| Fiber-reinforced silica aerogel thermal insulation composites have the characteristics of low density,low thermal conductivity and good mechanical properties,and have been widely used in aerospace,petrochemical and other fields.However,the current preparation process is complicated,which limits its application.In this paper,aiming at the goal of rapid preparation of thermal insulation composites with low density,low thermal conductivity and good mechanical properties,using silica aerogel,rock wool fiber,white cement,silicon carbide,etc.as raw materials,silica aerogel thermal insulation composites with low density,low thermal conductivity and good mechanical properties were prepared through a simple pouring process.The composition,structure and properties of composites were studied,and optimal preparation parameters were obtained.The main research contents and conclusions of this paper are drawn as follows:（1）Through composition and process design,it is determined that silica aerogel is used as thermal insulator,rock wool fiber is used as reinforcement,white cement is used as binder,silicon carbide is used as infrared opacifier,propylene glycol block polyether is used as surfactant,and DI water is used as solvent.The forming process is determined that fiber is solid-dispersed,and cement is post-added.（2）Through the orthogonal experiment of four factors and three levels,the influence of the raw material ratio on the density,room temperature thermal conductivity and compressive strength of the composites was studied.White cement and rock wool fiber have a great influence on the properties of composites.The influence of factors on the properties of composites is in following order:white cement>rock wool fiber>propylene glycol block polyether diluent>DI water.As a binder,the amount of white cement directly determines the degree of bonding between the components in the composites,which has an important impact on the density,thermal conductivity and compressive strength of the composites.（3）Through the single-factor experiment,the influence of the mass of white cement and rock wool fiber,and reinforcement form on the composition,structure and properties of the composites was studied,and the optimal preparation parameters were obtained.As the mass of white cement increases,the density of the composites changes little,the pores and cracks in the composites decrease,and the room temperature thermal conductivity,high temperature thermal conductivity and compressive strength increase.With the increase of rock wool fiber mass,the compressive strength of the composites first increases and then decreases,and the density and thermal conductivity do not change much.Compared with glass fiber chopped yarn,the glass fiber mesh can greatly improve the compressive,flexural and tensile strength of the composites,and has little effect on the density,the room temperature thermal conductivity,and the high temperature thermal conductivity.When the raw material ratio is silica aerogel:Si C:rock wool fiber:white cement:propylene glycol block polyether diluent:DI water（mass ratio）=135:15:45:48:3.6:570,the glass fiber mesh with mesh of 1.5 mm×1.5 mm is used to reinforce at the upper,middle,and lower surfaces of the composites,and the reinforced composites has low density,low thermal conductivity and good mechanical properties.The density of the composites is 0.26 g·cm-3,the room temperature thermal conductivity is 0.040W·m-1·K-1,the high temperature thermal conductivity at 800℃is 0.057 W·m-1·K-1,the compressive strengths at 3%and 10%strain are 0.309 MPa and 0.673 MPa,the flexural strength is 0.674 MPa,and the tensile strength is 0.128 MPa. |
