Influence of TiO<sub>2</sub> and ZrO<sub>2 </sub>Nano Particles Addition in Al<sub>2</sub>O<sub>3</sub> Base Coating Using Plasma Spraying

The additive (3wt%) nano-particles of anatase-TiO 2 and monoclinic-ZrO 2 were prepared using ball-milling method to form Al 2 O 3 /3wt%TiO 2 and Al 2 O 3 /3wt%ZrO 2 nanocomposite powders. The incorporation of nano-particles can significantly enhance the microstructure and mechanic properties of Al 2 O 3 -base coating. The phase of microstructure coating was present mostly of γ-Al 2 O 3 and α-Al 2 O 3 phases, while anatase-TiO 2 was transformed to rutile-TiO 2 and monoclinic-ZrO 2 was changed to tetragonal-ZrO 2 due to such high temperature of plasma plume. SEM microstructures of the coatings mainly displayed a lamellar structure of Al 2 O 3 with interlarmellar pores and well dispersed splats of TiO 2 and ZrO 2 phases. The Al 2 O 3 /3wt%ZrO 2 presented the lowest value of friction coefficient and sliding wear rate. It was found that the plasma-sprayed composite coating possessed better wear resistance than that of monolithic Al 2 O 3 coating. The addition of nano-particles was found to improve friction coefficient and sliding wear resistance.