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Nowadays, there is a growing need for using functionally graded materials (FGM) for using in bio-medical application. This need is prominent especially for the effect of gradient structures and in implant applications. To optimize both mechanical and biocompatibilities properties or change bio reactivity in each region, powder metallurgy technique is used in this study to fabricate titanium/hydroxyapatite (Ti/HAP) and other FGM implants with the concentration changed gradually in the longitudinal direction of cylindrical shapes. Concentration gradient was formed by packing dry powders into mold or sedimentation in solvent liquid processes. For the sintering process, three spark plasma sintering (SPS), high-frequency induction heating and electric furnace heating techniques were used to sinter the materials. During the fabrication of Ti/HAP FGMs and due to the stress relaxation in the implanted regions of bones, Brinell hardness decreased gradually from Ti part to HAP part. The results showed that the tissue reaction occurred gradiently in response to the graded structure of the FGM, which implies the possibility of controlling the tissue response through the gradient function of the FGM.

Fatigue properties of Ti-6Al-4V (TC4) subjected to 0.9% physiological saline solutions were presented in this paper. The ultrasonic fatigue test method has been used to investigate the very high cycle fatigue properties of commercial titanium alloy TC4 with the microstructure of tramsformed lamellar dipped into 0.9% physiological saline solution prior to testing. Three estimated times have been decided for subjecting at 37 °C, such as 24 hours, 2 weeks and 4 weeks. The results show that physiological saline solution treatment makes a little influence on the ultrasonic fatigue life of TC4. The slope of S-N curve decreases as the dipping time increases. Dipping tests for three estimated times also have been performed. When TC4 has been dipped into physiological saline solution for 4 weeks, homogeneous white points have been observed on specular facet specimen. And in the fracture surface of which has been dipped for 4 weeks, new inclusion sized 5-10 µm in the crack initiation has been observed. The fractography pictures show the fracture to be transcrystalline plastic. Cracks are initiated because of the subsurface inclusion and the facet slip of α-phase.

The possibilities of movement and electrochemical reduction of fibroin macroions in the presence of tricalcium phosphate ions in the form of a nanocoating during electrolysis have been studied. The manifestation of a non-Newtonian flow of a mixture of macroions and ions in a shear flow, the conditions for their electrochemical reduction in the form of a nanocoating with uniform morphology, and thickness on the electrode surface are revealed. It was found that the excess ions in the mixture and the uneven relief of the electrode surface contribute to the formation of a nanocoating with an inhomogeneous and uneven thickness.

Since the discovery of Bioglass^® by Hench, bioactive glasses have been used in many medical applications, such as drug delivery systems, nonload-bearing implants, and bone cements because of their excellent bioactivity and biocompatibility. However, due to their poor mechanical properties, these glasses cannot be used in load-bearing applications, where the metallic alloys are still main materials. One useful approach to solving the mechanical limitations of bioactive glasses is to apply the glasses as the coating on mechanically tough substrates; it was also recognized early that bioactive glasses could be used as coatings for prosthetic metallic implants. In this paper, the mechanism, characterization, and current status of some methods of preparation for bioactive glass coating on implants are introduced. In the end, to get the homogeneous and compact coating with perfect bonding strength, some ideas of improving the performance of coatings are also presented.

The present work deals with the fabrication of forsterite–hydroxyapatite (FS–HA) hybrid coatings on stainless-steel 316L using the pulsed laser deposition (PLD) technique. The stainless steel (SS 316L) as a metallic implant is widely used in hard tissue applications. The XRD studies have confirmed the crystalline behavior of synthesized FS powder with an average crystallite size of 54nm. The synthesized FS powder was mixed in different compositions (10, 20, 30wt.%) into HA for preparing PLD targets (pellets). The XRD of the prepared pellets by UTM has confirmed both phases of FS and HA. The Scanning Electron Microscopy (SEM) of the coated samples depicted the successful deposition of composite powders on the substrates (SS 316L). The Ellipsometer was used to investigate the thickness of different substrates and it was found as 243, 251, 255, and 257nm for CP1, CP2, CP3, and CP4, respectively. The bioactivity of the coated substrates with different compositions (pure HA, 10%, 20%, 30%, and pure FS) was investigated by immersing the samples in simulated body fluid (SBF) for 14days. The same samples were then characterized by SEM which confirms the apatite layer formation that reflects the bioactivity. The addition of FS powder into HA will stimulate the apatite formation which enhances the bioactivity. The Raman Spectroscopy of coated samples reveals the successful deposition of different compositions of FS–HA nanocomposite. The peaks of Raman spectroscopy were corresponding to the XRD results of the pellets (different compositions of FS–HA). The antimicrobial activity of different compositions of FS–HA against Escherichia coli (E. coli) bacteria also showed a significant zone of inhibition. The bioactivity and antimicrobial behavior of FS–HA along with successful deposition by PLD have shown better potential applications for biomedical implant coating.