Project Details
Projekt
Generation of polyethylene powder for the fiber laser based Direct Energy Deposition process: Parametric studies, microstructure and mechanical properties
Subject Area
Polymeric and Biogenic Materials and Derived Composites
Primary Shaping and Reshaping Technology, Additive Manufacturing
Primary Shaping and Reshaping Technology, Additive Manufacturing
Term
since 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 493935114
The objective of this project is the development of silica core-HDPE/dUHMWPE-shell particles for a dedicated use in a laser-based Directed Energy Deposition (DED-LB) process. The synthesis of spherical particles with a 60-150 µm sizedistribution, high density and an acceptable flowability for DED-LB is targeted. This will be performed by using micron-sized silica loaded with activated polymerization catalysts. The silica simultaneously supports the crystallization dynamics of the PE blend and the fast-cooling rate in the DED-LB process, in order to obtain stress-free objects. Templates for the particles will be prepared to meet the requirements for preparing a dense shell of PE at the size of DED-LB powder handling, with respect to an optimum of the shell thickness /density ratio, which will be investigated to allow a direct synthesis of DED-LB suitable particles. The temperature of polymerization, ethylene pressure and solvent are the parameters to be varied. Of particular interest is the application of disentangled ultrahigh molecular weight polyethylene (dUHMWPE) and its in-reactor blends with HDPE. The main advantage of the dUHMWPE is its low melt viscosity in relation to that of molten commercial UHMWPE powders. The final object in contrast would have a very similar property profile as entanglements form directly after melting. The crystallization behavior itself will be investigated by modifying blends with various HDPEs. The particles will be inherently additivated for absorbing NIR-laser light, with an overall goal of preparation of powders at the 10 kg scale directly suitable for DED-LB. DED-LB performance will be screened, and an optimization loop will be established with respect to powder handling and quality of the built part. Spectroscopic- and thermal imaging will be used to gain a deeper understanding of melting and recrystallisation mechanics and will be used to finetune the core/shell ratio and melt viscosity. Produced specimen will be characterized by means of tensile-, hardness and 3-point bending tests to reveal their mechanical properties. Microstructure and porosity will be analyzed by scanning electron microscopy and computer tomography scans. The physical data will be collected for a broad spectrum of laser parameters and deposition strategies, and will be made accessible for all priority program participants upon requests.
DFG Programme
Priority Programmes
Subproject of
SPP 2122:
Materials for Additive Manufacturing
