Influence of the Infill Orientation on the Properties of Zirconia Parts Produced by Fused Filament Fabrication.

The fused filament fabrication (FFF) of ceramics enables the additive manufacturing of components with complex geometries for many applications like tooling or prototyping. Nevertheless, due to the many factors involved in the process, it is difficult to separate the effect of the different parameters on the final properties of the FFF parts, which hinders the expansion of the technology. In this paper, the effect of the fill pattern used during FFF on the defects and the mechanical properties of zirconia components is evaluated. The zirconia-filled filaments were produced from scratch, characterized by different methods and used in the FFF of bending bars with infill orientations of 0°, ±45° and 90° with respect to the longest dimension of the specimens. Three-point bending tests were conducted on the specimens with the side in contact with the build platform under tensile loads. Next, the defects were identified with cuts in different sections. During the shaping by FFF, pores appeared inside the extruded roads due to binder degradation and or moisture evaporation. The changes in the fill pattern resulted in different types of porosity and defects in the first layer, with the latter leading to earlier fracture of the components. Due to these variations, the specimens with the 0° infill orientation had the lowest porosity and the highest bending strength, followed by the specimens with ±45° infill orientation and finally by those with 90° infill orientation.

Mechanical performance, corrosion and tribological evaluation of a Co-Cr-Mo alloy processed by MIM for biomedical applications.

In this study, the processing parameters mechanical performance, corrosion and tribological evaluation of a low carbon content Co-Cr-Mo alloy are discussed. The production of parts using the Metal Injection Moulding (MIM) process is optimized, specifically concerning the rheological analysis of the prepared feedstocks, the optimum choice of the powder loading and the design of the debinding and sintering cycles. The mechanical properties as regards hardness, tensile strength and bending strength, as well as fatigue tests and wear characterization, are discussed for the full densified specimens obtained. Additionally, corrosion behaviour with the different methods and electrolytic solutions that simulate the biological environment has also been investigated. This approach allows us to confirm that the low-carbon cobalt alloy processed by MIM exhibits an adequate equilibrium between its mechanical and corrosion behaviour, with a notable performance during fatigue and wear tests. In the light of these findings, the use of this material for biomedical applications is discussed.