Rock-cutting tool and method for mine and oil drilling
The invention relates to a rock-cutting tool and a method for manufacturing this tool, which comprises knives comprising a layer of polycrystalline synthetic diamond (PSD), a diamond impregnation layer with diamond particles and bonding cobalt, characterized in that the PSD layer is supported directly, along a planar interface, on the diamond impregnation layer whose interface surface is planar by machining and with which the diamond particles are flush.
1 . A method for manufacturing a knife of a rock-cutting tool, the method comprising:
preparing a mix of diamonds particles and a powder comprising carbon, tungsten, and cobalt;
cold pressing the mix in a mold to pre-form a diamond impregnation layer;
sintering the preformed diamond impregnation layer to create a sintered diamond impregnation layer having a homogenous distribution of the diamond particles therein, wherein the cobalt in the layer serves as binder in the sintering process;
mechanically machining the sintered diamond impregnation layer until obtaining a machined planar surface revealing the diamond particles which are flush with the machined planar surface;
depositing a layer of diamond powder onto the machined planar surface of the impregnation layer having the revealed diamond particles which are flush with the machined planar surface; and
at a high temperature, converting the diamond powder into a polycrystalline synthetic diamond (PSD) layer having covalent chemical bonds between carbon from the layer of diamond powder and the revealed diamond particles which are flush with the machine planar surface of the sintered diamond impregnation layer, and wherein the homogeneity of the sintered diamond impregnation layer allows a homogeneous migration of the cobalt toward the entire surface where the diamond powder has been deposited on the machined surface; wherein the cobalt in the impregnation layer further serves as catalyst to carbon-carbon bond formation during diamond formation.
2 . The method of claim 1 wherein:
machining the surface comprises either grinding or laser.
3 . The method according to claim 1 wherein:
the sintering of the diamond impregnation layer is done by a hot isostatic method.
4 . The method according to claim 1 wherein:
the conversion of the layer of diamond powder into a PSD layer is catalyzed by cobalt.
5 . The method according to claim 1 wherein:
the diamond impregnation layer is machined on at least one face until obtaining diamond particles that have a planar surface.