Abstract
Formulation of high solid load slurries is an important aspect in achieving dense, high quality ceramic green body shaping by additive manufacturing techniques. To this end, the understanding and control of interparticle interactions in non-aqueous organic slurry systems is imperative. With nanosized powders gaining increasing interest, particle stabilization by long-chain polymeric dispersants is undesirable due to the high exclusion volume associated and the subsequent decrease in the maximum solid load of the suspension. In this study, we focus on the stabilization mechanisms provided by metal cation complexes in methyl ethyl ketone and isopropanol-based spinel slurries. Special focus is given to chromium (III) 2-ethylhexanoate. Hemi-micelle formation at the powder surface in methyl ethyl ketone is suggested as a highly efficient stabilization mechanism. Complexes of metal dopant cations may open new pathways towards future advances in ceramic slurry formulation, especially in the field of additive manufacturing. Furthermore, the importance of solvation forces is discussed on the basis of the protic or aprotic character of the solvent used.
Highlights
Production of fully dense and defect-free ceramics is an important milestone to boost the technological relevance of additive manufacturing (AM) in the ceramic industry
We examine the use of metal cation complexes with varying cation valence as dispersing agents to control the interparticle forces
The particle stabiliza tion mechanisms brought forward in the present work may lay out the pathway towards a more knowledge-based selection of appropriate dispersing agents for future slurry formulation in the AM ceramic field
Summary
Production of fully dense and defect-free ceramics is an important milestone to boost the technological relevance of additive manufacturing (AM) in the ceramic industry. Achievement of highly dense and homogeneous green bodies is hereby key and remains a topic of research for many material systems [1,2,3] It requires the formulation of stable powder suspensions with high solid loads that respect the rheological property requirements of a given AM technology [4,5]. The influence of the chemical structure of disper sants on their stabilizing effects [22,23,24,25,26,27,28] as well the effect of micelle formation [29,30] on the colloidal stability in organic media has been reported Despite this body of literature, its application to ceramic powder stabilization in non-aqueous systems remains challenging, as demonstrated by numerous empirical studies. The particle stabiliza tion mechanisms brought forward in the present work may lay out the pathway towards a more knowledge-based selection of appropriate (dopant compatible) dispersing agents for future slurry formulation in the AM ceramic field
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