Glass

 

In the Department of Glass and Ceramic Composites, headed by Professor Christian Roos, topics reaching from material science and physicochemical basics of glass forming systems to industrial melting and manufacture processes are covered.

Key Research Areas

The present research topics are focused on experimental and theoretical works concerning the thermodynamic state of glass forming oxide systems, including the modeling of the thermochemical and physical properties of multi component glasses and glass melts and the development of glasses and sealants with given properties. Other main topics are the chemistry and tribochemistry of the glass surface, the thermodynamics, kinetics and process technology of melting caved mass from primary and secondary raw materials, as well as thermotechnical analysis of industrial melting processes.

A) Thermochemistry

Theoretical expertise

Thermodynamic modeling of the properties of multi component glasses and glass melts: heat of formation, free enthalpy of formation, chemical potential of individual oxides, entropies, viscosity-temperature-relations

Experimental application

  • measurement of caloric variables from room temperature to 1600 °C: DSC; solution calorimetry; differential thermal analysis (DTA); high precise long-term stable thermogravimetry (TG)
  • determination of thermochemical data: heat of phase transition, formation and mixing; quantitative analysis of caloric processes
  • Evaporation processes: vapor pressure, chemical potential in glass melts, DTA-TG in combination with mass spectrometry
  • Electrochemistry: development of ionic sensitive electrodes for identification of activities of oxides in melts; development of glass products for fire protection

B) Process technology

Theoretical expertise

Thermotechnical process analysis; mass-, heat-, power- and entropy-balances for glass melting tanks; development of time depending balance models

Experimental application

  • Experimental characterization of high temperature reactions in multi component caved masses: thermal, chemical, caloric properties; heat transfer by radiation
  • Measurement and visualization of the melting process: melting, dissolution processes, evaporation, fining (pressure dependent)
  • Primary, secondary raw materials and recycling: raw material situation; effect of organic, ceramic and metallic extraneous material on glass quality
  • Prevent the offgas in pipes and filters behind glass melting tanks from forming aggressive and corrosive condensates

C) Glass surface

Theoretical expertise

Thermodynamic modeling of complex, aqueous systems under consideration of inorganic and organic substances; modeling of adsorption equilibriums on glass surfaces, as well as the hydrolytic stability and the pace of corrosion of oxide glasses in contact with abovementioned aqueous solutions

Experimental application

  • Corrosion behavior of technical glasses: long-term tests, hydrolytic stability of optical glasses, dish washer resistance of table glassware, biocompatibility of glass in contact with in vivo
  • Chemical-mechanical polishing of optical glasses: process behavior of polishing compounds, characterization of polishing suspensions

D) Glass ceramic composites

Theoretical expertise

Expansion of thermodynamic modelling to thermomechanic properties of glasses

Experimental application

  • Customized development of materials
  • Development of glass sealant systems from ceramic to ceramic, ceramic to metal and metal to metal bonding
  • Development of gas proofed glass ceramic layers for metals (Al, steel)
  • Development and optimization of fiber-reinforced glass ceramic composites