MXPA99005932A - Method of treating metal components - Google Patents

Abstract

A method of forming a metal product. The attributes of a final workpiece product are selected (step one). An appropriate substrate composition is determined depending on the selected attributes (step two). A workpiece substrate is formed to near finished dimensions (step three). An appropriate coating material composition is determined depending on the selected attributes (step four). The workpiece substrate is prepared for a high-density coating process (step five). The high-density coating process, such as HVOF thermal spray, is performed to coat the workpiece substrate with the coating material (step six). The coating material is built-up to a thickness effective to obtain desired finished dimensions after performing a hot isostatic pressing treatment. The appropriate hot isostatic pressing treatment parameters are determined (step seven). The hot isostatic pressing treatment is performed on the coated workpiece substrate to obtain a metal product having the desired finished dimensions and diffusion bonding between the coating material and the workpiece substrate (step eight).

Description

METHOD FOR TREATING METAL COMPONENTS BACKGROUND OF THE INVENTION The present invention relates to a method for treating metal components. In particular, the present invention relates to a method for treating metal components by first accumulating a thickness of metal on a metal substrate using a thermal spray process-Hyper Speed Oxygen Fuel (HVOF) followed by a treatment process. of Hot Isostatic Pressure (HIP). Often during the manufacture of metal components, a coating operation is performed to build a layer of coating material on the surface of a component substrate. The layer of coating material is formed to accumulate the metal component to the desired finished dimensions and to provide various surface attributes to the finished product. For example, an oxide layer could be formed to provide a smooth and corrosion-resistant surface. Also, a wear resistant coating, such as Carbide, Cobalt or TiN, is often formed in cutting tools to provide wear resistance. Chemical Vapor Deposition is commonly used to deposit a thin film wear-resistant coating on a cutting tool substrate. For example, in order to increase the useful life of a drill hole, chemical vapor deposition could be used to form a wear resistant Cobalt coating on a high speed steel cutting tool (HSS) substrate. The bond between the substrate and the coating occurs mainly through mechanical adhesion within a narrow-link interface. During use, the coating on the cutting surface of the cutting tool is subject to cutting forces that result in the peeling of the substrate from the tool. The fault in the narrow link interface is likely to occur. Figure 12 (a) is a side view of a prior art blade coated with a wear resistant coating. In this case, the wear resistant coating could be applied by the Chemical Vapor Deposition method so that the entire substrate of the blade receives a uniform thin film of a relatively hard material, such as Carbide, Cobalt or TiN. Since the coating adheres to the blade substrate primarily through a mechanical bond located at a limiting interface, peeling and chopping of the substrate during use is likely to occur, limiting the life of the blade. Figure 12 (b) is a side view of a prior art blade with a fixed wear resistant cutting nozzle. In this case a cutting nozzle of relatively hard material is fixed to the relatively smooth blade substrate. The metal cutting nozzle, which is commonly composed of a carbide or cobalt alloy, is fixed to the blade substrate by means of brass. During prolonged use, the blade is likely to fail at the relatively brittle brass interface between the metal blade and the tool substrate, and again, the life of the blade is limited. Another coating method known as Conventional Plasma Spray uses an overheated inert gas to generate a plasma. The energy supply is introduced and carried to the workpiece by a plasma stream. Conventional plasma spray coating methods deposit the coating material at a relatively low speed, and as a result, gaps are formed within the coating and at a coating density that commonly has a porosity of about 5.0%. Again, the bond between the substrate and the coating occurs mainly through mechanical adhesion at a bonding interface, and if the coating is subject to sufficient cutting forces it will be peeled from the substrate of the workpiece. Another coating method known as the hyper-speed oxygen fuel plasma (HVOF) thermal spray process is used to produce coatings that have almost no voids. In fact, the coatings could be produced with a density of almost 100%, with a porosity of less than 0.5%. In the HVOF thermal spray, a fuel gas and oxygen are used to create a combustion flame at 2500 to 3100 ° C. The combustion is carried out in a very high pressure chamber and a supersonic gas stream forces the coating material through a barrel of reduced diameter at very high particle speeds. The HVOF process results in extremely well bonded and dense coatings. Commonly the HVOF coatings could be formed with a density of almost 100%, with a porosity of >0.5%. The high particle velocities obtained by using the HVOF process result in a relatively better bond between the coating material and the substrate, when compared to other coating methods such as the conventional plasma spray method or the chemical deposition method. steam. However, the HVOF process also forms a bond between the coating material and the substrate that occurs mainly during mechanical adhesion at a binding interface. Detonation gun coating is another method that produces a relatively dense coating. Suspended energy is fed into a long tube along with oxygen and fuel gas. The mixture ignites in a controlled explosion. Therefore a high temperature and pressure is created to release the particles out of the end of the tube and into the substrate to be coated. The emptying is a known method to form metallic components. Commonly, a substrate mold is emptied into almost finished dimensions. Various machining operations, such as cutting, sanding, and polishing, are carried out in the casting substrate mold to finally obtain the metal component in the desired finished dimensions. A metallic casting component will commonly have various imperfections caused by voids and contaminants in the casting surface structure. The imperfections could be eliminated by machining the surface layer of the component, and / or by applying a surface coating. All emptying processes must deal with problems that forged processes do not have. Mainly, with the porosity and the contraction by means of elaborated techniques of mazarotaje and other methods that increase the cost and sometimes reduce the yield. However, the ability to produce a network form or almost in the form of a network is the motivating factor. In some cases, it is more cost-effective to empty the part intentionally, not using elaborate and expensive ligation techniques, and to treat the part by means of HIP to eliminate porosity below the surface. Then, the surface of the part is machined until the dense substrate is obtained. The manufacture of metal components often involves costly operations to manufacture products with the desired surface texture, material properties and dimensional tolerances. For example, a known process for manufacturing a metal component requires, among other steps, performing a casting of the metal component, treating the metal component using a hot isostatic pressure (HIP) treatment process, and then, machining the metal component to eliminate the imperfections of the surface and obtain the desired dimensional tolerances. The HIP treatment is used in the densification of metallic casting components and as a diffusion. In the HIP treatment process a part to be treated is elevated at a high temperature and isostatic pressure. Commonly, the part is heated to 0.6 -0.8 times the melting point of the material comprising the part, and is subjected to pressures in the range of 0.2 to 0.5 times the elastic limit of the material. Pressurization is achieved by pumping an inert gas, such as Argon, into a pressure vessel. Inside the pressure vessel is a high-temperature furnace, which heats the gas to the desired temperature. The temperature and pressure are maintained for a set time, and then the gas is cooled and vented. The HIP treatment process is used to produce almost network-like components that reduce or eliminate the need for subsequent machining operations. Additionally, by means of precise control of the temperature, pressure and time of a HIP treatment program, a particular microstructure could be obtained for the treated part.

Metal alloy components, such as gas turbine parts such as blades and blades, are often damaged with use. During operation, the gas turbine parts are subject to considerable degradation due to the high pressure and centrifugal force in a hot corrosive atmosphere. The gas turbine parts also suffer considerable damage due to impacts caused by foreign particles. This degradation results in a limited service life for these parts. Since its manufacture is expensive, several repair methods are used to renew the damaged blades and blades of the gas turbine. Some examples of the methods employed to repair gas turbine blades and blades include U.S. Pat. No. 4,291,448, published for Cretella et al .; US Patent 4,028,787, published for Cretella et al .; US Patent No. 4,866,828, published for Fraser; and U.S. Patent No. 4,837,389, published to Shankar et al. The '448 patent by Cretella describes a process for restoring turbine blade covers that have lost their original dimensions due to wear while in service. This reference describes the use of known processes of worn TIG welding portions of a part with a chemical welding wire similar to that of the part substrate, followed by milling the finish. The part is then sprayed with plasma with a chemistry material similar to a network form that requires little or no finishing. Then, the part is realized in an atmosphere of argon. The plasma spray process used in accordance with the '448 patent of Cretella results in a coating porosity of approximately 5.0%. Even after the concretion, the coating remains stuck to the substrate and welding material and the welding material which is only a mechanical bond in an interface bond layer which makes the finished part susceptible to chopping and shelling. The '787 Cretella patent describes a process for restoring turbine blades that have lost their original dimensions due to wear and tear in service. Again a plasma spray process is used to restore worn areas of the blade before performing a concreting process in a vacuum or hydrogen furnace. The porosity of the coating and the interface bond layer results in a structure susceptible to chopping and shelling. Fraser describes a process for repairing blades or steam turbine blades that use some method or that bind them together (i.e. wire lattice). According to the method described by Fraser, the area of the part that has been deformed is removed and a new piece of similar metal is welded onto the part. The lattice holes in the part are welded with a button. The part is then subjected to thermal impact to restore it to its original contour, and the lattice holes are drilled again.

Shankar et al. describe a process for repairing gas turbine blades that deform due to motor operation. A low pressure plasma spray coating is applied to the blades and the contour of the part is re-routed through grinding. An aluminum coating is then applied using a diffusion coating process. Again the low pressure plasma spray process forms a mechanical bond and a limiting interface between the coating and the substrate, resulting in a structure subject to failure due to chopping and shelling.

BRIEF DESCRIPTION OF THE INVENTION The present invention overcomes the disadvantages of the conventional art and provides a method for forming, treating and / or repairing metallic components so that the resulting metallic component possesses improved metallurgical characteristics. It is an object of the present invention to provide a method for forming a metal product with diffusion bond that occurs between a metal substrate and an applied coating. It is another object of the present invention to provide a method for forming cutting tools with a wear resistant coating diffusion bonded to a cutting surface of a tool substrate. AdditionallyIt is another object of the present invention to provide a method for forming a cast metal product with a diffusion bonded coating formed in a cast metal component. Additionally, it is another object of the present invention to provide a method for repairing turbine engine parts where a similar metal is diffusion bonded to a metal turbine engine part. In accordance with the present invention, there is provided a method for forming a metal product with a diffusion bond that occurs between a metal substrate and an applied coating. The first step of the inventive method is to determine the attributes of a final work piece product. For example, if the final work piece product is a cutting tool, the attributes include a wear resistant surface formed in a relatively inexpensive tool substrate. A suitable substrate composition is then determined depending on the selected attributes. In the example of a cutting tool, the substrate composition could be high speed steel, which is relatively inexpensive to manufacture but durable enough for the purpose for which it is intended. A work piece substrate is manufactured to almost finished dimensions, using known processes such as casting, extrusion, molding, machining etc. A suitable coating composition is determined depending on the selected attributes. Again in the example of the cutting tool, the coating material could be selected from a range of alloys and relatively hard and durable metals such as Cobalt, Carbide TiN, etc. The selection of both the substrate and the coating composition also depends on the metallurgical compatibility between them. The substrate of the workpiece is prepared for a high density coating process. The preparation could include cleaning, blasting, machining, protection or other similar operations. Once the substrate of the workpiece has been prepared, a high density coating process is carried out to coat the substrate of the workpiece. The coating material is accumulated to a suitable thickness to obtain the desired finished dimensions after having performed the hot isostatic pressure treatment (hereinafter described). The high density coating process could include the performance of a high-speed oxygen fuel thermal spray process. In the case of HVOF, a fuel gas and oxygen are used to create a fuel flame of 2500 to 3100 ° C. Combustion is carried out in a very high pressure chamber and a supersonic gas stream forces the coating material through a barrel of reduced diameter at very high particle speeds. The HVOF process results in extremely dense and well-bonded coatings. Commonly, HVOF coatings could be formed with a density of almost 100%, with a porosity of approximately 0.5%. The high particle velocities obtained using the HVOF process result in a relatively better bond between the coating material and the substrate, when compared to other coating methods such as the plasma spray method or the chemical vapor deposition method . However, the HVOF process also forms a bond between the coating material and the substrate that occurs primarily through mechanical adhesion at a binding interface. As described below, according to the present invention this mechanical link becomes a metallurgical bond by creating a diffusion link between the coating material and the substrate of the workpiece. The broadcast link does not have a limiting interface, which is usually the site of the failure. The diffusion bond is created by subjecting the substrate of the coated workpiece to a hot isostatic pressure (HIP) treatment. The hot isostatic pressure treatment parameters are selected depending on the coating, the substrate of the piece and the desired final attributes. The hot isostatic pressure treatment is carried out on the substrate of the coated workpiece to obtain a metal product with the desired finished dimensions and with the diffusion bond between the coating material and the substrate of the workpiece. HIP treatment is commonly used in the densification of cast metal components and as a diffusion bonding technique to consolidate powdered metals. In the HIP treatment process, the part to be treated is elevated to a high temperature and isostatic pressure. Commonly the part is heated 0.6-0.8 times the melting point of the material comprising the part, and is subjected to pressures in the range of 0.2 to 0.5 times the elastic limit of the material. Pressurization is achieved by pumping an inert gas, such as Argon, into a pressure vessel. Inside the pressure vessel is a high-temperature furnace, which heats the gas to the desired temperature. The temperature and pressure are maintained for a certain time, and then the gas is cooled and ventilated. . The HIP treatment process is used to produce components almost in the form of a network, reducing or eliminating the need for subsequent machining operations. Additionally, by means of precise control of the temperature, pressure and time of a treatment program a particular microstructure could be obtained for the treated part. In accordance with the present invention, the HIP treatment process is carried out on a substrate coated with HVOF to convert the bond of adhesion, which is merely a mechanical bond, to a diffusion bond, which is a metallurgical bond. In accordance with the present invention, an HVOF coating process is used to apply the coating material having sufficient density to efficiently support the densification changes that occur during the HIP process. If the coating material and the substrate of the workpiece are included in the same metal composition, then the diffusion bond results in a seamless transition between the substrate and the coating. The inventive method could be used to form a metallic product having a wear resistant surface. This method could be used to manufacture, for example, a long-term cutting tool of a relatively inexpensive cutting tool substrate. In accordance with this aspect of the invention, a workpiece substrate is formed to near-finished dimensions. A high density coating process, such as an oxygen fuel thermal spray process, is carried out to coat the substrate of the workpiece with a wear resistant coating material. The coating material accumulates to a thickness that is adequate to obtain the desired finished dimensions after having performed a hot isostatic pressure treatment. The hot isostatic pressure treatment is carried out on the substrate of the coated workpiece to obtain a metal product having the desired finished dimensions and the diffusion link between the coating material and the substrate of the workpiece. The inventive method could also be used to form a cast metal product. This method could be used to produce, for example, a cast part with a smooth and / or hard surface. According to the present invention, a part is emptied to smaller dimensions than those of a finished product, or an emptied part is machined to smaller dimensions than the finished ones. The pouring part is coated using the HVOF coating method as described herein. The HVOF coating is applied in a sufficient thickness so that the part reaches its finished dimensions. The hollowed out and HVOF coated part is then treated with HIP as described herein to obtain a finished part with the desired dimensions and surface characteristics. In accordance with this aspect of the invention, a cast metal workpiece is provided. The cast metal workpiece can then be formed with any conventional casting method such as: lost wax fusion, sand casting, resin shell casting. The cast metal part is machined, if necessary, to almost finished dimensions. A high density coating process, such as an oxygen combustion thermal spray process, is carried out to coat the substrate of the workpiece with a coating material. The coating material is accumulated to a suitable thickness to obtain the desired finished dimensions after having carried out a hot isostatic pressure treatment. The hot isostatic pressure treatment is carried out on the substrate of the coated workpiece to obtain a metallic product having the desired finished dimensions and the diffusion link between the coating material and the substrate of the workpiece. The inventive method could be used to repair a turbine engine part, such as a blade or blade. According to this aspect of the invention, a turbine motor part, comprised of a metal or metal alloy, is cleaned as a first step. If necessary, the worn portions of the turbine engine part are welded using a welding material composed of the same metal or metal alloy as the part of the original metal motor or of the parts to be welded. The welding operation is carried out to accumulate highly worn or damaged portions of the engine turbine part. If the part is not highly damaged, the welding operation could be eliminated. The welding operation will commonly produce welding test lines. The welding test lines are recessed with the grinding wheel to prevent the explosion material from being trapped in the welding test lines. Portions of the part of the motor that are not sprayed with HVOF are hidden. Plasma HVOF is sprayed from the non-hidden portions of the engine part. The plasma spray material (coating material) is comprised of the same alloy as the motor part of the original metal or to be welded. The HVOF plasma spray material is applied to accumulate a rope dimension of the engine part to a thickness that is greater than the thickness of an original rope dimension of the engine part. A hot isostatic pressure (HIP) treatment is carried out on the coated motor part to increase the density of the coating material, to create a diffusion bond between the coating material and the original and welding material, and to eliminate the gaps between the turbine engine part, the welding material and the coated material. Finally, the engine part is machined, rectified and / or polished to the original rope dimension.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a flow chart showing the steps of an inventive method for forming metal products and metal components with a wear resistant coating; Figure 2 (a) is a schematic view of a tool substrate provided in accordance with the inventive method for forming metal components with a wear-resistant coating; Figure 2 (b) is a schematic view of the tool substrate with a wear resistant coating applied to a HVOF thermal spray process according to the inventive method for treating metal components with a wear resistant coating; Figure 2 (c) is a schematic view of the HVOF spray coated tool substrate passing through a HIP treatment process in a HIP container according to the inventive method to form metal components with a wear resistant coating; Figure 2 (d) is a schematic view of the tool HVOF spray coated and HIP treated having a wear resistant coating layer bonded by diffusion to the substrate of the tool according to the inventive method of forming metal components that It has a wear-resistant coating; Figure 3 (a) is a schematic perspective view of a cast metal component undergoing a machining operation according to the inventive method for forming a metal product; Figure 3 (b) is a perspective view of the cast metal component machined according to the inventive method for forming a metal product; Figure 3 (c) is a perspective view of the cast metal component machined with an applied coating using a thermal spraying process HVOF according to the inventive method to form a metallic product; Fig. 3 (d) is a schematic perspective view of the HVOF spray-coated, machined, cast metal component undergoing a HIP treatment process in a HIP container according to the inventive method of forming a metal product; Figure 3 (e) is a schematic perspective view of the final metallic product cast, machined and treated with HVOF and HIP spray coating with a coating layer diffusion bonded to the cast metal component machined according to the inventive method to form a metallic product; Figure 4 is a flow diagram showing the steps of an inventive method for repairing a turbine engine part; Figure 5 (a) is a schematic side view of a worn turbine part before going through the inventive method of repairing a turbine engine part; Figure 5 (b) is a schematic cross-sectional view of the worn turbine engine part before going through the inventive method for repairing a turbine engine part; Figure 6 (a) is a schematic side view of the worn turbine engine part showing the worn areas to be repaired using the inventive method for repairing a turbine engine part; Figure 6 (b) is a schematic cross-sectional view of the worn turbine engine part showing worn areas to be repaired using the inventive method to repair a turbine engine part; Figure 7 (a) is a schematic side view of the worn turbine engine part showing the worn areas filled with a similar welding material according to the inventive method for repairing a turbine engine part; Figure 7 (b) is a schematic cross-sectional view of the worn turbine engine part showing worn areas filled with a similar welding material according to the inventive method for repairing a turbine engine part; Figure 8 (b) is a schematic cross-sectional view of the welded turbine engine part showing the areas to be augmented with a similar coating material using a HVOF spray coating process according to the inventive method for repairing a part turbine engine; Figure 9 (a) is a schematic side view of the HVOF accumulation and the part of the welded turbine engine showing a covered area before carrying out the HVOF spray coating process according to the inventive method for repairing a part of turbine engine; Fig. 10 is a schematic view of the increase by HVOF, and of the welded turbine engine part passing through a HIP treatment process in a HIP container according to the inventive method for repairing a turbine engine part; Fig. 11 (a) is a schematic side view of the repaired and spray coated turbine engine part HVOF and HIP with a diffusion of metal coating layer bonded to the original substrate and welded portions according to the inventive method for repair a part of turbine engine; Fig. 11 (b) is a schematic cross-sectional view of the repaired and spray coated turbine engine part HVOF and HIP with a similar metal coating layer diffusion bonded to the original substrate and the welded portions according to the inventive method to repair a part of turbine engine; Figure 12 (a) is a side view of a prior art blade coated with a wear resistant coating; and Figure 12 (b) is a side view of a prior art blade with a cutting nozzle of a prior art with a fixed and wear resistant cutting nozzle.

DETAILED DESCRIPTION OF THE INVENTION For the purpose of promoting and understanding the principles of the invention, reference will be made to the modalities illustrated in the drawings and a specific language will be used to describe them. However, it will be understood that no attempt is made to limit the scope of the invention by this means, once the alterations and modifications of the illustrated device have been contemplated, as well as the additional applications of the principles of the invention as described in FIG. present, as would normally occur to one skilled in the art to which the invention pertains. Figure 1 is a flow chart showing the steps of the inventive method for forming metal products and metal components with a wear resistant coating. In accordance with the present invention there is provided a method for forming a metal product with a diffusion bond occurring between a metal substrate and an applied coating. The first step of the inventive method will be to determine the attributes of a final work piece product (Step One). For example, if the product of the final work piece is a cutting tool, the attributes would include a wear resistant surface formed on a relatively inexpensive tool substrate 10. If the final work piece is a metal casting component, a surface Smooth and decorative final will be required on a drainage substrate 16.

A suitable substrate composition is then determined (Step Two) depending on the selected attributes. In the example of a cutting tool, the substrate composition may be high speed steel, which is relatively inexpensive to manufacture but durable enough for the purpose for which it is intended. In the case of a metallic casting component, the substrate of the cast workpiece could be formed from cast iron or aluminum (or other cast material or metal alloy). A work piece substrate is formed to almost finished dimensions (Step Three), using known processes such as casting, extruding, molding, machining, etc. A composition of suitable coating material 12 is determined depending on the attributes selected (Step Four): Again, in the example of the cutting tool, the coating material 12 could be selected from several durable and relatively hard metals and alloys such as such as Cobalt, Carbide, TiN, etc. In the example of a cast metal component, aluminum oxide could be chosen to provide both a corrosion and decorative surface. The selection of both the substrate and the coating composition also depends on the metallurgical compatibility between them. The substrate of the workpiece is then prepared for a high density coating process (Step Five). The preparation could include cleaning, blasting, machining, protection or other similar operations. Once the substrate of the workpiece has been prepared, a high density coating process is carried out to coat the substrate of the workpiece (Step Six). The coating material 12 is accumulated to a suitable thickness to obtain the desired finished dimensions after having carried out a hot isostatic pressure treatment (hereinafter described). The high density coating process could comprise the execution of a thermal spray process with high speed oxygen fuel. In the case of HVOF, a fuel gas and oxygen are used to create a combustion flame of 2500 to 3100 ° C. The combustion is carried out in a very high pressure chamber and a supersonic gas stream forces the coating material 12 through a barrel of reduced diameter at very high particle speeds. The HVOF process results in well-bonded and extremely dense coatings. Commonly, HVOF coatings could be formed with a density of 100% with a porosity of about 0.5%. The high particle velocities obtained using the HVOF process result in a relatively improved bond between the coating material 12 and the substrate, when compared to other coating methods such as the Conventional Plasma Spray method or the Chemical Deposition method. steam. However, the HVOF process also forms a bond between the coating material 12 and the substrate, which occurs mainly through mechanical adhesion at a binding interface. As described below, according to the present invention this mechanical link becomes a metallurgical bond by creating a diffusion link between the coating material 12 and the substrate of the workpiece. The broadcast link does not have the interface limitation where the fault commonly occurs. The diffusion bond is created by subjecting the substrate of the coated workpiece to a hot isostatic pressure (HIP) treatment. The appropriate parameters of the hot isostatic pressure treatment are selected depending on the coating, the substrate of the workpiece and the desired final attributes (Step Seven). The hot isostatic pressure treatment is carried out on the substrate of the coated workpiece to obtain a metal product having the desired finished dimensions and a diffusion link between the coating material 12 and the workpiece substrate. (Step Eight). From the proper formation of the substrate of the workpiece, the final product dimensions of the finished workpiece could be accurately achieved through precise control of the accumulation of the coating material 12 when the processing process is carried out. plasma spray HVOF. Alternately, the substrate of the workpiece coated with HVOF and treated with HIP could be machined to its final dimensions, as needed (Step Nine). HIP treatment is normally used in the densification of cast metal components and as a diffusion bonding technique to consolidate powdered metals. In the process of the HIP treatment, the part to be treated is elevated to a high temperature and isostatic pressure. Commonly, the part is heated 0.6 -0.8 times the melting point of the material comprising the part and is subjected to pressures in the range of 0.2 to 0.5 times the elastic limit of the material. Pressurization is achieved by pumping an inert gas, such as Argon, into a pressure vessel 14. Inside the pressure vessel 14 is a high temperature furnace, which heats the gas to the desired temperature. The temperature and pressure are maintained for a set time, and then the gas is cooled and vented.

The HIP treatment process is used to produce almost network-like component, reducing or eliminating the need for subsequent machining operations. Additionally, through precise control of the temperature, pressure and time of a HIP treatment program, a particular microstructure could be obtained for the treated part. In accordance with the present invention, a HIP treatment process is performed on a substrate coated with HVOF to convert the adhesive bond, which is merely a weaker mechanical bond, to a diffusion bond, which is a relatively stronger metallurgical bond. In accordance with the present invention, an HVOF coating process is used to apply the coating material 12 having sufficient density to efficiently support the densification changes that occur during the HIP process. If the coating material and the substrate of the workpiece are composed of the same metal composition, then the diffusion bond results in a seamless transmission between the substrate and the coating. As shown in Figures 2 (a) to 2 (d), the inventive method could be used to form a metal product with a wear-resistant surface. Figure 2 (a) is a schematic view showing a tool substrate 10 provided according to the inventive method for forming metal components with a wear resistant coating. The inventive method could be employed to produce, for example, a long-life cutting tool from a relatively inexpensive cutting tool substrate 10. In accordance with this aspect of the invention, a work piece substrate is formed to almost finished dimensions. The substrate of the tool 10 could be a drill hole, universal cutter, lathe blade, saw blade 18, brush blade, cutting tool inserts, or other parts of cutting tools. The substrate could, in an alternate way, be different from a tool. For example, the ice skate blades 18 and the edges of the snow skis could be treated in accordance with the present invention to obtain a shore with high wear resistance. Kitchen knives could be treated in accordance with the present invention to reduce or even eliminate the need for constant sharpening. Additionally, those products such as ballpoint pen points and fishing hooks could be treated according to the present invention to have the benefit of a long durability. Almost any metallic component that could benefit from more prolonged wear and dense surface structure could be a candidate for the present invention. For example, shields against the erosion of steam turbines, inclusions in metals, fan blades, 18s, power plant conveyors and / or forces against surface erosion. The present invention could be used to provide the protective surface features, as described herein, that improve the efficiency of products such as this one. Figure 2 (b) is a schematic view of the substrate of the tool 10 with a wear resistant coating 10 applied using an HVOF term sprinkling process according to the inventive method. A high density coating process, such as an oxygen fuel thermal spray process, is carried out to coat the substrate of the workpiece 10 with a high strength coating material 12, using for example a nozzle HVOF The coating material 12 accumulates to an efficient thickness to obtain the desired finished dimensions after having carried out a hot isostatic pressure treatment. Figure 2 (c) is a schematic view of the HVOF 10 spray coated tool substrate passing through a HIP treatment process in a HIP container 14. The hot isostatic pressure treatment is carried out on the substrate of the coated workpiece to obtain a metallic product with the desired finished dimensions and the diffusion link between the coating material 12 and the substrate of the workpiece. Figure 2 (d) is a schematic view of the tool HIP treated and spray coated HVOF with a coating diffusion of use resistant coating bonded to the substrate of the tool 10. According to the present invention the mechanical bond formed between The original substrate and the applied coating becomes a metallurgical bond by creating a diffusion bond between the coating material 12 and the original substrate. The diffusion bond does not have the interface limitation that is commonly where the fault occurs, therefore a superior product is obtained with the desired surface properties, such as resistance to wear, color, uniformity, texture, etc. These surface properties do not end abruptly at a linking interface (as is the case with conventionally coated or brassized products), but are maintained to a continuously variable degree from the surface of the product to the related material. Figures 3 (a) to 3 (e) illustrate the present inventive method employed to form a cast metal product with predetermined dimensions and surface characteristics. Figure 3 (a) is a schematic perspective view of a cast metal workpiece substrate passing through a machining operation. As shown in Figure 3 (a), the cast metal part is machined, as necessary, to almost finished dimensions. Figure 3 (b) is a schematic perspective view of the metal component cast and machined. A high density coating process, such as the oxygen fuel thermal spray process, is carried out to coat the substrate of the workpiece with a coating material 12. Figure 3 (c) is a view of schematic perspective of the metallic component casting and machining with a coating applied using a HVOF thermal spray process. The coating material 12 is accumulated to an efficient thickness to obtain the desired finished dimensions after having carried out a hot isostatic pressure treatment. Figure 3 (d) is a schematic perspective view of the HVOF sprayed, machined and spray coated metal component passing through a HIP treatment process in a HIP container 14. The hot isostatic pressure treatment is carried out in the substrate of the coated workpiece to obtain a metal product with the desired finished dimensions and the diffusion link between the coating material 12 and the substrate of the workpiece. Figure 3 (e) is a schematic perspective view of the metal product cast, machined, HIP treated and HVOF spray coated having a coating layer diffusion bonded to a metal component, cast and machined. Figure 4 is a flow diagram showing the steps of the inventive method for repairing a turbine engine part. The present inventive method could be used to repair a turbine engine part, such as a blade 18 or blade. According to this aspect of the invention, a turbine motor part composed of a metal or metal alloy is cleaned as a first step (Step One). If necessary, the worn portions of the engine turbine part are welded using a welding material composed of the same metal or metal alloy as the original metal motor part (Step Two). The welding operation is carried out to increase highly damaged or worn portions of the engine turbine part. If the part is not seriously damaged, the welding operation could be suppressed. The welding operation will commonly produce welding indicator lines. The welding indicator lines are recessed with the grinding wheel to prevent the explosion material from accumulating in the welding indicator lines (Step Three). The portions of the motor part not sprayed with HVOF are covered (Step Four) and the motor part is cleaned again to prepare it for the HVOV spray (Step Five). The HVOF plasma spray of the uncovered portions of the motor part is carried out (Step Six). The HVOF plasma spray material (coating material 12) is comprised of the same metal alloy as the original metal part. The HVOF plasma spray material is applied to increase to a rope dimension of the engine part to a thickness greater than the thickness of the original rope dimension of the engine part. A Hot Steady Pressure (HIP) treatment is performed on the coated motor part to increase the density of the coating material 12, to create a diffusion bond between the turbine motor part, the welding material and the material Coated (Step Seven). Finally, the engine part is machined, ground and / or polished to the original rope dimension (Step Eight). Fig. 5 (a) is a schematic side view and Fig. 5 (b) is a schematic cross-sectional view of a portion of the worn turbine engine before going through the inventive method for repairing a turbine engine part. Metal alloy components, such as gas turbine parts such as blades and blades 18s, commonly damage during use. During operation, the gas turbine parts are subject to considerable degradation of the high pressure and centrifugal force in a hot corrosive atmosphere. The gas turbine parts also suffer considerable damage due to damage caused by foreign particles. This degradation results in a limited shelf life for these parts. Since they are expensive to manufacture, several conventional methods of repair are used to renew the blades and blades of gas turbine 18s. However, these conventional methods of repair generally require intensive machining and welding operations that commonly subject the part to harmful stress. Also, there are conventional repair methods that commonly use a low pressure plasma spray for the application of a coating material 12. Conventional plasma spray coating methods deposit the coating material 12 at a relatively low speed, which it results in the formation of voids within the coating and in a coating density which commonly has a porosity of about 5.0%. Again the bond between the substrate and the coating occurs mainly through mechanical adhesion at a bonding interface, and if the coating is subjected to sufficient shear forces it will be peeled from the substrate of the workpiece. Additionally, the high porosity of the coating obtained through the conventional plasma spray coating makes them unsuitable candidates for the diffusion bond through the HIP treatment process described herein. Figure 6 (a) is a schematic side view and Figure 6 (b) is a schematic cross-sectional view of the worn turbine engine part showing worn areas 20 to be repaired using the inventive method to repair a motor part. turbine. The area surrounded by the stripes represents the material that has been worn or otherwise has been lost from the original turbine engine part. In accordance with the present invention, this area is reconstituted using the same material as the original blade 18 and using the Inventive metal treatment process. The worn out turbine motor part (in this case, a turbine blade 18) is first cleaned to prepare the worn surfaces for welding (see Step, 1 Figure 4). Figure 7 (a) is a schematic side view and Figure 7 (b) is a schematic cross-sectional view of the worn turbine engine part showing the worn areas filled with a similar welding material 22 according to the inventive method to repair a turbine engine part (see Step 2, Figure 4). According to the present invention the welding material is the same as the material of the original blade 18 which makes the bond between the weld and the substrate exceptionally strong. Fig. 8 (a) is a schematic side view and Fig. 8 (b) is a schematic cross-sectional view of the welded turbine engine part 25 showing areas 24 to be augmented with a similar cover material 12 using a process of HVOF spray coating according to the inventive method to repair a part of turbine engine. According to the present invention, the coating material 12 is the same as the original material of the blade 18, which again makes the bond between the weld and the substrate exceptionally strong. Fig. 9 (a) is a schematic side view and Fig. 9 (b) is a schematic cross-sectional view of the turbine engine part welded and augmented by HVOF 27 showing a covered area 26 before performing the coating process by HVOF spray according to the inventive method to repair a part of turbine engine. The coating material 12 accumulates to a thickness that is efficient to obtain the desired finished dimensions after having performed a hot isostatic pressure treatment (described hereinafter). The high density coating process could comprise performing a high speed oxygen fuel thermal spray process. In the case of HVOF, a fuel gas and oxygen is used to create a combustion flame of 2500 to 3100 ° C. The combustion is carried out in a very high pressure chamber and a supersonic gas stream forces the coating material through a barrel of reduced diameter at very high particle speeds. The HVOF process results in extremely dense and well-bonded coatings. Commonly, HVOF coatings could be formed with a density of almost 100%, with a porosity of about 0.5%. The high particle speeds obtained using the HVOF process results in a relatively better bond between the coating material 12 and the substrate, when compared to other coating methods such as the conventional plasma method or the chemical vapor deposition method. . However, the HVOF process also forms a bond between the coating material 12 and the substrate that occurs mainly through mechanical adhesion at a binding interface. As described below, according to the present invention, this mechanical link becomes a metallurgical link by creating a diffusion link between the coating material 12 and the substrate of the workpiece. The broadcast link does not have the interface limitation that is commonly where the failure occurs. The diffusion bond is created by subjecting the substrate of the coated workpiece to a hot isostatic pressure (HIP) treatment. The hot isostatic pressure treatment parameters are selected depending on the coating, the substrate of the workpiece and the final attributes that are desired. The hot isostatic pressure treatment is carried out on the substrate of the coated workpiece to obtain a metal product with the desired finished dimensions and a diffusion bond between the coating material 12 and the substrate of the workpiece. Fig. 10 is a schematic view of the HVOF welded turbine engine part that passes through a HIP treatment process in a HIP container 14 according to the inventive method for repairing a turbine engine part. HIP treatment is conventionally used in the densification of cast metal components and as a diffusion bonding technique to consolidate powdered metals. In the HIP treatment process, the part to be treated is raised to a high temperature and isostatic pressure. Commonly, the part is heated 0.6 - 0.8 times the melting point of the material comprising the part, and is subjected to pressures in the range of 0.2 to 0.5 times the elastic limit of the material. Pressurization is achieved by pumping an inert gas, such as Argon, into a pressure vessel 14. Inside the pressure vessel 14 is a high temperature furnace, which heats the gas to the desired temperature. The temperature and pressure is maintained for a certain time, and then the gas is cooled and vented.

The HIP treatment process is used to manufacture components almost in the form of a network, reducing or eliminating the need for subsequent machining operations. Additionally, through precise control of the temperature, pressure and time of a HIP treatment program a particular microstructure could be obtained for the treated part. Fig. 11 (a) is a schematic side view and Fig. 11 (b) is a schematic cross-sectional view of the turbine engine part repaired by HIP and spray coated HVOF 28 with a similar metal coating layer diffusion linked to the original substrate and welded portions according to the inventive method for repairing a turbine engine part. Through the proper formation of the substrate of the workpiece, the final product dimensions of the finished workpiece could be achieved accurately through precise control of the accumulation of the coating material 12 when the process is carried out. of plasma spray HVOF. Alternately, the substrate of the workpiece coated with HVOF and treated with HIP could be machined to its final dimensions as needed (Step Eight). An experimental test piece was prepared according to the inventive method for treating metal components. Photomicrograms of the test piece showed the grain structure and the diffusion bond of the coating material 12 and the substrate after the inventive method was performed. The HIP treatment process was performed on a coated HVOF test substrate to convert the bond of adhesion between the coating and the substrate, which is merely a mechanical bond, to a diffusion bond, which is a metallurgical bond. In accordance with the present invention, an HVOF coating process is used to apply the coating material 12 with sufficient density to pass efficiently through the densification changes that occur during the HIP process. In the case of the example of the test piece, the coating material 12 and the substrate of the workpiece are composed of the same metal composition. The diffusion bond results in a transition between the substrate and the coating that has a much stronger structural integrity as well as anti-wear characteristics when compared to the conventional technique. The test piece was prepared by accumulating the coating material 12 to a thickness of approximately 0.0508 cm, and the composition of the test pieces was determined in seven places (A-G) through a cross section of the piece. The composition was found to be substantially uniform across the cross section of the workpiece, as shown in the following table. Table One Elemental Composition (Weight%) Element B D Aluminum 5.4 5.2 5.5 6.2 6.3 6.4 6.5 Titanium 0.6 0.6 1.0 0.6 1.0 0.6 0.9 Chrome 12.9 13.2 14.5 12.7 11.5 13.7 14.1 Nickel REM REM Niobium 1.4 1.5 1.8 2.1 1.7 2.3 2.6 Molybdenum 3.7 4.1 3.6 3.3 3.4 3.9 3.0 A photomicrogram of the treated workpiece shows the grain structure and bond diffusion of the coating material 12 and the substrate after the inventive method has been carried out. In accordance with the present invention, the HIP treatment process is carried out in a turbine engine bed welded and accumulated by HVOF to convert the bond of adhesion, which is merely a mechanical bond, to a diffusion bond, which is a metallurgical bond In accordance with the present invention, an HVOF coating process is used to apply the coating material 12 with sufficient density to pass efficiently through the densification changes that occur during the HIP process. If the coating material 12 and the substrate of the workpiece are comprised of the same metal composition, then the diffusion bond results in a smooth transition between the substrate and the coating. By contrast, a conventional method of plasma spraying results in a relatively weak bond between the coating and the substrate. The binding is mainly due to a mechanical bond that occurs locally relatively in a limiting environment. In connection with the above description, it is discernible that the optimal dimensional relationships for the parts of the invention, including variations in size, materials, shape, function and form of operation, assembly and use, are considered obvious and obvious to an expert in the art. technique. All equivalent ratios for those illustrated in the drawings and described in the specification are intended to be included in the present invention. Therefore, the above is considered illustrative only of the principles of the invention. Additionally, since those skilled in the art will readily devise various modifications and changes, it is not desired to limit the invention to the exact construction and operation that is shown and described. Accordingly, all modifications and equivalents within the scope of the invention will be considered.

Claims (11)

1. A method for manufacturing a metallic product, characterized by the steps of: selecting the attributes of a final work piece product; determine a suitable substrate composition dependent on the selected attributes; forming a workpiece substrate to almost finished dimensions; determine an appropriate coating material composition depending on the selected attributes; prepare the substrate of the workpiece for a high density coating process; performing the high density coating process to coat the substrate of the workpiece with the coating material to a thickness that is efficient to obtain the desired finished dimensions after having performed the hot isostatic pressure treatment; determine the appropriate parameters for hot isostatic pressure treatment; and performing the hot isostatic pressure treatment on the substrate of the coated workpiece to obtain a metallic products with the desired final dimensions and with a diffusion bond between the coating material and the substrate of the workpiece.

2. A method for manufacturing a metal product according to claim 1; where the step of performing the high density coating process comprises performing a process of thermal spraying of hyper-speed oxygen fuel.

3. A method for forming a metal product according to claim 2; wherein the step of hot isostatic pressure treatment comprises the step of heating the motor part to a temperature substantially at 80% of the melting point of the metal alloy; and pressurizing the motor part at a pressure substantially between 20 and 50 percent of the elastic limit of the metal alloy in a gas atmosphere.

4. A method for forming a metal product with a wear resistant surface, characterizing the steps of: providing a workpiece substrate to near-finished dimensions; performing a high density coating process to coat the substrate of the workpiece with a coating material with wear resistance to a suitable thickness to obtain the desired finished dimensions after having performed a hot isostatic pressure treatment; and performing a steady hot pressure treatment on the substrate of the coated workpiece to obtain a metal product with the desired finished dimensions and a diffusion link between the coating material and the substrate of the workpiece.

5. A method for forming a metallic product according to claim 4; where the step of performing the high density coating process involves performing a process of thermal spraying of hyper-speed oxygen fuel.

6. A method for forming a metal product according to claim 5; wherein the hot isostatic pressure treatment step comprises the step of heating the motor part to a temperature substantially 80% of the melting point of the metal alloy; and pressurizing the motor part at a pressure substantially between 20 and 50 percent of the elastic limit of the metal alloy in an inert gas atmosphere.

7. A method for forming a cast metal product, characterized by the steps of: providing a cast metal workpiece; machining the cast metal part to almost finished dimensions; performing a high density coating process to coat the substrate of the workpiece with a coating material to a suitable thickness to obtain the desired finished dimensions after having performed a hot isostatic pressure treatment; and performing the hot isostatic pressure treatment on the substrate of the workpiece to obtain a metal product with the desired finished dimensions and a diffusion link between the coating material and the substrate of the workpiece.

8. A method for forming a metal product according to claim 7; where the step of performing the high density coating process involves performing a process of thermal spraying of hyper-speed oxygen fuel. A method for repairing a turbine engine part according to claim 8, wherein the step of the isostatic pressure treatment comprises the step of heating the engine part to a temperature substantially of 80% of the melting point of the alloy metal; and pressurizing the motor part at a pressure substantially between 20 and 50 percent of the elastic limit of the metal alloy in a gas atmosphere. A method for repairing a turbine engine part, characterized by the steps of: cleaning the turbine engine part, the turbine engine part composed of a metal alloy; welding the worn portions of the turbine engine part using a welding material composed of the metal alloy, the weld producing weld indication lines; to reduce the weld indication lines to the cloth with the grinding wheel to avoid that the material of the explosion is trapped in the welding test lines; covering portions of the engine part that will not be sprayed with HVOF; re-clean the engine part in preparation for the HVOF spray; spraying the engine part with HVOF using an HVOF spray material composed of the metal alloy to increase the engine part to a rope dimension; perform the hot isostatic pressure treatment on the engine part to eliminate the gaps between the turbine engine part, the welding material and the HVOF spray material; and finish the engine part up to the original rope dimension. 11. A method for repairing a turbine engine part according to claim 10; wherein the step of the hot isostatic pressure treatment comprises the step of heating the engine part to a temperature substantially of 80% of the melting point of the metal alloy; and pressurizing the motor part at a pressure substantially between 20 and 50 percent of the elastic limit of the metal alloy in an inert gas atmosphere.