Fluid activated disintegrating metal system

Abstract

An engineered composite system designed to be passive or inert under one set of conditions, but becomes active when exposed to a second set of conditions. This system can include a dissolving or disintegrating core, and a surface coating that has higher strength or which only dissolves under certain temperature and pH conditions, or in selected fluids. These reactive materials are useful for oil and gas completions and well stimulation processes, enhanced oil and gas recovery operations, as well as in defensive and mining applications requiring high energy density and good mechanical properties, but which can be stored and used for long periods of time without degradation.

Claims

1. A down-hole article for use in down-hole applications that is partially or fully formed of a hierarchically-designed reactive component and which said down-hole article is designed to controllably fully or partially dissolve or degrade in a down-hole fluid environment, said hierarchically-designed reactive component comprising: a. a core, said core dissolvable, reactive, or combinations thereof in the presence of a fluid environment, said core includes a propellant, said propellant includes one or more water-reactive materials selected from the group consisting of lithium, sodium, potassium, lithium aluminum hydride, sodium aluminum hydride, potassium aluminum hydride, magnesium aluminum hydride, lithium borohydride, sodium borohydride, calcium borohydride, magnesium hydride, n-Al, borohydride mixed with alanates, metal hydrides, borohydrides, and divalent cation alanates, said propellant formulated to react with said fluid environment to cause rapid heat generation which in turn causes said core to ignite; and, b. a surface layer that partially or fully encapsulates said core, said surface layer having a different composition from said core, said surface layer including a polymer, said surface layer forming a protective layer about said core to inhibit or prevent said core from dissolving, reacting, or combinations thereof when said component is exposed to said fluid environment, said surface layer non-dissolvable in said fluid environment until said surface layer is exposed to an activation event which thereafter causes said surface layer to controllably dissolve in said fluid environment and then thereafter allow said core to dissolve, react, or combinations thereof when said core is exposed to said fluid environment, said activation event including one or more events selected from the group consisting of a temperature change of said fluid environment, a pH change of said fluid environment, exposure of said surface layer with an activation compound, a change in composition of fluid environment, exposure of said surface layer to an electrical charge, exposure of said surface layer to certain electromagnetic waves, a change in salt content of said fluid environment, a change in electrolyte content of said fluid environment, exposure of said surface layer to certain sound waves, exposure of said surface layer to certain vibrations, exposure of said surface layer to certain magnetic waves, and exposure of said surface layer to a certain pressure.

2. A down-hole article for use in down-hole applications that is partially or fully formed of a hierarchically-designed reactive component and which said down-hole article is designed to controllably fully or partially dissolve or degrade in a down-hole fluid environment, said hierarchically-designed reactive component comprising: a. a core, said core dissolvable, reactive, or combinations thereof in the presence of a fluid environment, said core including a metal fuel and oxidizer composite which includes one or more mixtures of a reactive metal, an oxidizer or thermite pair, said reactive metal including one or more metals selected from the group consisting of magnesium, zirconium, tantalum, titanium, hafnium, calcium, tungsten, molybdenum, chromium, manganese, silicon, germanium and aluminum, said oxidizer or thermite pair including one or more compounds selected from the group consisting of fluorinated or chlorinated polymer, oxidizer, and intermetallic thermite; and, b. a surface layer that partially or fully encapsulates said core, said surface layer having a different composition from said core, said surface layer including a polymer, said surface layer forming a protective layer about said core to inhibit or prevent said core from dissolving, reacting, or combinations thereof when said component is exposed to said fluid environment, said surface layer non-dissolvable in said fluid environment until said surface layer is exposed to an activation event which thereafter causes said surface layer to controllably dissolve in said fluid environment and then thereafter allow said core to dissolve, react, or combinations thereof when said core is exposed to said fluid environment, said activation event including one or more events selected from the group consisting of a temperature change of said fluid environment, a pH change of said fluid environment, exposure of said surface layer with an activation compound, a change in composition of fluid environment, exposure of said surface layer to an electrical charge, exposure of said surface layer to certain electromagnetic waves, a change in salt content of said fluid environment, a change in electrolyte content of said fluid environment, exposure of said surface layer to certain sound waves, exposure of said surface layer to certain vibrations, exposure of said surface layer to certain magnetic waves, and exposure of said surface layer to a certain pressure.

3. A down-hole article for use in down-hole applications that is partially or fully formed of a hierarchically-designed reactive component and which said down-hole article is designed to controllably fully or partially dissolve or degrade in a down-hole fluid environment, said hierarchically-designed reactive component comprising: a. a core, said core dissolvable, reactive, or combinations thereof in the presence of a fluid environment, said core including a reactive polymeric material that includes one or more materials selected from the group consisting of aluminum-potassium perchlorate-polyvinylidene difluoride and tetrafluoroethylene polymer; and, b. a surface layer that partially or fully encapsulates said core, said surface layer having a different composition from said core, said surface layer including a polymer, said surface layer forming a protective layer about said core to inhibit or prevent said core from dissolving, reacting, or combinations thereof when said component is exposed to said fluid environment, said surface layer non-dissolvable in said fluid environment until said surface layer is exposed to an activation event which thereafter causes said surface layer to controllably dissolve in said fluid environment and then thereafter allow said core to dissolve, react, or combinations thereof when said core is exposed to said fluid environment, said activation event including one or more events selected from the group consisting of a temperature change of said fluid environment, a pH change of said fluid environment, exposure of said surface layer with an activation compound, a change in composition of fluid environment, exposure of said surface layer to an electrical charge, exposure of said surface layer to certain electromagnetic waves, a change in salt content of said fluid environment, a change in electrolyte content of said fluid environment, exposure of said surface layer to certain sound waves, exposure of said surface layer to certain vibrations, exposure of said surface layer to certain magnetic waves, and exposure of said surface layer to a certain pressure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1-2 are a cross-sectional illustration of layered ball actuators in accordance with the present invention wherein the core represents a disintegrating high strength material.

DETAILED DESCRIPTION OF THE INVENTION

(2) Referring now to the figures wherein the showings illustrate non-limiting embodiments of the present invention, the present invention is directed to the formation and use of disintegrating components and materials that can be stored for long periods of time until activated. The present invention also relates to the production of a reactive hierarchically-designed component or system having controlled reaction kinetics that can be catalyzed by an external stimulus. The invention further relates to a reactive hierarchically-designed component or system that is inert or essentially inert unless initiated by a certain temperature, pH, and/or other external stimulus after which it disintegrates in a controlled and repeatable manner. The components of the present invention have particular applicability to components used in the forming of wells; however, it will be appreciated that the components of the present invention can be used in many other industries and applications.

(3) Referring to FIGS. 1-2, there are cross-sectional illustrations of layered composite ball actuators in accordance with the present invention wherein the core represents a disintegrating high strength composite. The cross-sectional shape of the core illustrated as being circular; however, it can be appreciated that the core can have any shape.

(4) In one non-limiting configuration, the core can be formed of a metal such as, but not limited to, lithium, sodium, magnesium, magnesium-carbon-iron composite system, and the like. As can be appreciated, the core can also or alternatively include a polymer material. The core can be formed or more than one type of material; however, that is not required. The core can be formed of one or more layers. When the core includes two or more layers, the layers are generally formed of different materials; however, this is not required. The surface layer of the composite ball actuator can include a protective or delay coating. The surface layer can be a metal layer, a polymer layer, and/or a ceramic layer. The surface layer can be formed of one or more layers. When the surface layer includes two or more layers, the layers are generally formed of different materials; however, this is not required.

(5) In one non-limiting arrangement, the surface layer can be a temperature-sensitive polymer such as, but not limited to, PVA, that is inert and insoluble until exposed to certain environmental conditions. For example, when the surface layer is PVA, and when the PVA reaches a critical temperature in water, the PVA dissolves to expose the underlying reactive core, thereby causing the core to react. Surface layers that activate under exposure to specific temperatures, pressures, fluids, electromagnetic waves and/or mechanical environments to delay the initiation of a dissolution reaction are envisioned by the present invention.

(6) In accordance with the present invention, a metal, metal alloy, metal matrix composite, polymer, or polymer composite having a specified reactive function can form all or part of the core. One of the primary functions of the core is for the material of the core to partially or fully disintegrate in a controlled and uniform manner upon exposure an environmental condition (e.g., exposure to saltwater, etc.). On the surface of the core (which core can be a casting, forging, extrusion, pressed, molded, or machined part), a surface layer is included to modify the conditions to which the core will react. In one non-limiting configuration, the core has a strength above 25,000 psig, and is selected to respond to a set of environmental conditions to perform a function (e.g., react, dissolve, corrode, fracture, generate heat, etc.).

(7) In one non-limiting formulation, the core can be or include magnesium or magnesium alloy that has a temperature-dependent dissolution or disintegration rate. This disintegration rate of the core can be designed such that the core dissolves, corrodes, reacts, and/or chemically reacts in a certain period of time at a given temperature. One non-limiting application that can use such a core is a frac ball. The composite system can be designed such that the core does not disintegration at a temperature of less than about 100° F. via protection from the surface layer. As can be appreciated, the temperature can be any temperature (e.g., below 10° F., below 50° F., below 100° F., below 150° F., below 200° F., etc.). In one embodiment, wherein the hierarchically-designed component or system is designed to inhibit or prevent reaction of the core at a temperature below 100° F., the core would have a near-infinite life at conditions below 100° F. To accomplish this non-limiting embodiment, the hierarchically-designed component or system has a surface layer that is applied to the surface of the core, wherein the surface layer is inert under conditions wherein the temperature is below 100° F., but dissolves, corrodes, or degrades once the temperature exceeds 100° F. (e.g., dissolves, corrodes, or degrades in the presence of water that exceeds 100° F., dissolves, corrode, or degrades in the present of air that exceeds 100° F., etc.) In this non-limiting embodiment, the kinetics of the reaction can be changed by inhibiting the initial reaction, and then accelerating the reaction once specific conditions are met. As can be appreciated, the surface layer can be caused to dissolve, corrode, or degrade upon exposure to other conditions (e.g., certain liquids, certain gasses, certain temperatures, certain electromagnetic waves, certain vibrations, and/or certain sound waves, certain pH, certain salt content, certain electrolyte content, certain magnetism, certain pressure, electricity, and/or certain temperature, etc.).

(8) Because the surface layer may be exposed to high stress, surface layer can be thin (e.g., 0.01-50 mils, typically 0.01-10 mils, more typically 0.01-5 mils, etc.); however, this is not required. Alternatively, the surface layer can be designed to be strong and to contribute mechanically to the system, such as through the use of fiber, flakes, metals, metal alloys, and/or whisker reinforcement in the layer. The thickness of the surface layer about the core can be uniform or vary.

EXAMPLE 1

(9) A magnesium frac ball is produced having a disintegration rate of about 0.7-1.4 mm/hr at 200° F. and about 0.01-0.04 mm/hr at 100° F. The frac ball is designed to able to withstand at least a 24-hour exposure to 80° F. water in a ball drop system. The magnesium core can be magnesium, magnesium alloy or a magnesium composite. As can be appreciated, the core can be formed of other metals and/or non-metals that react, dissolve, corrode, or disintegrate at a rate of 0.1-100 mm/hr at 100-300° F. in water or salt water. The magnesium frac ball can be undermachined by 0.001-0.2″ (e.g., 0.005″, etc.) from final dimensions, and a 0.001-0.2″ coating (e.g., 0.005″ coating, etc.) of PVA can be applied to the surface through a spray-coating process. FIG. 1 illustrates one non-limiting configuration of the frac ball. Although not illustrated in FIG. 1, the core can be formed of multiple layers of material wherein each layer has a different composition from the adjacently positioned layer. For example, the first or central layer of the core could include a magnesium composite material, and a second layer that is applied about the first layer could be magnesium or magnesium alloy. Likewise, the surface layer can include one or more different layers wherein each layer has a different composition from the adjacently positioned layer. The thickness of the two or more layers of the surface layer (when used) can be the same or different. Likewise, the thickness of the two or more layers of the core (when used) can be the same or different. The PVA is very insoluble in water up to about 130-150° F. At temperatures above 150° F., the PVA becomes dissolvable and ultimately exposes the magnesium core. The magnesium frac ball has excellent mechanical properties (e.g., generally above 30 ksi strength), and when the magnesium frac ball is exposed to slightly acidic or salt solutions, the magnesium frac ball corrodes at a rate of about 0.1-15 mm/day. However, when the magnesium frac ball is exposed to temperatures below about 130° F., the magnesium frac ball does not dissolve or corrode. As can be appreciated, the thickness of the coating of PVA can be selected to control the time needed for the PVA to dissolve and thereby expose the core to the surrounding environment.

EXAMPLE 2

(10) A high-strength frac ball is produced using a low-density core, which frac ball is selected for having good compressive strength and low density, and having a surface layer of a higher tensile strength and a denser material than the core. The core is selected from a magnesium composite that uses a high corrosion magnesium alloy matrix with carbon, glass, and/or ceramic microballoons or balls to reduce its density to below 1.7 g/cc (e.g., 0.5-1.66 g/cc and all values and ranges therebetween) and typically below about 1.3 g/cc. As can be appreciated, other densities of the core can be used. This composite core has very good compressive strengths, but tensile strengths may, in some applications, be inadequate for the intended application. For example, the tensile strength of the composite core may be less than 35 ksi, typically less than 32 ksi, and more typically less than 30 ksi. As such, the composite core can be surrounded by another layer having a greater tensile strength. This surrounding layer can have a thickness of about 0.035-0.75″ (and all values and ranges therebetween) and typically about 0.1-0.2″. The surrounding layer can be formed of magnesium, magnesium alloy or a high-strength magnesium composite. The high strength outer layer is designed to have adequate tensile strength and toughness for the applications, and generally has a tensile strength that is greater than 33 ksi, typically greater than 35 ksi, and more typically greater than 45 ksi; however, the tensile strength can have other values. The resultant component can have an overall density of about 5-45% lower (and all values and ranges therebetween) than a pure magnesium alloy ball, and typically about 30% lower than a pure magnesium alloy ball, but also has the high tensile and shear strengths needed to perform the desired ball actuator application.

(11) The core of the high-strength frac ball can be heat treated and machined after fabrication. A surface layer can optionally be applied to the core using thermal spray, co-extrusion, casting, or through power metallurgy techniques suitable for its fabrication as discussed in Example 1.

EXAMPLE 3

(12) A magnesium frac ball is produced having a disintegration rate of about 0.7-1.4 mm/hr at 200° F. and about 0.01-0.04 mm/hr at 100° F. The frac ball is designed to be able to withstand at least a 24-hour exposure to 80° F. water in a ball drop system. The magnesium frac ball can be undermachined by 0.001-0.2″ (e.g., 0.005″, etc.) from final dimensions, and a 0.001-0.2″ coating (e.g., 0.005″ coating, etc.) of zinc metal can be applied to the surface of the magnesium core. The magnesium core can be magnesium, magnesium alloy or a magnesium composite. As can be appreciated, the core can be formed of other metal and/or non-metals that react, corrode, dissolve or disintegrate at a rate of 0.1-100 mm/hr at 100-300° F. in water or salt water. The resultant compact has high mechanical properties, generally about 28 ksi and typically above 30 ksi strength (e.g., 30-45 ksi and all values and ranges therebetween). When the core of the magnesium frac ball is exposed to salt solutions, the magnesium frac ball corrodes at a rate of about 0.1-15 mm/day depending on the environment and temperature. The magnesium frac ball is designed to not react or corrode until activated with an acid exposure that removes the zinc surface layer and exposes the underlying magnesium core.

EXAMPLE 4

(13) A high-strength frac ball is produced using a low-density core, which frac ball is selected for having good compressive strength and low density, and having a surface layer of a higher tensile strength, and a denser material than the core. The core is selected from a magnesium composite that uses a high corrosion magnesium alloy matrix with carbon, glass, and/or ceramic microballoons or balls to reduce its density to below 1.7 g/cc (e.g., 0.5-1.66 g/cc and all values and ranges therebetween) and typically below about 1.3 g/cc. As can be appreciated, other densities of the core can be used. This composite core has very good compressive strengths, but tensile strengths may, in some applications, be inadequate for the intended application. For example, the tensile strength of the composite core may be less than 35 ksi, typically less than 32 ksi, and more typically less than 30 ksi. As such, the composite core can be surrounded by another layer having a greater tensile strength. Surrounding the composite core is high-strength metal or metal alloy (e.g., zinc, etc.) that has a layer thickness of about 0.035-0.75″, and typically about 0.1-0.2″. The high-strength metal or metal alloy outer layer is designed to have adequate tensile strength and toughness for certain the applications, and is generally greater than 33 ksi, typically greater than 35 ksi, and more typically greater than 45 ksi; however, the tensile strength can have other values. The resultant component can have an overall density of about 5-60% lower (and all values and ranges therebetween) than a pure zinc alloy ball, and typically about 50% lower than a pure zinc alloy ball, but also has the high tensile and shear strengths needed to perform the desired ball actuator application.

EXAMPLE 5

(14) A reactive material containing a water-reactive substance such as, but not limited to, lithium, is formed into a particle. The lithium is added to a propellant mixture. The propellant mixture can include polyvinylidene difluoride (PVDF), ammonium nitrate, and/or aluminum to form a gas-generating composition. The lithium particle can optionally include a polymer coating (e.g., PVA, etc.) that is applied to its surface to protect it from contact with water. The polymer coating is formulated to be insoluble at room temperature, but can dissolve in hot water (e.g., +140° F.). Once the coating is dissolved to expose the lithium, the lithium reacts with water and releases heat, thus igniting the propellant (e.g., aluminum-ammonium nitrate-PVDF propellant, etc.) to generate heat and gas pressure. As can be appreciated, other reactive particles can be used (e.g., lithium, sodium, potassium, lithium aluminum hydride, sodium aluminum hydride, potassium aluminum hydride, magnesium aluminum hydride, lithium borohydride, sodium borohydride, calcium borohydride, magnesium hydride, n-Al, borohydride mixed with alanates, metal hydrides, borohydrides, divalent cation alanates, and/or other water-reactive materials, etc.).

EXAMPLE 6

(15) A reactive material containing a water-reactive substance such as, but not limited to, sodium, is formed into a particle. The sodium is added to a propellant mixture. The propellant mixture can include PVDF, ammonium nitrate, and/or aluminum to form a gas-generating composition. The sodium particle can optionally include a polymer coating (e.g., PVAP, etc.) that is applied to its surface to protect it from contact with water. The polymer can optionally be a polymer that is insoluble in water-containing environments having an acidic pH, but is soluble in neutral or basic water containing environments; however, this is not required. One such polymer is polyvinyl acetate phthalate (PVAP). As can be appreciated, the polymer can optionally be selected to be insoluble in water-containing environments having a basic or neutral pH, but is soluble in an acidic water-containing environments; however, this is not required. The reactive material can be pumped into a formation using a solution having a pH wherein the polymer does not dissolve or degrade. Once the reactive material is in position, the pH solution can be changed to cause the polymer to dissolve or degrade, thereby exposing the sodium to the water and thus igniting the propellant by the heat generated by the sodium exposure to water to thereby generate localized heat and pressure. As can be appreciated, other reactive particles can be used (e.g., lithium, sodium, potassium, lithium aluminum hydride, sodium aluminum hydride, potassium aluminum hydride, magnesium aluminum hydride, lithium borohydride, sodium borohydride, calcium borohydride, magnesium hydride, n-Al, borohydride mixed with alanates, metal hydrides, borohydrides, divalent cation alanates, and/or other water-reactive materials, etc.).

EXAMPLE 7

(16) A magnesium frac ball is produced having a disintegration rate of about 0.7-1.4 mm/hr at 200° F. and about 0.01-0.04 mm/hr at 100° F. The frac ball is designed to able to withstand at least one day, typically at least seven days, and more typically at least 14 days exposure to 80° F.+ water or a water system having an acidic pH in a ball drop system or a down hole application (e.g., ball/ball seat assemblies, fracture plugs, valves, sealing elements, well drilling tools, etc.). The magnesium core can be magnesium, magnesium alloy or a magnesium composite. As can be appreciated, the core can be formed of other metal and/or non-metals that react, corrode, dissolve or disintegrate at a rate of 0.1-100 mm/hr at 100-300° F. in water or salt water. The magnesium frac ball can be undermachined by 0.001-0.2″ (e.g., 0.005″, etc.) from final dimensions, and a 0.001-0.2″ coating (e.g., 0.005″ coating, etc.) of PVA can be applied to the surface through a spray-coating process. The PVA is very insoluble in water up to about 130-150° F. At temperatures above 150° F., the PVA becomes dissolvable. To prevent dissolution of the PVA above 150° F., the PVA coating is modified with a silicone component such as, but not limited to, trimethylsilyl group to convert the PVA to a protected ether silyl layer that is insoluble in water, salt water, and acidic water solutions, even when such solutions exceed 150° F. Non-limiting examples of compounds that include the trimethylsilyl group include trimethylsilyl chloride, bis(trimethylsilyl)acetamide, trimethylsilanol, and tetramethylsilane. FIG. 2 illustrates an example of a surface treatment layer such as compound having a trimethylsilyl group that is applied to the outer surface of a surface layer of PVA, and wherein the PVA surrounds a core. The converted PVA can be converted back to PVA (e.g., the protected ether silyl is removed from the PVA) by exposing the converted PVA to an ammonium fluoride solution or similar solution which thereby converts the surface back to PVA. At temperatures above 150° F., the PVA becomes dissolvable and ultimately exposes the magnesium core. The magnesium frac ball has excellent mechanical properties (e.g., generally above 30 ksi strength), and when the magnesium frac ball is exposed to slightly acidic or salt solutions, the magnesium frac ball corrodes at a rate of about 0.1-15 mm/day. However, when the magnesium frac ball is exposed to temperatures below about 130° F., the magnesium frac ball does not dissolve or corrode. As can be appreciated, the thickness of the coating of PVA can be selected to control the time needed for the PVA to dissolve and thereby expose the core to the surrounding environment. Also as can be appreciated, the modification of the coating of PVA can be selected to achieve control of exposure of the core to the surrounding environment.

EXAMPLE 8

(17) A silicone coating (e.g., polymer-based siloxane two-part coating) was sprayed onto a dissolvable metal sphere and cured for seven days. The dissolvable metal sphere can be formed of magnesium, magnesium alloy, a magnesium composite or metal and/or non-metals that react, corrode, dissolve or disintegrate at a rate of 0.1-100 mm/hr at 100-300° F. in water or salt water. The coating thickness was about 0.003″; however, the coating thickness can be other thicknesses (e.g., 0.001-0.1″ and any value or range therebetween, etc.). The coated ball was then submersed in 200° F. of HCl (e.g., 0.1-3M HCl) for 65 min with no evidence of reaction of the metal sphere. 0.1 M HF was thereafter added to the 200° F. HCl solution (e.g., 0.1-3M HCl) and the silicone coating separated from the metal sphere in less than 30 minutes (e.g., 0.1-30 minutes and all values and ranges therebetween). The silicone coating is generally formulated to separate from the metal sphere when exposed to certain solutions in about 0.1-180 minutes (and all values and ranges therebetween), depending on the type, concentration and temperature of the solution. The metal that was dissolvable then started dissolving in the HCl solution. In another example, the same silicone polymer was sprayed onto a dissolvable metal plate and cured for seven days. The dissolvable metal plate can be formed of magnesium, magnesium alloy, a magnesium composite or metal and/or non-metals that react, corrodes, dissolves or disintegrate at a rate of 0.1-100 mm/hr at 100-300° F. in water or salt water. The coating thickness was about 0.006″. The coated plate was then subjected to a simulated pipe line sliding wear equivalent to 5000 feet of sliding wear. The silicone coating exhibited little or no removal of material and the dissolvable metal plate was not exposed to any sliding wear.

EXAMPLE 9

(18) A polymer-based polyurethane coating (e.g., one-or two-part coating) was applied (e.g., electrostatically, etc.) to the surface of a dissolvable metal sphere and cured above 300° F. for about 15 min. The dissolvable metal sphere can be formed of magnesium, magnesium alloy, a magnesium composite or metal and/or non-metals that react, corrode, dissolve or disintegrate at a rate of 0.1-100 mm/hr at 100-300° F. in water or salt water. The coated sphere was cooled to room temperature and submerged in 80° F. 15% HCl solution (i.e., 2.75M HCl) for 60 min. No degradation of the coating or ball was observed and no dimensions changed. The coated sphere was then moved to a 200° F. 3% KCl solution (i.e., 0.4M KCl). The coating started to degrade after about 30 minutes at the elevated temperature and the dissolvable metal sphere thereafter degraded with the removal of the silicone coating. The silicone coating is generally formulated to separate from the metal sphere when exposed to certain solutions in about 0.1-180 minutes (and all values and ranges therebetween), depending on the type, concentration and temperature of the solution.

EXAMPLE 10

(19) A polymer-based PVB coating was coated (e.g., electrostatically applied, etc.) to the surface of a dissolvable metal sphere and cured above 300° F. for about 30 minutes. The dissolvable metal sphere can be formed of magnesium, magnesium alloy, a magnesium composite or metal and/or non-metals that reacts, corrode, dissolves or disintegrates at a rate of 0.1-100 mm/hr at 100-300° F. in water or salt water. The coating was abrasion resistant and had excellent adhesion to the sphere. The coated sphere was cooled to room temperature and submerged in 80° F. 15% HCl solution for about 60 minutes. No degradation of the coating or metal sphere was observed and the coated sphere did not exhibit any dimensional changes. The coated sphere was then moved to a 200° F. 3% KCl solution. The coating on the metal sphere started to degrade after about 30 min at the elevated temperature and the dissolvable metal sphere degraded with the removal of the PVB. The PVB coating is generally formulated to separate from the metal sphere when exposed to certain solutions in about 0.1-180 minutes (and all values and ranges therebetween), depending on the type, concentration and temperature of the solution.

EXAMPLE 11

(20) A polymer-based PVB coating was coated (e.g., coated using a solvent, etc.) to the surface of a dissolvable metal sphere and cured above 300° F. for about 30 minutes. The dissolvable metal sphere can be formed of magnesium, magnesium alloy, a magnesium composite or metal and/or non-metals that react, corrode, dissolve or disintegrate at a rate of 0.1-100 mm/hr at 100-300° F. in water or salt water. The coating was abrasion resistant and had excellent adhesion to the sphere. The coated sphere was cooled to room temperature and submerged in 80° F. 15% HCl solution for about 60 minutes. No degradation of the coating or metal sphere was observed and the coated sphere did not exhibit any dimensional changes. The coated sphere was then moved to a 200° F. 3% KCl solution. The coating on the metal sphere started to degrade after about 30 minutes at the elevated temperature and the dissolvable metal sphere degraded with the removal of the PVB. The PVB coating is generally formulated to separate from the metal sphere when exposed to certain solutions in about 0.1-180 minutes (and all values and ranges therebetween), depending on the type, concentration and temperature of the solution.

(21) It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and since certain changes may be made in the constructions set forth without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. The invention has been described with reference to preferred and alternate embodiments. Modifications and alterations will become apparent to those skilled in the art upon reading and understanding the detailed discussion of the invention provided herein. This invention is intended to include all such modifications and alterations insofar as they come within the scope of the present invention. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention, which, as a matter of language, might be said to fall there between. The invention has been described with reference to the preferred embodiments. These and other modifications of the preferred embodiments as well as other embodiments of the invention will be obvious from the disclosure herein, whereby the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation. It is intended to include all such modifications and alterations insofar as they come within the scope of the appended claims.