关键词: 镁质轻质骨料, 显微结构, 羟基化TiO₂

Abstract: In order to address the challenges of high load and high thermal conductivity of refractory materials in the firing zone of cement rotary kilns,suitable lightweight aggregates for cement kilns were developed.Foaming slurries were first prepared employing light-burned magnesia powder as the raw material,sodium dodecyl benzene sulfonate (SDBS) as the foaming agent,triethanolamine (TEA) as the dispersant,and TiO₂ as the sintering aid.Then MgO foam slurries were prepared,and lightweight magnesia aggregates were successfully synthesized after firing the MgO foam slurries at 1 600 ℃ for 2 h.The effects of the TiO₂ addition (0,0.5%,1.0%,1.5%,2.0%,and 2.5%,by mass)on the properties and microstructure of magnesia foam slurries and lightweight magnesia aggregates were investigated.The results show that (1)TiO₂ surface hydroxylates;as the TiO₂ addition increases,the viscosity of the foam slurries increases,while the surface tension and contact angle decrease;the average size of the bubbles in the slurries ranges from 114.30 to 53.76 μm;(2)TiO₂ reacts with CaO in the light-burned magnesia powder,forming CaTiO₃;as the TiO₂ addition increases,the average grain size of magnesia increases,the amount of intergranular pores decreases,the bulk density of the lightweight aggregates increases,and the apparent porosity decreases;(3)the optimum physical properties were achieved when the TiO₂ addition was 1.0%.

Key words: lightweight magnesia aggregate, microstructure, hydroxylated TiO₂