Microstructure and properties of highly porous Y2SiO5 ceramics produced by a new water-based freeze casting

This study introduced a new structural/functional porous yttrium silicate (Y2SiO5) ceramic, which was prepared using a water-based freeze-casting technique. Moreover, the effects of sintering temperature on the microstructure, compressive strength, thermal conductivity, and dielectric properties of porous Y2SiO5 ceramics were investigated. The microstructure consisting of 3-D interconnected pores were created using the freezing process, and the formation mechanism was discussed. The microstructure observation indicated an increase in the sintering temperature from 1250 degrees C to 1450 degrees C and a decrease in porosity from 71% to 62%. In addition, the pore channel size decreased from 50 mu m to 25 mu m, but the average grain size increased from 1.0 mu m to 3.0 mu m. Consequently, the compressive strength, thermal conductivity, and dielectric constant of the porous Y2SiO5 ceramics increased from 3.34 MPa to 16.51 MPa, from 0.07 W/m K to 0.22 W/m K, and from 1.89 to 2.22, respectively. Porous Y2SiO5 ceramics with such properties can be applied to ultra-high temperature broadband radome structures and thermal insulators. (C) 2012 Elsevier Ltd. All rights reserved.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000314870000091&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Materials Science, MultidisciplinarySCI(E)EI18ARTICLE746-7504