Hybrid Additive Manufacturing of Ferroelectric Oxides and Aerospace Alloys

Additive manufacturing enables the aerospace industry to re-design metallic structural components for improved specific strength. Many structural components are equipped with complex sensing systems, for example, to probe structural health. This dissertation investigates hybrid additive manufacturing: processing of multiple materials using one or more additive manufacturing techniques. The research is directed toward ferroelectric oxides as the functional element and aerospace alloys as the structural component. The specific materials examined are ferroelectric oxide lead zirconate titanate (PZT) and aerospace alloys Inconel 718, Ti-6Al-4V, and 17-4 PH stainless steel. The objective is to develop a new processing strategy utilizing a dual hybrid additive manufacturing approach with material jetting of the ferroelectric oxide and powder bed fusion of the aerospace alloys. Chemical solution deposition of PZT 20/80 films on commercial metal foils and additively manufactured Inconel 718 substrates demonstrate feasibility of piezoelectric behavior on traditionally fabricated and additively manufactured metal surfaces. Promising dielectric and ferroelectric measurements are obtained through robust polarization-electric field hysteresis loops; however, prominent interfacial layers require processing optimization. Therefore, mesoscopic models of tetragonal PZT compositions on various alloy classes are generated in order to understand the role of thermal strains on dielectric, piezoelectric, and pyroelectric properties. The emanating Ashby plots suggest titanium and some iron-based alloys as suitable candidates for sensing systems, but as a whole, serve as a guide for materials selection for future applications of PZT on metallic substrates. Finally, the dual hybrid approach of inkjet printing of PZT 20/80 films on commercial metal foils and additively manufactured Ti-6Al-4V and 17-4 PH stainless steel allow direct patterning of functional elements onto structural components. The overall implications of structure-processing-property relationships pave a path for integrated functionality, and point toward the feats attainable by additive manufacturing