materials and coatings
Computer-implemented energy depletion radiation shielding
The difference between Layered Energy Depletion Radiation Shielding (LEDRS) and Stacked Energy Depletion Radiation Shielding (SEDRS) is how the piece of matter, or shield, is analyzed as radiation passes through the matter. SEDRS involves using a defined and ordered stack of layers of shielding with different material properties such that the thickness and chemical properties of each material maximizes the absorption of energy from the radiation particles that are most damaging to the target. The SEDRS shielding method aims to provide the maximum level of energy absorption while still keeping shielding mass and volume low. The process of LEDRS involves using layers of shielding material such that the thickness of each material is designed to absorb the maximum amount of energy from the radiation particles that are most damaging to the target after subsequent layers of shielding. The more energy is absorbed by the shielding material, the less energy will be deposited in the target minimizing the required mass to achieve a resulting lower dose for a given geometrical feature. The LEDRS shielding method aims to provide the maximum level of energy absorption. The process for designing LEDRS views potential radiation shields as a cascade of effects from each shielding layer to the next and is helpful for investigating the particular effects of each layer. SEDRS and LEDRS can improve any technology that relies on the controlled manipulation of a radiation field by interaction with a material element.
Materials and Coatings
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High Atomic Number Coatings for Fabrics
High atomic number materials, such as tantalum, do not bond well to oxygen- and hydroxyl-rich surfaces, such as glass fibers. These metals often form surface oxides when layered on glass fabric, resulting in flaking of the high atomic number material off the fabric during cutting, folding, and/or handling. To improve coating durability, this invention applies a lower atomic number metal as a tie down layer first before applying the high atomic number metal layer. The tie down layer reduces oxide formation between the substrate and the high atomic number material, promoting adhesion. Titanium has shown strong adhesion with different metals and is effective at reducing oxide formation when diffusion bonded to itself or other materials. It has been shown to be effective at improving durability when thermally sprayed onto a glass fiber fabric as a tie down layer for a subsequent tantalum layer (also applied via RF plasma spray). The titanium layer is only approximately 1 mil thick but results in strong adhesion of the tantalum layer by inter-metallic or diffusion bonding. A thermal spray process may be used, as well. This innovation enables the delivery of high atomic metal coating on glass fiber fabrics and other polymeric substrates that are lower cost, lighter weight, and durable to form a flexible cloth material with Z-graded radiation shielding. Coated samples have been produced and the technology is currently at a technology readiness level (TRL) of 4 (prototype).
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