Atmospheric Plasma Spraying of Different MgO/Al2O3 Feedstocks

Nine commercial and experimental powders from the MgO/Al2O3 system have been investigated in the present project. The composition ranged from MgO/MgAl2O4 composites with more than 70% MgO to an alumina-rich spinel powder (94% Al2O3). The powders were fused and crushed or agglomerated and sintered. The influence of the composition, the manufacturing route as well as the particle size distribution on the microstructure and the phases in the produced coatings have been investigated. For several of the powders, detailed design of experiment plans have been made and properties such as deposition efficiency, hardness and porosity were optimized. With optimized spray conditions coatings have been produced from all powders which were characterized in depth. Here, the results of microstructure, porosity values and thermal cyclic tests will be presented in more detail.