Chemical Machining of Copper-Based Aerospace Alloys Produced Through Additive Manufacturing: A Preliminary Approach to Improve Surface Quality

Additive Manufacturing (AM) is transforming the production of high-performance components, particularly in the aerospace sector. However, the surface quality of AM products often does not meet industry standards, necessitating additional treatments. Chemical machining processes are especially advantageous for preserving the intricate geometries of AM parts, yet their application can be challenging for certain metals due to the presence of alloying elements. The objective of this study is to evaluate the enhancement of surface properties, with a focus on roughness reduction, in GRCop-42 components fabricated via powder bed fusion technology, through the application of chemical machining treatments. Two distinct chemical machining solutions were considered: one formulated with ferric chloride and the other composed of a mixture of sulfuric and nitric acids. Furthermore, two experimental setups were implemented to assess the efficacy of ultrasound assistance during the chemical machining process. The results demonstrated that both chemical solutions effectively removed surface material, with the integration of ultrasound significantly accelerating the process. Surface roughness was reduced by up to 13 pct and the steepness of the surfaces was markedly decreased, achieving a nearly uniform finish. However, the utilization of ultrasound with the lower viscosity solution resulted in cavitation erosion, which created undesirable cavities on the surface.