This article describes physical, chemical, and mechanical characterizations of porous titanium implants made by an additive manufacturing method to gain insight into the correlation of process parameters and final physical properties of implants used in orthopedics. For the manufacturing chain, the powder metallurgy technology was combined with the additive manufacturing to fabricate the porous structure from the pure tanium powder. A 3D printing machine was employed in this study to produce porous bar samples. A number of physical parameters such as titanium powder size, polyvinyl alcohol (PVA) amount, sintering temperature and time were investigated to control the mechanical properties and porosity of the structures. The produced samples were characterized through porosity and shrinkage measurements, mechanical compression test and scanning electron microscopy (SEM). The results showed a level of porosity in the samples in the range of 31-43%, which is within the range of the porosity of the cancelluous bone and approaches the range of the porosity of the cortical bone. The results of the mechanical test showed that the compressive strength is in the wide range of 56-509 MPa implying the effect of the process parameters on the mechanical strengths. This technique of manufacturing of Ti porous structures demonstrated a low level of shrinkage with the shrinkage percentage ranging from 1.5 to 5%.

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This article addresses the influence of macro-scale channels with a diameter of 1 mm on the physical and mechanical properties of additive-manufactured porous titanium (Ti) structures, which can be used as bone implants. Different orientations and numbers of channels within the additivemanufactured structures were used in this study. The produced samples were characterized through porosity, shrinkage measurements, as well as mechanical compression tests. The results demonstrate that the channel orientation in the structure influences the shrinkage rate in the parts made with horizontally or vertically orientated channels, in which a relatively isotropic shrinkage is achieved after sintering. In addition, mechanical ultimate strength of the structure can be tailored to the desired properties (such as the surrounding bone) via the channel orientation in the structure, where the overall porosity is affected by the number of channels existing in the structure.

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A novel additive manufacturing-based technique for developing bio-structures with conformal channels and encapsulated voids. The network of macro-channels in the structure of cortical bone is crucial, particularly for nutrition. Therefore, a successful bone implant should simulate the real bone architecture by including such channels in its structure. The introduction of additive manufacturing (AM) techniques in the orthopedic implant industry brings the potential of producing customized bone implants that mimic the structure of real bone. However, the depowdering issue in the powder bed AM technique has hindered the creation of macro-sized channels in bone implants composed of biocompatible materials. In this study, we introduce a new method for manufacturing implants which is composed of titanium and includes networks of channels. This technique is primarily based on printing individual components of a sliced structure, followed by depowdering and assembling the components before the sintering process. This new technique has the potential to control the internal features of 3D printed structures. A set of comparative physical and mechanical tests were conducted to characterize the resulting structures. Experimental characterization results showed that the shear strength of the sample that was made by the new technique was reduced by 24%-30%, where the porosity was slightly lower (∼2%) than that of a comparable control sample. However, the new technique had no effect on the compressive strength of the structure.