Coating hydroxyapatite/alpha alumina composites by mechanical alloying

The biomaterials field has become a vital area, as these materials can enhance the quality and longevity of human life and science and technology associated with this field has now led to multi-million dollar business. Hydroxyapatite [Ca10(PO4)6(OH)2-HA] and alumina ceramics materials have been clinically applied in many areas of dentistry and orthopaedics. Their widespread use is based on a combination of good strength, modest fracture toughness, high wear resistance, good biocompatibility and excellent corrosion resistance. Alumina has also been used in jaw bone reconstruction. Other clinical applications include knee prostheses, bone segment replacements, bone screws, middle ear bone substitutes, and corneal replacements. Optimization of the surface structure of materials is of great concern at the present time since most failures occur on the surface (fatigue, fretting corrosion, corrosion, wear, etc.). As a result, improving the surface properties would greatly enhance the overall behaviour of materials. It is widely recognized that titanium displays poor wear resistance and that its fatigue performance depends to a large extent on its surface properties. The newly developed process, mechanical alloying MA, is therefore of considerable technological importance since it provides the possibility of dramatically improving the surface properties of titanium. Presented work describes the effect of MA treatment, as a non-conventional solid-state process, on the microstructure of IA/α-Al2O3 composites. Also, the necessary conditions for coating HA/α- Al2O3 composites on Ti-substrate were examined. To make HA and Al2O3 composites, α-Al2O3 powder was used because of its better sinterability than γ-AI2O3. HA/α-Al2O3 was successfully deposited on Ti-substrate by mechanical alloying (MA). From the X-Ray Diffraction (XRD) the as-synthesized and heat treated samples between 300C and 600C have not any phase transition or decomposition. From the scanning electron microscope, the as-coated sample shows particles agglomeration of HA/α-Al2O3 composites on Ti-substrate. Also, the Ti-substrate was partially covered with inhomogeneous distributed IA/α-AI2O3 composites. This could be due to the continuous welding and fracturing of the powder particles during the mechanical milling process.