Design,Preparation And Performance Of Basalt Fiber/Boron Phenolic Resin Lightweight Composites

Effective thermal protection materials are essential for achieving hypersonic flight of aircraft.Currently,thermal protection materials based on fiber-reinforced resin ablation are considered to be a highly efficient,reliable,and mature form of thermal protection.However,due to factors such as the high cost of fibers and the large weight of the structure,the effective load and maneuverability of spacecraft are negatively impacted.Therefore,this study proposes to use lightweight boron-phenolic resin as the matrix and basalt fiber as the reinforcement to design and prepare lightweight composite materials,based on the low cost,high-temperature resistance,and excellent mechanical properties of basalt fibers,and the high residual carbon content and excellent high-temperature resistance of boron-phenolic resin,and then conduct performance research.The main research conclusions are as follows:Based on the multiscale characteristics of composite materials,homogenization methods are introduced to achieve cross-scale correlation.A prediction method for the effective thermal and mechanical properties of composite materials based on periodic boundary conditions is developed and validated with experimental values in the literature.The prediction errors of the equivalent thermal and mechanical parameters are both less than 10%,indicating good reliability.Using lightweight boron-phenolic resin as the matrix and basalt fiber as the reinforcement,finite element models of the matrix with different pore sizes,pore distributions,and porosities can be established based on a stochastic algorithm at the microscale.Combined with the developed prediction method,it is found that composites with the smaller pore size and more uniform distribution in the matrix show better overall thermal and mechanical performance.By establishing finite element models of fiber bundles at the microscale and single/composite fiber structures with various process structures at the mesoscale,it is found that the best thermal and mechanical performance is achieved by using composite form with diagonal fiber cloth and in-plane randomly distributed long fibers.Based on the optimized design structure and boron-phenolic resin with different densities,basalt fiber-reinforced boron-phenolic resin lightweight composite materials can be prepared.Analysis of their microstructures shows that the pore size is small and evenly distributed,consistent with the optimized design results.The mechanical properties increased with the increased concentration of boron-phenolic resin.The tensile modulus and tensile strength are up to 857.4MPa and 31.3 MPa,and the bending strength is up to 36.4 MPa.Compression strength up to206.4 MPa.The heat insulation property decreases with the concentration of boron-phenolic resin,the thermal conductivity rises from 0.035 W/(m·K)to 0.067 W/(m·K).Under the condition of oxyacetylene ablation,the mass ablation rate and line ablation rate of the composites are 0.059 g/s and 0.141 mm/s,respectively.