Surface Modification and Plasma Diagnostics of Biomedical Ti Coating with Nb Alloy Using Sputtering Plasma

Abstract

Titanium and its alloy is commonly used in surgical implants (orthopedic surgery) to replace biological tissue or to help stabilize a biological structure, such as bone tissue to aid the healing process. It is important that a surgical implant is not susceptible to corrosion when placed inside the human body. The corrosion resistance and biological compatibility of titanium and alloy are very useful in a variety of applications like surgical implants, it is used for surgical implants because the human body accepts it, and it is non-poisonous. Enhancing processes were done by coating Titanium with Niobium coating material using DC and RF Radio frequency magnetron sputtering device. Magnetron sputtering system was used for depositing a thin layer of Niobium (as corrosion material) on Titanium, glass substrate. DC- magnetron sputtering device was used for depositing a thin layer of nanoparticles over the layer of Niobium on titanium samples. Structural, morphological and thickness of the layers (Niobium/glass and Niobium/ Titanium) were studied by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Atomic force microscopy (AFM) and Thickness Optical Measurement. XRD patterns for Niobium thin films deposited with different sputtering power show polycrystalline structure. A dual structure, cubic and hexagonal, for cubic and hexagonal, for films deposited on glass substrates. We found by studying the AFM and FESEM images that the Nano crystalline Nb films were formed with the increase in grain average diameter and particles size. Electrical plasma discharges Pachens curve, I-P and I-V characteristics were investigated. The optimum condition of coating process were determined through plasma diagnostics using optical emission spectroscopy (OES) technique. Also, the surface morphology, structural properties, and thickness of prepared samples at different operation condition were obtained. Finally, corrosion and biocompatibility measurements. The obtained results of open circuit potential OCP measurements manifested a positive shifting in OCP value with increasing RF sputtering power. The value of OCP for the samples coated by Niobium showed that the OCP measurements manifested a positive shifting in OCP value, Biocompatibility measurement was carried out in simulated body fluid (SBF). The optical camera images are for all samples prepared. Samples obviously show the hydroxyapatite layer is form after immersing in simulated body fluid (SBF) solution for two week. From all results we conclude that the NbN/Ti sample is the best new modified alloy, because it has an excellent hydroxyapatite growth and very good corrosion resistance. So it can be used as bone substitutes. Mechanical properties contain the corrosion and hardness measurements have been investigated. Micro-hardness measurements show an increment in Vickers hardness with increasing RF sputtering power. The curve of corrosion measurements in simulated body fluid shows an improvement occur to samples coated Niobium, while the sample coated Niobium NbO( 50%) has a corrosion rate 7.0×10-4 mm/y, NbN (50%) 4.26×10-4 mm/y. The appeared peaks in all patterns were matched with standard lines from NIST website. It was noticed that the line intensities increases by increasing the RF power from 80 to 160 Watt and applied voltage from 500 to 800 volt. We found that the electron temperature, calculated using intensity ratio method, increase with increasing sputtering power and applied voltage. The electron density decrease with increased sputtering power.