Application of Electrostatic Adhesion Method in Metal-Powder-Based Additive Manufacturing Layer-Forming Process

Similar to direct energy deposition (DED) technology, electrostatic adhesion method can also be employed to deposit powder on targeted areas without direct contact. In this paper, feasibility of utilizing the electrostatic adhesion method (EAM) in material deposition step of metal-power-based additive manufacturing is assessed through theoretical models and experimental verifications. A dielectric layer is proposed to be pre-coated on targeted areas to keep the powders being electrostatically attracted and charged without dropping before laser scanning process. Through this study, it is found that the net force of a single metallic particle on top of the deposited powder layer with a different thickness of the dielectric layer can be determined, leading to the suggestion of suitable coating thickness corresponding with desired particle radius. Results showed that the deposition layer thickness can be predicted with the knowing coated dielectric layer thickness and the powder size distribution. With the proposed electrostatic deposition method, a thinner layer compared to DED technology can be deposited, while maintaining its ability to deposit powder layer over a larger area. Through experiments, the developed electrostatic model is validated with results indicating that the deposition layer thickness can be predicted and controlled with the knowing coated dielectric layer thickness and the powder size distribution.

Production of Ti-13Nb-13Zr Alloy by PM for Biomedical Applications Using Zirconium Oxide Grinding Bowl and Balls

In this present work Ti-13Nb-13Zr alloy was produced by PM using planetary ball mill with zirconium oxide grinding bowl and balls to reduce contamination. The effect of milling time upon microstructure and microhardness was studied. Powders have been produced by hydrogenation of Ti, Nb and Zr at 1MPa. Milling speed was 200 rpm during 90 to 360 min. Sintering was carried out at 1150°C during 10h. Powder size distribution was analyzed using CILAS equipment and chemically characterized by X-Ray Fluorescence (XRF). Microhardness was determined by means of a Vickers microhardness tester. Microstructure and phases were analyzed employing scanning electron microscopy (SEM) and X-Ray diffraction.