Structure and Mechanical Properties of the New Ti30Ta20Nb Biomedical Alloy.

In order to better understand the relationship between parameters of a mechanical alloying process and microstructure, especially the structure of porosity, some research and studies were carried out. The current study investigates the possibility to prepare the porous materials by mechanical alloying and annealing. A high-energy ball-milling process in the planetary ball mill Fritch PULVERISETTE 7 premium line was used for the solid-state synthesis of the single phase powders for titanium based biomedical alloy. The influence of the high-energy ball-milling time on the structure and morphology of the synthesized precursors after annealing was investigated. Additionally, the effect of the variable time of the ball-milling on the structural characteristics, pore morphology and mechanical properties of a biomedical Ti30Ta20Nb (wt.%) was investigated as well. This study confirms the predominance of the titanium ß phase and also the presence of the titanium α phase. The analysis of the diffraction patters obtained using the Rietveld method showed that when the milling time increases, the lattice parameters for the tested samples become reduced. Summing up, it should be pointed out that the areas of pure unreacted titanium still exist in the material. These areas were correlated to the results of an X-ray diffraction analysis. This research starts the process of converting mechanical alloying into a production method which could become an alternative to the space holder technique for the new titanium alloys used for medical applications.

Dispersion and Structure Analysis of Nanocrystalline Ti-mZrO2 Composite Powder for Biomedical Applications.

Titanium and titanium alloys are widely employed in biomedical applications but these alloys have unsatisfactory tribological properties because of their low hardness. Much better biomaterials for hard tissue replacement implants may be acquired by the preparation of titanium composites. Therefore, the connection of excellent biocompatibility and bioactivity of ZrO2 ceramics with good properties of titanium is considered to be a promising approach for the fabrication of more perfect hard tissue replacement implants. This study describes the formation of Ti-ZrO2 nanostructure composite biomaterial. Weighted amounts with the composition corresponding to Ti-xZrO2 (x = 10, 30 and 50 wt.%) were high energy milled in the planetary ball mill PULVERISETTE 7 premium line by Fritch at 10, 30 and 50 h milling times. Structural evolution and morphological changes of the powder particles during mechanical alloying were studied using the X-ray diffractometer, scanning electron microscopy and transmission electron microscopy analysis. The Rietveld method was applied for the verification of the qualitative and quantitative phase composition of the studied material. The parameters of diffraction line profiles were determined by PRO-FIT Toraya procedure. The crystallite sizes and lattice distortions were analyzed by Williamson-Hall method. It was found that during high-energy milling a significant decrease of crystallite size to nanoscale is observed for α-Ti and mZrO2 phases. The images from scanning and transmission electron microscopes of the milled powders show that the size of the agglomerates of Ti nanocrystallites changes in a broad range and that ZrO2 particles can be immersed in larger agglomerates or occur separately.

Influence of Sandblasting Process on Tribological Properties of Titanium Grade 4 in Artificial Saliva for Dentistry Applications.

Titanium Grade 4 (Ti G4) is widely used in medicine for dental implants. The failure-free life of implants depends on their properties such as resistance to wear and friction processes. This paper presents an analysis of the influence of sandblasting on tribological wear of commercial dental implants made of TiG4 in artificial saliva. Tribological wear measurements were performed in a reciprocating motion in the ball-on-disc system. The scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) method was used to characterize the surface of the implants before and after the tribological wear test. The microhardness of Ti G4 was measured before and after sandblasting by the Vickers method. The contact angle was determined by the method of sitting drop in air. The residual stress test using the X-Ray Diffraction (XRD) single-{hkl} sin2ψ method was carried out. The compressive residual stress of 324(7) MPa and surface hardening of Ti G4 was revealed after sandblasting with Al2O3 particles of 53-75 µm in diameter. It was found that sandblasting changes the surface wettability of Ti G4. The intermediate wettability of the mechanically polished surface and the hydrophobicity of the sandblasted surface was revealed. Sandblasting reduces the tribological wear and friction coefficient of Ti G4 surface in saliva. The three-body abrasion wear mechanism was proposed to explain the tribological wear of Ti G4 in saliva.

Evaluation of mechanical properties, in vitro corrosion resistance and biocompatibility of Gum Metal in the context of implant applications.

In recent decades, several novel Ti alloys have been developed in order to produce improved alternatives to the conventional alloys used in the biomedical industry such as commercially pure titanium or dual phase (alpha and beta) Ti alloys. Gum Metal with the non-toxic composition Ti-36Nb-2Ta-3Zr-0.3O (wt. %) is a relatively new alloy which belongs to the group of metastable beta Ti alloys. In this work, Gum Metal has been assessed in terms of its mechanical properties, corrosion resistance and cell culture response. The performance of Gum Metal was contrasted with that of Ti-6Al-4V ELI (extra-low interstitial) which is commonly used as a material for implants. The advantageous mechanical characteristics of Gum Metal, e.g. a relatively low Young's modulus (below 70 GPa), high strength (over 1000 MPa) and a large range of reversible deformation, that are important in the context of potential implant applications, were confirmed. Moreover, the results of short- and long-term electrochemical characterization of Gum Metal showed high corrosion resistance in Ringer's solution with varied pH. The corrosion resistance of Gum Metal was best in a weak acid environment. Potentiodynamic polarization studies revealed that Gum Metal is significantly less susceptible to pitting corrosion compared to Ti-6Al-4V ELI. The oxide layer on the Gum Metal surface was stable up to 8.5 V. Prior to cell culture, the surface conditions of the samples, such as nanohardness, roughness and chemical composition, were analyzed. Evaluation of the in vitro biocompatibility of the alloys was performed by cell attachment and spreading analysis after incubation for 48 h. Increased in vitro MC3T3-E1 osteoblast viability and proliferation on the Gum Metal samples was observed. Gum Metal presented excellent properties making it a suitable candidate for biomedical applications.