Wear behavior at high temperatures of ZrO2 - Al2O3 plasma sprayed coatings and an electro-melted AZS refractory

Abstract Two ZrO2-Al2O3 atmospheric plasma coatings were applied to a pressed and sintered aluminosilicate refractory brick, which were compared to an electro-melted alumina-zirconia-silica (AZS) refractory typically used in the glass industry for its high temperature wear resistance. The samples were subjected to sliding contact using a ball-on-disk test at 25, 500, 750, and 1000 °C and then, physical, crystallographic, and mechanical characterizations were performed before and after the wear tests in order to monitor the wear behavior. Both ZrO2-Al2O3 coatings exhibited better wear performance than the electro-melted AZS refractory at all temperatures evaluated, owing to their high hardness and fracture toughness, which were mainly related to the increase of α-Al2O3 and t-ZrO2 phases from γ-Al2O3 and the crystallization of amorphous phases respectively. In the same way, both coatings also showed the same wear mechanisms at all temperatures evaluated. At 25 °C, wear by ductile deformation was identified, while at 500 and 750 °C, wear by brittle deformation was produced, and at 1000 °C, the transition of wear from brittle to ductile deformation was evident. For the electro-melted AZS refractory, until 750 °C, wear by brittle deformation was developed, while at 1000 °C, wear by both, brittle and ductile deformation was detected.