Farqad Saleem  Murad, Elham  Abdalmajeed, Samir Hamid  Awad, 
    Effects of Natural Rock and Nano-TiO<sub>2</sub> Additives on Al<sub>2</sub> O<sub>3</sub> Layer 
Deposited on Al Alloys by Micro-Arc Oxidation (MAO),
    Journal of Engineering and Applied Sciences,
    Volume 13,Issue 5,
    2018,
    Pages 1201-1209,
    ISSN 1816-949x,
    jeasci.2018.1201.1209,
    (https://makhillpublications.co/view-article.php?doi=jeasci.2018.1201.1209)
    Abstract: Ceramic coatings on Al alloys were prepared via. micro arc oxidation process using natural
rock (10 g/L fired and unfired porcelanite) and (2.4 g/L) nano-TiO<sub>2</sub> additives. The phase composition, 
microstructure (SEM and EDX), micro hardness, thickness, roughness and wear resistance of the coatings were
studied. The results showed that the thick and hard (&gamma;-Al<sub>2</sub> O<sub>3</sub> ceramic coatings can be deposited by MAO
process on Al alloys using electrolytes contained fired porcelanite with modified tribological properties and
less porosity and its non-uniform distribution in the structure. The addition of nano-TiO<sub>2</sub> recorded the highest 
hardness and reduced the pore size and tunnels in coatings structure.
    Keywords: rock additive and wear resistance;hardness;micro arc oxidation;Aluminium alloy;structure;Iraq