TWI Frequently asked questions

What are the principal characteristics, properties and applications for the Keronite® process?

by Dave Harvey and Suman Shrestha

Characteristics

A typical Keronite coating consists of three zones:
  • porous outer layer
  • low porosity functional layer (the bulk of the coating) which exhibits the highest hardness values
  • a narrow, transitional layer in the substrate

Keronite is applied at temperatures below 100°C and, therefore, has no impact on the microstructure of the substrate material. A uniform coating thickness is applied over geometrically complex and restricted access surfaces, such as inner surfaces and holes.

Keronite coating structure

Keronite coating structure
(Courtesy Keronite Ltd)

The porous outer layer offers the potential for further enhancement by subsequent impregnation with lubricants (e.g. MoS 2), low friction polymers (e.g. PTFE), carbides, ceramics or metals, thus producing composite coatings with multiple properties.

Initial trials indicate that impregnation of Keronite coated aluminium with electroless nickel may be technically superior to electroplated composite coatings (such as nickel-silicon carbide, e.g. Nikasil ®) currently used as cylinder bore linings in automotive aluminium engine blocks.

Properties

Keronite appears particularly suited to improving the surface performance of light metal alloys. For example, preliminary trials indicate that Keronite coated aluminium alloys have a surface micro-hardness of up to 2000HV, with wear and corrosion resistance superior to that of hard anodising or hard chrome plating. Keronite coated aluminium may provide a lightweight alternative to steel components surface treated with electrolytic hard chrome or thermal sprayed coatings.

Magnesium alloys treated with Keronite have a surface micro-hardness of 350-600HV. The ability to improve the wear and corrosion resistance of Mg alloys offers the possibility of using these alloys in more functional, weight-saving applications such as pump internals, pistons, valve trains and sliding bearings. Preliminary trials also indicate that Keronite applied to titanium can eliminate galling, allowing Ti alloys to be considered for high strength, lightweight and functional applications such as titanium gear sets.

Applications

  • Automotive industry: pistons, cylinder blocks, sliding bearings, cylinder liners, exhaust nozzles, valve trains, suspension elements, fuel pumps, gearboxes, engine block covers, structural elements, wheels, axles, spindles, swivels, ratchets, slides

  • Aerospace: actuators and gears, structural elements, bearings and wheels, details of landing gear

  • Textile industry: shuttles, spin rotors, gripping devices, thread guides, collets, bobbins, slides and twisters

  • Marine equipment: propellers, capstan winches, guide rails, shackles, bulkhead attachments

  • Oil, gas & chemical engineering: valves, pumps, hydraulic and pneumatic systems, submerged oil pumps

  • Cookware: Frying pans, saucepans, knife sharpeners

  • Medicine: Bone prostheses, medical mixers, turbo-molecular pumps

  • Printing & packaging industry: packaging line parts, guide plates, Anilox and other rolls

  • Robotics: pneumatic drives, pumps and hydraulic systems, guide rods

Further information

FAQ: What is the Keronite process?

Group Sponsored Project on Keronite. 13946: Validation of KERONITE ® - A novel hard coating for light metal alloys Copyright © 2003 TWI Ltd
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