CoCrMo-base Alloys for Dental Applications Obtained by Selective laser melting (SLM) and CAD/CAM Milling

Abstract

In this work, CoCrMo-base alloys specimens were produced by additive manufacturing using selective laser melting (SLM) as well as CAD/CAM milling. For SLM specimens, spherical particles were laser processed at 1320°C under argon atmosphere and submitted to thermal stress relieving at 750°C-45min. Specimens from CoCrMo blocks were milled by CAD/CAM machining and sintered at 1300°C-60min. The materials from both techniques were characterized by relative density, dilatometry, SEM/BSE, OM and XRD analysis. The mechanical properties were determined by Vickers hardness and tensile tests. The specimens from both techniques exhibited single phase γCo (FCC) and CTE of 14 x10 -6 °C-1 . Relative density of 95.4%/ 85.6%, hardness values near 400HV/ 350HV and UTS of 905MPa/ 780MPa were measured for SLM and CAD/CAM specimens, respectively. Higher relative density is the main factor for increased mechanical properties of SLM specimens. On the other hand, both SLM and CAD/CAM specimens present properties in accordance with ISO-22674 recommendations, compatible with dental applications such as bridges containing four or more elements as well as fully dense pontics.

Influence of interlayer time on the microstructural state of CoCrMo coatings applied by selective laser melting on an iron-based substrate for different numbers of layers

“…Where"h l ˝is the real thickness of the layer after laser fusion and solidification, "h pow.theo ˝is the powder layer thickness before fusion (in our conditions h pow.theo = 50 µm) which increases after the first layer because of metallic matter withdrawal. The value "a" is the filling density, which is the ratio between the powder density ρ pow (=5.1 g/cm 3 ) and the density of the full dense material ρ CoCrMo (=8.5 g/cm 3 ) [17,26].…”