Strengthening of glass-ceramic of the LiO2-Al2O3-SiO2 system by surface crystallization

Abstract

Opaque and translucent glass-ceramic materials can be obtained from lithium aluminum silicate (LAS) glass. In this material, the presence of a surface layer with thermal coefficient of expansion (TCE) much lower than that of the precursor glass leads to a material with surface tensions of compression. The mechanical strength is increased due to this effect, representing a promising material for various applications, for example, if they are translucent, on screens of electronic devices. In this application, flexural strength and fracture toughness are responsible for good impact strength, while high hardness provides greater scratch resistance. The potential of this material has never been studied for this application, and there is very little data in the literature regarding it. This scientific initiation project aims to evaluate the influence of the thickness of the crystallized layer on the mechanical properties of glass-ceramics LAS. The material will be obtained from the crystallization of a precursor glass under conditions of time and temperature, that will be determined experimentally. The characteristic glass temperatures, ie, glass transition (Tg), crystallization start (Tx) and liquids (Tliq) temperatures, will be obtained by differential scanning calorimetry. The characteristics of the crystalline layer will be determined by optical and electron microscopy and X-ray diffraction. Samples treated in different conditions will be subjected to tests of hardness, scratch resistance, modulus of elasticity and mechanical resistance to flexion.