Patent ID: 7784381

Claim:
A method of making a matrix drill bit comprising: placing at least a first layer of a first matrix selected from the group consisting of cemented carbides and spherical carbides material in a matrix bit body mold; placing a metal blank in the mold; placing at least a second layer of a second matrix material selected from the group consisting of microcrystalline tungsten carbide and cast carbide in the mold with the second matrix material operable to improve infiltration of a hot, liquid binder material throughout the first matrix material to minimize incomplete infiltration of the first matrix material by the hot, liquid binder material; placing a binder material in the mold with the binder material disposed proximate the second layer of matrix material and the metal blank; heating the mold and the materials disposed therein in a furnace to a selected temperature to allow the binder material to melt and to allow the hot, liquid binder material to infiltrate the second matrix material and the first matrix material with the second matrix material operable to improve infiltration of the first matrix material by the hot, liquid binder material; starting solidification of the hot, liquid binder material with the first matrix material before the hot, liquid binder material solidifies with the second matrix material; and cooling the mold and the materials disposed therein to form a coherent composite matrix bit body securely engaged with the metal blank.