Subliming ablators

Ablative materials in design and construction, are materials that are generally resistant to high temperatures in one of three ways and used for thermal protection. Subliming ablators perform through sublimation and eventual melting.

Subliming ablators, act as heat sinks until the surface of the material reaches sublimation or melting point (thus also referred to as - subliming / melting ablators), thus removing the heat from the protected object. In some cases a layer of gas is formed which helps remove heat from the object, in other cases an endothermic reaction occurs increasing the material temperature whilst decreasing the surrounding temperature, sacrificially.

In doing this ablative materials may pyrolyse mitigating a heat load, so in effect they decompose or change as a result of the heat being applied. For example ablative coating might contain hydrates, as they are heated, they decompose, and water vapour is released, this has a cooling effect, the insulation characteristics of the charred remains after the water is vaporised can slow the heat transfer. These types of materials are also often carbon related composites such as Teflon.

Two other types of related ablative materials are charring ablators and Intumescent ablators.

[edit] Related articles on Designing Buildings

• Ablative batt.
• Batt.
• BS 476.
• Cavity barrier.
• Compartment floor.
• Compartment wall.
• Fire resistance.
• Fire separation.
• Fire.
• Fire-separating element.
• Fire-stopping.
• Pyrolysis
• Sacrificial timber.

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