Laser-based Direct Energy Deposition (L-DED) is one of the most commonly employed metal additive manufacturing technologies. In L-DED, a laser beam is employed as a heat source to melt the metal powder that is deposited on a substrate layer by layer for the generation of a desired component. The powder is commonly fed through a nozzle into the molten pool by means of a carrier gas and therefore, a nozzle design that ensures optimal deposition of the material is of critical importance. Additionally, its design also affects the powder and gas flows that arise in the nozzle and during the deposition. This, in turn will affect the characteristics of the generated clad and the performance of the whole deposition. Therefore, an optimization of deposition nozzle geometry can be as important as the controlling of deposition process parameters in order to obtain best component qualities. In this context, the present review work is aimed at analysing the different nozzle designs employed in powder-based L-DED processes and the influence of different geometrical features and configurations on the resulting powder and gas flows. Concretely, the main characteristics of each design, their advantages and their possible shortcomings are analysed in detail. Additionally, a review of most relevant numerical models employed during the development of new and optimised nozzle designs are also addressed.

Additive Manufacturing (AM) enables the generation of complex geometries and controlled internal cavities that are so interesting for the biomedical industry due to the benefits they provide in terms of osseointegration and bone growth. These technologies enable the manufacturing of the so-called lattice structures that are cells with different geometries and internal pores joint together for the formation of scaffold-type structures. In this context, the present paper analyses the feasibility of using diamond-type lattice structures and topology optimisation for the re-design of a dental implant. Concretely, a new ultra-short implant design is proposed in this work. For the manufacturing of the implant, digital light processing additive manufacturing technique technology is considered. The implant was made out of Nano-zirconia and Nano-Calcium Silicate as an alternative material to the more common Ti6Al4V. This material combination was selected due to the properties of the calcium-silicate that enhance bone ingrowth. The influence of different material combination ratios and lattice pore sizes were analysed by means of FEM simulation. For those simulations, a bio-material bone-nanozirconia model was considered that represents the final status after the bone is integrated in the implant. Results shows that the mechanical properties of the biocompatible composite employed were suitable for dental implant applications in dentistry. Based on the obtained results it was seen that those designs with 400 μm and 500 μm pore sizes showed best performance and led to the required factor of safety.