玻璃纤维基隔热多孔陶瓷的制备及其对中子的屏蔽性能

Preparation and Neutron Shielding Properties of FiberglassBased Thermal Insulating Porous Ceramics

以玻璃纤维和玻璃颗粒为主要原料、以Isobam-104为分散剂、羧甲基纤维素钠为稳泡剂、十二烷基硫酸钠为发泡剂、氧化钆为中子屏蔽填料,用泡沫凝胶注模法制备玻璃纤维基隔热多孔陶瓷复合材料,研究了热处理温度对其物相组成、微观结构、机械性能和热导率的影响以及氧化钆的含量对其理化性能和中子屏蔽性能的影响。结果表明,热处理温度从700℃提高到800℃,使多孔陶瓷的强度、体积密度和热导率显著提高、气孔率降低,其抗压强度和抗折强度分别从0.75和0.3 MPa提高到10.7和5.1 MPa,热导率从0.075 W/(m·K)提高到0.28 W/(m·K)。热处理温度为750℃的材料其抗折强度、抗压强度、开口气孔率和热导率分别为1.4 MPa、2.1 MPa、79.8%和0.11 W/(m·K)。氧化钆的添加量(质量分数,下同)从0提高到6%,多孔陶瓷复合材料的强度逐渐降低、对中子的屏蔽效率逐渐提高。氧化钆添加量为6.0%的多孔陶瓷其抗折强度仅为0.63 MPa,抗压强度为0.86 MPa,中子屏蔽率为50.8%,热中子屏蔽率高达82.9%,但是不影响多孔陶瓷的热导率。

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)Isobam-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,microstructure,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 properties,microstructure,neutron shielding performance and thermal conductivity of the porous ceramic composites 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 700oC to 800oC,the size and the number of pores(open pores and window pores)decreased gradually,the pore walls became thick and dense,the flexural and compressive strength of the porous ceramics increased from 0.3 MPa and 0.75 MPa to 5.1 MPa and 10.7 MPa,respectively,while the thermal conductivity increased from 0.075 W/(m·K)to 0.28 W/(m·K).After being treated at 750oC,the physical properties 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.