Fabrication of ice-templated tubes by rotational freezing: microstructure, strength, and permeability

TL;DR

This paper introduces a scalable rotational freezing technique to produce porous ceramic tubes with controlled microstructure, strength, and permeability, suitable for membrane support applications.

Contribution

It presents a novel rotational freezing method for fabricating radially porous ceramic tubes with tunable properties, expanding the capabilities of ice-templating processes.

Findings

Pore volume and size are controllable via solid loading and freezing temperature.

Tube thickness can be adjusted by slurry volume.

Higher strength correlates with smaller pores and lower permeability.

Abstract

We demonstrate a facile and scalable technique, rotational freezing, to produce porous tubular ceramic supports with radially aligned porosity. The method is based on a conventional ice-templating process in a rotatory mold and demonstrated here with yttria-stabilized zirconia (YSZ). We investigated the effects of solid loading, freezing temperature, and volume of the slurry on the microstructure, strength (o-ring test and four-point bending), and air permeability. The results show that pore volume and pore size can be controlled by the solid loading and freezing temperature respectively, and overall tube thickness can be adjusted by the volume of slurry initially poured into the mold. Decreasing pore size and pore volume increases the mechanical properties but decreases the air permeability. These tubes could be particularly interesting as tubular membrane supports such as oxygen transport membranes.