Temperature resistant abrasive polycrystalline diamond bodies

Abstract

Temperature resistant abrasive polycrystalline diamond bodies are described, intended for use as tools in various mechanical operations like turning, milling, drilling, sawing and drawing, having different additions, i.e. amount and composition, of binding, fluxing, catalyst metals at different distances from the working surface. Preferably the metal concentration of the polycrystalline diamond body is decreasing towards the working surface while the metal composition is varied in a way that gives a mechanically stiffer matrix that also has a lower thermal expansion. In one embodiment the diamond body is high pressure-high temperature-bonded to a supporting body, e.g. of cemented carbide, in order to facilitate the clamping of the tool. In another embodiment the diamond body is brazed to a supporting body or used in a surface-set rock drill bit, i.e. held by a braze metal. Especially good results have been obtained if the hard polycrystalline diamond body comprises three different homogeneous diamond layers on top of each other, each layer having its special amount and composition of relatively low-melting binding metal. These three diamond layers are bonded to each other and to the supporting body, if any, by using intermediate layers of the thickness 3-300 .mu.m, consisting of more high-melting metals or other materials like nitrides or borides, etc. in order to lock in the low-melting binding metals and to prevent diffusion of these metals between the different diamond layers and between the supporting body and the nearest diamond layer.