Interactions of alkaline earth zirconate perovskites with titanium and titanium alloys at high temperatures

• Applicant: Professor Dr.-Ing. Stefan Schafföner
• Subject Area: Glass, Ceramics and Derived Composites ; Metallurgical, Thermal and Thermomechanical Treatment of Materials ; Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials
• Term: from 2016 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 329849558

Titanium and titanium alloys are highly reactive with many ceramic materials at high temperatures. This impairs, among others, the melting, casting, and coating of titanium alloys and the processing of titanium matrix composites. However, in recent studies CaZrO3 was identified as a refractory material with a remarkable corrosion resistance in contact with the predominant titanium alloy Ti6Al4V. On the other hand, quite severe reactions were observed with commercially pure titanium (cp-Ti) and TiAl melts. Thus, the reactivity of titanium alloy melts in contact with CaZrO3 depends significantly on the alloy composition. Furthermore, previous studies only used vacuum induction melting to investigate the interface reactions of CaZrO3 with titanium and titanium alloy melts. However, although vacuum induction melting is a severe and realistic testing method for refractory materials, it is generally very time-consuming and difficult to perform.The intention of the present project is to obtain reliable experimental results to explain and predict the interface reactions of alkaline earth perovskites with different titanium alloys using diffusion couples. The focus will be broadened from CaZrO3 to a whole material class (perovskite materials, especially alkaline earth zirconates including SrZrO3 and BaZrO3). Using diffusion couples, solid titanium alloys and pure alkaline earth zirconates are in immediate contact. These diffusion couples are then annealed for a prolonged time at high temperatures. After annealing and quenching these diffusion couples, the microstructure and chemical interactions will be investigated using scanning electron microscopy (SEM) in combination with wavelength-dispersive spectroscopy (WDS) and electron backscatter diffraction (EBSD).These investigations help to understand the mechanisms during melting, sintering, joining, and coating of titanium based alloys in contact with alkaline earth zirconate ceramics. Moreover, these investigations are also valuable for further thermodynamic calculations and constructions of phase diagrams, due to the present lack of sufficient experimental data of the relevant quaternary systems (e.g. Ca-O-Zr-Ti). Another intention, which is interrelated with the experiments, is to learn and master the relevant experimental procedures. This includes especially spray pyrolysis and infrared spectroscopy for the synthesis and analysis of the ceramic materials, respectively, and the application and analysis of diffusion couples.Intended host institution is the NTNU, Trondheim, Norway, as the working group of Prof. Dr. Tor Grande investigates the synthesis and stability of perovskite ceramics and refractory materials for many years. Moreover, the NTNU is worldwide known for its research on the metallurgy of light metals including titanium.

• DFG Programme: Research Fellowships
• International Connection: Norway
• Host: Professor Dr. Tor Grande