Study On The Structure And Properties Evolution Of Integrated Thermal Protection And Insulation Composites

In recent years the success of the X-37B with the new toughened uni-piece fibrous refractory oxidation-resistant ceramic?TUFROC?represents the highest level of reusable space maneuver aircraft at this stage.It is one of the core technologies in the development of space maneuvering aircraft because of its combination of high temperature dimension,high efficiency heat insulation,light weight,reliable reliability and reusable performance.Non-ablative thermal insulation integrated thermal protection material is also the same type of thermal protection material.Its outer surface is carbon cap,whose surface is impregnated with non-ablation of ultra-high temperature ceramic to resistant to1700?.The inner layer of porous oxide fiber can achieve the effect of insulation and support.While the inner layer is divided into resistant to 1500?and resistant to1200?double-decker structure.The material structure is complex and there is a large temperature gradient,so it is necessary to solve these problems by identifying the material failure mode,revealing the failure mechanism,establishing the reusability evaluation method,and predicting the service life limit in the material service environment.In this paper,different monolayer structural materials in this material were tested under static high temperature condition,and their microstructure and properties were analyzed.The structure and property evolution of single layer materials were obtained and their reusable performance was discussed.The static oxidation resistance of ZrB₂-based ultra-high-temperature ceramics with different compositions at 1700?was studied.The oxidation behavior,catalysis and radiation properties of ZrB₂-based ultra-high temperature ceramics were studied,and make a suggestion to the preparation of surface materials.Repeated static oxidation at1700?indicated that the solid product in the oxidation products of ZrB₂-20%SiC,ZrB₂-20%MoSi₂,ZrB₂-10%SiC-10%MoSi₂ could cover the surface of the material completely,and the liquid product was sufficient,Covering the oxidation of the outermost layer,to prevent further oxygen,play the role of antioxidant.For the ZrB₂-20%TaSi₂ and ZrB₂-10%SiC-10%TaSi₂ oxidation products,the solid products are more and the liquid SiO₂ is less,which in the latter part of the oxidation can not fully cover the material surface to achieve the protective effect,thus material failure.For the ZrB₂-20%SiB₆,the gaseous borides are more generated,the gas is volatilized to form the porous morphology,and the solid product can not completely fill the matrix,thus it does not have the repeated use conditions.The structure and property evolution of resistant to 1500?ceramic thermal insulation materials treated at different temperature,repeated treatment times and heat treatment way were studied.First,the treatment at 1200?to 1500?for 35 min showed that the shrinkage rate increased,the porosity decreased,the degree of interfiber adhesion increased,the mechanical strength decreased.After 1500?treatment,the material shrinks greatly and was crushed by force.Secondly,the repeated treatment at different temperatures from 1200?to 1400?showed that the fiber gradually crystallized with the increase of the number of treatment,and the higher the temperature,the faster the crystallization rate.Finally,the single-sided repeat treatment at 1500?for 9 times showed that the material had high macro-dimensional stability,but the rate of crystallization was fast,and the material was crushed after being subjected to stress.In short,the material shrinkage is too large or excessive crystallization,the material will be crushed by force damage.The structure and property evolution of resistant to 1200?ceramic thermal insulation materials treated at different temperature,repeated treatment times and heat treatment way were studied.First,the treatment of 800?to 1200?for 20min showed that the shrinkage rate increased with the increase of treatment temperature,the porosity decreased and the degree of interfiber adhesion increased.After 1400?treatment,the material shrinks greatly and was crushed by force.Secondly,repeated treatment at 1200?for 20 times showed that the fiber had obvious crystallization tendency,but the change of mechanical properties was not obvious.Finally,the single-sided repeat treatment at 1200?for 50 times showed that the macro-dimensional stability of the material was high,and the strength in the range of the elasticity of the mechanical properties was reduced to 1.5 MPa.