Patent Application
20150014067
Polycrystalline diamond compact (“PDC”) cutters have been used in industrial applications including rock drilling and metal machining for many years. Generally a compact of polycrystalline diamond (PCD) (or other superhard material) is bonded to a substrate material, which is a sintered metal-carbide to form a cutting structure. PCD includes a polycrystalline mass of diamonds (generally synthetic) that are bonded together to form an integral, tough, high-strength mass or lattice. The resulting PCD structure produces enhanced properties of wear resistance and hardness, making PCD materials extremely useful in aggressive wear and cutting applications where high levels of wear resistance and hardness are desired.
A PDC cutter may be formed by placing a cemented carbide substrate into the container of a press. A mixture of diamond grains or diamond grains and catalyst binder is placed atop the substrate and treated under high pressure, high temperature conditions. In doing so, metal binder (often cobalt) migrates from the substrate and passes through the diamond grains to promote intergrowth between the diamond grains. As a result, the diamond grains become bonded to each other to form the diamond layer, and the diamond layer is in turn bonded to the substrate. The substrate often includes a metal-carbide composite material, such as tungsten carbide. The deposited diamond layer is often referred to as the “diamond table” or “abrasive layer.”
Conventional PCD includes 85-95% by volume diamond and a balance of the binder material, which is present in PCD within the interstices existing between the bonded diamond grains. Binder materials that are generally used in forming PCD include Group VIII elements, with cobalt (Co) being the most common binder material used. The binder material is often removed to improve the thermal stability of the PDC cutter.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
In one aspect, embodiments disclosed herein relate to a method of treating a cutting element that includes providing a cutting element including polycrystalline diamond fixed to a substrate; enclosing the substrate and at least a portion of the polycrystalline diamond within a protective element to form a partially enclosed cutting element; exerting a compressive squeeze on the cutting element of about 5-25%; and exposing the partially enclosed cutting element to a leaching solution so that at least part of an unenclosed portion of the polycrystalline diamond is in contact with the leaching solution.
In another aspect, embodiments disclosed herein relate to a protected cutting element that includes a cutting element including polycrystalline diamond fixed to a substrate; and a protective element enclosing the substrate and at least a portion of the polycrystalline diamond and exerting a compressive squeeze of about 5-25% on the cutting element.
In yet another aspect, embodiments disclosed herein relate to a method of treating a cutting element that includes providing a cutting element including polycrystalline diamond attached to a substrate; enclosing the substrate and at least a portion of the polycrystalline diamond within a protective element including at least one FFKM perfluoroelastomeric material to form a partially enclosed cutting element; and exposing the partially enclosed cutting element to a leaching solution so that at least part of an unenclosed portion of the polycrystalline diamond is in contact with the leaching solution.
Other aspects and advantages of the claimed subject matter will be apparent from the following description and the appended claims.
Leaching of intact cutting elements with an acid (or a mixture of acids, such as a mixture of HF and HNO3) may remove catalyst from the substrate. Such treatments tend to take time, for example, several weeks, which puts substantial demands on the types of materials that can be utilized to protect the vulnerable parts of cutting element from the acidic and corrosive nature of a leaching solution. To expedite leaching, cutting elements exposed to an acidic leaching solution may also be exposed to heat. Under these harsh conditions, protective materials may embrittle, swell, degrade, or otherwise experience changes in properties resulting in failure, which may lead to irreversible damage to the cutting elements (e.g., damage to the substrate) or to dangerous exposure to leaching solutions for those handling the cutting elements during and after the leaching process.
In one aspect, embodiments disclosed herein relate to methods of leaching cutting elements containing a polycrystalline diamond body. More particularly, embodiments disclosed herein relate to protective methods and elements for the protection of regions of a cutting element which are not desired to be exposed to a leaching solution during a leaching process. Specific embodiments described may serve to concentrate the contact sealing forces between the protective element and the cutting element to minimize the potential of leaching solution ingress past the seal surfaces during the leaching process (or past a particular part of the seal during the leaching process). Further, the design features expressed in some embodiments may also improve the useful service life of the protective element during the leaching process. These protective methods and elements can be used in conjunction with conventional leaching protocols including those involving accelerating techniques such as elevated temperatures, pressures, and/or the use of ultrasound.
Forming Polycrystalline Diamond
A polycrystalline diamond body may be formed in a conventional manner, such as by a high pressure, high temperature sintering of “green” particles to create intercrystalline bonding between the particles. “Sintering” may involve a high pressure, high temperature (HPHT) process. To form the polycrystalline diamond body, an unsintered mass of diamond crystalline particles is placed within a metal enclosure of the reaction cell of a HPHT apparatus. A metal catalyst, such as cobalt or other Group VIII metals, may be included with the unsintered mass of crystalline particles to promote intercrystalline diamond-to-diamond bonding, may be included adjacent to the unsintered mass of crystalline particles, or may be provided from the substrate. The catalyst material may be provided in the form of powder and mixed with the diamond grains, or may be infiltrated into the diamond grains during HPHT sintering. An example minimum temperature is about 1200° C. and an example minimum pressure is about 35 kilobars. Generally, processing may occur at a pressure of about 45 kbar and 1300° C. Those of ordinary skill in the art will appreciate that a variety of temperatures and pressures may be used, and the scope of the present disclosure is not limited to specifically referenced temperatures and pressures.
Diamond grains useful for forming a polycrystalline diamond body may include any type of diamond particle, including natural or synthetic diamond powders having a wide range of grain sizes. For example, such diamond powders may have an average grain size in the range from submicrometer in size to 100 micrometers, and from 1 to 80 micrometers in other embodiments. Further, one skilled in the art would appreciate that the diamond powder may include grains having a mono- or multi-modal distribution.
The diamond powder may be combined with the desired catalyst material, and the reaction cell may then be placed under processing conditions sufficient to cause intercrystalline bonding between the diamond particles. If too much additional non-diamond material is present in the powdered mass of crystalline particles, appreciable intercrystalline bonding may be prevented during the sintering process. Such a sintered material where appreciable intercrystalline bonding has not occurred is not within the definition of PCD. Following such formation of intercrystalline bonding, a polycrystalline diamond body may be formed that has, in some embodiments, at least about 80 percent by volume diamond, with the remaining balance of the interstitial regions between the diamond grains occupied by the catalyst material. In other embodiments, such diamond content may include at least 85 percent by volume of the formed diamond body, and at least 90 percent by volume in yet other embodiments. However, one skilled in the art would appreciate that other diamond densities may be used in other embodiments. Thus, the polycrystalline diamond bodies being leached in accordance with the present disclosure include what is frequently referred to in the art as “high density” polycrystalline diamond. One skilled in the art would appreciate that conventionally, as diamond density increases, the leaching time (and potential inability to effectively leach) similarly increases.
Further, one skilled in the art would appreciate that, frequently, a diamond layer is sintered to a carbide substrate by placing the diamond particles on a preformed substrate in the reaction cell and sintering. However the present disclosure is not so limited. Rather, the polycrystalline diamond bodies treated in accordance with the present disclosure may or may not be attached to a substrate.
In some embodiments, the polycrystalline diamond body may be formed using solvent catalyst material provided as an infiltrant from a substrate, for example, a WC—Co substrate, during the HPHT process. In such embodiments where the polycrystalline diamond body is formed with a substrate, it may be desirable to remove the polycrystalline diamond portion from the substrate prior to leaching so that leaching agents may attack the diamond body in an unshielded manner, i.e, from each side of the diamond body without substantial restriction.
Further, one skilled in the art would appreciate that the same techniques used with polycrystalline diamond may be applied to polycrystalline cubic boron nitride (PCBN). Similar to polycrystalline diamond, PCBN may be formed by sintering boron nitride particles (often CBN) via a HPHT process, similar to those for PCD, to sinter “green” particles to create intercrystalline bonding between the particles. CBN refers to an internal crystal structure of boron atoms and nitrogen atoms in which the equivalent lattice points are at the corner of each cell. Boron nitride particles generally have a diameter of approximately one micron and appear as a white powder. Boron nitride, when initially formed, has a generally graphite-like, hexagonal plate structure. When compressed at high pressures (such as 106 psi), CBN particles will be formed with hardness very similar to diamond, and stability in air at temperatures of up to 1400° C.
According to some embodiments, PCBN may include a content of boron nitride of at least 50% by volume; at least 70% by volume in other embodiments; at least 85% by volume in yet other embodiments. In other embodiments, the cubic boron nitride content may range from 50 to 80 percent by volume, and from 80 to 99.9 percent by volume in yet other embodiments. The residual content of the polycrystalline cubic boron nitride composite may include at least one of Al, Si, and mixtures thereof, carbides, nitrides, carbonitrides and borides of Group IVa, Va, and VIa transition metals of the periodic table. Mixtures and solid solutions of Al, Si, carbides, nitrides, carbonitrides and borides of Group IVa, Va, and VIa transition metals of the periodic table may also be included.
An example of a rock bit for earth formation drilling using PDC cutters is shown in
A factor in determining the longevity of PDC cutters is the generation of heat at the cutter contact point, specifically at the exposed part of the PDC layer caused by friction between the PCD and the work material. This heat causes thermal damage to the PCD in the form of cracks (due to differences in thermal expansion coefficients) which lead to spalling of the polycrystalline diamond layer, delamination between the polycrystalline diamond and substrate, and back conversion of the diamond to graphite causing rapid abrasive wear. The thermal operating range of conventional PDC cutters is generally 750° C. or less.
As mentioned, conventional polycrystalline diamond is stable at temperatures of up to 700-750° C., after which observed increases in temperature may result in permanent damage to and structural failure of polycrystalline diamond. This deterioration in polycrystalline diamond may be due to the difference in the coefficient of thermal expansion of the binder material, cobalt, as compared to diamond. Upon heating of polycrystalline diamond, the cobalt and the diamond lattice will expand at different rates, which may cause cracks to form in the diamond lattice structure and result in deterioration of the polycrystalline diamond. Damage may also be due to graphite formation at diamond-diamond necks leading to loss of microstructural integrity and strength loss.
In order to overcome this problem, strong acids may be used to “leach” the cobalt from the diamond lattice structure (either a thin volume or entire tablet) to at least reduce the damage experienced from heating the diamond-cobalt composite. Briefly, a strong acid, such as nitric acid or combinations of several strong acids (such as nitric and hydrofluoric acid) may be used to treat the diamond table, removing at least a portion of the catalyst from the PDC composite. By leaching out the cobalt, thermally stable polycrystalline (TSP) diamond may be formed. In certain embodiments, a select (less than all) portion of a diamond composite is leached, in order to gain thermal stability without losing impact resistance. As used herein, the term TSP includes both of the above (i.e., partially and completely leached) compounds. Interstitial volumes remaining after leaching may be reduced by either furthering consolidation or by filling the volume with a secondary material.
However, it is highly undesirable for the substrate of a cutting element including a
PCD cutting table to be exposed to the leaching solution. Exposure of the substrate to the leaching solution can weaken both the structural integrity of the substrate itself, along with the interfacial bond attaching the PCD cutting table to the substrate. This vulnerability has led to leaching processes being performed with unattached PCD cutting tables, which then require attachment/re-attachment to a substrate via brazing or high-temperature high-pressure sintering. The attachment/re-attachment of TSP cutting tables may lead to weak interfacial attachment. Leaching processes may also use protection methods for the substrate of intact (with substrate bonded to cutting table) cutting elements. Furthermore, while shear cutters are described throughout the text and shown in the figures, in some embodiments, the leaching methods and protective elements described in this disclosure may also be used with any other type of cutting element that could benefit from leaching.
Leaching Process
In various embodiments, a formed PCD body having a catalyst material or other metal in the interstitial spaces between bonded diamond grains is subjected to a leaching process in conjunction with at least one protective element, whereby the catalyst material or other metal is at least partially removed from the PCD body. In addition to the catalyst material that may be removed by a leaching process, it is also within the scope of the present disclosure that the present disclosure also relates to the leaching of a metal infiltrant that may occupy the interstitial spaces when a preformed PCD body is attached to a substrate during a subsequent HPHT sintering process, thereby infiltrating a metal from the substrate into the preformed body. As used herein, the term “removed” refers to the reduced presence of catalyst material or other metal in the PCD body, and is understood to mean that a substantial portion of the catalyst material no longer resides in the PCD body. However, one skilled in the art would appreciate that trace amounts of catalyst material or other metal may still remain in the microstructure of the PCD body within the interstitial regions and/or adhered to the surface of the diamond grains.
The quantity of the catalyst material or other metal remaining in the material PCD microstructure after the PCD body has been subjected to a leaching treatment may vary, for example, on factors such as the treatment conditions, including treatment time. Further, one skilled in the art would appreciate that it may be desired in certain applications to allow a small amount of catalyst material or other metal to stay in the PCD body. In some embodiments, the PCD body may include up to 1-2 percent by weight of the catalyst material or other metal. However, one skilled in the art would appreciate that the amount of residual catalyst or other metal present in a leached PCD body may depend on the diamond density of the material, and body thickness.
As described above, a conventional leaching process involves the exposure of an object to be leached with a leaching agent. In select embodiments, the leaching agent may be a weak, strong, or mixtures of acids. In other embodiments, the leaching agent may be a caustic material such as NaOH or KOH. Suitable acids may include, for example, nitric acid, hydrofluoric acid, hydrochloric acid, sulfuric acid, phosphoric acid, or perchloric acid, as well as any organic acids (such as formic, lactic, oxalic, citric, or acetic acid), or combinations of these acids. In addition, other acidic and basic leaching agents may be used as desired. Those having ordinary skill in the art will appreciate that the molarity of the leaching agent may be adjusted depending on the time desired to leach, concerns about hazards, etc.
Additionally, in select embodiments, accelerating techniques may be applied to the leaching process to decrease the amount of treatment time to reach the same level of catalyst or other metal removal. In some embodiments, the leaching of a PCD body may be accelerated by subjecting the leaching environment and thus the PCD body to an elevated pressure. As used herein, the term “elevated pressure” refers to pressures greater than atmospheric pressure. Suitable pressure levels may include elevated pressure levels ranging from about 5 to 345 bar, and ranging from about 5 to 100 bar in other embodiments. However, one skilled in the art would appreciate that the particular pressure may be dependent, for example, on the particular equipment used, the temperature selected, amount (and type) of leaching agent present, and total system volume. Additionally, in one or more embodiments, the temperature of the leaching agent may be increased relative to ambient temperature during the leaching process to a temperature up to about the boiling point of the leaching solution. In yet other embodiments, the temperature of the leaching agent may be up to three times the boiling point of the leaching solution. Further, in one or more embodiments, the application of ultrasonic energy to accelerate the leaching process may be used. Ultrasonic energy is mechanical, vibratory energy in the form of sound that operates at frequencies beyond audible sound (18,000 cycles per second and greater). An ultrasonic stack is generally formed of a converter or piezoelectric transducer, an optional booster and a sonotrode (also called a horn).
In one or more embodiments, the substrate of the cutting element and at least a portion of the polycrystalline diamond cutting table may be enclosed by a protective element. The protective element may be configured to allow for the protection of the substrate and at least a portion of the polycrystalline diamond cutting table of a cutting element from exposure to an external leaching environment, by placing, for example, a compressive squeeze on the cutting element. Such a protective element may include at least one of an o-ring seal, a snap ring, or a “sleeve”, for example. In particular embodiments, the protective elements may include two or more components: one to partially enclose the cutting element and a second to exert a compressive squeeze on the cutting element. In some embodiments, the enclosure and the compressive squeeze may be achieved by a single component. In embodiments using two components, an elastomeric material may be used as one of the materials and a thermoplastic polymer, such as polypropylene (PP), polyethylene (PE), high density polyethylene (HDPE), ultra high molecular weight polyethylene (UHMWPE), cross-linked polyethylene (PEX), polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) may be used as the other.
Due to the chemical composition of the leaching solutions, it may be beneficial for protective elements to include one or more thermoset elastomers or halogen containing polymers. However, the present disclosure is not limited and in one or more embodiments, polymers which may be useful in the material composition of a protective element may be at least one material from FKM fluoroelastomers, tetrafluoroethylene/propylene copolymers, polychloroprene, chlorinated polyethylene, chlorosulfonated polyethylene, epichlorohydrin, fluorosilicone, hydrofluorocarbon, fluoroelastomers, halobutyl elastomers, polypropylene, polyethylene, polyvinylidene fluoride, polytetrafluoroethylene, a liquid crystal polymer, polyetherketone, high density polyethylene, ultra high molecular weight polyethylene, cross-linked polyethylene, and/or FFKM perfluoroelastomers. These may be used alone or in combination to achieve the desired performance when exposed to leaching solutions.
Changes in physical properties such as volume swell, loss of tensile strength, loss of elongation, stress relaxation, permanent set and changes in hardness, etc. may be reduced through proper selection of the base polymer, including blends of polymers, sometimes referred to as alloys, and proper selection of fillers, cure systems and other additives. In addition to the material composition, the design of the protective element may take these physical property changes into consideration so that an effective seal and consistent sealing surface can be maintained throughout the leaching process. Specific embodiments described in the present disclosure concentrate the contact sealing forces between the protective element and the cutting element to minimize or reduce the potential of acid ingress past the seal surfaces during the leaching process. These design features may also significantly improve the useful service life of the protective element during the leaching process.
FFKM perfluoroelastomers are differentiated from FKM fluoroelastomers, a class within which VITON® is included, in that FFKM perfluoroelastomers have a fully fluorinated polymer backbone and thus a greater weight percentage of the elastomer is made up of fluorine. This difference imparts a higher resistance to degradation brought on by high temperatures and/or reactive chemicals. In general, FFKM perfluoroelastomers are copolymers of tetrafluoroethylene (TFE), which is the precursor to polytetrafluoroethylene (PTFE) or TEFLON®, and polymethylvinylether (PMVE) or other poly(alkyl vinyl ethers) or poly(alkoxy vinyl ethers). At least one cure site monomer, with the monomer having a functional group to promote curing, may also be incorporated therein to permit crosslinking of the curable polymer. Further, other polyalkylvinylethers (PAVEs) may be used to make FFKM perfluoroelastomers and include those with alkyl or alkoxy groups that may be straight or branched and which may also include ether linkages such as polyethylvinylether (PEVE), polypropylvinylether (PPVE), and polymethoxy vinylether, or other monomers represented by the following formula: CF2═CFO(Rf—O)n(Rf′—O)mRf″ where Rf and Rf′ are different linear or branched perfluoroalkylene groups of 2-6 carbon atoms, m and n are independently 0 or 1, and Rf″ is a perfluoroalkyl group of 1-6 carbon atoms. Mixtures of the different PAVEs may also be used. In one or more embodiments, the amount of PAVE monomer in the FFKM perfluoroelastomer may be from about 15-65 mol %.
Examples of the cure site functionality may include nitrogen containing groups (such as nitrile or cyano), carboxyl groups, and/or alkoxy carbonyl groups. Such functional groups may be provided on a fluorinated olefin or fluorinated vinylether. It is within the scope of the present disclosure that the cure site monomer may be partially or fully fluorinated. In one or more embodiments, the amount of cure site functionality in the FFKM perfluoroelastomer may be from 0.1-5 mol %.
Further, it is also within the scope of the present disclosure that other perfluoro olefins, such as hexafluoropropylene (HFP) may be used in place of or admixed with TFE in the FFKM perfluoroelastomer. In one or more embodiments, the perfluoro olefins may account for the balance or about 35 mol % in the FFKM perfluoroelastomer.
In embodiments using FKM fluoroelastomers, monomers may include hexafluoropropylene (HFP), vinylidene fluoride (VF2/VDF), terfluoroethylene (TFE), a fluorinated vinyl ether (PMVE). In particular embodiments, the FKM elastomer may be one of Type 1, Type 2, or Type 3. Copolymers derived from the polymerization of VF2 and HFP, are broadly defined as a FKM type 1, and generally have a fluorine content by weight of approximately 66%. In FKM type 2, termed a terpolymer, the TFE addition to the monomer composition variably increases the fluorine content between 67% and 70%, depending on the polymer grade. A FKM type 3 is generally composed of VF2, TFE, and PMVE. At least one cure site monomer, with the monomer having a functional group to promote curing, such as those described above, may also be incorporated therein to permit crosslinking of the curable polymer.
In some embodiments, the substrate and at least a portion of the polycrystalline diamond table of the cutting element may be coated with a curable liquid including one of the above described elastomer materials. The coating on the cutting element may be formed by any means known in the art, although dipping the cutting element within the curable liquid, or spray-coating the cutting element with the curable liquid may be used. In one or more embodiments, prior to coating the substrate and at least a portion of the polycrystalline diamond table of the cutting element at least a portion of the polycrystalline diamond table may be masked with a masking material to prevent it from being coated with the curable liquid. The mask may allow for easier application and/or specific patterning of the curable liquid. After coating the cutting element, the curable material may be cured according to known teachings in elastomers, to form a sleeve in-situ. In one or more embodiments, the masking material may be removed after the coating with the curable liquid and prior to the exposure of the partially enclosed cutting element to the leaching solution. In other embodiments, the masking material may be retained on the cutting element and substantially degraded during the leaching process. A cross-section of a resultant partially enclosed cutting element 20 is shown in
In one or more other embodiments, the substrate and at least a portion of the polycrystalline diamond table may be enclosed within a protective element by inserting a portion of the cutting element into a pre-molded sleeve made of one of the above described elastomer materials. The pre-molded sleeve may possess substantially the same dimensions as the portion of the cutting element to be enclosed or may possess slightly smaller dimensions than the portion of the cutting element to be enclosed. Specifically, in one or more embodiments, the diameter of the molded sleeve may be less than the diameter of the substrate and polycrystalline diamond table. The smaller diameter of the pre-molded sleeve may allow for an interference fit between the pre-molded sleeve and the enclosed portion of the cutting element leading to the exertion of a compressive squeeze on the enclosed portion of the cutting element which may increase the degree of protection provided by the sleeve. Additionally, the pre-molded sleeve may be engineered so that the degree of compressive squeeze exerted on the enclosed portion at an area adjacent the interface of the molded sleeve and the uncovered portion of the polycrystalline diamond table is higher than at an area not adjacent the interface. This type of engineering may take the form of a bulge or substantially thicker area of sleeve made of one of the above described materials located near an area adjacent the interface of the molded sleeve and the uncovered portion of the polycrystalline diamond table. In one or more embodiments, the compressive squeeze exerted at any point on the enclosed portion of the cutting element may range from about 5% to 25%, 10% to 20%, or at least 5%, 10%, 15%, 20%, or 25% in other embodiments.
Shown in
In one or more embodiments, a snap ring sealing element 70, whether embedded within the elastomeric sleeve 30 portion of the protective element or located on the outside of the sleeve 30, may include at least one thermoplastic material such as polypropylene, polyethylene, polyvinylidene fluoride, polytetrafluoroethylene, high density polyethylene, ultra high molecular weight polyethylene, or cross-linked polyethylene. The snap ring 70 may be reinforced with appropriate fillers to increase the resistance to stress relaxation and to increase their stiffness. In some embodiments, the resistance of a snap ring 70 to radial expansion and stress relaxation due to installation stress may be high and upon exposure to the leaching solution the volume change of the snap ring 70 may be substantially lower than the volume change of the protective element.
In yet other embodiments, the substrate and at least a portion of the polycrystalline diamond table may be enclosed within a protective element by securing the substrate and at least a portion of the polycrystalline diamond table within an inert housing by a sealing element including one of the above described materials. In such embodiments, the sealing element may be an o-ring made of FFKM perfluoroelastomeric materials or one of the other elastomeric materials described above. In one or more embodiments, the o-ring may exert a compressive squeeze ranging from about 5 to 25%, or at least 5%, 10%, 15%, 20%, or 25% in other embodiments. In one or more embodiments, the inert housing may be made of an FFKM perfluoropolymer, an FKM fluoropolymer i.e., KYNAR®, or a PTFE fluoropolymer i.e., TEFLON®, or combinations thereof fabricated to accommodate the substrate and at least a portion of the polycrystalline diamond cutting table therein. The inert housing may be configured to utilize an o-ring as the sealing element to secure the substrate and at least a portion of the polycrystalline diamond table therein.
In one or more embodiments, a magnetic component may be disposed within the protective element, and magnetism may be utilized to suspend the partially enclosed cutting element in the leaching solution. Specifically, the magnetic component may be disposed within the protective element between the backface of the cutting element (e.g., the top surface of the substrate 22) and the protective element so that it is positioned directly opposite that of the exposed surface to be leached and may interact with another magnetic component outside of the protective element to suspend the protected cutting element. This suspension may allow for a more efficient and controlled packing of a plurality of the partially enclosed cutting elements in the leaching solution while also exposing the entirety of their exposed surfaces to the leaching solution. In one or more embodiments, the magnetic component may be embedded within the protective element. In one or more other embodiments, the partially enclosed cutting element may be leached within a leaching solution unsuspended with the polycrystalline diamond table faced downward or faced upwards.
Additionally, it may be desirable to combine any of the embodiments disclosed above with subjecting the partially enclosed cutting element to a temperature from about the boiling point of the leaching solution to three times the boiling point of the leaching solution. Further, it may be desirable to expose the partially enclosed cutting element to the leaching solution under elevated pressure and/or ultrasonic conditions.
Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the embodiments without materially departing from this disclosure. Accordingly, all such modifications are intended to be included within the scope of this disclosure. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.
This Application claims the benefit of U.S. Provisional Application 61/845,774 filed on Jul. 12, 2013 and U.S. Provisional Application 61/921,165 filed on Dec. 27, 2013, both of which are herein incorporated by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61921165 | Dec 2013 | US | |
| 61845774 | Jul 2013 | US |
