Architectural control of freeze-cast ceramics through additives and templating

TL;DR

This paper investigates how additives and templating influence the microstructure of freeze-cast ceramics, aiming to improve control over architecture and enhance mechanical properties through processing variables.

Contribution

It provides experimental insights into how suspension composition, freezing rate, and patterning affect microstructure, advancing the understanding of architectural control in freeze-cast ceramics.

Findings

Reducing lamellar thickness by less than half significantly increases compressive strength.

Processing variables can be manipulated to tailor microstructure at multiple scales.

Experimental relationships between conditions and microstructure are explored.

Abstract

The freezing of concentrated colloidal suspensions is a complex physical process involving a large number of parameters. These parameters provide unique tools to manipulate the architecture of freeze-cast materials at multiple length scales in a single processing step. However, we are still far from developing predictive models to describe the growth of ice crystals in concentrated particle slurries. In order to exert reliable control over the microstructural formation of freeze-cast materials, it is necessary to reach a deeper understanding of the basic relationships between the experimental conditions and the microstructure of the growing solid. In this work, we explore the role of several processing variables (e.g., composition of the suspension, freezing rate, and patterning of the freezing surface) that could affect the formulation strategies for the architectural manipulation of freeze-cast materials. We also demonstrate, using freeze-cast lamellar structures, how reducing the lamellar thickness by less than half increases compressive strength by more than one order of magnitude.