Roller cone bits with wear and fracture resistant surface

Abstract

Rock bits comprising wear and fracture resistant surface of this invention include a steel bit body having at least one leg extending therefrom. A steel cone is rotatably disposed on the leg. The steel cone includes a plurality of steel cutting elements that each projecting outwardly a distance therefrom. At least a portion of the cone comprises a wear resistant surface formed from a wear resistant composite material. The wear resistant composite material is made by the process of combining powders selected from the group consisting of carbides, borides, nitrides, carbonitrides, refractory metals, cermets, Co, Fe, Ni, steel, and combinations thereof, to form a material mixture. The material mixture is applied onto a designated surface of the cone, in one form or another, when the cone is in a pre-existing rigid state. Depending on the particular application, the material mixture can be applied in as a slurry to the designated surface of the cone to form a coating thereon. Alternatively, the material mixture can be preformed into a green part that is configured to be placed over the designated surface prior to being disposed thereon. The material mixture is then pressurized under conditions of elevated temperature to form the wear resistant surface. In the event that the material mixture is preformed into a green part, the preformed green part can be sintered prior to its placement on the designated cone surface. The sintered part can then be attached to the cone surface by brazing process.