Direct ink writing of macroporous lead‐free piezoelectric Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃

Abstract

Direct ink writing (DIW) has become a widespread additive manufacturing technique for material engineering, but its application in lead‐free Ba0.85Ca0.15Zr0.1Ti0.9O3 piezoelectric ceramics from aqueous systems has not been reported so far to our knowledge. The main obstacle is the high extent of hydrolysis reactions undergone by the starting powders when dispersed in water, hindering the attainment of stable water‐based colloidal suspensions. This paper reports on the preparation of stable aqueous inks from a deagglomerated and surface‐treated powder synthesized by solid‐state reaction and on DIW of macroporous lead‐free piezoelectrics. Based on zeta potential and rheological measurements, the optimal amounts of processing additives (dispersant, binder, and coagulating agent) were selected to transform the initial fluid suspension to a viscoelastic paste with sufficient stiffness and stability for the printing process. Dielectric and piezoelectric properties of samples sintered under different temperatures were also investigated.

Direct Ink Writing Glass: A Preliminary Step for Optical Application

“…For the glass inks, the critical shear strain to break the ligation between the polymer and glass particles decreases with the increasing concentration of glass, because the glass particles are distributed homogeneously in the polymer solutions and the bonding is weaker between the particles and polymer chains than that among the polymer micelles, with a greater number of particles introduced, causing the critical shear strain to decrease. Different from the previous reports of the ink system consisting of dispersant-HPMC-PEI in [24,25], where a strain thinning behavior (type I) is shown, the ones of Pluronic solutions and glass inks exhibit a weak strain overshoot behavior (type III) [30], and their corresponding chain structures can be found in [31]. The different structures lie in the homogeneity of the as-mixed ink caused by the discrepancy of the particle size, that is to say, the glass powder still has larger particles than those in ceramic powder.…”

“…During each mixing interval, the as-mixed suspension was immediately taken out from the mixer and kept into an iced water tank to cool it down for 3 min. In contrast to the preparation procedures previously reported, involving the successive mixing steps after adding each kind of processing additive (dispersant-binder-coagulant) [24][25][26], the one-step mixing utilized in this study simplifies and facilitates the preparation of the inks. The final as-mixed suspension was sonicated for 5 min to destroy the possible agglomerates prior to any further use.…”

3D Printing of Macro Porous Sol-Gel Derived Bioactive Glass Scaffolds and Assessment of Biological Response

“…This option for Pluronic F-127 hydrogels is fully justified when the powder to be dispersed undergoes some ionic leaching that would promote early and undesirable coagulation phenomena and unstable inks [21], or when dealing with poor wetting powders, such as metallic Al [20]. On the other hand, when the powder undergoes hydrolysis and non-stoichiometric dissolution reactions, the standard approach of using dispersant and PEI can only be used for surface-treated powders against hydrolysis [32]. Moreover, the option for Pluronic F-127 hydrogels also brings some associated drawbacks, including an increased difficulty in preparing inks with high solids loadings.…”

Cost-Effective Additive Manufacturing of Ambient Pressure-Dried Silica Aerogel

“…With the consideration of expensive equipment costs of freeze-drying, the actual cost-saving is substantial. For the sintering drying method, although it is widely used for direct ink writing [31,32] to help remove all the organic solvent and additives, it suffers from the potential internal cracks during and after sintering, which requires adding the additives, such as binder to help prevent the structure from collapse. Furthermore, the sintering process also requires precise temperature control, which will incur considerable equipment costs.…”