Studying the effect of composition on the in vitro wear behavior and elastic modulus of titanium-niobium-based alloys for biomedical implants

Corrosion and wear behavior of Ti-5Cu-xNb biomedical alloy in simulated body fluid for dental implant applications

The present study examined the corrosion and tribological behavior of novel Ti-5Cu-xNb alloy synthesized via powder metallurgy as a new biomedical material in a simulated bodily fluid (SBF) solution. The electrochemical impedance spectroscopy (EIS) study reveals the formation of two protective layers on the surface of alloys during the test. The alloys spontaneously produce a passivating oxide coating on their surfaces, and the breakdown potential (1.14-1.17 V) and re-passivation current density (2.07-3.04 μAcm^-2) were observed during the potentiodynamic polarization test. The highest corrosion resistance was observed for the alloy Ti-5Cu-10Nb (i_corr = 21.44 nA-cm^-2). The SEM and XPS analysis of the corroded surface showed the formation of oxide on the surfaces of the alloys. The samples were tested at 10 N, 15 N, and 20 N loads against the zirconia counterpart to investigate the effect of loading on friction and wear. The lowest coefficient of friction was obtained for Ti-5Cu-5Nb (0.25-0.41) at 20 N loading, while the maximum for Ti-5Cu-10Nb at 15 N load falls in the range of (0.71-0.25). Additionally, they present the wear rate in the range of (5.3 × 10^-8-1.45 × 10^-6 mm³/mm), in accordance with the change in microstructure and mechanical properties. However, the wear rate increases with the addition of niobium and reaches the maximum for Ti-5Cu-15Nb at 20 N loading condition, but it is relatively deficient compared to commonly used implant material. Therefore, it is suggested that this β-type Ti-5Cu-xNb alloy is a promising candidate, more suitable than the commercially used Ti and Ti-6Al-4V for dental applications.

Investigation of Coatings, Corrosion and Wear Characteristics of Machined Biomaterials through Hydroxyapatite Mixed-EDM Process: A Review

Together, 316L steel, magnesium-alloy, Ni-Ti, titanium-alloy, and cobalt-alloy are commonly employed biomaterials for biomedical applications due to their excellent mechanical characteristics and resistance to corrosion, even though at times they can be incompatible with the body. This is attributed to their poor biofunction, whereby they tend to release contaminants from their attenuated surfaces. Coating of the surface is therefore required to mitigate the release of contaminants. The coating of biomaterials can be achieved through either physical or chemical deposition techniques. However, a newly developed manufacturing process, known as powder mixed-electro discharge machining (PM-EDM), is enabling these biomaterials to be concurrently machined and coated. Thermoelectrical processes allow the migration and removal of the materials from the machined surface caused by melting and chemical reactions during the machining. Hydroxyapatite powder (HAp), yielding Ca, P, and O, is widely used to form biocompatible coatings. The HAp added-EDM process has been reported to significantly improve the coating properties, corrosion, and wear resistance, and biofunctions of biomaterials. This article extensively explores the current development of bio-coatings and the wear and corrosion characteristics of biomaterials through the HAp mixed-EDM process, including the importance of these for biomaterial performance. This review presents a comparative analysis of machined surface properties using the existing deposition methods and the EDM technique employing HAp. The dominance of the process factors over the performance is discussed thoroughly. This study also discusses challenges and areas for future research.