Tribology Characterization of Plasma Sprayed Zirconia-Alumina and Fused Zirconia-Alumina Composite Coated Al-Si Alloy at Different Sliding Velocity and Load Conditions

Zirconia-Alumina composite coatings have been extensively used in the field of tribology applications. Particularly, the partially stabilized zirconia has been employed in the recent years due to the combination of high hardness and chemical stability at aggressive environment. To the best of the knowledge, there is a lack of literature pertaining to the comparative evaluation on the frictional-wear behavior of partially stabilized Zirconia-Alumina composite (PSZAC) and fused zirconia-Alumina coating (FZAC). Hence, the present article aims to evaluate the frictional-wear behavior of PSZAC and FZAC coatings on Aluminium-Silicon (Al-Si) alloy engineered using the atmospheric plasma-spray technique. Tribo-parameters like Applied load (10 N, 20 and 30 N) and sliding velocity (0.5 m/s, 1.0 m/s and 1.5 m/s) have been varied during the dry sliding wear measurement. Scanning Electron Microscopy (SEM) reveals the hybrid pattern of grain structure with a less porosity for the respective composite coatings. The crystalline nature and the surface roughness are examined using the XRD analyser and surface profilometer respectively. The wear resistance of the dual ceramic coatings is improved compared to the Al-Si surface under all dry sliding conditions. The wear rate and Coefficient of Friction (CoF) of the FZA coating are lower around 1.2 times compared to ZAC coating due its improved surface hardness and the solid lubricant tribo effect. The worn surface of FZA coating evidences a solid ceramic lubricative layer, which acts as a preventive tribo layer. Further, the Taguchi methodology is adopted to optimize the wear rate and the CoF with respect to the tribo factors, which predicts the minimal wear rate and CoF of 0.75 × 10− 4 gm− 1 and 0.352 respectively for FZA coatings with 94.9 % of desirability.