Diopside glass sinter-crystallization kinetics for different particle diameters and Clusters model testing

• Grant number: 25/09019-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2025
• End date: August 31, 2026
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials
• Principal Investigator: Eduardo Bellini Ferreira
• Grantee: Victor Hugo Lavandoski
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass, AP.CEPID

Abstract

Sintered glass-ceramics stand out for their applications in architectural coatings as a building material, biomaterials and electronic circuits. Among these, sintered glass-ceramics made from diopside glasses (CaO·MgO·2SiO¿) are promising as substrates for electronic circuits using the low-temperature cofired ceramic (LTCC) process. The sintering of these glasses occurs above the glass transition temperature by viscous flow with concurrent crystallization of the particle surface, processes that the Clusters and Volumetric Contraction Models can help to understand. However, experimental evidence suggests that for diopside, below a critical particle diameter, crystallization occurs by heterogeneous nucleation in the volume, with results that deviate from those obtained by these models. The aim of this project is to verify the existence of this critical diameter and to improve existing theoretical models. To this end, stoichiometric diopside glass will be produced by melting raw materials, ground into different particle sizes and characterized by laser diffraction. Compacts will be pressed and heat-treated, with linear shrinkage monitored by optical dilatometry. The relative density will be obtained from linear shrinkage and by measuring the mass and dimensions of the specimens together with powder pycnometry. The crystallized fraction will be characterized by optical and scanning electron microscopy. The experimental data will be compared with that obtained by the Clusters and volumetric contraction models, enabling a better understanding of the deviation reported in previous studies, so that the models can be improved and their application can more accurately assist in the manufacture of sintered diopside-based glass-ceramic products.