over time at temperatures between 5 and 25 K below the fictive temperature, which was initially set 5 K below the glass-transition temperature. Equilibrium shear viscosity was measured above and below the glass-transition range, expanding the current knowledge by one order of magnitude. The Kohlrausch equation described very well the experimental structural relaxation kinetics throughout the investigated temperature range and the Kohlrausch exponent increased with temperature, in agreement with studies on other glasses. The experimental average structural relaxation times were much longer than the values computed from isostructural viscosity, as expected. Still, they were less than one order of magnitude higher than the average relaxation time computed through the Maxwell equation, which relies on equilibrium shear viscosity. Thus, these results demonstrate that the structural relaxation process is not controlled by isostructural viscosity and that equilibrium shear viscosity only provides a lower boundary for structural relaxation kinetics. (AU) | |
| Processo FAPESP: | 17/12491-0 - Processos cinéticos em vidros e novas formulações vítreas via aprendizagem de máquina |
| Beneficiário: | Daniel Roberto Cassar |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |
| Processo FAPESP: | 19/15108-8 - Relaxação estrutural de vidros metassilicato de chumbo e dissilicato de lítio |
| Beneficiário: | Ricardo Felipe Lancelotti |
| Modalidade de apoio: | Bolsas no Brasil - Mestrado |
| Processo FAPESP: | 13/07793-6 - CEPIV - Centro de Ensino, Pesquisa e Inovação em Vidros |
| Beneficiário: | Edgar Dutra Zanotto |
| Modalidade de apoio: | Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs |