Laser Powder Bed Fusion Applied to a New Biodegradable Mg-Zn-Zr-Ca Alloy

Abstract

The aim of the present paper is to apply the laser powder bed fusion process to a new biodegradable Mg-Zn-Zr-Ca alloy powder prepared via a mechanical alloying method from powder pure components. This additive manufacturing method is expected to allow for the obtaining of high biomechanical and biochemical performance. Various processing parameters for laser powder bed fusion are tested, with a special focus on laser energy density—E [J/mm3]—which is calculated for all experiment variants, and which represents an important processing parameter, dependent upon all the rest. The goal of all the trials is to find the most efficient schema for the production of small biodegradable parts for the medical domain, meaning the selection of optimal processing parameters. An important observation is that the most robust and homogeneous samples without cracks are obtained for lower values of the E, around 100 J/mm3. Thus, the most performant samples are analyzed by scanning electron microscopy, X-ray diffraction and by compression mechanical test.

Biodegradable Magnesium Alloys for Personalised Temporary Implants

“…In brief, the AM-SLM method is a powder bed fusion process using a high-density laser beam (L-PBF) on a micro scale, which allows for the rapid manufacture of metal parts with the desired geometry without the need for post-processing or possibly only a very small one [ 45 ]. The pre-processing step of L-PBF consists of the CAD design of the model based on doctors’ digital information for the customised implant or based on the shape and dimensions of standard implants.…”

“…Then, it is necessary to design and set the process parameters corresponding to the specific characteristics of the metal powder to be processed and the desired geometry. The next step is 3D printing using the SLM machine software (CAMbridge 2018, 3Shape A/S, Copenhagen, Denmark), which takes the slicing data from the STL, scans each layer of powder fed successively into the building chamber until the designed geometry is achieved [ 45 ]. The quality of the manufactured product depends on the selection of the right process parameters, such as laser power, scan speed, layers, and hatch distance, including their correlation [ 45 ].…”

“…The next step is 3D printing using the SLM machine software (CAMbridge 2018, 3Shape A/S, Copenhagen, Denmark), which takes the slicing data from the STL, scans each layer of powder fed successively into the building chamber until the designed geometry is achieved [ 45 ]. The quality of the manufactured product depends on the selection of the right process parameters, such as laser power, scan speed, layers, and hatch distance, including their correlation [ 45 ]. For reactive metals, such as Mg and its alloy, the 3D printing must occur in an inert Ar atmosphere.…”

“…This present paper concerns the attempt to obtain a demonstrative temporary implant from a Mg bio-alloy with the composition Mg-10Zn-0.8Ca-0.5Zr (wt.%) already developed by the present authors [ 45 , 46 ]. The objective is to investigate whether this high-biocompatible material is suitable for biodegradable temporary custom implants obtained via additive manufacturing.…”

“…The objective is to investigate whether this high-biocompatible material is suitable for biodegradable temporary custom implants obtained via additive manufacturing. Our previous investigations [ 45 , 46 , 47 ] were related to the optimisation of process parameters for mechanical alloying, for obtaining the alloy in the powder stage, and for additive manufacturing by L-BPF (laser bed powder fusion), the process of obtaining a sample for a demonstrative implant. Now, the investigations have focused on the main functional properties of the alloy, corresponding to all processing stages, from a powder to demonstrative implant, i.e., structural and mechanical characteristics and corrosion resistance in simulated body fluids.…”