Background technology
For improving the performance of cutting element on the earth-boring tools such as drill bit, one or more wear surface of cutting element or operation surface are made up of one deck polycrystalline diamond (PCD) of composite polycrystal-diamond (PDC) form being attached to substrate.This layer of PCD is often called as " diamond table " or " diamond hat ".The common substrates of PCD layer is cemented tungsten carbide.Although PDC is very hard, antiwear property is strong, usually relatively crisp.Substrate is generally cobalt consolidation diamondite, although hard not as PDC, toughness is stronger, thus has better impact resistance.The composite construction being bonded to the rigid table of toughness substrate is applicable to boring and other down-hole application.
For many abrasivity application, cubic boron nitride (CBN) is the applicable substitute of PCD, therefore, except as otherwise noted, otherwise the polycrystalline diamond mentioned in literary composition or PCD and composite polycrystal-diamond or PDC, the composite sheet equally also referring to CBN and be made up of CBN.
Composite polycrystal-diamond is made by the following method: the powdery polycrystalline diamond particle that will be called as " diamond abrasive grain " mixes with one or more granulated metal catalyst and other material, mixture is configured as composite sheet, then sinters at high temperature under high pressure.Metallic catalyst promotes to form diamond to adamantine combination between adjacent diamond particles.Although cobalt or cobalt alloy are modal catalyst, other metal of group VIII, as nickel, iron and alloy thereof also can be used as catalyst.Sintering process produces bonded diamond catalyst platform or main body, and it is described as be in has continuous, the contact in interstitial void or space or the diamond substrate (matrix) of one or lattice between diamond particles.Described interstitial void is filled with metallic catalyst at least partly.
For cutter or other wear members with sintering carbonization metallic substrates, especially the element used in downhole tool, PDC is formed in a mold by the diamond abrasive grain of the metal carbide substrate materials such as close such as tungsten carbide and metallic catalyst being filled.Afterwards, by applying HTHP sintering PDC material to mould.Metallic catalyst in base material is generally cobalt or cobalt alloy, and in sintering process, metallic catalyst scans, and (sweep) enters and infiltrate in diamond abrasive grain.Metallic catalyst strengthens the combination between diamond particles, also in a single step the PDC obtained is bonded to substrate simultaneously.
The compound of PDC and substrate can be made by many different modes.Described compound can comprise transition zone, and in transition zone, metal carbides and diamond mix with other element, combines and the stress reduced between PDC and substrate to strengthen.Unless otherwise stated, the metal carbide substrate mentioned herein comprises the substrate with transition zone.
Owing to there is catalyst metals in diamond substrate, the PCD of sintering presents thermal instability.Metallic catalyst has the larger coefficient of expansion compared with diamond.When using cutter, the thermal expansion of the catalyst comprised in the interstitial air space of rigidity diamond lattic structure may cause structure breaking, the structural integrity of infringement platform.Residual metallic catalyst also may cause the diamond crystal in PDC to start graphitization, and this can weaken PCD structure.
In order to improve the heat endurance of PDC, vast scale, being generally more than 50%, is often 70%-85%, also may be that more a high proportion of catalyst at least removes near the region of standing by the diamond lattic structure of one or more scope of operations of the maximum temperature caused that rubs.
Described metallic catalyst is removed by leaching process.Described leaching process comprises: PDC is placed in strong acid, and the example of described strong acid comprises nitric acid, hydrofluoric acid, hydrochloric acid or perchloric acid and their combination.In some cases, can heat and/or stir described acid blend, to accelerate leaching process.Under any circumstance, described leaching process can by catalyst metals, and as cobalt, being converted into can by aqueous medium, i.e. acid, from the soluble-salt that diamond table removes.
Remove the toughness that cobalt can reduce PDC, thus reduce its impact resistance.Leach also can remove by platform bonding or be bonded to substrate platform/substrate interface near some cobalts, thus affect the intensity or globality that substrate and/or substrate engage with diamond interface.In order to optimize the structural intergrity of cutter, the certain depth only measured from the one or more operation surfaces apart from PDC or the PDC of distance remove catalyst.Such as, the operation surface of drill bit cutting elements is the cutter surface of designing or being intended to for engaging rock stratum.For PDC cutter, it typically is diamond hat or the upper surface of platform, at least partially side surface and the hypotenuse between upper surface and side surface, rounding transition or conformal transition (if any).Usually, only have the upper operation surface of PDC to be exposed to and leach bath.The impact from acid at the bottom of cover and strip of paper used for sealing protecting group can be used.Leach the degree of depth and depend on the micro-structural of diamond, the infusion solution of use and extraction time.
For the acid of leaching may toxicity very large, leaching process may need a lot of littlely week to leach cutter up to a lot of.Leaching process needs the equipment carefully being processed material and complexity by trained operator, and these considerably increase the cost producing cutter.
Summary of the invention
Sintered diamond compact through high pressure-temperature process for producing generally comprises and remains in intergranular catalyst material, and this can damage the structural intergrity of composite sheet under running conditions.Remove or replace with the material that compatibility is stronger the operating temperature range that catalyst material can expand diamond compact, and greatly cut down finished cost.The present invention uses the solid catalyst in metal solvent dissolving diamond compact.Use solvent metal can both environmental protection and toxicity is low.
An aspect of of the present present invention, a kind of consolidated diamond composite sheet with interstitial air space comprises composite sheet Part I and composite sheet Part II, described composite sheet Part I has catalyst metals in interstitial air space, and described composite sheet Part II has solvent metal in interstitial air space.
Of the present invention another optional in, a kind of cutter for ground engagement instrument comprises substrate, and it is bonded to the diamond table with interstitial air space, wherein, being occupied by solvent metal at least partially of described interstitial air space.
Of the present invention another optional in, a kind of method processing sintered diamond comprises heated solvent metal, and soaks described sintered diamond at least partially with described solvent metal.
In certain embodiments of the present invention, the residual catalyst in diamond is cobalt, described cobalt by the solvent metal in interstitial air space, as gallium, tin and/or other dissolving metal.In some embodiments, solvent metal is heated between 600 DEG C-750 DEG C, preferably greater than 650 ° of C.Can in vacuum or inert gas environment heated solvent metal.When completing heating in vacuum or inert gas environment, before diamond compact is exposed to solvent metal, described solvent metal can be heated to the temperature up to 1500 DEG C.In some embodiments, diamond compact and/or cutter such as indium, gallium, tin, gallium-indium-tin alloy or other element or alloy material process, to improve course of dissolution.
In some embodiments, the cobalt in interstitial air space is removed or volume is reduced.In some embodiments, cobalt is replaced by solvent metal at least partly, thus in the part that diamond is treated, the weight of catalyst is less than solvent.In some embodiments, cobalt is replaced by solvent metal at least partly or is replaced, and in the part that diamond is treated, the volume that catalyst occupies is less than solvent.In some embodiments, cobalt is replaced by solvent metal at least partly, and in the part that diamond is treated, the volume that catalyst occupies is less than 25% of catalysts and solvents volume.
After sintering, stay metallic catalyst in polycrystalline diamond (PCD) structure from described structure at least partially, as the part near one or more operation surface, remove by removing with solvent metal and replace, described solvent metal fusing point is lower than metallic catalyst, and the preferred operating temperature lower than end product.In some embodiments, solvent is one or more metals being selected from the group be made up of gallium, indium, tin.
The metallic catalyst of this operation surface near PCD structure is had the heat endurance of improvement at least partly by the PCD structure that solvent metal is replaced.Even if the thermal coefficient of expansion of solvent metal is different from sintering PCD, liquid phase solvent metal also can not apply expansive force or pressure to sintering PCD matrix, thus avoids producing the stress that can cause breaking in PCD structure.Gallium, tin and indium can not with carbon miscible, adamantine graphitization can not be increased the weight of.
To remove and the representative instance replacing the method for metallic catalyst in PCD structure with the lower solvent metal of fusing point comprises: with fusing point lower than the solvent metal of metallic catalyst by metallic catalyst solvation or dissolving, and once dissolve in metal solvent, allow metallic catalyst to diffuse in bath and allow solvent metal to diffuse in diamond table, thus realizing catalyst and remove from PCD structure and replace catalyst with solvent metal.For to dissolve or the Material examples with more low melting point of metallic catalyst of solvation such as cobalt and cobalt alloy comprises: gallium, indium, tin, rubidium, sodium, thallium, lead, cadmium, bismuth, polonium, potassium, mercury and their alloy.
The representative instance comprising the abrasion structure of sintering PCD structure comprises for drill bit or the cutter of reamer (reamer) comprising tungsten carbide substrate, and described sintering PCD structure at least comprises near comprising the region of fusing point lower than the PCD surface of the metal of the catalyst for sintering PCD.
Not Metal Substrate acid for leaching the acid of catalyst, and usually comprising fluorine, chlorine, sulphur, nitrogen.When catalyst-solvent, the kish composition in interstitial air space is not stayed in these acid.For object of the present invention, displacement catalyst refers to and removes catalyst and make it spread away from interstitial air space.For object of the present invention, replacement catalyst refers to and removes catalyst and make it spread away from interstitial air space, and moves into solvent molecule in the position of interstitial air space inner catalyst.
Detailed description of the invention
Diamond is a kind of common industrial materials, application widely, as grinding-material or for Surface hardened layer instrument.The diamond being consolidated into cutter is used in many different application, as the downhole drill bit for tunneling boring, drill hammer, wear member and other such as the cutting of digging up mine and abrasion application.Aggressive application in these grinding environment causes the service life of cutter very short, and millions of cutter is all with comprising the method manufacture removing catalyst from diamond.Unless otherwise stated, term catalyst, catalyst metals or the metallic catalyst in the present invention refers in formation consolidated diamond composite sheet, in the diamond table as bit cutting device, as the metal that catalyst uses.
Fig. 1 illustrates the example of PDC drag bit.Described drill bit is that it comprises the drill main body 104 being connected to handle 106 for rotating around its central axis 102, and handle 106 has the tapered thread hookup 108 for drill bit being connected to drill string; And " bit breaker " surface 111, tighten up and loosen hookup 108 and drill string for coordinating with instrument.Described main body be called as bit face for the outer surface substantially towards boring direction.Described the plane be substantially positioned at perpendicular to drill bit central axis 102.Described main body is not limited to any concrete material.Such as, it can be made by steel or such as with the host material of the powder tungsten carbide of metallic bond combination.In main body, arrange multiple projection blade along bit face and side, each blade represents with 110, and it is from drill main body projection.Each blade is installed multiple discontinuous cutting element or cutter 112.Each discontinuous cutting element is arranged in recess or bag.Element similar in subsequent drawings uses similar Reference numeral.
Fig. 2 A, 2B and 2C illustrate and are applicable to drill bit, as shown in Figure 1 PDC drill bit, the representative instance of PDC cutter.Typical cutter 200 comprises the substrate 202 being attached with one deck polycrystalline diamond (PCD) 204 (also claiming diamond table).Cutter 200 is not drawn in proportion, its object is to the cutter that general expression has the polycrystalline diamond structure being attached to substrate, the one or more PDC cutters 112 especially on drill bit 100 shown in Fig. 1.In this example, the edge tilt between the upper surface 206 of PCD layer 204 and side surface 208 forms hypotenuse 210.In this example, described upper surface and skewed surface are all the operation surfaces for contacting and cut stratum.A part for side surface, especially more near a part for upper surface 206, also can contact stratum or chip.
The abrasion insert comprising sintering PCD structure is by raw material are placed in mould, forms through high temperature and pressure manufacture.Replaced by metal or alloy after occupying the residual metal catalyst of calking between bonded diamond particle or be replaced at least partly, to strengthen heat endurance.Typical catalyst, as cobalt, has 13 × 10-6m/m-Klinear expansion coefficient, diamond has approximate 1 × 10-6m/m-Kthe coefficient of expansion.The fusing point of cobalt is about 1500 DEG C, under the drillng operation typical work condition that can reach 700 DEG C or higher temperature, keep solid state.Solid cobalt in platform interstitial air space expands to during operating temperature at Delta.Cobalt is limited in the interstitial air space of diamond substrate.These interstitial air spaces do not expand in the mode corresponding with cobalt.Described expansion cobalt may cause diamond to break, and destroys diamond table matrix.
But the liquid of displacement catalyst can flow out interstitial air space when it expands, instead of applies huge stress to diamond substrate.Low melting material effectively can be replaced catalyst and reduce the stress in operation in diamond.Term " low melting material ", " comparatively low melting material " or " having the material compared with low melting point " have both represented that metal also represents metal alloy, it can as catalyst solvent, and there is the fusing point being significantly less than catalyst, and preferably there is the fusing point lower than anticipation operating temperature.
This kind of have compared with low melting point, the alloy that can comprise gallium, titanium, molybdenum, indium, iron, tin, zirconium and often kind in sintering PCD structure as the Material examples of metallic catalyst solvent, and/or other transition metal that carbon compatibility is strong, to promote to infiltrate diamond.Other example of solvent metal comprises sodium, potassium, mercury and their alloys of often planting.Arbitrarily the alloy of metal and strong other transition metal of titanium, molybdenum, iron, zirconium and/or carbon compatibility all contributes to reducing capillary resistance and strengthening capillarity above.Reducing capillary resistance allows solvent more freely to immerse interstitial regions, and increases the contact with catalyst material when soaking diamond.
Some these kind solvents also can be considered as catalyst.Such as, gallium (and other metal) can as catalyst in diamond table.On the one hand, method of the present invention relates to replaces with the second metal in diamond table the first metal being used as catalyst formation diamond table, and described second metal originally can as catalyst in diamond.Unless otherwise stated, in the present invention, term solvent, solvent metal or metal solvent refer to the non-aqueous metal medium dissolved for the formation of the catalyst of consolidated diamond composite sheet.
Liquid flux dissolving metal solid cobalt follows Fick's law.Fick's first law determines that the first material enters the dissolution velocity of the second solvent material and migration or velocity of liquid assets.Circulation makes material move from high concentration region to low concentration region, size and concentration gradient proportional, or dissolved matter strides across concentration gradient from high concentration region and moves to low concentration region.In (space) dimension, described law is:
Wherein J represents " diffusion flow " or (material amount) of unit are in time per unit.J measures the amount of the first material by flowing through small size within the very short time interval.D is length2time-1diffusion coefficient in dimension or diffusivity, Φ (for ideal mixture) is the concentration in per unit volume first quantity of material dimension, and x is position (length).D and particles diffusion speed square proportional, according to Stokes-Einstetn equation, it depends on temperature, fluid viscosity and particle size.In dilution aqueous solution, the diffusion coefficient of most of ion is similar, and number range is at room temperature 0.6 × 10-9to 2 × 10-9m2/ s.
The people such as S.P.Yatsenko (JournalofPhysics:ConferenceSeries98062032doi:10.1088/174 2-6596/98/6/062032) in one section of document of 2008 examine the corrosion of several metal in gallium or dissolution velocity is the function of temperature.They determine: when temperature is 637K, and the dissolution velocity of cobalt in gallium is 2.3 millis gram/cm per hour.Dissolution velocity controls primarily of temperature.Can by the migration velocity of dissolved cobalt away from cobalt/gallium interface, and the real area of gallium catalyst and interstitial air space internal solvent metallic interface limits dissolution velocity.
Fig. 3 is the schematic diagram of a part for the platform 300 of consolidated diamond particle 302, wherein before solvent contact 306, has catalyst 304 in the interstitial air space between particle.In the HTHP consolidation process forming diamond table, liquid catalyst promotes that diamond particles interface is formed and combines.Leave interstitial regions in the discontiguous place of particle, in these spaces between particles, leave solid catalyst.
Fig. 4 is the schematic diagram of a part for the consolidated diamond platform 300 immersed at least partly in solvent 306, and the catalyst 304 be wherein present between diamond particles is solid.Solvent 306 shown in figure immerses between diamond particles to contact solid catalyst.The speed that catalyst is determined with Fick's law in heated solvent is dissolved, and catalyst molecule 304' is away from solvent/catalyst interface, towards the bulk solvent migration that catalyst concn is lower.
Fig. 5 is the schematic diagram of the part immersing consolidated diamond platform shown in the Fig. 4 in solvent 306, wherein carries out described process to produce the diff area of diamond table.In the 300A of first area, catalyst remains in the interstitial regions between diamond particles in a large number.In second area 300B, catalyst is also replaced at least partly by dissolution with solvents in interstitial air space.In a preferred embodiment, catalyst is cobalt, and solvent is gallium, tin or other solvent metal.Alternatively, can use the catalysts and solvents that other works in a similar manner, this also belongs within scope of the present invention.Maintain an equal level although Fig. 5 illustrates that the top of second area 300B and solvent metal are bathed, catalyst also can be replaced in the level height higher than bath.
Although the region shown in figure is rectangle, described region can be any shape.Such as, except the front shown in figure, when solvent area may be limited to front periphery driving drilling operation, cutter can contact in the operating area of boring.The border comprised between solvent metal and the region of catalyst metals also can be obvious or accurate unlike shown in figure.In fact the border in region that metallic catalyst is replaced by the lower solvent metal of fusing point at least partly is as illustrated in the drawing only schematic diagram, is intended to as typical case.Multiple region is possible, and each region may have identical or different geometry, and these regions also may have different pattern or arrangement mode.
Displacement cobalt region can extend to desired depth from surface.Fig. 6 illustrates that the cutter 200 with substrate 202 and platform 204 is exposed to solvent.Fig. 6 A is the detail view of polycrystalline diamond platform 204, and it has and does not exhaust catalyst area 300A and exhaust catalyst area 300B.In fact, exhaust catalyst area and can extend to any degree of depth.In an example, the degree of depth exhausting catalyst area can be 100 microns.Exhaust catalyst area can the extend to 200 microns degree of depth from surface.In a preferred embodiment, the degree of depth that catalyst area extends to 200-250 micron is exhausted.Darker catalyst depleted region is also possible.As mentioned above, catalyst depleted region can comprise and removes catalyst wholly or in part.
This course of dissolution is different from Ore Leaching.Such as, cobalt metal slowly consumes in dilute sulfuric acid, is formed and comprises hydration Co (II) ion and hydrogen H2solution.In reality, Co (II) is as complex ion [Co (OH2)6]2+exist.
Co(s)+H2SO4(aq)→Co2+(aq)+SO42-(aq)+H2(g)
Solvent also can be divided into polarity with nonpolar.Usually, the dielectric constant of solvent provides the rough tolerance of solvent polarity.When 0 DEG C, the strong polarity of water is expressed as dielectric constant 88.Sulfuric acid is typically used as the leaching agent of cobalt in diamond, and it has the dielectric constant of 100, and the dielectric constant of nitric acid is 50.The solvent that dielectric constant is less than 15 is commonly considered as nonpolar.Polarity be in conjunction with element to form the function of molecule, make them have electronegative molecular moiety.Such as the element of tin, indium or gallium is nonpolar, and their dielectric constant can be appointed as 1.
When liquid is at interface contact solid, the some parts of solid may be dissolved in liquid.According to the chemical property of solid and liquid, certain part of solid will be dissolved in a liquid, until reach the saturation point with molar percentage or other term description.Described saturation point depends on temperature.Normally, high-temperature can improve saturation point or solubility limit.Fig. 7 illustrates the phase-solubility diagrams of cobalt and tin.When 250 DEG C, tin is liquid, but the solubility of cobalt in tin is very low.During 700 ° of C, the solubility of cobalt in tin is about 4%, is dissolved with 4 cobalt atoms in every 96 tin atoms.
Cobalt-Xi phasor shown in Fig. 7 only exemplarily.Other metal solvent and catalyst combination have the similitude phase diagram that may be used for determining solubility.In a preferred embodiment, when being heated to more than 600 DEG C, the solubility of catalyst metals in solvent metal is at least 2%, but the material at different temperatures with higher or lower solubility may be used for replacing the catalyst in diamond.Solvent disclosed herein also can think non-aqueous solvent.Solvent disclosed herein also can be considered to inorganic solvent.In some embodiments, solvent is combined with catalyst chemical, forms intermediate alloy and/or intermetallic compound.
Some solvent metals are used to cutter platform to remove cobalt.In each case, diamond immerses solvent bath and in solvent bath after process, diamond table breaks to be provided for the cross section analyzed.Energy Dispersive X-ray spectrometer (EDS) is for determining along extending inwardly to from diamond table operation cross section platform is not affected the material of the line 310 of part formation (see Fig. 6 A) by solvent metal.Described EDS utilizes the electron stream accelerated towards target material to impact constituting atom.Described impact electronics causes the electron transition of atom to the more high level of atomic structure.When electronic decay gets back to initial level, it launches the X-ray with element energy feature.Institute's column data is the X-ray counting with target element energy feature herein.Afterwards, described counting is associated with the atomicity of constituent material.The change of Elements Atom size and atomic shell feature needs regularization factors to provide concrete concentration.The enumeration data of regularization factors is not had to represent the depletion depth of catalyst and the degree of depth of moving into of solvent metal herein.
Cross-sections surfaces along analytical line comprises the diamond particles distributed alternately with interstitial air space.This causes the data of specific constituent material to become noise data or " jump " data.In order to observe the general trend of constituent, smooth function is applied to data.
In an example, gallium bath is heated to the temperature of 600 DEG C.Cutter diamond table containing Co catalysts in interstitial air space is placed 72 hours in bath.EDS line analysis result as shown in Figure 8.Gallium infiltrates the degree of depth of about 40 microns, and the concentration of cobalt reduces at similar depth.
In another example, indium bath is heated to the temperature of 700 DEG C.Cutter diamond table containing Co catalysts in interstitial air space is placed 24 hours in bath.EDS line analysis result as shown in Figure 9.Indium infiltrates the degree of depth of about 50 microns, and the concentration of cobalt reduces at similar depth.
In another example, tin bath is heated to the temperature of 700 DEG C.Cutter diamond table containing Co catalysts in interstitial air space is placed 24 hours in bath.EDS line analysis result as shown in Figure 10.Tin infiltrates the degree of depth of about 80 microns, and the concentration of cobalt is suppressed at similar depth.
In another example, the bath of the alloy (gallium-indium-tin alloy) of gallium, indium and tin is heated to the temperature of 700 DEG C.Cutter diamond table containing Co catalysts in interstitial air space is placed 24 hours in bath.EDS line analysis result as shown in figure 11.Gallium-indium-tin alloy infiltrates the degree of depth of about 60 microns, and the concentration of cobalt is suppressed near same depth.
Alternatively, course of dissolution can carry out under vacuum or inert gas environment, and diamond can be suppressed like this to transform to graphite.Under such circumstances, solvent can be heated to higher temperature and make the limited graphitization of diamond table.According to Fick's law, at higher temperature, solvent will be accelerated the dissolving of catalyst, can process the platform of greater part in same time.Alternatively, the platform of similar large fraction can be processed within the shorter time.In an example, gallium is heated in a vacuum the temperature between 1000 DEG C-1500 DEG C, and cutter table top liquid-gallium is soaked.
Base material may cause because of solvent contact metal destroying.Solvent metal can dissolve substrate composition, thus causes loss structure integrality.At the bottom of protecting group, can apply protective finish in substrate, restriction solvent metal contacts with base material.Figure 12 illustrates similar to cutter shown in Fig. 2, to have substrate 202 and diamond table 204 cutter 200.Described cutter comprises protective layer 352, and it separates substrate, avoids substrate to contact with any of solvent metal.Protective layer can be coated in suprabasil metal sputtering plated film or plated metal.Also can with other method Deposition of protective layer.Alternatively, protective layer can be high temperature plastics, pottery or other material of matching with solution temperature and material.
Make solvent metal immerse diamond lattic structure can not need to soak diamond.Figure 12 illustrates the porous body or sponge material 350 that support cutter.Porous body 350 is immersed in solvent metal 306, and cutter platform 204 is positioned on the porous body upper surface higher than solvent metal.Conductor is porous, and is easily infiltrated by solvent metal, thus makes metal by capillarity by porous body rising contact platform.The Contact of substrate and solvent metal can be limited so further.Porous body 350 and protective layer 352 not necessarily will use simultaneously.Porous body or coat self all can provide enough protections for substrate, can use one of them or another.
Refer again to Fig. 1, each blade of drill bit roughly extends radially outward to cutting face periphery.In this example, have six blades around central axis roughly equi-spaced apart, and in this embodiment, each blade scans with the direction of rotation shown in arrow 115 or bends backward.
In drag bit, cutter is placed along (expection direction of rotation) forward side of blade, their scope of operation roughly towards forward direction, with when drill bit rotates around its central axis shear stratum.Shown in figure, described cutter arranges along blade, is formed and cuts or cut a hole the structure of hitting stratum, and the chip produced is rinsed by the brill liquid sprayed from drill bit by nozzle 117.Chip or cutting object are upwards delivered to surface by boring by described brill liquid.
In this drag bit example, all cutters 112 are all PDC cutters.But in other embodiments, not all cutter must be all PDC cutter.PDC cutter in this example have formed primarily of adamantine polycrystalline diamond etc., by the scope of operation of substrate support, described substrate is formed for being formed at the installation stud placed in the bag on blade.Each PDC cutter is independent manufacture, is then loaded in the bag be formed on drill bit by hard solder, press-in cooperation or alternate manner.But described PDC layer and substrate are used with the cylinder form manufacturing them usually.This drill bit example comprises gauge pad (gaugepad) 114.In some applications, drill bit, as drill bit 100, gauge pad can comprise the thermally-stabilised polycrystalline diamond (TSP) of insertion.These TSP elements also can process according to the present invention be processed.
Although PDC cutter is often cylindrical, it is not limited to a certain given shape, size or geometry, is also not limited to individual layer PCD.Be not all cutters on drill bit must be all same size, structure or shape.Except being sintered to different size or shape, PDC cutter can also change shape by cutting, grinding or mill.In addition, cutter can be formed by multiple independent PCD structure.Other possible cutter shape instance can comprise gauge cutter (gaugecutter) flat in advance, tip or line cutter (scribecutter), scalpriform cutter and cheese insert.
Figure 13 illustrates the basic step of process 400 representative instance manufacturing the abrasion insert comprising sintering PCD structure, and described process comprises: replace by utilizing metal or alloy the metallic catalyst occupying calking between bonded diamond particle and make its heat endurance better.Process 400 comprises two basic steps or process: the first, forms the process of sintering PCD structure; The second, separation process, for after sintering with low-melting-point metal replace PCD structure at least partially in residual metallic catalyst.Above two processes can be carried out respectively.Second process comprises with the metallic solvent of bag from the dissolving at least partially of PCD structure and/or diffuse metal catalyst.In a preferred embodiment, the fusing point of solvent is lower than catalyst.Second process, by dissolving and spreading, removes at least most of metallic catalyst from least one region of PCD, and replaces with the metal that fusing point is lower.Above-mentioned second process is by being placed in PCD structure the bath that comprises liquid metals solvent at least partially or contacting with described bath, or otherwise PCD structure is exposed to liquid metals solvent, to allow metal catalyst dissolution and to be diffused in solvent metal, and solvent metal is allowed to diffuse in described PCD structure.Described bath is preferably heated to the temperature of more than 625 DEG C, but this temperature can change to some extent according to the various factors such as concrete solvent, replacement catalyst desired depth used.
Step 402 represents the process with metallic catalyst polycrystalline diamond particle.An example of sintering process comprises and first forms granule or fine grain synthesis or natural diamond composite sheet.These particles are called diamond abrasive grain or bortz powder in the industry.Described composite sheet can comprise other materials and structures.In alternate embodiments, PCD particle can according to particle size layering in described composite sheet.Such as, the one deck near work layer may comprise thinner particle (namely particle is less than predetermined particle size), and farther one deck, may be the basic unit near substrate, comprise the particle being greater than predetermined particle size.But according to particle size, any amount of arrangement of diamond abrasive grain and geometry are all possible.Such as, these geometries can be formed as generating the region with predetermined geometry, and because diamond density is different, described region can relatively be improved or reduce metal catalyst dissolution and/or be diffused out the speed of sintering PCD structure.Selecting dissolving in part and/or diffusion velocity by changing sintered diamond structure, metallic catalyst can be constructed to by the region that more low-melting-point metal is replaced at least partly and there is more complicated geometry.
Unless otherwise expressly specified, otherwise process described herein is not limited to the concrete percentage of diamond abrasive grain in any concrete geometry of diamond abrasive grain or arrangement, any concrete size being not limited to diamond abrasive grain or composite sheet.Can there is catalyst in the composite sheet formed, as sintered under high pressure-temperature (HPHT) under the condition of cobalt, cobalt alloy or any group VIII metal or alloy.Composite sheet is placed in the process of HPHT sometimes referred to as " compacting ".Catalyst can not mix with diamond abrasive grain, but infiltrates in composite sheet by forming composite sheet in the tungsten carbide substrate combined with catalyst, then both is added hot pressing together.Catalyst also can mix with diamond abrasive grain.Can be formed in a similar manner by the composite sheet that CBN particle makes.
If sinter in advance with metallic catalyst, to form PCD structure be available, and metallic catalyst remains at least one region of PCD body structure surface, then method 400 can from any one in step 404,406 or 408.Step 404 and 406 is optional.The representative instance of this type of PCD structure includes but not limited to PDC cutter, described PDC cutter comprise as by step 402 the process of carrying out or other process be attached to the sintering PDC wear surface of substrate.But described structure does not need to have substrate.
Step 404 comprises that maybe can not be dissolved in such as tungsten, tantalum, gallium oxide, tungsten tantalum mixture will as the side of other Material coating of the metal of solvent at least substrate.Described step expection obtains the PCD structure being attached to sintering carbonization substrate.The example of this type of substrate is cobalt consolidation tungsten carbide.Described step can reduce the risk that solvent metal surprisingly dissolves some metal in substrate.Such as, gallium can destroy rapidly sintering metal-carbide by dissolution of metals matrix.
Wear member to be brazed in the isostructural application of such as drill bit, use tungsten to have advantage as coating, because tungsten generally can be infiltrated by most of brazing alloy.Metal coating can at least partly along the side of described PCD structure to downward-extension.Further, if needed, all surfaces except being exposed to solvent of PCD structure can be all coated.
Step 406 relates to one or more surfaces of the PCD structure that will be exposed to solvent with pre-invasion Material coating.What the coating containing such as indium, tin or gallium-indium-tin alloy equal solvent metal can be coated on PCD structure when immersing solvent bath will be exposed on one or more surfaces of solvent, to accelerate to infiltrate diamond table.
In step 408, in the bath that the submerging at least partially of PCD structure comprises the solvent be made up of solvent metal.As mentioned above, alternatively, PCD structure can be placed as and contact with the structure immersed in solvent, and no matter be which kind of situation, described PCD structure is all exposed to described solvent.In one embodiment, PCD structure is suspended or is kept, thus only has the predetermined portions of PCD to be exposed to bath.Such as, this part can be the one or more selected surface of PCD structure, or the part on described one or more surface.The temperature that the bath comprising solvent metal is heated to more than the liquidus curve of solvent metal, PCD structure has below the temperature of serious graphitization risk, and maintain a period of time.Start in PCD that graphited temperature occurs and be generally 750 DEG C.In vacuum or inert gas environment, graphitization temperature may be higher.Diamond can heat in a vacuum and reaches 1600 DEG C and limited graphitization only occurs.
Depend on solvent metal, be heated beyond fusing point and can accelerate to infiltrate diamond lattic structure, assist in ensuring that better capillarity, improve and dissolve and diffusion.Capillarity can help to keep the contact between solvent metal and catalyst metals.High temperature also can improve and dissolves and diffusion velocity.
In an exemplary embodiment in which, the temperature of bath is between solvent metal fusing point and 750 DEG C.In another exemplary embodiment, the temperature of bath is between 600 DEG C and 723 DEG C.The solvent metal example of this embodiment is the alloy of gallium, indium and tin, is sometimes referred to as gallium-indium-tin alloy.Bath can be heated to described temperature before PCD structure is placed in bath, or to have melted and PCD structure is promoted to described temperature after putting into bath at solvent metal.In step 410, described solvent to flow in the PCD structure exposed and contacts solid catalyst.Catalyst dissolution, in metal solvent, then diffuses to outside described structure.Once PCD structure removes in step 412 from bath, then can by bath cooling to impel the metallic catalyst be dissolved in bath to solidify.Solid-phase catalyst can from solvent (if fusing point is a little more than the gallium-indium-tin alloy of room temperature) machinery or isolated by filtration, simultaneously solvent still be liquid phase, thus permission solvent (as gallium-indium-tin alloy) is reused.Other method being separated solvent and catalyst is all well known to those skilled in the art.
Solvent metal dissolved solid cobalt, the cobalt of dissolving diffuses in metal solvent, then leaves diamond lattic structure.Solvent metal can replace the cobalt in interstitial air space at least partly.Compared with pickling, gallium and other metal solvent can more easily infiltrate PCD structure.Positive capillarity pulls solvent to enter PCD structure.
Although what the present invention described is the cutter used in drag bit, its object is to illustrate, described PCD structure can be widely used in other application, as the wear member for excavating, for the pick of lower wall exploitation and material processing operation etc.PDC drag bit 100 is intended to usually as the representative instance of downhole tool, more specifically, as the representative instance boring soil working tool, Oil/gas Well drill bit and PCD drag bit.
Foregoing description is exemplary and preferred embodiment.The scope of the invention is defined by the claims, can't help above-mentioned embodiment limit.Can variants and modifications be carried out to embodiment disclosed in the present invention and not depart from the scope of the present invention.Unless expressly stated otherwise, otherwise the implication of term used herein is its common accustomed meanings, and object do not lie in limit explain or the details of description scheme or embodiment.