General Properties of Keronite Layers

Keronite ceramics can include up to ~80% of extremely hard crystalline phases such as corundum (which is the basis of the mineral sapphire). 

Hardness's of over 2000 HV_0.1 can therefore be achieved, although this will depend on the substrate and the coating variant - more typically, hardness's of ~1600 HV_0.1 are achieved on aluminium. 

This is far harder than hard anodising, or even common wear counterparts such as hard steels, glass and sand. 

Despite their extreme hardness, the Keronite ceramics are also surprisingly compliant, with typical Young's modulus values of just ~30 GPa.  This, together with excellent adhesion, makes them very strain tolerant.  Altogether, these properties deliver exceptional wear resistance.

The Keronite ceramics also possess complex fine-scale pore structures which enable them to retain friction modifiers or lubricants to provide further enhancements.

As with anodising, precise dimensional control is achievable, even on components with complex geometries.  The Keronite ceramic does not suffer from the problems encountered by anodising on sharp corners.

Our process engineering ensures exceptional control and repeatability in production. 

Keronite also has great experience in masking and selective coating and in engineering pre or post-treatments.

The Keronite layers are complex mixtures of ceramic phases which are very resistant to a wide range of chemicals and thus present exceptional corrosion protection for a wide range of aluminium and magnesium alloys.

Unlike anodizing which presents corrosion paths from the surface all the way down to the substrate, the Keronite layer protects even sharp radii and presents a continuous ceramic barrier, offering excellent corrosion protection - for instance over 2000 hours of ASTM B117 salt spray endurance without change, even on magnesium!

The Keronite layers can withstand continuous exposure to temperatures of up to 900°C: well above the capabilities of the parent metals, without undergoing any microstructural changes or damage. 

The excellent adhesion to the substrate, combined with the layer's strain tolerance, makes it resistant to thermal shock or cycling.

A wider range of thermal conductivities can be achieved: from ~0.2 to ~7 W m^-1 K^-1.  Low values are used for thermal barrier protection applications, whilst at the opposite extreme, thin layers with relatively high thermal conductivity offer electrical insulation with minimal thermal resistance for applications such as heat sinks in electronic thermal management.

At the opposite extreme, thin layers can provide wear, corrosion or electrical protection whilst presenting minimal thermal resistance.

As with the thermal properties, the Keronite process is versatile enough to deliver electrical resistance at either end of the scale.

For instance, on aluminium, the Keronite layer can deliver dielectric strength in excess of 2.5kV even at temperatures of over 500°C, with dielectric strengths of up to ~120 kV/mm.

Conversely, thin layers can also be formed that provide wear and corrosion protection and are also electrically conductive, making them particularly suited to RF shielding applications.

Unlike many surface treatments, Keronite is not a deposited "coating".  It is grown from the parent metal and has an excellent interfacial adhesion.  This combines with the layer's strain tolerance ("compliance" or "flexibility") to give excellent mechanical stability.

The wide range of Keronite ceramic surfaces, with unique fine-scale and multi-scale pore structures also provides an ideal base for top-coats such as polymeric paints or adhesives.

Keronite is proud of its status as a Clean Technology.

The process does not use or produce:

• Heavy metals, such as chrome and vanadium
• Strong Acids.
• VoCs
• Toxic or hazardous waste