Materials fabricated from Zirconium metal and ZrO2 were developed for use particularly in aero-space vehicles and where resistance to heat is absolutely necessary.

Ceramic Coating technology has made it possible for a wide variety of applications to perform better at lower temperatures for prolonged periods than imaginable.

High temperature components as used in jet engines, gas turbines and high performance motors are increasingly being protected by Ceramic Coatings. These coating layers are usually composed of a mixture of Zirconia and Yttria which are applied as a 'thermal barrier' for protection against extreme heat.

Thermal barrier coatings are highly advanced materials initially developed for aero-space technology by NASA. Ceramic Coatings are usually applied to metallic surfaces as used for protection on aero-engine parts, space rockets, gas turbines and naturally aspirated and performance engines such as V8 engine powerplants aided by a supercharger, turbocharger and nitrous oxide systems.

These heat insulating and hard ceramic coatings are usually applied to areas where excessively high concentrations of heat is generated or transferred. Thermal barrier coating is applied at a thickness ranging between 100μm to 2mm. Amazingly these coatings allow components to perform better by protecting them from prolonged heat loads and are able to withstand drastic temperature differences between the load-bearing alloys and their coated surfaces.

In doing so, the coatings limit the amount of heat absorption of structural components such as pistons, combustion chambers, superchargers and turbo’s, exhaust valves, heat exchange manifolds and gas turbines, for example, thereby extending the life of such components by reducing fatigue caused by excessive heat.

An effective thermal barrier coating is required to meet certain standards to perform well in any particular thermo-mechanical environment. The coating is typically made up of three essential layers above the metal substrate.

There are three coatings that are usually applied. The first coating is called the ‘Metallic Bond Coat’ followed by the ‘Thermally Grown Oxide Coat’ and lastly the ‘Ceramic Coating’ is applied. The component is then slowly heated to the correct temperature and time according to specification and then slowly cooled.

To deal with heat expansion and contraction stresses, adequate porosity is required, as well as, appropriate matching of thermal expansion coefficients with the metallic surface that is to be coated. Phase stability is essential to prevent significant volume changes in the metal which would cause the thermal barrier coating to crack or flake.

The top Ceramic Coating is typically composed of ‘Yttria-Stabilized-Zirconia’, which is desirable for having very low conductivity while remaining stable at operating temperatures. This ceramic layer creates the largest thermal gradient of the thermal barrier coating and keeps the lower layers at a lower temperature than on the surface layer of Ceramic Coating. However, above 1200 °C, the Zirconia / Yttria, suffers from unfavorable phase transformations. Such phase transformations lead to crack formation within the top coating.

CLICK HERE for more information on Ceramic Coatings for protection in any engine.

Parts such as: Pistons, conrods, camshafts, crankshafts, combustion chambers, valves, superchargers, turbochargers, exhaust manifolds, exhaust pipes and brake calipers can be coated for strength, insulation, durability and reliability.

Contact Nick at 'V8 ENGINE' for expert advice on ceramic coatings.