Nitrogen Ion Beam Modification of Alumina for Hard Tissue Implants

摘要

Alumina has wide applications in industry, automobiles, electrical appliances etc. However its application as biomaterial has started recently. We propose to improve the bio-physical, bio-chemical and bio-medical properties of alumina for its application as biomaterial by nitrogen ion implantation. Alumina is implanted with nitrogen ions at different energies (30 keV to 90 keV) and various ion doses (11015 ions/cm2 to 51017 ions/cm2). The microstructural changes and surface roughness of the specimens are characterized using Optical Microscope, Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM). Nanolayered compound formation of nitrides & oxynitrides were observed using Glancing angle X-ray Diffraction (GXRD). Mechanical changes like hardness are studied using nanoindentation method. It is observed that corrosion resistance studied using Electrochemical analyzer (ECA) increases at lower energy and at intermediate ion dose. At higher energy and higher ion doses corrosion resistance deteriorates which is in co-ordinance with the micrstructural analysis. Bio-medical characterization of the specimens has been carried out by Wettability and Thrombogenicity tests. Wettability decreases in comparison with unimplanted samples. The thrombogenicity of unimplanted and implanted samples were evaluated using a whole blood kinetic clotting time method. From thrombogenicity test, it is concluded that at lower energy, thrombogenicity increases whereas for higher energy thrombogenicity decreases in comparison with the unimplanted samples. On the basis of all the above studies, best suitable energy and ion-dose is decided for the hard tissue replacement by alumina.