Preparation And Property Of Silica-Alumina Composite For High Temperature Insulation Tile

With the hypersonic vehicle and Near space vehicle Maher number continuous improving and the flight time prolonging in the atmosphere, which is represented by HTV-2 and X-37 B, the aerodynamic heating environment of the new aircraft is becoming increasingly severe, and the thermal protection is becoming more and more serious. It is urgent to develop a new type of thermal protection material to solve the key problems in the development of aircraft.Insulation tile is a kind of porous material made of chopped fiber after high temperature sintering, which has high porosity and low density. It is a kind of high efficiency thermal protection material with the advantages of stable shape and mechanical properties at high temperature, and also has the function of heat insulation, anti impact erosion and keeping the aerodynamic shape of the vehicle. It can be application in large thermal protection area except the high temperature zone(nose and wing leading edge, etc.). in the new vehicle thermal protection materials a large proportion is vehicle thermal protection and thermal control problem of the subject. A large proportion of thermal protection materials for aircraft is the main body of thermal protection and thermal control problems of aircraft.In this paper, the high purity ultrafine quartz fiber and alumina fiber are main raw material, with the boron silicon glass as the high temperature binder.The silica-alumina composite insulation tile was prepared through cutting short fiber processing, effectively dispersed, wet molding and high temperature heat treatment process, and its preparation process, microstructure, conventional thermal physical properties, mechanical properties and reusable performance were characterization and evaluation.The results show that the ratio of length to diameter of quartz fibers can be controlled by the high speed shearing process. Hydrochloride by adjusting the p H value to be 2-4 can get uniform dispersion of the fiber slurry, controlling vacuum degree-0.08 MPa and holding time 5-10 min can realize every tile vacuum forming, gradual drying process excluded insulation tiles in excess water. After heat treatment temperature 1200-1260℃ and keeping 1-3 hour, the high temperature insulation tile with a certain strength and excellent heat insulation performance is obtained.The silicon-alumina high temperature insulation tile coefficient of thermal conductivity was less than 0.05W/m?K under normal temperature, the density was controllable between 0.2-0.5g/cm3, the compressive strength of thickness is between 0.2-2MPa, the tensile strength is between 0.1-1MPa, and the material has excellent workability. Repeated test results show that the heat insulation tile can be recycled 10 times under the conditions of 1200 degrees, the overall performance changes can meet the application conditions.High radiation coating was prepared on the surface of insulation tile by slurry spraying and heat treatment process, typical insulating tile samples by the wind tunnel test, test after heat insulation tile structure complete, there is no change in the size, back temperature to meet the design requirements. After the wind tunnel test, typical insulation tile samples keep complete structure, and back temperature can meet the design requirements.By adding the aerogel, the internal gas heat conduction was further reducing. The results show that: the density of the insulation tile composite increased after adding the aerogel, the room temperature thermal conductivity decreased by 30%, and the thermal conductivity of 1000℃ decreased by 22% while the compressive strength was greatly improved. With the increasing of the insulation tile original density, the adding of the aerogel content decreased, and the compressive strength increasing trend becomes slow.