红柱石的莫来石化作用及机理

Transformation and Mechanism of Andalusite to Mullite

介绍了以红柱石为骨料、堇青石为基质、粘土为结合剂,在1350℃×4h、1400℃×4h、1450℃×4h三种不同烧成工艺条件下红柱石的莫来石化作用,通过对试样的性能测试和显微结构分析表明:在1400℃×4h条件下莫来石的针状晶体发育良好且呈网络结构,大大提高了材料的物理性能:常温抗折强度(MPa)由1350℃×4h和1450℃×4h时的11.3MPa和8.9MPa提高为1400℃×4h的15.5MPa;常温耐压强度由1350℃×4h和1450℃×4h时的18.4MPa和16.7MPa提高为1400℃×4h的25.2MPa。同时还研究了红柱石的莫来石化机理:红柱石的莫来石化作用通常由颗粒边沿或颗粒裂隙部位开始,逐步向颗粒的中心部位扩展。红柱石的莫来石化针状晶体互相平行,且与颗粒边沿垂直。在相同的烧成制度下,小颗粒的红柱石较大颗粒红柱石的莫来石化程度高。对红柱石的开发和利用具有一定的实际指导意义。

By using andalusite as aggregate,cordierites as substrate and clay as binder,the transformation of andalusite to mullite is studied respectively under such different sintering systems as 1 350℃×4h,1 400℃×4h and 1 450℃×4h.The properties test and micro-structure analyses show that the crystals of mullite have a good growth at 1 400℃×4h,and the crystals of mullite play very important rule in improving the properties of the material,i.e.Cold Modulus Of Rupture(CMOR) can be improved from 11.3MPa and 8.9MPa respectively under the sintering systems of 1 350℃×4h and 1 450℃×4h to 155MPa,and Cold Crushing Strength (CCS) from 184MPa and 167MPa to 252MPa respectively under the above same systems.It was proved that the transformation of andalusite to mullite begun in the fringe or fissure of the pellet then gradually extended to the center.The crystals of mullite are parallel each other,and perpendicular to the pellet of mullite.At the same sintering system,the smaller the pellet of andalusite,the easer the transformation than the bigger.The study lays a foundation for the use of andalusite.