Selective laser sintering of metallic oxide powder mixtures for bi/tri-metallic-oxide formation

Abstract

The objective of this work is to investigate the formation, relative concentrations, and chemical states of bi/tri-metallic oxides within the sintered layers of three naturally non-combinable oxides, namely ZnO, ZrO2 and TiO2. The novelty of this effort is in utilizing a single-step laser-based approach to chemically combine these three oxide powders, which are otherwise not conventionally combinable. The motivation lies in being able to achieve desired/tuneable combinatorial properties inherent to individual oxides like corrosion-resistance, self-cleaning and photocatalytic properties, besides customizing the location/extent of sintering; this has the potential to revolutionize multi-functional coatings for harsh environments. Various volume ratios of the three oxide powders were spread on a substrate, and a high-energy laser used to sinter and solidify it at different volumetric energy densities (VED). Morphological characterization showed the increasing concentrations of Ti- and Zr-based oxides when increasing the laser energy imparted, suggesting that their higher specific/latent heats (compared to ZnO) in fact requires higher energies for liquid phase sintering of the mixture, besides forming grains and grain boundaries at higher VED. Further, the formation of a tri-metallic oxide, as well as several bimetallic oxides was detected, thus paving the path for designing and applying tailored multi-functional coatings for multifaceted applications.