Abstract
Additive manufacturing (AM) enables fully dense biomimetic implants in the designed geometries from preferred materials such as titanium and its alloys. Titanium aluminum vanadium (Ti6Al4V) is one of the pioneer metal alloys for bone implant applications, however, the reasons for eliminating the toxic effects of Ti6Al4V and maintaining adequate mechanical strength have increased the potential of commercially pure titanium (cp-Ti) to be used in bone implants. This literature review aims to evaluate the production of cp-Ti and Ti6Al4V biomedical implants with laser powder bed fusion (L-PBF) technology, which has a very high level of technological matureness and industrialization level. The optimization of L-PBF manufacturing parameters and post-processing techniques affect the obtained microstructure leading to various mechanical, corrosion and biological behaviors of the manufactured titanium. All of the features are considered in the light of specifications and needs of bone implant applications. The most critical disadvantages of the L-PBF technology, such as residual stresses and leading deformations are introduced and the potential solutions are discussed. Moreover, the manufacturability of porous bone implants that causes benefit and harm in L-PBF applications are assessed.
Highlights
Biomedical implants may replace damaged tissues, organs and joints [1]
Titanium aluminum vanadium (Ti6Al4V) is one of the pioneer metal alloys for bone implant applications, the reasons for eliminating the toxic effects of Ti6Al4V and maintaining adequate mechanical strength have increased the potential of commercially pure titanium to be used in bone implants
This literature review aims to evaluate the production of commercially pure titanium (cp-Ti) and Ti6Al4V biomedical implants with laser powder bed fusion (L-PBF) technology, which has a very high level of technological matureness and industrialization level
Summary
Biomedical implants may replace damaged tissues, organs and joints [1]. They require a homogeneous and stable microstructure to obtain integrity according to International Standards Organization (ISO) 20160 [2]. Metallic implants, including stainless steel, cobalt-chromium and titanium alloys, are preferred for joint replacement and fracture fixation of bones when high mechanical reliability is required. An important disadvantage of titanium implants is the high elastic modulus leading to stress shielding effect causing bone resorption due to unconformity of elastic modulus between cortical bone (10e17 GPa) and titanium (105e114 GPa) [13,14] To address this major problem leading to revision surgeries and high discomfort for patients, similar elastic modulus to cortical bone can be attained with porous structured titanium implants [15,16]. Among different AM technologies, laser powder bed fusion (L-PBF) is the most widely used process for producing titanium implants in need of enhanced mechanical properties and feature complexity [18]. The effects of L-PBF process parameters and microstructure is reviewed on the mechanical, corrosion and biological properties of cp-Ti and Ti6Al4V biomedical implants. The advantages obtained with hierarchical porosity as well as economic factors are reviewed in this study
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