Fusible metal clay, structures formed therefrom, and associated methods
Structures for a tool surface of a downhole tool are constructed from a metal clay molded in a wet state. The wet state clay is a workable combination that can have a braze alloy grain, a tungsten carbide grain, and a binder. Additional cutting inserts can be embedded in the molded clay. Heat treatment applied to the molded metal clay causing the binder to be combusted and consumed. The braze alloy melts and then cools into a fused state with the tungsten carbide grain therein. The structure can affix to the tool surface of the tool by first being fused and then attached by brazing to the tool. Alternatively, the structure can be positioned in a fusible state adjacent the tool surface. When the heat treatment is applied, the structure fuses together and forms a metallurgical bond with the tool surface of the tool.
1. A method of overlaying a downhole tool for engagement downhole, the method comprising:
molding a clay in a wet state into a structure, the clay in the wet state being a workable combination comprising a first grain, a second grain, and a binder, the first grain comprising a metal alloy having a first hardness and a first melting point, the second grain comprising a second material, the second material having a second hardness greater than the first hardness of the metal alloy and having a second melting point higher than of the first melting point of the metal alloy, the binder binding the first and second grains into the workable combination and having a combustion temperature at least not greater than the first melting point; and
affixing the structure to the downhole tool by:
positioning the structure in a fusible state adjacent the downhole tool;
applying a heat treatment to the structure at least up to the first melting point;
fusing the structure together with the applied heat treatment; and
forming a metallurgical bond between the structure with the downhole tool with the applied heat treatment.
2. The method of claim 1 , wherein the first grain comprising the metal alloy comprises a powder comprising: a braze alloy; an alloy of nickel, copper, and cobalt; an alloy of copper and nickel; or a CuNi10 alloy with 90% copper and 10% nickel.
3. The method of claim 1 , wherein the second grain comprises a powder, frit, pieces, chips, fragments, particles, shapes, elements, chunks, or combination thereof having the second material.
4. The method of claim 1 , wherein the second material comprises interstitial carbide, tungsten carbide, titanium carbide, polycrystalline diamond compact, diamond powder, abrasive material, cubic boron nitride, steel, or combination thereof.
5. The method of claim 1 , wherein the binder comprises a synthetic binder, an organic binder, a water-based binder, a polyurethane-based binder, an adhesive, a glue, or a combination thereof.
6. The method of claim 1 , wherein the clay further comprises a flux agent.
7. The method of claim 6 , the flux agent comprises a powder having borax.
8. The method of claim 1 , wherein a level of plasticity for the workable combination depends on a particle size, a percentage by volume, and a particle wettability of at least one of the first and second grains relative to one or more characteristics of the binder.
9. The method of claim 1 , wherein molding the clay in the wet state into the structure comprises forming the clay in the wet state in a mold, injecting the clay in the wet state from a piston, or manually forming the clay in the wet state.
10. The method of claim 9 , wherein molding the clay further comprises allowing the molded clay to dry from the wet state to a dry state; and further machining or shaping the molded clay in the dry state.
11. The method of claim 1 , wherein molding the clay further comprises embedding one or more prefabricated cutting elements in the molded clay.
12. The method of claim 11 , wherein the one or more prefabricated cutting elements comprises one or more inserts composed of tungsten carbide.
13. The method of claim 1 , wherein applying the heat treatment to the molded clay at least up to the first melting point comprises applying the heat treatment with induction heating, torch heating, furnace heating, resistance welding, or combination thereof.
14. The method of claim 13 , wherein cooling the fused structure comprises cooling to a relief temperature, holding the relief temperature for a time period, and subsequently cooling below the relief temperature.
15. The method of claim 1 , wherein positioning the structure adjacent the exterior of the downhole tool comprises tinning a substrate surface of the exterior of the downhole tool; and placing a base surface of the structure adjacent the tinned substrate surface.
16. The method of claim 1 , wherein applying the heat treatment to the structure at least up to the first melting point comprises applying induction heating, applying torch heating, furnace heating, resistance welding, or a combination thereof.
17. The method of claim 1 , wherein applying the heat treatment to the structure at least up to the first melting point comprises applying resistance welding by scanning the structure with a conforming electrode.
18. The method of claim 17 , wherein scanning the structure by the conforming electrode comprises producing a continuous arc for fusing by:
moving the conforming electrode having a carbon fiber brush, a compliant conductive material, and/or a conductive fluid across an irregular surface of the structure; and
maintaining electrical continuity between the conforming electrode and the irregular surface as the conforming electrode moves across the irregular surface.
19. A method of overlaying a downhole tool for engagement downhole, the method comprising:
molding a clay in a wet state into a structure, the clay in the wet state being a workable combination comprising a first grain, a second grain, and a binder, the first grain comprising a metal alloy having a first hardness and a first melting point, the second grain comprising a second material, the second material having a second hardness greater than the first hardness of the metal alloy and having a second melting point higher than of the first melting point of the metal alloy, the binder binding the first and second grains into the workable combination and having a combustion temperature at least not greater than the first melting point;
fusing the structure by applying a heat treatment to the molded clay at least up to the first melting point;
cooling the fused structure; and
attaching the fused structure to the downhole tool.
20. A downhole tool dressed by a method of overlaying the downhole tool for engagement downhole, the method comprising:
molding a clay in a wet state into a structure, the clay in the wet state being a workable combination comprising a first grain, a second grain, and a binder, the first grain comprising a metal alloy having a first hardness and a first melting point, the second grain comprising a second material, the second material having a second hardness greater than the first hardness of the metal alloy and having a second melting point higher than of the first melting point of the metal alloy, the binder binding the first and second grains into the workable combination and having a combustion temperature at least not greater than the first melting point; and
affixing the structure to the downhole tool by:
positioning the structure in a fusible state adjacent the downhole tool;
applying a heat treatment to the structure at least up to the first melting point;
fusing the structure together with the applied heat treatment; and
forming a metallurgical bond between the structure with the downhole tool with the applied heat treatment.