Viscosity is the single most important property governing the efficacy, rates, and nature of melt transport. Viscosity is intimately related to the structure and thermodynamics properties of the melts and is a reflection of the mechanisms of single atoms slipping over potential energy barriers. The ability to predict melt viscosity accurately is, therefore, of critical importance for gaining new insights into the structure of silicate melts. Simple composition melts, having a reduced number of components, offer an advantage for understanding the relationships between the chemical composition, structural organization and the rheological properties of a melt. Here we have compiled a large database of ~970 experimental measurements of melt viscosity for the simple chemical systems MAS, CAS and MCAS. These data are used to create a single chemical model for predicting the non-Arrhenian viscosity as a function of temperature (T) and composition (X) across the entire MCAS system. The T-dependence of viscosity is accounted for by the three parameters in each of the model functions: (i) Vogel–Fulcher–Tamman (VFT); (ii) Adam–Gibbs (AG); and (iii) Avramov (AV). The literature shows that, in these systems, viscosity converges to a common value of the pre-exponential factors (A) that can be assumed to be independent of composition. The other two adjustable parameters in each equation are expanded to capture the effects of composition. The resulting models are continuous across T–X space. The values and implications of the optimal parameters returned for each model are compared and discussed. A similar approach is likely to be applicable to a variety of non-silicate multicomponent glassforming systems.

A rheological model for glassforming silicate melts in the systems CAS, MAS, MCAS

GIORDANO, Daniele;
2007-01-01

Abstract

Viscosity is the single most important property governing the efficacy, rates, and nature of melt transport. Viscosity is intimately related to the structure and thermodynamics properties of the melts and is a reflection of the mechanisms of single atoms slipping over potential energy barriers. The ability to predict melt viscosity accurately is, therefore, of critical importance for gaining new insights into the structure of silicate melts. Simple composition melts, having a reduced number of components, offer an advantage for understanding the relationships between the chemical composition, structural organization and the rheological properties of a melt. Here we have compiled a large database of ~970 experimental measurements of melt viscosity for the simple chemical systems MAS, CAS and MCAS. These data are used to create a single chemical model for predicting the non-Arrhenian viscosity as a function of temperature (T) and composition (X) across the entire MCAS system. The T-dependence of viscosity is accounted for by the three parameters in each of the model functions: (i) Vogel–Fulcher–Tamman (VFT); (ii) Adam–Gibbs (AG); and (iii) Avramov (AV). The literature shows that, in these systems, viscosity converges to a common value of the pre-exponential factors (A) that can be assumed to be independent of composition. The other two adjustable parameters in each equation are expanded to capture the effects of composition. The resulting models are continuous across T–X space. The values and implications of the optimal parameters returned for each model are compared and discussed. A similar approach is likely to be applicable to a variety of non-silicate multicomponent glassforming systems.
2007
19
205148
205159
http://iopscience.iop.org/0953-8984/19/20/205148
GIORDANO D; RUSSELL J.K
File in questo prodotto:
File Dimensione Formato  
Giordano_Russell_2007.pdf

Accesso riservato

Tipo di file: POSTPRINT (VERSIONE FINALE DELL’AUTORE)
Dimensione 960.04 kB
Formato Adobe PDF
960.04 kB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/95532
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 27
  • ???jsp.display-item.citation.isi??? 26
social impact