Rock-cutting tool and method for mine and oil drilling

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.