Rotary cone bit with functionally-engineered composite inserts

Abstract

A rotary cone bit, having a functionally-engineered surface of this invention, comprises a bit body having at least one leg extending therefrom, and a cone that is rotatably disposed on the leg. The cone typically comprises a plurality of cutting elements that project outwardly therefrom. The cutting elements comprises a cermet material selected from the group consisting of refractory metal carbides, nitrides, borides, carbonitrides and mixtures thereof. A functionally-engineered material is disposed over a surface portion of at least one of the cutting elements to form a wear resistant surface thereon. The wear resistant surface has a hardness that is different than that of the underlying cutting element. The wear resistant surface is provided by forming a conformable material mixture by combining one or more powders selected from the group consisting of cermets, carbides, borides, nitrides, carbonitrides, refractory metals, Co, Fe, Ni, and combinations thereof, with an applying agent. The applied material mixture is pressurized under conditions of elevated temperature to consolidate and sinter the material mixture, thereby forming the wear resistant surface. The material mixture is consolidated and sintered in a manner that avoids unwanted material migration between the applied material mixture and substrate, thereby providing a fully-densified wear surface having desired properties of hardness and/or fracture toughness.