Thin-walled high temperature alloy structures fabricated from additively manufactured polymer templates

Abstract

Additive manufacturing is enabling a paradigm shift in design and production, but conventional techniques reach their limits when metallic structures require walls with <0.5mm thickness. Here we introduce an approach for indirect additive manufacturing of thin-walled alloy structures. First a polymer template is additively manufactured, then metal layers are deposited by electroplating, physical or chemical vapor deposition. After removal of the polymer, the metal layers can be interdiffused to form an alloy via homogenization heat treatments. Three different alloys designed for three elevated temperature regimes are demonstrated: Monel alloys based on Ni-Cu-Al-Ti, nickel superalloys based on Ni-Cr-Al and refractory rhenium alloys based on Re-Co. A process was developed to co-deposit rhenium and cobalt via aqueous electroplating, resulting in an alloy with a melting point of 2000°C and a Vickers hardness of 480±50HV0.2 after homogenization. Two applications of interest for the aerospace industry were chosen to demonstrate the technology. High temperature truss core sandwich structures and rocket engine thruster demos where fabricated.