Inkjet printing (IJP), as an additive manufacturing technology, is widely spreading due to its high resolution, low-cost, simple, contactless process, the application range of materials/substrates, the scaling possibility, low material waste, and precise control of different coating compositions. Recent progress in IJP has led to a wide range of its applications. The technique is mainly being used for pattern printing, while its advantages attract interest to extend its application for protective coatings.
In the present study, the focus is to develop a diffusion barrier and electrical contact layer on solid oxide cell (SOC) metal interconnects (IC) to protect the steel substrate from degradation at high temperatures. In order to achieve a dense protective layer, it is advantageous to prepare an ink with high solid fractions. However, this brings a risk of nozzle blocking. Such highly loaded inks have to be stable, well-dispersed, and agglomerate-free to avoid blocking the nozzles. Moreover, there are other criteria for the physical properties of the ink to form printable and stable single droplets. In the current study, a batch of inks was prepared using lanthanum strontium manganite (LSM) powders. The critical properties of the colloidal suspensions including dispersion, rheology, surface tension, zeta potential, and wettability were characterized. A printability phase diagram was then composed with dimensionless parameters defined by measured physical properties. The printable ink was deposited on interconnect steel substrates. Thermal treatment was performed to remove ink solvents in order to obtain a uniform, dense printed layer with good surface coverage. The morphology, crystalline structure, and chemical state of the deposited coating are analyzed and discussed.