Glasses: Aluminosilicates - Archive ouverte HAL Accéder directement au contenu
Chapitre D'ouvrage Année : 2021

Glasses: Aluminosilicates

Verres : aluminosilicates

Résumé

Aluminosilicate glasses are widely used and investigated materials with current and promising technological applications such as high-power laser gain media, flat-panel displays, solid oxide fuel cells, sealing materials, glass-fiber composites and long-term immobilization of wastes, to name a few. They are also abundant in nature and relevant for geological processes as they are chemically close to the natural magmatic compositions of the Earth mantle. Finally at low SiO 2 content, quenched metallurgical slags are mainly composed of aluminosilicate glasses. Introducing Al 2 O 3 strongly affects many physico-chemical properties. For instance, it improves fracture strength, increases elastic modulus and chemical resistance or hinders the trend to phase separation. Many properties correlate with the nature of non-framework cations present in the glass and to the flexibility for Al to adopt multiple coordination states. Different aspects of the disorder (network connectivity, Si/Al disorder, short range environment) affect the topological and configurational entropies. In this article we address the specificities of the atomic-scale structure in diverse glass models containing alumina with important implications for interpreting and controlling the physico-chemical properties. Commercial Glasses Aluminosilicate (AS) glasses, notably at low-alkali content, have high values of tensile strength, resistance to high temperature and excellence resistance to chemical corrosion (Varshneya and Mauro, 2019). They have found widespread commercial application as fibers to reinforce plastics or concrete. E-glass (a low-alkali Ca-Mg alumino-borosilicate glass with 10-15 mol% Al 2 O 3) is the most common glass fibers. Nowadays, a major application concerns alkali-free aluminosilicates used as thin glass sheets for liquid crystal flat displays. With higher amounts of alkalis, aluminosilicate glasses can be used to obtain high surface strength via an ion exchange process. The chemical exchange (typically Na replaced by K) produces a permanent compressive stress in the glass surface that improves resistance to cracks and scratches. This type of glass is exploited in smartphone screens or aircraft windshields and further applications (for instance in automotive) are foreseen. Alkali or alkaline-earth aluminosilicate systems are also the precursor glasses for most glass-ceramics successfully designed for consumer applications. Al 2 O 3 , The Archetypical Intermediate Oxide Al 2 O 3 itself cannot form a glass as it does not satisfy the rules proposed by Zachariasen (1932) for a network former. However, a specificity of Al 2 O 3 is to be able to form a glass when it is mixed with some modifying cations (typically alkaline earths or rareearths). Sun (1947) has classified Al 2 O 3 as an intermediate oxide acting as network former or modifier according to the composition. Indeed, Al 2 O 3 can be added into the vitreous silicate network by replacing Si 4 þ cations in a tetrahedral environment. In that case, it plays the role of a network former and even small amounts of Al 2 O 3 considerably modify the glass properties. Alternatively, Al can enter into high coordinated sites, playing the role of a modifier.
Fichier principal
Vignette du fichier
Glasses - Aluminosilicates.pdf (7.15 Mo) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)

Dates et versions

hal-03450045 , version 1 (07-11-2022)

Identifiants

Citer

Laurent Cormier. Glasses: Aluminosilicates. Encyclopedia of Materials: Technical Ceramics and Glasses, Elsevier, pp.496 - 518, 2021, 9780128185421. ⟨10.1016/b978-0-12-818542-1.00076-x⟩. ⟨hal-03450045⟩
196 Consultations
455 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More