Architectural Control of Freeze‐Cast Ceramics Through Additives and Templating

TLDR

Freezing concentrated colloidal suspensions is a complex process governed by many parameters that can be used to manipulate freeze‑cast material architecture across multiple length scales, yet predictive models for ice crystal growth in particle slurries remain undeveloped. The study aims to deepen understanding of how experimental conditions relate to microstructure in freeze‑cast materials to enable reliable control. The authors investigate how processing variables such as suspension composition, freezing rate, and freezing surface patterning influence architectural manipulation of freeze‑cast materials. They show that halving lamellar thickness in freeze‑cast lamellar structures boosts compressive strength by over tenfold.

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, that reducing the lamellar thickness by less than half increases the compressive strength by more than one order of magnitude.