基于水合硅酸镁结构记忆特性制备低硅镁质浇注料  

Effect of Magnesium Silicate Hydrate on Properties of Low-Microsilica Bonded Magnesia-Based Castables

作　　者：李亚伟 廖宁[2] 刘文静[2] 张思思[2] 徐义彪[2] 铁生年[1] 柳馨[1] 李月英[1] LI Yawei;LIAO Ning;LIU Wenjing;ZHANG Sisi;XU Yibiao;TIE Shengnian;LIU Xin;I Yueying(Qinghai University,Key Laboratory of Advanced Materials and Applied Technology for Qinghai,Xining 810016,China;Wuhan University of Science and Technology,National-Provincial Joint Engineering Research Center of High Temperature Materials and Lining Technology,Wuhan 430081,China)

机构地区：[1]青海大学,青海省先进材料与应用技术重点实验室,西宁8100161 [2]武汉科技大学,高温材料与炉衬技术国家地方联合工程研究中心,武汉430081

出　　处：《硅酸盐学报》2023年第3期649-657,共9页Journal of The Chinese Ceramic Society

基　　金：青海省自然科学基金面上项目(2022-ZJ-928)。

摘　　要：水合硅酸镁是炼钢连铸过程中间包用镁质浇注料的重要结合相,其含量多少决定着浇注料的强度大小。本工作以Na_(2)SiO_(3)·9H_(2)O和MgCl_(2)·6H_(2)O为原料,采用水热法合成水合硅酸镁(MgO–SiO_(2)–H_(2)O,M–S–H),研究了焙烧温度和焙烧次数对水合硅酸镁的“结构记忆”特性;随后将预合成M–S–H复合硅微粉制备镁质浇注料,研究其对镁质浇注料性能的影响。结果表明:当焙烧温度低于400℃时,水合硅酸镁具有“结构记忆”特性,焙烧次数增加有利于M–S–H凝胶中层间羟基的插入,促进其层状结构晶粒的长大和结构稳定性的提高;在镁质浇注料制备过程中引入一定量的预合成水合硅酸镁和少量的硅微粉,使浇注料具有很好的施工性能和足够的早期结合强度;同时减少了高温热处理后浇注料缺陷形成,提高了材料力学性能,为开发低硅微粉镁质浇注料提供支撑。Magnesium silicate hydrate(MgO–SiO_(2)–H_(2)O M–S–H)is a main bonding phase for microsilica bonded magnesiumcastables used for tundish.Its content determines the mechanical properties after demolding.In this paper,M–S–H was synthesized with Na_(2)SiO_(3)·9H_(2)O and MgCl_(2)·6H_(2)O as raw materials.The effect of M–S–H at different calcination parameters was investigated by X-ray diffraction,scanning electron microscopy,specific surface area measurement,nuclear magnetic resonance,and thermogravimetry-differential scanning calorimetry.Moreover,the synthesized M–S–H with microsilica powder(1%)was introduced into the magnesia-based castables to evaluate their influences on the properties.The results show that M–S–H has a memory effect when the calcination temperature is below 400℃.Increasing the calcination time can facilitate the insertion of interlayer hydroxyl groups in M–S–H gels and contribute to the formation of a lamellar structure with a higher structure stability.A certain amount of pre-synthesized M–S–H and a small amount of silica powder can assure the castable with a good workability and a sufficient early bonding strength.The reduced silica can suppress the formation of large sized defects due to the volume shrinkage of matrix,in the interface of aggregates and matrix,thus improving the mechanical properties of castables.This work provides a support for the development of magnesia-based castables with a low silica content.

关 键 词：镁质浇注料 低硅微粉 水合硅酸镁 “结构记忆”特性 低温焙烧 

分 类 号：TQ175[化学工程—硅酸盐工业]