Glass - Back to the Future!

Presenting Author:
Klara Kölker

article posted 6 April 2016

Klara Kölker graduated in 2013 from RWTH Aachen University with a Master of Science in Materials Engineering. Afterwards she joined the group of Professor Reinhard Conradt at the Institute of Mineral Engineering at the RWTH Aachen University as a PhD student. Her research interests focus on the development of new glass compositions for various applications, but especially in the field of reinforcement fibres. Klara has presented her work at international conferences such as 12th ESG Conference 2014 (Parma, Italy), ACERS GOMD-DGG Joint Annual Meeting 2015 (Miami, USA), ICG Annual Meeting 2015 (Bangkok, Thailand).

Glass Development for Fibre Applications

Klara Kölker*, Reinhard Conradt, Katharina Philipps
Institute of Mineral Engineering, Department of Glass and Ceramic Composites, RWTH Aachen University, Germany

In the presented study, theoretical glass development on the basis of thermodynamic data is combined with a phase theoretical approach using the concept of the crystalline reference system, with a glass representing a state differing from the isochemical polycrystalline state by a small amount of excess enthalpy and entropy only. It is the purpose to explore novel compositional space and to deliberately design glasses with properties suitable for reinforcement fibre applications.

The above principle is used to systematically identify compositional ranges with respect to the melting behaviour and expected glass properties. The analysis is based on the fact that most industrial glasses may be represented to more than 95% of mass by a quaternary oxide system. Unfortunately, there is a lack of information about the constitutional ranges of many quaternary systems, especially when new areas of compositional space are to be explored.

By means of thermochemical calculations, the constitutional space of the glass forming systems, such as CaO–ZnO–Al2O3–SiO2 or CaO–P2O5–Al2O3–SiO2, is evaluated, and the systems comprehensively divided into adherent constitutional subranges. In a second step, oxide compositions of invariant points within the sub-systems are determined. As a final result of this theoretical approach, a network describing ternary and quaternary invariant comprising their liquidus temperatures and the corresponding saturation lines is derived. With regards to industrial requirements, promising compositional ranges are selected and tested for glass forming ability. Their macroscopic properties are predicted and verified by experiment.