Thermodynamics and Process Modelling

The Thermodynamics and Process Modelling Group of the NPL Materials Centre provides good quality thermodynamic data for an extensive range of material types including light alloys, steels, ceramics, glasses, slags, mattes, salts, polymers, aqueous solutions and gases. These data can be used to predict the chemical species and phases likely to form at equilibrium in the types of system of greatest industrial interest - those containing large numbers of chemical elements - and so provide a valuable guide to the solution of many industrial problems. Organisations can lease these databases and MTDATA for in-house use or ask for calculations to be done at NPL.

Services offered

• Provision of thermodynamic databases
  A range of high quality thermodynamic databases is available for lease. Consistent reference states are used throughout these databases so that they can be combined to explore systems containing many different phase types, for example metal-matte-slag-gas systems.

• Data assessment
  The group offers an assessment service to provide high quality thermodynamic data for any systems of interest not covered already by one of its databases.

• Consultancy
  A consultancy service is available which allows companies, whether large or small, to make use of the expertise within the Thermodynamics and Process Modelling Group in applying thermodynamic data to the solution of practical problems.

• Club projects
  The group is currently involved in a number of club projects, where a group of organisations get together to fund work in an area of common interest.

  • RC211 oxide project, sponsored through MIRO (Mineral Industry Research Organisation). A database has already been developed for liquid oxides and crystalline phases, see here for details of the systems currently covered. The direction of future work will be determined by the wishes of the project's sponsors. Examples of the sorts of calculations possible using this database are shown in the MTDATA demonstration.

  • MP0602 - High Temperature Lead-free Solders
    This is an extensive international project to increase the basic knowledge on alloy systems that are being or used or could be used as lead-free solder materials at temperatures up to 300 C and to provide a scientific basis for choosing which of these materials may be used for different soldering purposes. Basic scientific research is being carried out on various physical and chemical properties as well as providing understanding of practical issues concerned with their application, durability and their recycling. The project brings together researchers from universities, research institutions, and industrial research centres throughout Europe. It is organised through a number of working groups concerned with: Experimental studies of thermodynamic properties and phase diagrams, the critical assessment of thermodynamic and phase equilibrium data, physical properties, chemical properties, reliability and processing and packaging.

  • COST535 - Thermodynamics of alloyed aluminides (THALU)
    The main objective of COST535 is to create the basic thermodynamic platform for the development of new alloys based on intermetallic compounds. This will involve the development of models to represent the thermodynamic properties of engineering aluminides, the evaluation of existing data and to supplement these through the use of new theoretical and experimental approaches to provide new data. The project will involve simultaneous interdisciplinary efforts from experimentalists, physicists and metallurgists (i.e. materials scientists) and the programme has been devised around two different approaches: (i) the development of an extremely general database for alloy systems containing aluminides and (ii) the development of understanding of aluminides themselves and how they interact with selected alloying elements. The initial focus will be on the quaternary system Al-Fe-Ni-Ti partly because the three technologically most important aluminide containing systems, Fe-Al, Ti-Al and Ni-Al are subsystems of this quaternary system and also because all three limiting ternary systems involving Al are, themselves. of great practical interest.

  • Cements
    Cements and Concretes are such a fundamental part of the infrastructure that it is tempting to overlook the complex and fascinating chemistry involved in their production and use. MTDATA is well suited to modelling their behaviour as long as thermodynamic databases are available for the various liquid and crystalline phases present. Recent work has been concerned with the development and testing of thermodynamic models for calcium silicate hydrate (C-S-H) gels. The engineered component of a low and intermediate level nuclear waste repository in the United Kingdom will almost certainly consist primarily of ordinary Portland cement (OPC) based materials. OPC provides a chemical barrier by its ability to buffer the pH to be higher than about 12 as it dissolves in a percolating groundwater. A high pH in a repository is desirable because it helps to minimize the solubility of many radionuclides, metal corrosion and microbial activity. Reliable models are required in order to assess the likely performance of the chemical barrier and to make predictions beyond the spatial and temporal limits imposed by experiment and observation.The ability of the model to predict the thermodynamic and phase behaviour of C-S-H gels in different aqueous environments, from room temperature up to 85 °C, has been demonstrated by means of a comparison between calculations and measured solubility data, such as pH and calcium and silicon concentrations in solution.

  • Materials Algorithm Project (MAP)
    

• DIUS projects

  • Thermophysical and thermodynamic properties of Ni base superalloys
    NPL is currently involved in various projects which require the development of a thermodynamic database for Ni base superalloys. The main vehicle for this is in support of the development of a capability at NPL to measure accurately temperatures and enthalpies of transitions for high temperature materials using a single pan technique. The database development also supports a Technology Strategy Board project "Improved Modelling of Material Properties for Advanced Power Plant" which has the ultimate aim of developing new improved materials and increase the utilisation of power plant through a better understanding of degradation mechanisms. This will be achieved through integration of various material modelling techniques from nano scale through to macro scale. This work also feeds into the IMPRESS European FP6 project concerned with the development of new intermetallic alloys for industrial applications such as gas turbine blades and hydrogen fuel cells. Ultimately the thermodynamic database will be available commercially in conjunction with MTDATA and the Virtual Measurement System.

  • In support of a related project on measuring thermophysical properties for lightweight alloys, NPL is also developing a thermodynamic database for Mg alloys.

  • NPL is currently investigating methods of linking software for the calculation of materials chemistry (such as MTDATA) to third party CFD (Computational Fluid Dynamics) packages in order to study systems where there are significant temperature and concentration gradients.

  • Molecular Dynamics, in principle, provides a mechanism for calculating thermodynamic properties from force field data. NPL is looking into methods where this could be applicable in order to provide data where experimental data are lacking or difficult to obtain eg developing equations of state for real gases or measurement of the enthalpies of mixing in ionic melts.

  • NPL is currently involved in attempting to validate ab initio techniques against the best available experimental and critically assessed thermodynamic data for gaseous and condensed phases. NPL is aiming to work with existing users of such software and software developers to identify and understand any glaring discrepancies.

  • NPL is currently developing software packages for modelling transient heat transfer, taking account of changes in material properties with changes in temperature and phase. TherMOL 3D and MTDATA have been successfully linked and is able to model complex multi-material structures subjected to various heat transfer boundary conditions.

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  MTDATA leases, training and support
  The group is responsible for the development and support of MTDATA, a powerful and user-friendly software and data package for the prediction of phase equilibria in systems containing large numbers of chemical elements. MTDATA is leased to industrial, government and academic organisations worldwide and training courses are held regularly at NPL.

• Application software
  A programming interface is available which allows MTDATA users to set up phase equilibrium calculations and process their results directly from within their own or other commercial software. Calculations can be tailored to specific industrial applications in this way either by customising output or by using equilibrium calculations as part of a non-equilibrium process model. Organisations are able to write "application software" in-house or ask for this to done at NPL. The Materials Algorithm Project (MAP) aims to provide a library of subroutines, written in FORTRAN, to be used as a foundation for "application software" of this kind.

For further information about the services offered by the Thermodynamics and Process Modelling Group please contact Hugh Davies.