Charring 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. Charring ablators, partially burn and blacken, creating a greater surface thermal resistance.

Charring ablation describes where the surface chemical reaction (decomposition at high temperature) gradually consumes the char layer of the material, so is completely decomposed. For example in a char rating, which measures the depth of char of a timber being burnt, divided by the time period for this to occur, where a lower char rate indicates a slower rate of burn.

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. These types of materials are often carbon related composites such as Teflon.

Two other types of ablative materials are subliming 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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