en Infectious Diseases Infectious Diseases Original Article Original Article Background: Titanium (Ti) implants are commonly coated with hydroxyapatite (HA). However, HA has some disadvantages such as brittleness, low tensile strength and fracture toughness. It is desirable to combine the excellent mechanical properties of ZrO₂ and the chemical inertness of Al₂O₃ with respect to the purpose of this project which was coating Ti implants with HA-ZrO₂-Al₂O₃ to modify the surface of these implants by adding ZrO₂ and Al₂O₃ to HA. The purpose of this study was to evaluate the efficacy of hydroxyapatite coating nonocomposite.<br> Methods: From September 2009 to January2011, functionally graded HA-Al₂O₃-ZrO₂ and HA coatings were applied on Ti samples. HA-Al₂O₃-ZrO₂ and HA sols were orderly dip coated on the substrates and calcined. Scanning electron microscopy and EDS were used to estimate the particle size of the surfaces and for morphological analysis. The morphology of non-coated HA-coated HA-Al₂O₃-ZrO3 (composite-coated) and double-layer composite coated samples were compared with one other. Mechanical test (heat & quench) was also done for comparing single-phase (HA), composite and double-layer composite samples. <br>Results: The morphology of HA-Al₂O₃-ZrO₂ coating is more homogenous than HA-coated and uncoated samples. Furthermore, single-layer coating is more homogenous than double-layer coating. EDS analysis was done on HA-coated sample and showed that the Ca/P ratio in the film was similar to the theoretical value 1.67 in HA. <br>Conclusion: Surface modification of Ti implants can be done by coating them with single-layer of HA-Al₂O₃-ZrO₂. Single-layer hydroxyapatite-alumina-zirconia coated sample has the most homogenous morphology on the surface. Surface Modification, Ti Implants, Hydroxyapatite Nanocomposite 460 465 http://caspjim.com/browse.php?a_code=A-10-62-97&slc_lang=en&sid=1 Roxana Family 1003194753284600602 1003194753284600602 Yes Mehran Solati-Hashjin 1003194753284600603 1003194753284600603 No Shahram Namjoy Nik 1003194753284600604 1003194753284600604 No Ali Nemati 1003194753284600605 1003194753284600605 No