MAX phase and SMART materials for extreme environments in Concentrated Solar Power Systems

• Applicant: Professor Dr. Jesus Gonzalez-Julian
• Subject Area: Glass, Ceramics and Derived Composites
• Term: Funded in 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 540023994

Nowadays, there is a continuously growing demand for advanced materials with properties superseding those of elementary compounds and conventional material concepts for the energy transition. The demand for these new materials has been strongly accelerated due to the current energetic and political situation. Germany and Europe – as well as in general the world – are looking for sustainable energy systems with the main objective of being carbon neutral by 2050. These advanced materials should exhibit high thermal and chemical stability, good oxidation and corrosion resistance, and excellent mechanical properties such as thermal shock, strength, and fracture toughness. At the same time, these advanced materials should be sustainable, avoiding the use of rare-earth and other toxic/scarce elements that are typically used in high temperature superalloys. Among the different sustainable energy systems, Concentrated Solar Power (CSP) is one of the most relevant renewable energy systems for the energy transition, but some challenges hinder its spread around the world. In CSP systems, the sunlight reflected by hundreds to thousands of mirrors is concentrated onto the central element – the solar receiver that can reach temperatures of 900°C and above. The heat that is collected in the solar receiver is transferred to produce the electricity. The heat is transferred using a heat transfer fluid (HTF) that is typically a molten salt (mixture of nitrates). However, it is highly corrosive at high temperature limiting the maximal operating temperature of the materials to around 600 °C. In order to increase the efficiency of CSP systems, new materials with better oxidation and corrosion resistance are required. Based on these conditions, the number of potential candidates is rather limited, but we have identified two material systems that can operate under extreme environments: MAX phases and Self-passivating Metal Alloys with Reduced Thermal Oxidation (SMART). Consequently, the main objective of this project is to evaluate the realistic potential of solar SMART and MAX phase materials for CSP systems. Cr2AlC and W-17.8 Cr-6.4 Al wt.% compositions, as MAX phase and solar SMART respectively, have been selected due to their best balance between chemical stability at high temperature, and oxidation and hot corrosion resistance. During the project will focus on the synthesis, processing, microstructural characterization, and understanding of the oxidation and corrosion mechanisms under similar operating conditions.

• DFG Programme: Research Grants
• Co-Investigator: Dr. Andrey Litnovsky