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Refractory Oxides

Thermo-Calc can be used to predict thermophysical and phase-based properties of refractory oxides with application to the design of crucible materials and environmental and thermal barrier coatings.

Solutions for Refractory Oxides

Refractory oxides are widely used by metal producers for furnaces, incinerators, crucibles, and moulds for casting. They are also used in the aerospace and energy sectors for environmental and thermal barrier coatings (EBCs and TBCS) where they are employed to protect the turbine components against ever-increasing temperature requirements.

Phase equilibria calculations can provide important insight into reactions between the liquid metal and crucible which can be important for determining quality control and erosion. Similarly, such calculations can be made when considering the interactions between the EBC/TBC coatings and metal substrate for the design of more durable coatings and also the chemical stability of the coating relative to the environment. Thermo-Calc can be used to make such predictions for refractory oxide systems.

Calculate the following based on your actual oxide chemistry:

  • Thermophysical properties:
    • Specific heat, enthalpy, latent heat, density as a function of temperature, coefficients of thermal expansion, viscosity and more
    • Phase-based properties, such as:
      • Amounts and compositions of phases, solubility limits, activities, phase diagrams, and more
      • Chemical reactions between:
        • Liquid metal and crucible/moulds
          • Coatings and metal substrates
            • Coatings and the environment

Application Examples

Thermo-Calc has many applications to refractory oxides. Below is one such example.

Design of EBC-TBC Coatings

Advanced gas turbine blades rely on ceramic coatings to protect engine components in harsh combustion environments. These coatings are susceptible to accelerated degradation caused by silicate deposits formed when ingested environmental debris (dust, sand, ash) adheres to the coatings.

In this example, the yttrium silicate system was used as a case study to assess the utility of phase equilibrium modeling using the TCOX database in examining the factors controlling the interaction between coatings and silicate deposits. To replicate the progressive dissolution of the coating into the melt, the phase equilibria were calculated at 1300°C for incremental Y2Si2O7 additions to a fixed quantity of C33M9A13S45 deposit.

This calculation increases the size of the reacting system for successive Y2Si2O7 additions, just as the volume of material contained in the reaction layer increases with recession depth. By changing deposit compositions and reaction temperatures, researchers can understand how they will influence the depth of coating recession.

Plot showing a phase equilibria calculation at 1300°C for incremental Y2Si2O7 additions to a fixed quantity of C33M9A13S45 deposit.

Phase equilibria calculation at 1300°C for incremental Y2Si2O7 additions to a fixed quantity of C33M9A13S45 deposit.

Process Metallurgy Module for Steel and Slag

In addition to the calculations discussed above, we also offer an Add-on Module that makes it easy to set up calculations for steel and slag interactions, the Process Metallurgy Module. The Process Metallurgy Module includes a kinetic model that simulates the evolution of the steel, slag, and inclusion compositions as a function of time based on the actual steelmaking process. Process parameters such as blowing of gases into the steel, heating by electric arc, and slag additions can be considered.

Learn more about Applications to Refractory Oxides

A video tutorial demonstrating how to calculate a phase diagram for the oxide system Al2O3-MgO.

Developments in Thermodynamic Models of Deposit-Induced Corrosion of High-Temperature Coatings

Improving Steel and Steelmaking—an Ionic Liquid Database for Alloy Process Design

Performance Comparisons between Thermal Barrier Coating (TBC) Compositions at various Temperatures and Proportions

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