Surface Pretreatment, Excess Powder Removal and Surface Finishing for Additive Manufacturing Materials and Finished Articles Utilizing Environmentally Safe Aqueous Chemicals

Surface Pretreatment, Excess Powder Removal and Surface Finishing for Additive Manufacturing Materials and Finished Articles Utilizing Environmentally Safe Aqueous Chemicals Dr. Marvin C. Hawkins*, Sentecor Solutions, Tremonton, UT Dr. Dwayne D. Arola, Material Science and Engineering, University of Washington, Seattle, WA Surface preparation for Additive Manufacturing (AM) materials and finished articles is critical for manufacturing processes, final form and long-term fracture toughness. Data for environmentally safe aqueous surface preparation processes and final article treatment will be presented. Prior art has been complicated by the difficulty in removing residual powders and oxides associated with material processing and/or heat treatment processes. Surface treatment using toxic and hazardous materials such as hydrofluoric or chromic acids has typically been employed. These chemicals pose extreme hazards for operators and pose significant liability risks for the companies using the processes and those disposing of the waste. Application of the processes on aluminum, titanium and Inconel AM materials has been demonstrated. Etching to remove residual powders due to powder fabrication and introduction of surface residual stress has also been demonstrated. Elimination of Additive Manufacturing powders reduces or eliminates oxide inclusions in the final articles, provides for a homogeneous material and reproducible mechanical properties. Removal of manufacturing powders trapped inside interior cavities has been demonstrated without damage to or thinning of the manufactured article. Final AM surfaces have also been smoothed and near surface residual stresses applied in order to decrease or eliminate fatigue and fracture induced failures. These processes are operator safe and allow for etching solution disposal into municipal waste systems.