Abstract: To prepare high-performance low thermal conductivity porous anorthite refractory materials,anorthite ceramics were prepared by the high temperature solid-phase reaction at 1 100,1 200,1 300,and 1 400 ℃ holding for 3 h,respectively,using quartz sand fine powder as the silicon source,Al(OH)₃ as the aluminum source,and limestone fine powder (1 110.3 nm of average particle size) and nano calcium carbonate of four particle sizes (653.1,564.4,362.2,and 313.5 nm of average particle size) as the calcium sources.The effects of the heat treatment temperature and calcium source on the properties of the anorthite ceramics were studied.The results indicate that different types of calcium sources (limestone and nano calcium carbonate) have little effect on the phase composition of the synthesized samples,but nano calcium carbonate can significantly reduce the formation temperature of anorthite.As the nano calcium carbonate average particle size decreases from 653.1 nm to 313.5 nm,the anorthite ceramics transform from granular to lamellar and plate columnar;the apparent porosity of the samples is around 18% and the bulk density is around 1.40 g·cm^-3,both of which are not significantly affected;the cold compressive strength of the samples increases from 15.3 MPa to 19.3 MPa,and the thermal conductivity decreases from 1.893 W·m^-1·K^-1 to 1.633 W·m^-1·K^-1.Nano calcium carbonate can reduce the thermal conductivity of anorthite ceramics,providing a technical approach for preparing low thermal conductivity ceramics.

Key words: nano calcium carbonate, high temperature solid-phase method, anorthite, low thermal conductivity

摘要： 为制备性能良好的低导热多孔钙长石耐火材料,以石英砂细粉为硅源,Al(OH)₃为铝源,选取石灰石细粉(平均粒径为1 110.3 nm)、4种不同粒度的纳米碳酸钙(平均粒径分别为653.1、564.4、362.2和313.5 nm)作为钙源,分别在1 100、1 200、1 300和1 400 ℃保温3 h,采用高温固相反应制备了钙长石陶瓷,研究了热处理温度、钙源对钙长石陶瓷性能的影响。结果表明:不同种类钙源(石灰石和纳米碳酸钙)对合成的钙长石试样的物相组成影响不大,但纳米碳酸钙可明显降低生成钙长石相所需温度;随着钙源平均粒径从653.1 nm降低到313.5 nm,钙长石陶瓷由颗粒状向片层状和板柱状转变;试样的显气孔率在18.0%左右,体积密度在1.40 g·cm^-3左右,两者受影响不大;随着钙源粒度的减小,试样的常温耐压强度由15.3 MPa提升至19.3 MPa,热导率由 1.893 W·m^-1·K^-1降低至1.633 W·m^-1·K^-1,使用纳米碳酸钙可以降低钙长石陶瓷的热导率,为制备低导热陶瓷提供了一种技术途径。

关键词: 纳米碳酸钙, 高温固相法, 钙长石, 低热导率