Ablative material
Ablative materials in design and construction, are materials that are generally resistant to high temperatures and used for thermal protection, such as an ablative batt. Ablation itself means the removal or destruction of something, normally the upper layer by chipping, erosion, decomposition or vaporisation, and so might be referred to as a sacrificial layer.
There are in effect three types of ablative materials, which relate to the way the react to heat;
Contents |
[edit] Subliming ablators
Subliming ablators, act as heat sinks until the surface 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. These types of materials are often carbon related composites such as Teflon.
[edit] Charring ablators
Charring ablators, partially burn and blacken, creating a greater surface thermal resistance. 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. Charring ablation describes where the surface chemical reaction (decomposition at high temperature) gradually consumes the char layer of the material, so is completely decomposed.
[edit] Intumescent ablators
Intumescent ablators, swell as a result of heat exposure, which leads to an increase in the volume and decrease in density. Intumescence refers to the process of swelling and the most common examples in construction are known as Intumescence strips, used in fire proofing.
[edit] Related articles on Designing Buildings
Featured articles and news
Registered building inspectors
Building types and conflicts of interest updates explained.
BSRIA's commitment to sustainability and net zero
Key documents that represent an early shift in thinking.
A resource for Cleaner Air, Better Tomorrow.
Awe-inspiring medieval great barns.
A history of timber construction in the UK
From a timber Stonehenge to half timber houses.
Engineering services still struggle with labour shortages
According to latest quarterly services survey of the sector.
Infrastructure that connect the physical and digital domains.
Harnessing robotics and AI in challenging environments
The key to nuclear decommissioning and fusion engineering.
BSRIA announces Lisa Ashworth as new CEO
Tasked with furthering BSRIA’s impressive growth ambitions.
Public buildings get half a million energy efficiency boost
£557 million to switch to cleaner heating and save on energy.
CIOB launches pre-election manifesto
Outlining potential future policies for the next government.
Grenfell Tower Inquiry announcement
Phase 2 hearings come to a close and the final report due in September.
Progress from Parts L, F and O: A whitepaper, one year on.
A replicated study to understand the opinion of practitioners.
ECA announces new president 2024
Electrical engineer and business leader Stuart Smith.
A distinct type of countryside that should be celebrated.
Comments
[edit] o make a comment about this article, click 'Add a comment' above. Separate your comments from any existing comments by inserting a horizontal line.