Preparation and Neutron Shielding Properties of Fiberglass Based Thermal Insulating Porous Ceramics
Fiberglass based porous ceramics were prepared via foam-gelcasting process using 48.75% (mass fraction)fiberglass and 16.25% (mass fraction)glass particles as main raw materials,0.25% (mass fraction)lsobam-104 as dispersant,0.1% (mass fraction)sodium carboxymethyl cellulose as foam stabilizer,0.6% (mass fraction)sodium dodecyl sulfate as foaming agent,and gadolinium oxide as neutron shielding agent.The effects of heat treatment temperature on the phase composition,micro-structure,pore structure,linear shrinkage,flexural strength,compressive strength,thermal conductivity of and porosity of the porous ceramics,and the effect of gadolinium oxide content on the physical proper-ties,microstructure,neutron shielding performance and thermal conductivity of the porous ceramic com-posites were investigated.The results show that the heat treatment temperature had a great influence on the microstructure and mechanical properties of the porous ceramics.As the temperature increased from 700℃ to 800℃,the size and the number of pores(open pores and window pores)decreased grad-ually,the pore walls became thick and dense,the flexural and compressive strength of the porous ceram-ics increased from 0.3 MPa and 0.75 MPa to 5.1 MPa and 10.7 MPa,respectively,while the thermal con-ductivity increased from 0.075 W/(m·K)to 0.28 W/(m·K).After being treated at 750℃,the physical prop-erties of porous ceramics were excellent,namely the flexural strength,compressive strength and porosity were 1.4 MPa,2.1 MPa,79.8% (mass fraction)respectively and the thermal conductivity was as low as 0.11 W/(m·K).With the increase of gadolinium oxide content from 0 to 6% (mass fraction),the porosity and mechanical properties of porous ceramic composites decrease,but their neutron shielding properties are significantly improved.When added 6.0% (mass fraction)gadolinium oxide,the neutron shielding rate and the thermal neutron shielding rate of the as-prepared porous ceramics were 50.8% and 82.9% (mass fraction)respectively,but the thermal conductivity was still 0.11 W/(m·K).Compared with traditional shielding materials,the glass fiber based insulating porous ceramic composite prepared in this work has excellent mechanical properties,as well as excellent thermal insulation and neutron shielding properties.
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