A syntactic foam is a composite material that is made by filling a polymer, ceramic, or metal with pre-formed hollow glass or ceramic spheres called micro balloons. The term ‘syntactic’ refers to the ordered arrangement of the spheres, and the term ‘foam’ refers to the closed cellular structure.
Syntactic Foam Properties
The hollow spheres within syntactic foam provide most of the materials beneficial properties. They have high specific strength, a low coefficient of thermal expansion, and lower overall density due to their air- or gas-filled content.
Syntactic foams are extremely tailorable; there is a lot of choice for the matrix material, the size and composition of the microballoons. The compressive strength of syntactic foams are directly proportional to the microballoon volume fraction and wall thickness.
Tensile strength is influenced by the matrix material. Typically metals provide the highest tensile strength, followed by ceramics, and then polymers.
Syntactic foams also benefit from buoyancy, thermal insulation, and high energy dissipation.
Syntactic Foam Benefits
Due to the hollow sphere fillers, syntactic foams often have over 50% porosity, which provides significant weight savings compared to conventional materials. Syntactic foams exhibit high compressive strength, which can be enhanced even further if required. This high compressive strength is advantageous for foams that are exposed to hydrostatic pressure or heavy loading.
These materials are also excellent insulators as they exhibit low thermal conductivity due to their porous structure. Syntactic foams offer a range of additional engineering and economic benefits over traditional insulation.
Syntactic Foam Applications
Syntactic foams can be used in applications as alternatives to many traditional materials, including PVC, plastics, metals, and other foams. These alternatives can’t provide the same level of strength, weight savings, and density as syntactic foams.
One of the most popular applications of syntactic foams is in the marine industry due to their buoyancy and low moisture absorption. These materials can also be used for spacecraft, pipe insulation, underwater vehicles, boat hulls, and even soccer balls.
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