Tailoring wear and tribo-induced interaction of YSZ coating sliding against Si₃N₄ and Al₂O₃ counterparts

The friction and wear behaviors of plasma-sprayed yttria-stabilized zirconia (YSZ) coatings against Si₃N₄ and Al₂O₃ were evaluated from 25 °C to 800 °C in air. As the temperature increased, refined grains with severe lattice distortion and the phase transition from monoclinic to tetragonal were present within the wear track of the YSZ coating during friction. When the YSZ coatings were rubbed against Si₃N₄ and Al₂O₃ counterparts, all the worn samples showed common wear characteristics of fracture and fragmentation near the sliding surface. The wear discrepancy between the two tribo-pairs was due to the differences in tribo-induced interactions. In particular, TEM clarified the intense amorphization at the superficial regions of the YSZ coating when rubbed against Si₃N₄, which resulted in better wear resistance of the YSZ/Si₃N₄ sliding couple. The computational simulation using the semi-analytical model revealed higher contact temperatures and Von Mises stresses for the YSZ/Si₃N₄ sliding couple, which aided the amorphization of the regions near the sliding areas. Nevertheless, the higher normal stress between the YSZ/Al₂O₃ contacts caused cracking and localized fracture, leading to severe wear.