Effect of post-processing and variation of the building angle of Ti-6Al-4 V disks obtained by selective laser melting: A comparison of physical, chemical and mechanical properties to machined disks

Abstract

Additive Manufacturing (AM) is driving the development of dental implants with freedom of design, material savings, and predictable properties. The modification of a single parameter, and post-processing treatments affects the final macro and microstructure. The aim was to evaluate the effect of changing the building angle, using the Selective Laser Melting (SLM) technique, on the physical, chemical, and mechanical properties and to compare them with sanded manufacturing surfaces and machined surfaces, with and without chemical surface treatment. There were 8 groups of Ti-6Al-4 V discs (Ø 10 mm×2 mm), classified as machined (M), machined with acid-alkali treatment (TM), SLM 0° (AM0), SLM 0° with sanding (SAM0), SLM 45° (AM45), SLM 45° with sanding (SAM45), SLM 90° (AM90), and SLM 90° with sanding (SAM90). The tests used were Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), roughness, wettability, surface free energy, X-ray diffraction (XRD), and Vickers hardness. The normality of the data was checked using the Shapiro-Wilk test followed by Kruskal-Wallis and ANOVA, with Dunn and Tukey post-tests, with a significance level of 5%. SEM revealed angle dependence in the number of unmelted powder particles and topographical heterogeneity, and EDS reported the elemental composition of the base alloy. AM90 showed the highest wettability among the manufactured groups, and the chemical surface treatment increased the wettability of the machined sample (p<0.001). In the roughness analysis, the higher the building angle, the higher the surface roughness . Sanding provided homogeneity in roughness, wettability, surface free energy, and microhardness. It was concluded that the production routes, change in angle, sanding and surface treatment affect the macro and microstructure of titanium surfaces. Changing the building angle influenced all of the topographical characteristics of the material, a parameter that can be changed and improved that is important for determining properties.