Keronite on aluminium

Surface hardness is often regarded as the basis for good wear resistance.  In this respect, Keronite performs very well, because depending upon the alloy used and the thickness of the coating applied, the hardness of Keronite on aluminium can reach 2000 HV0.1: approximately three times harder than hardened tool steel and almost twice as hard as hard chrome surfaces.  This is because one of the main constituents of the layer is a-Al2O3, which is known as “corundum” in its mineral form, and is the hardest naturally occurring mineral apart from diamond.

Hardness alone, however, is not sufficient to give a surface wear-resistance, and it is the combination of high hardness with compliance which often gives best performance.  Here, Keronite benefits from the fact that its global stiffness is an order of magnitude lower than that expected for the fully dense ceramic, giving it high strain tolerance. 

Together, the high hardness and compliance often give the Keronite layer excellent wear performance.  Although it is strongly dependent on the wear mechanism and is very case-specific, examples include independent tests which have demonstrated that Keronite on aluminium is up to seven times more wear resistant than hard anodised aluminium, far less prone to cracking and that it easily out-performs electroless nickel coatings in pin-on-disk tests.

Keronite on magnesium
On magnesium, further independent tests have concluded that hardnesses of over 700 HV can be achieved on a typical AZ91 alloy, making it harder than most hard anodised aluminium, and enabling the much wider use of this strong, light weight material.

In two-body abrasive wear scenarios, magnesium alloy parts treated with Keronite have 20 times greater wear resistance than untreated magnesium, similar to that of case hardened steel.

Keronite also helps to eliminate the high friction and galling normally associated with magnesium. Once polished, the Keronite surface on magnesium has a friction coefficient of less than 0.15 against steel.