http://sistemas.eel.usp.br/docentes/arquivos/2166002/1234Nb/Geetha-review2009.pdf

Ti based biomaterials, the ultimate choice for orthopaedic implants – A review

Ti-based alloys are finding ever-increasing applications in biomaterials due to their excellent mechanical, physical and biological performance. Nowdays, low modulus β-type Ti-based alloys are still being developed. Meanwhile, porous Ti-based alloys are being developed as an alternative orthopedic implant material, as they can provide good biological fixation through bone tissue ingrowth into the porous network. This paper focuses on recent developments of biomedical Ti-based alloys. It can be divided into four main sections. The first section focuses on the fundamental requirements titanium biomaterial should fulfill and its market and application prospects. This section is followed by discussing basic phases, alloying elements and mechanical properties of low modulus β-type Ti-based alloys. Thermal treatment, grain size, texture and properties in Ti-based alloys and their limitations are dicussed in the third section. Finally, the fourth section reviews the influence of microstructural configurations on mechanical properties of porous Ti-based alloys and all known methods for fabricating porous Ti-based alloys. This section also reviews prospects and challenges of porous Ti-based alloys, emphasizing their current status, future opportunities and obstacles for expanded applications. Overall, efforts have been made to reveal the latest scenario of bulk and porous Ti-based materials for biomedical applications.

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New Developments of Ti-Based Alloys for Biomedical Applications

In the area of materials science, corrosion of biomaterials is of paramount importance as biomaterials are required for the survival of the human beings suffering from acute heart diseases, arthritis, osteoporosis and other joint complications. The present article discusses various issues associated with biological corrosion of different kinds of implants used as cardio stents, orthopedic and dental implants. As the materials used for these implants are manifold starting from metallic materials such as stainless steel (SS), cobalt chromium, titanium and its alloys, bioceramics, composites and polymers are in constant contact with the aggressive body fluid, they often fail and finally fracture due to corrosion. The corrosion behavior of various implants and the role of the surface oxide film and the corrosion products on the failure of implants are discussed. Surface modification of implants, which is considered to be the best solution to combat corrosion and to enhance the life span of the implants and longevity of the human beings is dealt in detail and the recent advances in the coating techniques which make use of the superior properties of nanomaterials that lead to better mechanical properties and improved biocompatibility are also presented.

Biomedical Implants: Corrosion and its Prevention - A Review~!2009-12-22~!2010-01-20~!2010-05-25~!

Metallic biomaterials are used in medical devices in humans more than any other family of materials. The corrosion resistance of an implant material affects its functionality and durability and is a prime factor governing biocompatibility. The fundamental paradigm of metallic biomaterials, except biodegradable metals, has been “the more corrosion resistant, the more biocompatible.” The body environment is harsh and raises several challenges with respect to corrosion control. In this invited review paper, the body environment is analysed in detail and the possible effects of the corrosion of different biomaterials on biocompatibility are discussed. Then, the kinetics of corrosion, passivity, its breakdown and regeneration in vivo are conferred. Next, the mostly used metallic biomaterials and their corrosion performance are reviewed. These biomaterials include stainless steels, cobalt-chromium alloys, titanium and its alloys, Nitinol shape memory alloy, dental amalgams, gold, metallic glasses and biodegradable metals. Then, the principles of implant failure, retrieval and failure analysis are highlighted, followed by description of the most common corrosion processes in vivo. Finally, approaches to control the corrosion of metallic biomaterials are highlighted.

Corrosion of Metallic Biomaterials: A Review

Study of corrosion in biocompatible metals for implants: A review

Influence of microstructure and alloying elements on corrosion behavior of Ti–13Nb–13Zr alloy

Effect of thermomechanical processing on microstructure of a Ti–13Nb–13Zr alloy

Titanium is a wonder metal, generally considered as one of the most biocompatible and corrosion resistant metals available for clinical applications. Since 1951, when Leventhal /1/ first published an article on the orthopaedic application of this metal, research activity and clinical experience resulted in new developments in the manufacturing and use of this metal and its varieties of alloys. Beginning with commercially pure titanium, and then to Ti-6A1-4V alloy, today the state of the art p-titanium alloys have been added to the list; there is a range of materials and devices based on titanium, which are available for a variety of medical applications. In this review article an attempt is made to bring out the various features of titanium as orthopaedic material, mainly focusing on the physical metallurgy, alloy development, microstructural aspects, and corrosion and wear resistances. An attempt is also made to highlight the role of surface modification in enhancing the corrosion resistance of titanium and its alloys.

Corrosion and microstructural aspects of titanium and its alloys as orthopaedic devices

Solution treatment and ageing (STA) is an effective strengthening method for α + β titanium alloys. This paper reports the effect of solution treatment and aging on the corrosion behaviour of Ti-6Al-7Nb alloy in a simulated body fluid (Ringer's solution). Ti-6Al-7Nb alloy is hot rolled in the α + β field and subjected to solution treatment above and below its beta transus temperature (1283 K). The solution treated specimens are water quenched (WQ), air-cooled (AC), and furnace cooled (FC) at three different rates, and subsequently aged at 823 K for 4 h. Microstructural changes were examined using optical microscopy and phases developed were analyzed using XRD. The influence of microstructure on the corrosion performance of the alloys are discussed in detail based on the Open Circuit Potential (OCP), passive current density and area of repassivation loop values obtained from the cyclic polarization study in Ringer's solution. The passive current density was low (0.5 μA/cm 2 ) for the specimen with duplex microstructure obtained for specimen solution treated at 1223 K, air-cooled, and aged, in comparison with that for as-rolled specimen (1.5 μA/cm 2 ). The corrosion aspects resulting from various heat treatments are discussed in detail.

R. Asokamani

Papers

Influence of microstructure and alloying elements on corrosion behavior of Ti–13Nb–13Zr alloy

Effect of thermomechanical processing on microstructure of a Ti–13Nb–13Zr alloy

Corrosion and microstructural aspects of titanium and its alloys as orthopaedic devices

Influence of microstructural changes on corrosion behaviour of thermally aged Ti-6Al-7Nb alloy