| 摘要 |
A matrix drill bit 20 comprises at least a first matrix material forming exterior portions of the body 50 having a first hardness and at least one layer of a second material 101-105 having a hardness greater than that of the first material disposed on exterior portions 122 of the body. The second material may be selected from the group of cemented carbides, composite carbides, spherical carbides, macrocrystalline tungsten carbides, cast carbides, low alloy sintered material and formulates thereof. The layer of second material may comprise two or more sublayers each including adhesive material with particles of the first matrix material and pellets of the second material, the pellets being substantially larger than the particles. The second material may comprise at least 50% by weight of tungsten carbide which may be formed with binding material in the range of 3% to 5% by weight. A method of making a matrix drill bi comprising placing layers of the second material at selected locations on interior portions of a mold.
|
