Mintek is working with some of the precious metals in order to enhance their properties. The precious metals, for example platinum and gold are renowned for their noble properties and good formabilities. Platinum is used extensively in the glass industry for containing the molten glass, because of its high melting point and excellent chemical resistance. Platinum is also used for autocatalysts for cleaning the emissions of automobiles, as well as jewellery.
The Advanced Metals Group is working on a range of Pt-based alloys for applications in high temperature and aggressive environments. These alloys have a similar structure to nickel-based super alloys, and are targeted to be used in similar environments to them, but where the higher mass of the Pt-based alloys will be less of a concern. As well as studying the microstructure, the mechanical properties, corrosion resistance and oxidation resistance of the alloys is being studied. This work is being run under the auspices of the Platinum Development Initiative, which was formed to promote further research into platinum, to lead to increased industrial applications.
Additionally, a thermodynamic database is being built using Pt-Al-Cr-Ru as the starting point, so that the phase diagrams, phases and phase proportions of the alloys can be calculated. This will ultimately save time and will be useful to designers wanting to utilise the alloys. To support the calculations, an extensive phase diagram project has been done and is largely completed for the phase diagrams in the Pt-Al-Cr-Ru and related systems, for which there was no, little, or conflicting information. This project has been running for several years and the collaborators include: NIMS, Japan, Bayreuth and Jena Universities in Germany, Leeds University, UK, as well as the Universities of the Witwatersrand, Nelson Mandela Metropolitan University, Cape Town and Limpopo. Parts of the project also fall within the DST/NRF Centre of Excellence for Strong Materials, and the Focus Area for Strong Metallic Alloys is based at Mintek. Several students have obtained their M.Sc.s and Ph.Ds. within the project (3 Ph.D.s obtained, and 2 in progress; 3 M.Sc.s achieved and five in progress), and three B.Tech. students have also done, or are currently undertaking, their research project within the scheme.
Work has also been done on developing alloys for jewellery applications in a number of the precious metals, and the group has been involved in the Hot Platinum project, based at UCT. There has also been some work done in alloy development and alloy optimisation for specific applications. As well as building the Pt-superalloy databases, the Thermo-CalcTM programme is also being used for developmental work on steels.