High temperature behavior of FeCrBSi-based ferromagnetic plasma spray coating

The ferromagnetic plasma spray coating with excellent high temperatures electromagnetic properties can be used in the field of high temperature electromagnetic protection materials. However, the ferromagnetic Curie temperature limits the application temperature of the ferromagnetic coating. On the other hand, ferromagnetic materials are easily oxidized at high temperature, making the coating susceptible to oxidative failure. In this paper, we designed new FeCrBSi-based materials, which has a Curie temperature of above 975K and excellent long-term oxidation resistance at 775K. The particle size distribution of water atomized FeCrBSi alloy powder has been studied. Alloy powder was mixed with nano-sized alumina powder by spray granulation technique. Alumina is used as an electromagnetic medium matrix. 500-micron thick FeCrBSi/Al2O3 composite coatings with different alloy/alumina ratio were prepared using progressive technology 100HE plasma spray system. The adhesion of coatings are above 17.8Mpa. We designed devices to test the Curie temperature and electromagnetic properties of the coating. Curie temperature of coatings are above 750¡ãC. The high-temperature real part of microwave permeability (@775K@2GHz) was greater than 2, and imaginary part (@775K@2GHz) was greater than 1.