(2jc) Effect of PZT Loading and Surfactant Concentration on Cure Depth of PZT Ceramic Ink

Lead zirconate titanate (PZT) ceramics in thick-film or structural forms are currently in active development for various device applications. However, the conventional manufacturing methods, such as tape casting and injection molding are not efficient in producing complex parts. On the other hand, three-dimensional (3D) printing, an additive manufacturing technique, is capable of manufacturing complicated parts without the requirement of a mold. In particular, slurry-based technologies, such as stereolithography (SLA) or masked stereolithography (MSLA) have come up as perspective techniques for manufacturing ceramic components because of their advantages like high resolution and reduced processing time. A major goal of ceramic ink development for SLA or MSLA is to fabricate complex three-dimensional structures having excellent mechanical, electrical, and/or functional properties. For SLA or MSLA, the ink is prepared by suspending ceramic particles of appropriate concentration in photocurable polymeric resins. The suitability of the ink depends on its dispersibility, ceramic loading, viscosity, and curing behavior. This study focuses on developing a PZT-based ceramic ink because of its diverse industrial and engineering applications. To improve the device performance, PZT ceramic concentration in the formulation should be as high as possible. However, higher concentration of PZT can lead to poor curing because of reduced photopolymerization. Moreover, to ensure proper mixing and prolonged suspension of the PZT particles in the ink, appropriate concentration of surfactant needs to be added. The effect of surfactant concentration on the ink properties also needs to be examined. Therefore, this research aims to demonstrate the possibility of developing a PZT-based ceramic ink via SLA process and improving the printing results.

Ceramic ink formulations with two different polymeric resins, namely, Peopoly and Clear resin of Form lab was attempted. The concentration of PZT powder (Stanford Advanced Materials, CA, USA) was varied along with the surfactant (Surfynol 420) to investigate their effect on the mixing characteristics and rheological properties. The Resodyn Resonant Acoustic Mixer, known as LabRAM II, was used for mixing the PZT powder with resin and surfactant. The resonant frequency (60 Hz) and acceleration (up to 100 g) of the LabRAM II enabled fast mixing of the formulation in small quantities, which otherwise would not have been possible by conventional methods, such as milling. The PZT loading was varied from 70 wt.% to 85 wt.%, and the surfactant wt.% ranged from 0 wt.% to 3 wt.% of the total formulation. The viscosities and shear behavior of the formulations were measured using the Malvern Panalytical rotational rheometer. The viscosity of the ink should be low for the self-leveling behavior during printing. The viscosity increased with increasing PZT loading, whereas it decreased for increasing surfactant concentration up to an optimum concentration. All ceramic formulations demonstrated shear thinning behavior except the ones with 0 wt.% and 1 wt.% surfactant concentration. Therefore, the ink formulations having 2 wt.% and 3 wt.% surfactant were considered for the curing depth measurement. A maximum solid loading of 75 wt.% PZT has been achieved with the average cure depth of 135 µm for an exposure time of 50 s under UV light (405 nm). Further, this study aims to optimize the solid loading and cure depth and subsequently print parts for testing.

Research Interests

My primary research interests are aligned towards additive manufacturing techniques, such as 3D printing, laser powder bed fusion process, and electroforming. I have worked towards the design and development of the pulse electroforming process as a micro and nanofabrication technique. I have also explored the synthesis of binary metal oxide semiconductor nanostructures and studied their surface properties. Currently, I am engaged in developing a ceramic ink for stereolithography that can facilitate the production of complex parts having improved mechanical, electrical, and functional properties.