Research Article

Thermal behavior of lead silicate vitreous materials for sealants

¹ National Research and Development Institute for Non-Ferrous and Rare Metals −IMNR, 102 Biruintei Blvd., Pantelimon, JudIlfov 077145, Romania
² Ilie Murgulescu Institute of Physical Chemistry of the Romanian Academy, 202 Splaiul Independenţei, Bucharest 060021, Romania

^* e-mail: oana.mocioiu@yahoo.com

Received: 2 November 2020
Accepted: 15 January 2021

Abstract

The objective of our investigations consists in the thermal characterization of SiO₂-PbO-Na₂O vitreous materials in order to establish their properties for applications mainly as sealants. In order to evaluate the vitreous material − metal adherence, the thermal expansion coefficients (α) from experimental and theoretic data were determined. The differential thermal analysis of studied materials give the information about temperatures characteristic to glass transition, crystallization and melting. Dilatometer measurements were performed in air atmosphere in order to establish thermal coefficients of the materials. Softening and flowing characteristic of the vitreous materials were established by heating microscope measurements. The difference between thermal expansion coefficient (α) of the vitreous materials (10.2 × 10⁻⁶K⁻¹ and 17.6 × 10⁻⁶K⁻¹) and thermal expansion coefficient of the steel substrate OL 38 (10.8 × 10⁻⁶K⁻¹) is under 37%. This value is fit for a good adherence between materials.