Making powder aerosol deposition accessible for small amounts: A novel and modular approach to produce dense ceramic films

Abstract Powder aerosol deposition is a promising technique to deposit dense ceramic films directly at room temperature. While previous developments pointed towards larger and more complex deposition devices, this work follows a different approach and proposes a simplified and miniaturized coating device (denoted as Micro‐PAD, µPAD). The aim is twofold: creating a smaller and flexible device consisting of an aerosol generation unit and a deposition chamber with a combined low areal footprint of 30 cm by 20 cm (that, e.g., easily fits in a glove box) as well as lowering the hurdle for other researchers to use the powder aerosol deposition. Therefore, we introduce a device mainly based on commercially available components/connectors as well as manual operated valves/flow meters. A key point is the elimination of moving components by just using a spot deposition that was enabled by using a circular de‐Laval‐type nozzle. The operational capability of µPAD is proven for the deposition of alumina films and compared to conventional PAD in terms of mechanical, crystalline, and optical film properties. Thick films with a bell‐shape‐like profile are deposited by µPAD, featuring a plateau in the center of the film with a diameter of 5 mm and a FWHM (full width at half maximum) diameter of about 10 mm. Alumina films produced by µPAD do not only match the properties of corresponding PAD films, but oftentimes outperform them. Here, µPAD films exhibit increased hardness and optical transmittance values, surpassing reference values of the conventional sprayed counterparts by at least 10%. Also, film integrity and adhesion to the substrate are slightly higher in case of µPAD. Reasons for the improved film properties are found by X‐ray diffraction, with a significantly higher fracturing of impacting particles during µPAD combined with improved film consolidation as observed by SEM. Furthermore, µPAD featured doubled to tripled the deposition rates and, markedly almost doubled the deposition efficiency.