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

Abstract

Two ZrO 2 -Al 2 O 3 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 ZrO 2 -Al 2 O 3 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-Al 2 O 3 and t-ZrO 2 phases from γ-Al 2 O 3 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. • The wear resistance at 1000 °C of two different ZrO 2 -Al 2 O 3 coatings was evaluated. • The quantity of α-Al 2 O 3 and t-ZrO 2 increased at 1000 °C in both coatings. • Both ZrO 2 -Al 2 O 3 coatings showed similar wear resistance at 1000 °C. • Both coatings showed better wear resistance at 1000 °C than the reference refractory. • Both coatings can protect the refractory used as substrate at 1000 °C.