Embedment of hydroxyapatite (HA) on titanium alloy (Ti6AI4V) via superplastic deformation method for medical application / Hidayah Mohd Khalid

• Main Author: Hidayah, Mohd Khalid
• Format: Thesis
• Published: 2011
• Subjects: T Technology (General); TJ Mechanical engineering and machinery
• Online Access: http://studentsrepo.um.edu.my/7998/4/Embedment_of_hydroxyapatite%2528HA%2529_on_titanium_alloy_%2528Ti6Al4V%2529_via_superplastic_deformation_method_for_medical_implant.pdf; http://studentsrepo.um.edu.my/7998/

Nowadays, many researchers focus on the development of new biomaterials, which combine the osteoconductive characteristics of bioactive ceramics with sufficient strength and toughness for medical implant applications. Therefore, new coating methods have attracted great interests in recent years for replacing the high temperature techniques like plasma spraying. In this research, embedment of HA-2 wt.% Ti composite powder on superplastic and as-received Ti-6Al-4V is conducted through continuous pressing technique to improve the low strength of the conventional pure HA coatings. The embedment process is carried out at temperature below the allographic temperature in Argon gas atmosphere. The characteristics and bonding strength of the embedded layer are investigated. The bond strength evaluation is performed using wear test method under different applied pressure. HA embedded layer on superplastic and as-received Ti-6Al-4V are used for comparison. The experimental results indicated that the HA-2 wt.% Ti composite layer has uniform thickness of 8.0±0.5 μm and well bonded to the substrate. EDX and line scanning analysis revealed that HA elements are detected at the superplastic substrate indicating embedment process is successful. The X-ray diffraction pattern showed the presence of TiO2 and Ti phase on the HA-2 wt.% Ti embedded surface. The surface hardness of HA-2 wt.% Ti composite layer is lower than the pure HA layer due to the intrinsic higher hardness of HA as a ceramic material. The wear test results show that the embedded layer of superplastic Ti-6Al-4V is much stronger than the as-received Ti-6Al-4V. The results also prove that the addition of Ti improves the low strength of pure HA. Observations on the surface morphology of the embedded surface show that the surface is porous but denser at the interface area. Additionally, the HA-Ti embedded layer also shows higher cohesion strength within the layer than the HA layer.