摘要
多孔骨料是对耐火材料进行轻量化设计的关键。以轻烧菱镁矿、氢氧化铝和铁红为原料,采用原位分解合成法,成功制备了多孔镁基镁铁铝复合尖晶石耐火骨料,在分析烧成温度(1000~1600℃)对显微结构与强度影响的基础上,研究了多孔骨料的合成机理。研究表明:当烧成温度为1000~1300℃时,试样内气孔来自微颗粒内和微颗粒之间,基本没有颈部连接;当烧成温度升高到1400~1600℃时,微颗粒内气孔合并长大、迁出,颈部显著长大,强度提高;镁铁铝复合尖晶石的形成过程分为2步,一是在氢氧化铝假象表面生成MgAl_(2)O_(4)后,再与Fe^(3+)反应生成环状镁铁铝复合尖晶石,二是在MgO位置生成MgFe_(2)O_(4),再与Al^(3+)反应生成粒状和条状镁铁铝复合尖晶石;当烧成温度为1550℃时,试样具有优异的综合性能,其显气孔率为24.4%,中位孔径为25.89μm,导热系数为2.79 W/(m·K)(1000℃),耐压强度为74.4 MPa,与市售烧结镁砂相比,导热系数降低了64.7%。
Porous aggregates are a key material for the lightweight refractory.Porous magnesia based composite spinel(Mg(Fe,Al)2O4)refractory aggregates were prepared by an in-situ decomposition synthesis method with calcined magnesite,Al(OH)3and iron oxide as raw materials.The influence of sintering temperature(i.e.,1000–1600℃)on the microstructures and strengths was investigated,and the synthesis mechanism of porous aggregates was analyzed.The results show that the pores in the samples are composed of the pores in the micron-sized particles and the pores among micron-sized particles as well as they have a few neck connections at the sintering temperatures of 1000–1300℃,and the pores in the micron-sized particles migrate to the gaps and the necks grow with a further increase of sintering temperature to 1400-1600℃,thus promoting the compressive strength of the samples.The formation of composite spinel(Mg(Fe,Al)2O4)in the samples involves that MgAl_(2)O_(4)is formed on the surface of Al(OH)3pseudomorph and reacts with Fe3+to form the composite spinel(Mg(Fe,Al)2O4)with a ring structure,and MgFe_(2)O_(4)is formed in the position of MgO and reacts with Al^(3+)to form the composite spinel(Mg(Fe,Al)2O4)with the granular and strip structures.The porous magnesia based composite spinel(Mg(Fe,Al)2O4)refractory aggregates have the optimum performance(i.e.,an apparent porosity of 24.4%,a median pore size of 25.89μm,a thermal conductivity of 2.79 W/(m·K)at 1000℃and a compressive strength of 74.4 MPa)at the sintering temperature of 1550℃.Meanwhile,compared with the existing sintered magnesia,the thermal conductivity of porous magnesia based composite spinel(Mg(Fe,Al)2O4)refractory aggregates synthesized can be reduced by 64.7%.
作者
陈茜琳
鄢文
王晓
CHEN Qianlin;YAN Wen;WANG Xiao(Wuhan University of Science and Technology,The State Key Laboratory of Refractories and Metallurgy,Wuhan 430081,China;Qinghai University,School of Chemical Engineering,Xining 810016,China)
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2023年第3期571-578,共8页
Journal of The Chinese Ceramic Society
基金
国家自然科学基金(U1908227,U21A2058)。
关键词
多孔耐火骨料
镁基镁铁铝复合尖晶石
原位分解合成法
显微结构
强度
porous refractory aggregates
magnesia based composite spinel(Mg(Fe
Al)2O4)
In-situ decomposition synthesis method
microstructures
strengths
