Diatom-Inspired SiC/SiOx Heat Shield for Re-entry Radiation Reflection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current thermal protection systems for re-entry vehicles are inadequate in withstanding high-speed atmospheric re-entry heating, particularly radiative heating, which poses risks for crewed missions and limits payload capacity due to the need for heavy heat shields.
Innovation Solution
A heat shield material composed of a mixture of SiC and SiOx with a quasi-periodic diatom pore structure, processed to enhance radiation reflection and phase change characteristics, is developed using diatoms and magnesium, forming MgO, Si, and SiC to create a refractory layer with high optical reflectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heat shield is made heavier to withstand high-speed re-entry heating, then thermal protection capability is improved, but payload capacity deteriorates
Solution Approach 1:
The patent employs a composite material system consisting of a refractory ceramic matrix (containing alumina, silica, and other oxides) reinforced with silicon carbide particles and whiskers. This composite structure provides both the thermal protection capability needed to withstand high-speed re-entry heating and the reduced density required to minimize heat shield mass, thereby improving payload capacity while maintaining reliability
Solution Approach 2:
The refractory ceramic matrix incorporates a controlled porous structure with pore sizes ranging from 0.1 to 10 micrometers. These pores provide thermal insulation by reducing heat conduction through the material, allowing the heat shield to achieve adequate thermal protection with reduced material density and mass
2Weight of moving object
If a heat shield is made lighter to increase payload capacity, then payload mass is improved, but thermal protection capability deteriorates
Solution Approach 1:
The silicon carbide-reinforced refractory ceramic composite provides high strength-to-density ratio, enabling the heat shield to be made lighter while maintaining structural integrity and thermal protection capability during high-speed re-entry
Solution Approach 2:
The heat shield material utilizes phase change mechanisms, including the transformation of silicon carbide and the melting/vaporization of selected matrix components at high temperatures, to absorb thermal energy and maintain thermal protection capability with reduced material mass
3Reliability
If conventional heat shield materials are used to withstand heating, then thermal protection is achieved, but radiative heat load reflection is insufficient
Solution Approach 1:
The silicon carbide particles and whiskers in the refractory ceramic matrix provide enhanced radiative heat load reflection capabilities. Silicon carbide has optical properties that reflect a significant portion of incident radiative heating, reducing the thermal energy absorbed by the heat shield and improving overall thermal protection efficiency
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The material effectively reduces heat absorption by reflecting radiation and withstanding high temperatures, allowing for reduced heat shield mass and increased payload capacity while maintaining thermal protection.
Implementation Method 1
Provision of a heat shield that has an approximately periodic structure that is preferentially reflective for wavelengths in the range {λrad} would reduce the fraction of radiation that contacts the RV surface
Implementation Method 2
the primary heat shield material is refractory and has a high phase change temperature for ablating
Implementation Method 3
The optical reflectivity value OR tends to increase with increasing incidence angle of radiation received at the heat shield component
Data Source
AI summary
A thermal protection system (TPS) comprising a mixture of silicon carbide and SiOx that has been converted from Si that is present in a collection of diatom frustules and at least one diatom has quasi-periodic pore-to-pore separation distance d(p-p) in a selected range. Where a heat shield comprising the converted SiC/SiOx frustules receives radiation, associated with atmospheric (re)entry, a portion of this radiation is reflected so that radiation loading of the heat shield is reduced.