Patent ID: 7544410

Claim:
A hard metal or cermet body with a hard material phase of WC and at least one carbide, nitride, carbonitride or oxycarbonitride of at least one of the elements of Group IVa or Group Va of the periodic system and a binder phase of Fe, Co or Ni with a proportion amounting to 3 to 25 mass % with a single surface or a plurality of mutually adjoining surfaces, wherein beneath the single surface or at least one of the plurality of adjoining surfaces, a) a 2 to 100 μm thick first layer is disposed that has a binder metal proportion of 2 to 25 mass % and up to 25 volume % of a nitride or carbonitride of one or more metals of Group IVa of the periodic system or up to 10 volume % of a carbide or carbonitride of V, Nb, Ta or Cr, balance WC, whereby the amount of nitride, carbonitride or carbide of the aforementioned metals amounts to at least 0.01 volume %, and further wherein b) under the first layer a 2 to 40 μm thick second layer with an enhanced nitrogen proportion relative to the first layer, is disposed and that is comprised substantially of nitrides or carbonitrides of the metals of the Group IVa of the periodic system and includes phase proportions of up to 10 volume % of carbides, nitrides, carbonitrides or oxycarbonitrides of the elements W, Mo, V, Ta, Nb, Cr or a proportion solubilized in the hard material phase of up to 5 mass % V, Nb, Ta and up to 2 mass % Cr, Mo, W and that contains up to 15 mass % binder, whereby the amount of the aforementioned phase proportions make up at least 0.01 volume % or the amount of the proportion dissolved in the hard material phase amounts to at least 0.01 mass %, c) and that under the second layer a transition zone is arranged with a thickness of 2 to 100 μm in which the composition gradually changes to a homogeneous composition in the inner core of the hard metal or cermet body.