In a high heat flux ablative environment,the surface temperature of aircraft rises rapidly,leading to traditional high thermal conductivity materials being ineffective at protecting internal metal components.In this s...In a high heat flux ablative environment,the surface temperature of aircraft rises rapidly,leading to traditional high thermal conductivity materials being ineffective at protecting internal metal components.In this study,continuous carbon fiber reinforced Li_(2)O-Al_(2)O_(3)-SiO_(2)(C_(f)/LAS)glass ceramic composites doped with SiC particles(SiC_(p))were prepared by slurry immersion winding and hot pressing sintering.Effect of matrix crystallinity on ablative properties of the composites under ultra-high heat flux was investigated.By utilizing heat absorption and low thermal conductivity characteristics associated with SiO_(2)gasification within composite materials,both surface and internal temperatures of these materials are effectively reduced,thereby ensuring the safe operation of aircraft and electronic devices.Results indicate that the average linear ablation rate of composites doped with 10%(in mass)of SiC_(p)significantly decreases at a heat flux of 20 MW/m^(2).Transmission electron microscope observation reveals that the doped glass matrix exhibits increased crystallinity,reduced internal stress,and minimized lattice distortion,thereby enhancing the composites’high-temperature performance.However,excessive SiC_(p)doping leads to reduced crystallinity and deteriorated ablation performance.Ultimately,the average linear ablation rate of C_(f)/LAS composites with 10%(in mass)SiC_(p)at 20 MW/m^(2)heat flux is comparable to that of commercial carbon/carbon composites,accompanied by providing lower thermal conductivity and higher bending strength.This novel high-performance C_(f)/LAS composite is cost-effective,short-cycled,and suitable for mass production,offering promising potential for widespread application in ablation-resistant components of hypersonic vehicles.展开更多
Ultra-high temperature materials are desirable to withstand the severe aero-thermochemical environments of hypersonic flight,paving the groundworks for flight speeds exceeding Mach 5.Here,we present a novel ultra-high...Ultra-high temperature materials are desirable to withstand the severe aero-thermochemical environments of hypersonic flight,paving the groundworks for flight speeds exceeding Mach 5.Here,we present a novel ultra-high temperature composite with superior ablation resistances up to 3000℃for 900 s,utilizing a tailored ultra-high melting point HfC_(0.76)N_(0.24)matrix reinforced with short carbon fibers.The ablation-resistant capability of this composite is over 14 times greater than that of HfC at 3000℃.Furthermore,this research presents the first comprehensive investigation into the internal mechanisms governing thermal oxidation evolution of HfC_(0.76)N_(0.24)matrix through a combination of experimental results and theoretical simulations.The mechanistic details of these complex oxidation processes are elucidated in terms of chemical bonding and clusters evolutions,along with their relationship to cooperative oxygen atoms and molecules.Notably,nitrogen atoms do not directly generate gas and escape from the composites,rather,they interact with hafnium atoms to form Hf-C-N-O clusters with robust bonding for enhanced viscosity during ablation.These findings provide valuable insights into the transition from micro to macro scales,which will be the paradigm of inspiring and accelerating materials discovery in this field,as well as taking advantage of their full potential in the application of hypersonic aircraft and spacecraft vehicles.展开更多
基金National Natural Science Foundation of China(U23A6014,52103357)。
文摘In a high heat flux ablative environment,the surface temperature of aircraft rises rapidly,leading to traditional high thermal conductivity materials being ineffective at protecting internal metal components.In this study,continuous carbon fiber reinforced Li_(2)O-Al_(2)O_(3)-SiO_(2)(C_(f)/LAS)glass ceramic composites doped with SiC particles(SiC_(p))were prepared by slurry immersion winding and hot pressing sintering.Effect of matrix crystallinity on ablative properties of the composites under ultra-high heat flux was investigated.By utilizing heat absorption and low thermal conductivity characteristics associated with SiO_(2)gasification within composite materials,both surface and internal temperatures of these materials are effectively reduced,thereby ensuring the safe operation of aircraft and electronic devices.Results indicate that the average linear ablation rate of composites doped with 10%(in mass)of SiC_(p)significantly decreases at a heat flux of 20 MW/m^(2).Transmission electron microscope observation reveals that the doped glass matrix exhibits increased crystallinity,reduced internal stress,and minimized lattice distortion,thereby enhancing the composites’high-temperature performance.However,excessive SiC_(p)doping leads to reduced crystallinity and deteriorated ablation performance.Ultimately,the average linear ablation rate of C_(f)/LAS composites with 10%(in mass)SiC_(p)at 20 MW/m^(2)heat flux is comparable to that of commercial carbon/carbon composites,accompanied by providing lower thermal conductivity and higher bending strength.This novel high-performance C_(f)/LAS composite is cost-effective,short-cycled,and suitable for mass production,offering promising potential for widespread application in ablation-resistant components of hypersonic vehicles.
基金funding by the National Natural Science Foundation of China(52302128)the Foundation of State Key Laboratory of Science and Technology on Advanced Ceramic Fibers and Composites(No.6142907230303).
文摘Ultra-high temperature materials are desirable to withstand the severe aero-thermochemical environments of hypersonic flight,paving the groundworks for flight speeds exceeding Mach 5.Here,we present a novel ultra-high temperature composite with superior ablation resistances up to 3000℃for 900 s,utilizing a tailored ultra-high melting point HfC_(0.76)N_(0.24)matrix reinforced with short carbon fibers.The ablation-resistant capability of this composite is over 14 times greater than that of HfC at 3000℃.Furthermore,this research presents the first comprehensive investigation into the internal mechanisms governing thermal oxidation evolution of HfC_(0.76)N_(0.24)matrix through a combination of experimental results and theoretical simulations.The mechanistic details of these complex oxidation processes are elucidated in terms of chemical bonding and clusters evolutions,along with their relationship to cooperative oxygen atoms and molecules.Notably,nitrogen atoms do not directly generate gas and escape from the composites,rather,they interact with hafnium atoms to form Hf-C-N-O clusters with robust bonding for enhanced viscosity during ablation.These findings provide valuable insights into the transition from micro to macro scales,which will be the paradigm of inspiring and accelerating materials discovery in this field,as well as taking advantage of their full potential in the application of hypersonic aircraft and spacecraft vehicles.
