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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

Evaluation of the guided random parameterization method for critical cooling rate calculations

Texto completo
Rodrigues, Bruno Poletto [1] ; Zanotto, Edgar Dutra [1]
Número total de Autores: 2
Afiliação do(s) autor(es):
[1] Univ Fed Sao Carlos, Dept Mat Engn, Vitreous Mat Lab, BR-13565905 Sao Carlos, SP - Brazil
Número total de Afiliações: 1
Tipo de documento: Artigo Científico
Fonte: Journal of Non-Crystalline Solids; v. 358, n. 18-19, p. 2626-2634, SEP 15 2012.
Citações Web of Science: 3

We focus on a recently suggested approach to the calculation of critical cooling rates for glass formation. It is a ``random parameterization{''} method that is guided by a limited number of isothermal scanning calorimetry experiments. However, several assumptions have been made in its derivation that may not mirror the actual crystallization behavior of most supercooled liquids, which may jeopardize the estimation of glass forming ability. We evaluate those assumptions and the applicability of the method is tested for lithium disilicate glass (which displays moderate internal nucleation rates) and dibarium titanium silicate glass (which displays very high internal nucleation rates, similar to those of metallic glasses). Both glasses nucleate homogeneously and exhibit polymorphic crystallization. Our calculations show that some overlooked variables, such as the sample geometry, nucleation induction-times, surface crystallization and the breakdown of the Stokes-Einstein/Eyring equation, have significant roles on the calculated time-temperature-transformation curves during heating experiments. We demonstrate that the proposed random parameterization method can only be used when a glass forming liquid that undergoes internal crystallization is cooled from above its liquidus to various test temperatures. If the sample undergoes predominant surface crystallization or if it is heated to the test temperature several corrections must be made. (C) 2012 Elsevier B.V. All rights reserved. (AU)

Processo FAPESP: 07/08179-9 - Processos cinéticos em vidros e vitrocerâmicas
Beneficiário:Edgar Dutra Zanotto
Linha de fomento: Auxílio à Pesquisa - Temático