Abstract: A rotary tool that includes an elongate tool body and a hard insert affixed to the tool body is disclosed. The hard insert includes a WC-cermet including tungsten carbide and about 5 wt. % to 19 wt. % Co--Ni--Fe-binder. The Co--Ni--Fe-binder is unique in that even when subjected to plastic deformation, the binder substantially maintains its face centered cubic (fcc) crystal structure and avoids stress and/or strain induced transformations.

Abstract: An array of cutting inserts has been invented having a plurality of adjacent inserts, each insert comprising a body having a top surface, a bottom, and a base, and a plurality of spaced-apart chipbreaking indentations in the top surface of the body, and a strengthening ridge between adjacent indentations of the plurality of spaced-apart chipbreaking indentations, and a peripheral strengthening ridge around an outer edge of the top surface of the body surrounding the plurality of spaced-apart chipbreaking indentations.

Abstract: A combination metal milling and earth drilling tool, for use in performing a single trip kickoff from a casing in a well bore. The combination milling and drilling tool has a first, relatively more durable cutting structure, such as tungsten carbide, and a second, relatively harder cutting structure, such as polycrystalline diamond. The more durable first cutting structure is better suited for milling metal casing, while the harder second cutting structure is better suited for drilling through a subterranean formation, especially a rock formation. The first cutting structure is positioned outwardly relative to the second cutting structure, so that the first cutting structure will mill through the metal casing while shielding the second cutting structure from contact with the casing. The first cutting structure can wear away while milling through the casing and upon initial contact with the rock formation, thereby exposing the second cutting structure to contact with the rock formation.

Abstract: An anti-whirl rotary drag bit including one or more cutters, wear knots or other support structures disposed on the flank of a bit profile in a normally cutter-devoid region of the profile adjacent the gage of the bit in the circumferential segment of the gage used as a bearing zone for the bit to ride against the side of the bore hole. Such flank cutters or other structures reduce wear of the bearing zone but, due to their placement, do not come into play except under certain drilling situations such as reaming or high rates of penetration wherein whirl tendencies resulting from cutting forces are not as pronounced.

Abstract: A superabrasive cutting element, the substrate of which is structured with a reduced dimension circumferential portion about which is formed an annular portion of superabrasive material, such as sintered diamond in the form of a polycrystalline diamond compact, to provide a ring- or skirt-like portion of superabrasive material at the perimeter of the cutting element to reduce residual tensile stresses existing at the perimeter of the cutting element after formation.

Abstract: A rock drill bit for percussive drilling includes a steel body in which six gauge buttons and a single front button are mounted. The gauge buttons are arranged symmetrically and equally spaced about a central axis of the bit. The front button is arranged along the central axis. The front button is of larger diameter than the gauge button. At least three of the gauge buttons are diamond-enhanced, and the front button may be diamond-enhanced.

Abstract: A cutting insert for a tool for wellbore milling operations has been invented that has a body having a top, a bottom, and a base, and a plurality of cutting surfaces on the top of the body, one of the cutting surfaces at a different height above the base than the other cutting surface, each cutting surface defined by linear boundaries extending from a first edge of the cutting insert, and the linear boundaries parallel to each other, the plurality of cutting surfaces including at least two cutting surfaces including at least a first cutting surface and a second cutting surface, the second cutting surface at a height above the base which is greater than a height above the base of the first cutting surface.

Abstract: Mounting apparatus is described for locking an insertable stud cutter or slug cutter or fluid nozzle into a socket on a rotatable earth boring drill bit. The cutter may be readily removed and replaced without damaging either the cutter, nozzle or bit. Apparatus are shown for permitting or, alternatively, preventing rotation of the cutter or nozzle in its socket. The mounting apparatus is particularly applicable to cutters having a cutting disk of polycrystalline diamond or other superabrasive material mounted on a carbide supporting body, or carbide body nozzles or nozzles having a bore lined with such a material.

Abstract: Superabrasive cutting elements for rolling cutter bits, and mounting techniques for such cutting elements. The insert-type cutting elements employ self-supporting superabrasive masses on the exposed tips thereof, the elements being mounted to the rolling cutters by insertion of supporting stud-like insert bodies into apertures in the cutter shells so that the exposed exterior of the interface between the superabrasive mass and the supporting cemented tungsten carbide stud lies outside of the depth of cut of the cutting element into the formation, and in some instances beneath the surface of the shell.

Abstract: An anti-whirl rotary drag bit including one or more cutters, wear knots or other support structures disposed on the flank of a bit profile in a normally cutter-devoid region of the profile adjacent the gage of the bit in the circumferential segment of the gage used as a bearing zone for the bit to ride against the side of the bore hole. Such flank cutters or other structures reduce wear of the bearing zone but, due to their placement, do not come into play except under certain drilling situations such as reaming or high rates of penetration wherein whirl tendencies resulting from cutting forces are not as pronounced.

Abstract: The present invention relates to a novel domed polycrystalline diamond cutting element wherein a hemispherical diamond layer is bonded to a tungsten carbide substrate, commonly referred to as a tungsten carbide stud. Broadly, the inventive cutting element includes a metal carbide stud having a proximal end adapted to be placed into a drill bit and a distal end portion. A layer of cutting polycrystalline abrasive material disposed over said distal end portion such that an annulus of metal carbide adjacent and above said drill bit is not covered by said abrasive material layer. The geometry of the diamond cutting element provides control of interfacial stresses and reduces fabrication costs. The diamond cutting element may contain a pattern of ridges or bumps integrally formed in the abrasive layer which ridges are designed to cause high localized stresses in the rock, thus starting a crack. By initiating cracks in localized areas, the crushing action could be performed with less force.

Abstract: This invention relates to a novel domed polycrystalline diamond cutting element wherein a hemispherical diamond layer is bonded to a tungsten carbide substrate, commonly referred to as a tungsten carbide stud. Broadly, a pattern of ridges or bumps is integrally formed in the abrasive layer which ridges are designed to cause high localized stresses in the rock, thus starting a crack. By initiating cracks in localized areas, the crushing action could be performed with less force.

Abstract: An improved insert for use in a drilling device. The insert adapted to be mounted on the drilling device within a socket formed in the drilling device. The insert has a convex curved lead-in surface formed on the lower portion of the insert. The lead-in surface operates to enhance the retention of the insert within the socket during drilling operations.

Abstract: A tool bit for use in at least one of a drilling and cutting operation is formed of an axially extending carrier member (1) and a cutting member (2). The cutting member (2) has an expansion joint (2a) extending parallel to the axis of the carrier member (1). The expansion joint (2a) is formed by reducing the thickness of the cutting member (2) so that material webs (2b) remain. In the fabrication and formation of the tool bit, the cutting member (2) is a single unit. In the use of the tool bit, due to the expansion joint the cutting member forms individual operating units (2a) affording reduced material expense of the cutting member (2), because of reduced stresses.

Abstract: A gage surface cutting element (22, 30, 50, 70, 100, 120) for a cutter (20) in a roller cone drill bit (10) has a generally cylindrical body (32, 52, 72, 102, 122) formed of a hard and wear-resistant material. The cutting end (34, 54, 74, 104, 124) of the cutting element (22, 30, 50, 70, 100, 120) has a generally conical cutting surface (38, 58, 78, 108, 128) substantially perpendicular to a longitudinal axis of the cylindrical body (32, 52, 72, 102, 122). A plurality of generally parallel shallow and elongated grooves (40-42, 60-63, 80-82, 110-112, 130-132) are formed in the conical cutting surface (38, 58, 78, 108, 128), and a plurality of elongated strips of an ultra hard material (44-46, 64-67, 84-86, 114-116, 134-136) is disposed in the grooves. The result is a conical cutting surface (38, 58, 78, 108, 128) that has alternating hard and ultra hard cutting surfaces that can be oriented at 0.degree., 90.degree., or any angle in between with respect to the rotational direction of the cutter cone (20).

Abstract: A rotary cone drill bit (20 and 120)is provided with inserts (70 and 90) and compacts (50 and 150) having contoured cutting portions (66, 166, 72 and 92). The rotary cone drill bit (22 and 122) includes a bit body (26 and 126) having at least one downwardly extending arm (28) terminating in a spindle (40). A cutter cone (30) with a gauge face surface (62) and a plurality of holes (64) formed therein, is rotatably mounted on each spindle (40). A compact (50 and 150) having a cutting portion (66 and 166) with a radius approximately equal to the desired radius for the resulting borehole (100) is press fit into each hole (64) in the gauge face surface (62). A number of inserts (70 and 90) are also installed in the exterior of each support arm (28). Inserts (70 and 90) have a contoured cutting surface with a radius approximately equal to the desired radius for the resulting borehole (100).

Abstract: A bit body has at least one cantilevered bearing shaft depending inwardly and downwardly from the bit body. A cutter is mounted for rotation on the bearing shaft and includes a plurality of cutting elements arranged in generally circumferential rows on the cutter, the rows including a heel row. The cutting elements in the heel row include at least one chisel-shaped cutting element having a crest oriented transversely to the axis of rotation of the cutter. The remainder of the cutting elements in the heel row have a configuration different from the chisel-shaped elements. All of the cutting elements have approximately the same projection from the surface of the cutter.

Abstract: A rotary cone drill bit (10) with two-stage cutting action is provided. The drill bit (10) includes at least two truncated conical cutter assemblies (20) rotatably coupled to support arms (18), where each cutter assembly (20) is rotatable about a respective axis (44) directed downwardly and inwardly. The truncated conical cutter assemblies (20) are frusto-conical or conical frustums in shape, with a back face (60) connected to a flat truncated face (22, 62) by conical sides. The truncated face (22, 62) may or may not be parallel with the back face (60) of the cutter assembly (20). A plurality of primary cutting elements or inserts (24) are arranged in a predetermined pattern on the flat truncated face (22, 62) of the truncated conical cutter assemblies (20). The teeth (26) of the cutter assemblies (20) are not meshed or engaged with one another and the plurality of cutting elements (24) of each cutter assembly (20) are spaced from cutting elements (24) of other cutter assemblies (20).

Abstract: Mounting apparatus is described for locking an insertable stud cutter or slug cutter or fluid nozzle into a socket on a rotatable earth boring drill bit. The cutter may be readily removed and replaced without damaging either the cutter, nozzle or bit. Apparatus are shown for permitting, or alternatively, preventing rotation of the cutter or nozzle in its socket. The mounting apparatus is particularly applicable to cutters having a cutting disk of polycrystalline diamond or other superabrasive material mounted on a carbide supporting body, or carbide body nozzles or nozzles having a bore lined with such a material.

Abstract: Methods for making, methods for using and articles comprising cermets, preferably cemented carbides and more preferably tungsten carbide, having at least two regions exhibiting at least one property that differs are discussed. Preferably, the cermets further exhibit uniform or controlled wear to impart a self-sharpening character to an article. The multiple-region cermets are particularly useful in wear applications. The cermets are manufactured by juxtaposing and densifying at least two powder blends having different properties (e.g., differential carbide grain size or differential carbide chemistry or differential binder content or differential binder chemistry or any combination of the preceding).

Abstract: Methods for making, methods for using and articles comprising cermets, preferably cemented carbides and more preferably tungsten carbide, having at least two regions exhibiting at least one property that differs are discussed. Preferably, the cermets further exhibit uniform or controlled wear to impart a self-sharpening character to an article. The multiple-region cermets are particularly useful in wear applications. The cermets are manufactured by juxtaposing and densifying at least two powder blends having different properties (e.g., differential carbide grain size or differential carbide chemistry or differential binder content or differential binder chemistry or any combination of the preceding).

Abstract: An earth-boring bit is provided with hard gage inserts that protrude from the gage surface of the cutter to engage the side of the borehole for holding gage. The cutting end of the gage insert has a cutting end defining at least one sharp cutting edge and at least one cutting surface that define a negative rake angle with respect to the sidewall of the borehole that is being sheared by the gage insert. The cutting end, cutting edge, and cutting surface of the gage insert are formed of a super-hard and abrasion-resistant material such as polycrystalline diamond or cubic boron nitride. The body of the insert is formed of a hard, fracture-tough material such as cemented tungsten carbide. The improved gage inserts provide an actively cutting gage surface that engages the sidewall of the borehole to promote shearing removal of the sidewall material. Such an improved gage insert provides an earth-boring bit with improved gage-holding ability, and improved steerability in directional drilling operations.

Abstract: The present disclosure is directed to a crowned insert. The insert is elongate, right cylinder, two ended body of carbide, preferably bonded tungsten carbide particles. The near end is sized to fit in a hole in a drill bit while the remote end is provided with an enlargement. The enlargement in one embodiment is provided with a circular profile, and has an edge which is chamfered with a radius of curvature to avoid sharp edges. The end of the insert is crowned with a PDC layer integrally cast and bonded thereto so that the enlargement is fully surrounded by the PDC crown.

Abstract: A cutting element which has a metal carbide stud having a conic tip formed with a reduced diameter hemispherical outer tip end portion of said metal carbide stud. A layer of polycrystalline material, resistant to corrosive and abrasive materials, is disposed over the outer end portion of the metal carbide stud to form a cap. An alternate conic form has a flat tip face. A chisel insert has a transecting edge and opposing flat faces. It is also covered with a PDC layer.

Abstract: A drilling bit includes a carrier member (3) shaped, for instance, as a hollow annular crown. In such a crown several cutter members (4) are distributed angularly apart around the circumferentially extending leading end of the carrier member. The cutter members (4) project both radially outwardly and inwardly from the wall thickness of the carrier member. A step (S) is formed in the cutter members spaced from the leading end thereof opposite of the drilling direction. The step (S) is located at the trailing end of a region (K) with a continuous reduction in the radial dimension (R) of the cutter member and the radial dimension is further reduced at the step. Due to the further reduction in the radial dimension at the step (S), the length of the cutter member (4) in the drilling direction, causing friction with the wall surface of the borehole to be drilled, is limited after extended use of the drilling bit, so that the drilling bit retains a higher drilling efficiency even after such extended use.

Abstract: A cutting insert for wellbore milling operations is disclosed which, in certain embodiments, has two or more top milling surfaces on an insert body with the surfaces at different heights above a bottom of the insert body. In certain embodiments three top surfaces are used stair-stepped, with a central lower surface, or with a central higher surface. In one aspect all cutting surfaces have an array of chipbreaking indentations. Tools and methods are disclosed which use such inserts.

Abstract: A method of mounting a hard insert in a cutting tool such as a drill bit is disclosed. The insert has a head and a shank which tapers inwardly in a direction away from the head of the insert. The cutting tool body has several seats which are shaped and tapered complementally to the insert shank. The insert is pressed or tapped into the seat so that the insert shank engages the seat in the tool in a friction fit. The insert shank may be frustoconical, or, alternatively, polygonal or irregular in shape. The taper of the shank (and the complemental taper of the seat) should be relatively shallow, with an included angle in the range of 4.degree. to 14.degree.. Preferably, the included angle of the shank should be slightly greater than that of the seat.

Abstract: A drag bit is formed of an elongate tooth made of tungsten carbide and having an elongate right cylinder construction. The end face is circular at the end of a conic taper. The tapered surface is truncated with two 180.degree. spaced flat faces at 15.degree. to about 45.degree. with respect to the axis of the body. The end is capped by a PDC layer.

Abstract: A drag bit having a plurality of blades or ribs on its end face has one or more pockets milled into the top surfaces of said blades. A tungsten carbide button or insert is positioned at the gauge diameter to reduce impact on the gauge diameter cutter in each of the fibs. The tungsten carbide button extends to the borehole gauge diameter to stabilize the bit within the borehole to limit bit whirling. The tungsten carbide button extends just forward of at least the final cutter assembly with respect to the direction of bit rotation to take the impact instead of the cutters. An additional tungsten carbide button or a shaped cutter is used along the blades in line with PDC cutting assemblies for limiting the penetration of the PDC cutting assemblies to thereby limit bit whirling or tilting instabilities.

Abstract: A cutting element which has a metal carbide stud having a conic tip formed with a reduced diameter hemispherical outer tip end portion of said metal carbide stud. A layer of polycrystalline material, resistant to corrosive and abrasive materials, is disposed over the outer end portion of the metal carbide stud to form a cap. An alternate conic form has a flat tip face. A chisel insert has a transecting edge and opposing flat faces. It is also covered with a PDC layer.

Abstract: The present disclosure sets forth various forms of inserts for operating as elements in bearing drill bits and similar devices. A single insert is formed with an external side face of cylindrical construction. One or more strips of hardened materials such as diamond or other hard material are provided along the side face. At the end face, the insert incorporates exposed tungsten carbide, diamond or other hard material. A PDC layer is optionally placed over the end face. The PDC layer has the form of a covering terminating at a radius of curvature.

Abstract: An earth-boring bit of the fixed cutter variety is provided with hard gage inserts that protrude from the gage surface of the cutter to engage the side of the borehole for holding gage. The gage insert has a substantially flat, polygonal face defining at least a pair of sharp cutting edges and at least a pair of cutting surfaces that define a negative rake angle with respect to the sidewall of the borehole that is being sheared by the gage insert. The face, cutting edge, and cutting surface of the gage insert are formed of a super-hard and abrasion-resistant material such as polycrystalline diamond or cubic boron nitride. The body of the insert is formed of a hard, fracture-tough material such as cemented tungsten carbide. The improved gage inserts provide an actively cutting gage surface that engages the sidewall of the borehole to promote shearing removal of the sidewall material.

Abstract: A hard metal insert for a drill bit is disclosed having an outer body and an encapsulated inner body. The particle size and the chemical composition of the outer body and the inner body are such that the outer body is harder and more wear resistant than the inner body and the inner body is tougher than but not as hard as the outer body. The dimension of the outer body is approximately of equal thickness to the inner body at the cutting surface of the insert to ensure maintaining even wear.

Abstract: An earth-boring bit has a bit body, at least one cutter rotatably secured to the bit body and including a plurality of teeth formed integrally with the cutter and arranged in circumferential rows thereon. A pair of ribs is formed on at least one of the flanks of at least one of the teeth. The ribs are spaced apart to define a central depression therebetween extending through the crest of the tooth. A thickness of wear-resistant material fills the depression. According to a preferred embodiment of the present invention, wear-resistant material is applied over the ribs, crest, and a portion of the ends and flanks of the tooth, wherein the thickness of the wear-resistant material over the depressions greater, preferably 1/8 inch, than that elsewhere on the tooth.

Abstract: A method of fabricating rotary drag bits for subterranean drilling by layering techniques such as are employed in rapid prototyping technology. Thin layers of powder may be sequentially deposited and fused or otherwise bonded to define the bit body, or thin sheets of material may be stacked, bonded and cut. Bit body components may also be formed by the method, and subsequently assembled with other components made in like manner or by other methods to produce a bit body. Bits fabricated according to the method are also disclosed.

Abstract: A chisel type insert is disclosed having a contoured surface in which the vertical lines located on the surface are bowed outwardly in a convex manner thereby eliminating blend radii from the cutting tip and the high stress concentrations associated therewith.

Abstract: A cutter insert (34) is designed for mounting within a socket (48) bored in a roller cone cutter (10,12,14). The insert (34) includes a base (52) having a length (L2), a width (W2), and a depth (D), where the length (L2) differs substantially from the width (W2). The base (52) is sized to have an interference fit with the socket (48). A cutting tip (54) is integrally formed with the base (52) and protrudes outwardly from the socket (48) when the base (52) is mounted therein. The noncylindrical base (52) and socket (48) prohibit rotation of the insert (34) within the socket (48). Additionally, more inserts (34) with noncylindrical bases (52) can fit in a row (28-32, 36-46) than can cylindrical inserts having cylindrical bases and cutting tips of similar dimensions.

Abstract: A cutting element which has a metal carbide stud having a plurality of ridges formed in a reduced or full diameter hemispherical outer end portion of said metal carbide stud. The ridges extend outwardly beyond the outer end portion of the metal carbide stud. A layer of polycrystalline material, resistant to corrosive and abrasive materials, is disposed over the ridges and the outer end portion of the metal carbide stud to form a hemispherical cap.

Abstract: An insert for use in a roof bit for drilling bolt holes in a mine roof includes a pair of cutting edges interconnected by a chisel edge. Each cutting edge is formed by an intersection of front and side faces of the insert. Each side face further includes at least one chamfer intersecting the respective cutting edge and the chisel edge to divide that cutting edge into inner and outer sections, each of which being sharper than the chisel edge.

Abstract: Quality of a matrix body of a matrix body drill bit is tested by forming an extension of the matrix material near the nose of the matrix body drill bit. A notch is formed in a mold used to form the matrix body drill bit. The notch is filled with matrix powder during loading of the mold and subsequently infiltrated with binder alloy during infiltration of the matrix body. A matrix body extension is thus formed in the notch. The notch, and thus the matrix body extension, has a ratio of length versus diameter sufficiently high to allow the extension to be removed without permanently damaging the matrix body. The removed extension may then be subsequently tested.

Abstract: A drill bit has means at one end for connecting the bit to a drill string and a plurality of inserts at the other end for crushing the rock to be drilled. The inserts have a cemented tungsten carbide body partially embedded in the drill bit and at least two layers at the protruding drilling portion of the insert. The outermost layer contains polycrystalline diamond and particles of carbide or carbonitride of elements selected from the group consisting of W, Ti, Ta, Cr, Mo, Cb, V, Hf and Zr. The remaining layers adjacent the polycrystalline diamond layer are transition layers each comprising a composite containing diamond crystals, particles of tungsten carbide, and particles of titanium carbonitride. The average size of the diamond particles in the polycrystalline diamond layer is greater than the average size of the carbide or carbonitride particles; and the average size of the diamond particles in the transition layers is greater than the average sizes of the carbide and carbonitride particles.

Abstract: A rotary cone rock bit for drilling boreholes in an earthen formation is disclosed. One or more rotary cones are rotatively retained on a journal bearing connected to the rock bit. These rotary cones form a circumferential heel row with extended ultra hard shaped cutters spaced within the heel row. Each of the shaped cutters form a cutting surface that extends above the heel row or is angled with respect to the formation to maintain the cutters in compression while the cutters shear a borehole wall. The shaped cutters serve to maintain the borehole diameter.

Abstract: Drill bits having projecting inserts are completely coated with refractory material including on the edge margins about the inserts by thermally spraying with refractory particles whose particulate constituent under the spraying conditions is able to penetrate the inserts. Completely coated drill bits are provided.

Abstract: A rotary cone rock bit for drilling boreholes in an earthen formation is disclosed. One or more rotary cones are rotatively retained on a journal bearing connected to the rock bit. These rotary cones form a circumferential heel row with extended ultra hard shaped cutters spaced within the heel row. Each of the shaped cutters form cutting edges that shear a borehole wall formed by the formation as the rotary cone rotates against a bottom of the borehole formed by the formation. The shaped cutters serve to maintain the borehole diameter and to divert formation debris away from bearing surfaces formed between the rotary cone and the journal bearing.

Abstract: The present invention relates to a rock bit button of cemented carbide for percussive or rotary crushing rock drilling. The button is provided with a layer of diamond produced at high pressure and high temperature in the diamond stable area.The cemented carbide has a multi-phase structure having a core that contains eta-phase surrounded by a surface zone of cemented carbide free of eta-phase.

Abstract: A tungsten carbide chisel insert for rock bits is disclosed having a cylindrical base section and a cutting tip section, the top of the tip section having an elongated crest, the remainder of the cutting tip section below the crest is a contoured surface formed having cross-sections being shaped as to provide for better overall performance.

Abstract: A rock bit employs cemented tungsten carbide inserts for engaging a rock formation for drilling oil wells or the like. The cemented tungsten carbide inserts have as a binder phase a cobalt base alloy including from 10 to 35% by weight nickel, from 3 to 10% by weight chromium, from 1 to 6% by weight of molybdenum, and a balance primarily of cobalt. A particularly preferred composition has 6% by weight chromium, 17% by weight nickel, 4% by weight molybdenum and a balance of cobalt. Wear resistance is enhanced without loss of toughness in the inserts.

Abstract: A roof drill bit for drilling a bolt hole in a mine roof comprises a body defining a longitudinal axis of rotation and having an external periphery and a front face. A longitudinal fluid channel is formed in the external periphery for conducting a flow of flushing fluid to the front face. An imaginary longitudinal plane which contains the axis of rotation serves to bisect the front face into first and second sides. A cutting edge arrangement is defined by at least one cutting insert mounted on the body. The insert is positioned to be acted upon by the flow of flushing fluid. At least one support pad is mounted on the external periphery for balancing cutting forces acting on the drill bit. The cutting arrangement is asymmetrical with respect to the axis of rotation such that the cutting edge arrangement is disposed on one of the sides, and the other side is substantially free of the cutting edge arrangement.

Abstract: A sintered hard metal compact for use in earth-boring bits comprises 80 to 94% by weight tungsten carbide particles, 5.4 to 18% by weight cobalt particles and 0.6 to 2.0% by weight nickel particles wherein the ratio of cobalt to nickel is approximately 9:1 by weight. These materials are formed according to conventional powder-metallurgy techniques to provide a hard, sintered compact for use in earth-boring bits having superior properties for drilling applications.

Abstract: Drill bits having projecting inserts are completely coated with refractory material including on the edge margins about the inserts by thermally spraying with refractory particles whose particulate constituent under the spraying conditions is able to penetrate the inserts. Completely coated drill bits are provided.