QuickSilver are delighted to be able to offer customers the option of Zircotec ‘Thermohold GP’ ceramic coating for exhaust manifolds and components.
Developed by the former engineering division of the UK Atomic Energy Authority (AEA) at Harwell in Oxfordshire, the company now known as Zircotec, was privatised in 1996.
This is not intended as a cosmetic enhancement (though they do look good) it has the potential for a significant contribution to the engine’s thermal efficiency.
The function of the Zircotec coating is to consistently resist the loss of heat energy through the exhaust tube.
This zirconia-based ceramic coating was originally produced as a barrier for the thermal management of coolant pipes to & from reactor cores.
It has now been developed specifically for exhaust systems and is known as ‘Thermohold GP’.
Zirconia has a thermal efficiency of less than 1 watt per metre per kelvin.
By contrast, Alumina has a thermal efficiency of 4 watts per metre per kelvin.
The way the Thermohold coating works is, primarily, by inhibiting radiated heat from the surface of the material.
It forms a physical ceramic barrier so that the heat on the inside of the exhaust remains inside.
In some applications a difference, between the gas on the heated side and the external air, of up to 200°C can be seen.
The fact that the heat is held within the exhaust system, therefore effecting back pressure, can also provide power advantages.
Typical benefits of using Thermohold GP are:
· Significant improvement in heat management within the engine.
· Prevention of local component and chassis damage from radiated heat.
· Reduced thermal expansion of the coated product resulting in lower stress on the mountings and surrounding structure.
· Giving a
degree of fire resistance as a lightweight heat shield, the saving in weight over conventional insulation can be considerable.
· Enhanced component appearance.
· Increased power through retaining heat energy within the exhaust and providing greater gas velocity.
This is not a paint or surface treatment, it resembles a traditional enamel coating in its thickness.
It is applied in three stages, surface preparation, metal bond coat, ceramic coating.
Coating thickness: approx 300 - 350µ comprising ~ 100µ metal bond coat and 200-250µ ceramic.
Total weight increase will be 1.6 > 1.7 kg/m2
For Motorsport, an additional important reason for coating is to protect surrounding structures - carbon-fibre parts, if scorched, can delaminate.
It is also important to stop heat ingress into mechanical areas such as gear boxes and oil supply and radiator lines.
Compared to ‘wrapped-round’ glass fibre, it is not only less bulky but it also does away with the need for straps or brackets.
The natural finish colour is white, it can also be finished in grey or black by the application of an additional coating.
Typical Exhaust system applications include:
· Air-cooled engines where heat management is so important.
· Turbo-charged engines where exhaust gas velocity is paramount.
· Motorsport use for all the benefits noted above
· Heat management in a crowded engine bay.
· Emissions-critical engines where consistent engine & exhaust gas temperatures must be maintained over all conditions.
Notes:
In the early 1980s, Toyota researched production of a ceramic engine which could run at a temperature of over 6000 °F (3300 °C). Ceramic engines do not require a cooling system and hence allow a major weight reduction and therefore greater efficiency. Fuel efficiency of the engine is also higher at high temperature, as shown by Carnot’s theorem. In a conventional metallic engine, much of the energy released from the fuel must be dissipated as waste heat in order to prevent a meltdown of the metallic parts.
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Originally Posted by Frits Overmars
mmm....
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