Refractory metal based materials for applications at high temperatures
Beyond Ni-based superalloys, intermetallic compounds based on refractory metals offer high temperature stability as well as oxidation resistance for applications in harsh environments. MoSi2 is well known for several years and is used in heating elements already. Powder metallurgical methods have been used to produce intermetallic compounds and composites. Methods to improve the toughness of such intermetallic compounds will be briefly discussed. The manufacturing of these materials suffers from some technological difficulties due to steps like high-temperature synthesis (SHS) or high energy milling followed by expensive consolidation processes (Hot Pressing or Hot Isostatic Pressing). Alternative processing routes offering shorter processing times will be presented. The fast compaction technology SPS (Spark Plasma Sintering) possesses advantages in consolidation processes of silicides due to short duration times. The oxidation and corrosion resistance was determined by different methods. Specific parts were manufactured for biomass gasification. The excellent resistance against the corresponding corrosive atmospheres in comparison to other materials is documented.