Freeze-drying preparation of porous diatomite ceramics with high porosity and low thermal conductivity

ABSTRACT

Hierarchically porous diatomite ceramics were fabricated by the freeze-drying method using Xanthan Gum as a gelling agent. They showed high porosity of 84.8–92.7% and a low thermal conductivity value of 0.061–0.123 W m⁻¹ K⁻¹ (tested at 473–1073 K). Their compressive strength increased with increasing the preparation temperature and/or the solid loading level. The porous sample with 15 wt-% solid loading, after 2 h firing at 1373 K, showed a porosity level of 92.7%, a compressive strength of 0.11 ± 0.01 MPa and a thermal conductivity value as low as 0.061 ± 0.001 W m⁻¹ K⁻¹. The above data indicated that hierarchically porous diatomite ceramics prepared by the present freeze-drying method possessed reasonable mechanical strength but superior thermal insulation properties.

KEYWORDS:

• Freeze-drying
• porous diatomite ceramics
• hierarchically pore-structured
• high porosity
• thermal conductivity

Disclosure statement

No potential conflict of interest was reported by the author(s).

ORCID

Lei Han http://orcid.org/0000-0002-6900-227X

Haijun Zhang http://orcid.org/0000-0002-9546-8524

Quanli Jia http://orcid.org/0000-0002-0437-5358

Shaowei Zhang http://orcid.org/0000-0001-6861-5229

Additional information

Funding

This work was supported by National Natural Science Foundation of China [grant numbers 51672194, 51872210 and 51502211]; China Scholarship Council [grant number 201808420278]; Key Program of Natural Science Foundation of Hubei Province, China [grant number 2017CFA004]; Program for Innovative Teams of Outstanding Young and Middle-aged Researchers in the Higher Education Institutions of Hubei Province [grant number T201602].