| High strength and low thermal conductivity has always been the research direction of thermal insulation refractory materials.In order to further improve the strength and reduce the thermal conductivity of thermal insulation materials prepared by the traditional burnout method of plant pore-forming agent.The paper took Al2O3insulation refractory as the research object.Combining the burnout method of plant pore-forming agent with the preparation method of morph-genetic materials（sol-gel method）,sol-impregnated plant pore-forming agent template was introduced into the preparation of Al2O3 insulation material.The main research content includes:Corn stalk was impregnated with aluminum oxide,zirconia and silicon sol under vacuum to study the influence of sol types and concentrations on the structure and properties of the pore-forming agent.In addition,the sol-impregnated corn stalk was used as the plant pore-forming agent template to prepare thermal insulation materials.The pore structural analysis and related properties test were carried out to explore the influence of plant morph-genetic structure on the performance of thermal insulation materials.The results show that:（1）The hygroscopicity of pore-forming agent was greatly affected by the type of sol,and the degree of hygroscopicity affected by the concentration of sol varies with the type of sol.The spring-back height of pore-forming agent changed little.In addition,by using aluminum oxide sol as the impregnating agent,the original tube pore structure of the corn stalk could be retained at 1200℃without loosening and collapse.（2）Compared with the irregular macro-pores formed by using the untreated corn stalk as the pore-forming agent,most of the pore structures changed significantly when the sol-infiltrated corn stalk was used as the pore forming agent to prepare Al2O3 insulation material.When aluminum oxide sol-infiltrated corn stalk and silica sol-infiltrated corn stalk were used as pore-forming agent,the plant derived morph-genetic structure caused changes in the parameters of pore structure,such as the shape,size and distribution of pores.However,when zirconia sol-infiltrated corn stalk was used as pore forming agent,the morph-genetic structure of pore forming agent remained inside the irregular pores due to the volume change caused by the crystal transformation of zirconia.（3）Compared with the insulation materials prepared by three kinds ofsol-infiltrated corn stalk as pore forming agent,the best scheme in this experiment was determined to prepare the insulation materials by introducing 3 wt%silica sol-infiltrated corn stalk as pore forming agent.After sintering at 1110℃,the cold compressive strength was up to 48.64 MPa,and the thermal conductivity at 800℃was 0.447 W/m·K.The reduction of thermal conductivity and the improvement of material strength were realized at the same time.And based on the Maxwell-Eucken basic model,a model which can be used to predict the effective thermal conductivity of the insulation material at different temperatures was established. |
