Dense, nano-grained, multi-phase ceramic coatings by dry aerosol deposition of lunar regolith simulant

Abstract

Dry Aerosol Deposition (DAD) is a ceramic coating process with the ability to build films and low profile 3D structures layer by layer and is therefore a promising additive manufacturing technique. DAD is unique because it uses kinetic energy rather than thermal energy for densification, and the result is a nearly theoretically dense, nano-crystalline ceramic. The main objectives of this work were to demonstrate the fabrication of adherent ceramic thick films onto a variety of substrates using lunar regolith simulant as feedstock, and to investigate the compositional relationships between feedstock and resultant films. Thick films were successfully deposited onto glass, steel and polyimide substrates via DAD. Using a sequential two-step deposition, films up to (but not limited to) 25 μm thickness were deposited onto steel. Surface roughness increased with thickness and with some influence from substrate material. Utilizing the DAD process, a very heterogeneous mixture of silicate and titanate mineral phases was transformed in a single step to a fully dense, nano-grained coating with spatially homogeneous composition at the micro-scale. The final composition of the coatings was found to deviate slightly from the feedstock powder, becoming richer in ilmenite (FeTiO3) and poorer in plagioclase (feldspar) content. This work demonstrates the potential of DAD for in-space manufacturing and lunar In Situ Resource Utilization.