Method for manufacturing an object by joining two powder metallurgy components

Abstract

The invention relates to a method for manufacturing an object (24) by joining a first component (25) and a second component (26). The first component comprises a metal powder having a first alloy composition and a first soluble adhesive, and the second component comprises a metal powder having a second alloy composition and a second soluble adhesive. They may also contain ceramic powder. At least one of the surfaces to be joined is dissolved before they come into contact, or a mixture of a metal powder having a third alloy composition and a dissolved third adhesive is arranged between them. The chemical differences between the first, second and third alloy compositions are within predetermined limits. The components are sintered or oxidized together, whereby an object can be obtained in which the transition between the material phases from the joined components is barely perceptible when analyzed with a scanning electron microscope.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an object by joining two powder metallurgy parts. In particular, it relates to a method by which a uniform object without defects and having substantially constant properties at the interface between the joined parts can be obtained. Background Art

[0002] In many technical fields, including mechanical engineering, it is often necessary to manufacture an object from multiple components. This may be, for example, in connection with objects with a complex geometry that is more easily or only possible to obtain by assembly of components, each of which has a simple geometry that is easy to manufacture. Such a simple geometry may, for example, have a constant cross-section and a longitudinal extension suitable for manufacture by extrusion. When such objects are made of metal or metal matrix composites, they are often joined by, for example, welding or brazing. However, even if a strong connection can be obtained, it is well known that such a joining area may be critical, for example due to defects or thermal stresses generated during the joining process. Therefore, the connection may be a potential weak area in the object, which may be even more so in connection with fatigue loads, which may lead to cracks starting from small defects and developing to critical sizes during the use of the object.

[0003] Therefore, an improved method of joining two metal parts into one coherent object would be advantageous.

[0004] Purpose of the Invention

[0005] It is therefore an object of the present invention to provide a method of joining two components which allows a stronger bonding to be obtained compared to known methods.

[0006] Another object of the invention is to provide a method of joining two components by which a connection can be obtained which has a higher resistance to failure under fatigue load than known methods.

[0007] Another object of the invention is to provide a method for joining two parts with which it is possible to obtain an object having more homogeneous properties at the interface between the two joined parts than can be obtained using known methods.

[0008] Another object of the present invention is to provide an alternative to the prior art.

[0009] In particular, one object of the present invention may be seen as providing a method for manufacturing an object by joining two parts which solves the above-mentioned problems of the prior art. Summary of the invention

[0010] Therefore, the above objects and several other objects are intended to be achieved by providing a method of manufacturing an object by joining a first component and a second component, the method comprising the steps of:

[0011] - providing a first component, the first component comprising a metal powder having a first alloy composition and a first soluble binder, the first component having a first joining surface,

[0012] - providing a second component, the second component comprising a metal powder having a second alloy composition and a second soluble binder, the second component having a second joining surface to be joined with the first joining surface;

[0013] wherein the first alloy composition and the second alloy composition are each composed of a plurality of chemical elements, and wherein the chemical elements are selected such that for each chemical element present in an amount greater than 0.5 weight percent in each alloy composition, the chemical element is contained in both the first and second alloy compositions, and

[0014] - for a chemical element present in an amount of at most 5.0 wt. % in the first alloy composition, the amount of said chemical element differs by at most 1 percentage point between the first and second alloy compositions, and

[0015] - for a chemical element present in the first alloy composition in an amount greater than 5.0% by weight, the amount of said chemical element differs by at most 3 percentage points between the first and second alloy compositions;

[0016] The method achieves the bonding by the following steps:

[0017] - at least partially dissolving the first joining surface and / or the second joining surface by applying a solvent, and

[0018] - contacting the first engaging surface with the second engaging surface for a period of time to allow at least some of the solvent to evaporate; and

[0019] The first and second components are sintered or oxidized together while the first and second joining surfaces are kept in contact to obtain the object.

[0020] In an alternative to the method just described, the above objects and several other objects are intended to be achieved by providing a method for manufacturing an object by joining a first component and a second component, the method comprising the steps of:

[0021] - providing a first component, the first component comprising a metal powder having a first alloy composition and a first soluble binder, the first component having a first joining surface,

[0022] - providing a second component, the second component comprising a metal powder having a second alloy composition and a second soluble binder, the second component having a second joining surface to be joined with the first joining surface;

[0023] wherein the first alloy composition and the second alloy composition are each composed of a plurality of chemical elements, and wherein the chemical elements are selected such that for each chemical element present in an amount greater than 0.5 weight percent in each alloy composition, the chemical element is contained in both the first and second alloy compositions, and

[0024] - for a chemical element present in an amount of at most 5.0 wt. % in the first alloy composition, the amount of said chemical element differs by at most 1 percentage point between the first and second alloy compositions, and

[0025] - for a chemical element present in the first alloy composition in an amount greater than 5.0% by weight, the amount of said chemical element differs by at most 3 percentage points between the first and second alloy compositions;

[0026] The method achieves the bonding by the following steps:

[0027] - a mixture alloy composition comprising a dissolved third binder and a metal powder having a third alloy composition is arranged between the first and second joining surfaces, e.g. on at least one of the first and second joining surfaces, wherein the third alloy composition consists of a plurality of chemical elements, and wherein the chemical elements are selected such that for each chemical element present in the mixture in an amount greater than 0.5% by weight of the metal powder:

[0028] - for a chemical element present in an amount of up to 5.0 wt. % in the third alloy composition, the amount of said chemical element differs by at most 1 percentage point between the first and third alloy compositions, and

[0029] - for a chemical element present in the third alloy composition in an amount greater than 5.0% by weight, the amount of said chemical element differs by at most 3 percentage points between the first and third alloy compositions;

[0030] - placing the first and second joining surfaces as close together as possible while sandwiching the dissolved third binder and metal powder mixture therebetween, and maintaining the first and second joining surfaces in contact with the dissolved third binder and metal powder mixture for a period of time to allow at least part of the solvent to evaporate; and

[0031] The first and second components are sintered or oxidized together while keeping the first and second joining surfaces as close as possible to obtain the object.

[0032] "As close as possible" means sandwiching the mixture therebetween and taking into account the shapes of the first and second engaging surfaces. "Sandwiching between or between" means that the first and second components are disposed relative to each other so that the mixture is located between the first and second engaging surfaces. For some applications, pressure may be applied to cause the mixture to deform at least to some extent, such as to spread out, while for other applications, the mixture should retain the shape provided by the step of disposing the mixture.

[0033] In another alternative to the two methods just described, the above objects and several other objects are intended to be achieved by providing a method for manufacturing an object by joining a first component and a second component, the method comprising the steps of:

[0034] - providing a first component, the first component comprising a metal powder having a first alloy composition and a first soluble binder, the first component having a first joining surface,

[0035] - providing a second component, the second component comprising a metal powder having a second alloy composition and a second soluble binder, the second component having a second joining surface to be joined with the first joining surface;

[0036] wherein the first alloy composition and the second alloy composition are each composed of a plurality of chemical elements, and wherein the chemical elements are selected such that for each chemical element present in an amount greater than 0.5 weight percent in each alloy composition, the chemical element is contained in both the first and second alloy compositions, and

[0037] - for a chemical element present in an amount of at most 5.0 wt. % in the first alloy composition, the amount of said chemical element differs by at most 1 percentage point between the first and second alloy compositions, and

[0038] - for a chemical element present in the first alloy composition in an amount greater than 5.0% by weight, the amount of said chemical element differs by at most 3 percentage points between the first and second alloy compositions;

[0039] The method achieves the bonding by the following steps:

[0040] - placing at least one of the first component and the second component in a wet state, bringing the first joining surface into contact with the second joining surface for a period of time to allow at least some of the solvent to evaporate; and

[0041] The first and second components are sintered or oxidized together while the first and second joining surfaces are kept in contact to obtain the object.

[0042] In an embodiment of the third of the three alternative methods according to the invention, the joining step can be accomplished by making the parts wet again, for example by extrusion, shortly after the step of providing the parts. "Wet state" means that more than the surface is dissolved.

[0043] A "percentage point" is the unit of the arithmetic difference between two percentages. For example, a rise from 40% to 44% is an increase of 4 percentage points, but compared to the value being measured, it is an increase of 10%.

[0044] The expression "allowing at least some of the solvent to evaporate" may also be referred to as drying. This step may include heating and / or placing in an atmosphere containing a relatively small amount of solvent. The atmosphere may be, for example, air, for example air having a relative humidity lower than the surrounding environment. It may also include causing a gas flow (e.g., air) to flow along the part to be dried, and the speed of the gas flow may then also be controlled.

[0045] Sintering can be carried out, for example, in a reducing atmosphere, a vacuum or an inert atmosphere. Sintering is usually carried out in a furnace at a temperature of 950 to 1430 degrees Celsius.

[0046] Although the above and following description relates to first and second components, the method can also be used to connect a greater number of components.

[0047] In an alternative to any of the above embodiments, the method may include using first and second components, wherein the first alloy composition and / or the second alloy composition has only one chemical element, compared to including "both the first alloy composition and the second alloy composition are composed of multiple chemical elements". Such a composition may also be referred to as a "metal composition" rather than an "alloy composition". This means that in such an alternative embodiment, the composition of the first and / or second component may include only one chemical element, such as iron or copper. All other features and steps will be as described above.

[0048] The first and second parts are preferably kept in contact with each other by applying some force, so as to facilitate engagement. The force can be friction, gravity or externally applied. The externally applied force can be applied, for example, by using a clamp or fixture. The application of external force can be used to improve the quality and strength of the engagement. For some embodiments, this may be associated with applying a holding force that offsets all or part of the gravity and at least one of the first and second parts is kept in the desired position. In some embodiments, this may be associated with, for example, including a mixture being set between the first and second parts, and the weight of one of the parts is so large that it may affect (e.g., squeeze) the mixture in an undesirable manner. The force to be applied is usually determined by experiment, while visual inspection maintains contact without damaging the parts or mixture. The actual value for a given material and part shape or size can be determined as force or pressure, i.e., force per unit area.

[0049] By means of the method described above, an object in the form of a composite component having constant properties at the joint after sintering can be obtained. Thus, larger and still uniform components can be manufactured without the need for processing equipment capable of manufacturing such large components, which would otherwise require, for example, larger tools and greater pressures. It is also possible to manufacture such objects of several different sizes from first and second components of one or several sizes. Thus, a more flexible and more efficient manufacturing method is obtained, which can easily be adapted to the actual needs of a specific object for a given application. In addition, the method can be used to manufacture objects that cannot be formed by conventional methods. Such an object can, for example, include an internal cooling channel obtained by joining a first and a second component, each of which forms half of the object and is formed so that an internal channel is formed during the joining.

[0050] Another advantage of the method according to the invention is that it provides a coherent object without weak points along the joint (eg due to discontinuities), as is often seen in known joining methods such as welding and brazing.

[0051] In the method as described above, wherein the mixture is arranged between the first joining surface and the second joining surface, the mixture can be arranged in a predetermined pattern. Such a pattern can be determined, for example, to obtain effective drying, degreasing and / or sintering of the mixture material. The predetermined pattern can be selected from a straight line, a curve, a circle, a point and a combination thereof. Therefore, for a given amount of material, it is easier to ensure that the mixture is arranged in a pattern to provide a large surface area than would be possible if the mixture covered all of the first and second joining surfaces. Another advantage of arranging the mixture in the predetermined pattern is that it is thereby easier to ensure that the mixture remains between the first and second joining surfaces without being squeezed on the edges during the remaining process steps.

[0052] Alternatively or in conjunction with these arrangements of the mixture, the mixture may also be arranged as a plurality of layers in at least some regions. Thus, it is possible to arrange the mixture in a manner that results in the joining parts being at a distance from each other, the distance being obtained and maintained by the mixture.

[0053] In any method involving providing a mixture between the first and second engaging surfaces, the step of providing the mixture may be accomplished by 3D printing. Thus, the mixture may be provided in a predetermined pattern, for example, by controlling the use of a computer or other control unit, thereby easily ensuring that the mixture is provided as desired and in a repeatable manner.

[0054] Another advantage of the method in which the step of achieving the joining comprises arranging a mixture of dissolved adhesive and metal powder between the first joining surface and the second surface is that the surfaces to be joined do not need to be flat. In this method, the step of at least partially dissolving the first joining surface and / or the second joining surface by applying a solvent can occur before the arranging step. Alternatively, the step of bringing at least one of the first component and the second component into a wet state can occur before the arranging step. Thereby, voids can be avoided, or at least the amount of voids can be reduced.

[0055] The first and second components may be manufactured by powder extrusion, powder injection molding, additive manufacturing or tape casting.

[0056] The alloy composition of the first and second components may include one or more of: iron, chromium, aluminum, cobalt, nickel, manganese, molybdenum, vanadium, silicon or alloys thereof. Examples of specific alloys tested during the development of the present invention are given in the detailed description of the drawings.

[0057] In any of the embodiments described above, the first and / or second components may include ceramic material, preferably particles. Such ceramic material may, for example, be used to prepare an object having desired mechanical and electrical properties, such as resistivity and / or creep resistance, the desired properties being selected for the intended use of the object. In such an embodiment, the ceramic and its amount may be the same or different in the first and second components. Thus, the method provides for manufacturing an object having some different properties in two parts of the object while remaining a coherent object with respect to other properties. In addition to changing the type and / or amount of the ceramic material, the electrical and mechanical properties of the first and second components may also be changed by changing the size and / or shape of the ceramic particles. A non-exhaustive list of possible ceramics includes: AlO, SiO, ZiO, aluminum oxide, zirconium oxide, boron nitride, cordierite, and silicon nitride.

[0058] The sintering temperature generally used in the present invention is so low that only the metal powder is sintered, but the ceramic powder is not sintered.

[0059] In the embodiment as described above, wherein the step of achieving bonding is performed by arranging a mixture between the first and second bonding surfaces, the mixture comprising the dissolved third adhesive and the metal powder may further comprise ceramic powder. The amount of ceramic powder may vary along the interface between the first and second bonding surfaces. Since the electrical properties of metals and ceramics are significantly different, the addition of ceramic powder (possibly in different amounts) makes it possible to control the local electrical properties of the object formed by bonding. This can be obtained by using a method in which the amount of ceramic powder in the mixture can be changed during the step of arranging the mixture so that the mixture composition on the first and second bonding surfaces can be different. Sintering is usually carried out in a reducing atmosphere, a vacuum or an inert atmosphere to reduce or prevent the formation of oxides.

[0060] Binder or adhesive is any material or substance that other materials are held or pulled together to form a cohesive unit mechanically or chemically by adhesion or cohesion. Binder is preferably organic, such as cellulose ether, agarose or polyoxymethylene. Examples of binders are: methylcellulose, 25 poly (ethylene oxide), polyvinyl alcohol, sodium carboxymethylcellulose (cellulose gum), alginate, ethyl cellulose and asphalt.

[0061] In currently preferred embodiments of the invention, the first adhesive and the second adhesive have similar or identical solubility, for example, the first adhesive and the second adhesive are identical. In embodiments in which a mixture is disposed between the first and second joining surfaces, the third adhesive used in the mixture preferably has similar or identical solubility as the first and second adhesives.

[0062] In some embodiments of the invention, the adhesive of the first and second components is soluble in water. This provides a better working environment and handling process compared to some other possible adhesive types that require the use of, for example, acetone.

[0063] In some embodiments of the present invention, each of the first and second components includes a plurality of nearly parallel or parallel channels extending in the longitudinal direction of the first and second components. For such embodiments, the first and second components can be arranged side by side adjacent to each other so that the object has a certain number of channels, which is the sum of the number of channels in the first component and the number of channels in the second component. Alternatively, the first and second components can be arranged so that the channels of the first and second components are continuous with each other. In such embodiments, the geometry of the cross-sections of the first and second components perpendicular to the longitudinal direction can be such that the object has a continuous channel extending from the first component to the second component.

[0064] In a presently preferred embodiment of the invention, after sintering or oxidation, the previous interface between the first component, the second component and, when present, the mixture is not identifiable or barely perceptible by analysis using scanning electron microscopy.

[0065] In any of the above embodiments, a debinding step may be provided before the sintering or oxidation step. The debinding step preferably includes heating the first and second parts to a temperature at which at least some, for example all, of the binder is burned off. Debinding is the process of removing the binder from the green body to ensure that there is no residual carbon in the part during the sintering or oxidation process. This debinding is typically accomplished by heating to a temperature between 200 and 750 degrees Celsius and allowing the binder to burn off. Different binders require different debinding temperatures, so other temperatures may also be advantageous for certain materials. In an embodiment using methylcellulose, debinding is performed in an oxidizing atmosphere, typically air, but may also be performed partially in the same atmosphere as the sintering atmosphere if the final part is not damaged by the additional carbon content. In order to ensure that the debound first and second parts can still be handled, it may be necessary to slightly oxidize the powder together; these oxides will be removed during the sintering process.

[0066] BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The manufacturing method according to the present invention will now be described in more detail with reference to the accompanying drawings. The drawings show one way of implementing the invention and should not be interpreted as limiting other possible embodiments falling within the scope of the appended claims.

[0068] Figure 1 An embodiment of the method according to the invention is shown schematically.

[0069] Figure 2 A further embodiment of the method according to the invention is schematically shown.

[0070] Figure 3 Different examples of how the mixture can be arranged in different predetermined patterns are schematically shown.

[0071] FIG. 4 schematically shows an embodiment in which the mixture is arranged as multiple layers in some areas.

[0072] FIG. 5 schematically shows different examples of first and second components that can be joined by the method according to the invention.

[0073] Figure 6 Two different ways of arranging the first and second components with respect to each other to form the object are schematically shown.

[0074] FIG. 7 shows a microscope image of an object produced by joining the first and second components. DETAILED DESCRIPTION

[0075] Figure 1 An example of how the invention can be used to manufacture an object 24 by joining a first component 25 and a second component 26 is schematically shown. Figure 1 (a) shows that the first and second components 25, 26 are block-shaped, but the present invention also covers many other geometric shapes as long as they include two opposing surfaces suitable for bonding. The first component 25 includes a metal powder having a first alloy composition and a first soluble binder. The first component 25 has a first bonding surface 27, which is Figure 1 (a) is the upper surface. The second component 26 includes a metal powder having a second alloy composition and a second soluble binder. The second component 26 has a second joining surface 28 to be joined with the first joining surface 27. Figure 1 In (a), the first engagement surface 27 is the lower surface of the interface to be established, but the arrangement of the first and second engagement surfaces may be different from that shown. They may be, for example, horizontal.

[0076] As also described above, the first alloy composition and the second alloy composition are each composed of a plurality of chemical elements. The chemical elements are selected such that for each chemical element present in an amount greater than 0.5 weight percent in each alloy composition, the chemical element is included in the first and second alloy compositions; and for a chemical element present in an amount up to 5.0 weight percent in the first alloy composition, the amount of the chemical element differs by at most 1 percentage point between the first and second alloy compositions; and for a chemical element present in an amount greater than 5.0 weight percent in the first alloy composition, the amount of the chemical element differs by at most 3 percentage points between the first and second alloy compositions.

[0077] exist Figure 1 In the embodiment shown in (b), the bonding is usually achieved by dissolving both the first bonding surface 27 and the second bonding surface 28 using a solvent (not shown). However, it is also possible to dissolve only one of the first and second bonding surfaces 27, 28 or only a portion of one or both of the first and second bonding surfaces 27, 28. In an embodiment of the present invention, where the bonding step includes placing at least one of the first component 25 and the second component 26 in a wet state, this will be similar to Figure 1 , the difference is that a greater portion, such as the entirety, of at least one of the first and second components 25, 26 is in a wet state, as indicated by the shading in the figure.

[0078] Then the first joint surface 27 is brought into contact with the second joint surface 28, as shown in FIG. Figure 1 (c) The first and second engagement surfaces 27, 28 are maintained in contact for a period of time to allow at least some of the solvent to evaporate. This can be done while applying an external force F, such as Figure 1 (d) as shown.

[0079] The first and second components 25, 26 are then sintered together while the first and second joining surfaces 27, 28 are kept in contact to obtain the object 24. Figure 1 In the embodiment shown in (e), the sintering is carried out, for example, in a furnace 34 in a reducing atmosphere 33, but it can also be carried out in a vacuum or inert atmosphere. The sintering is usually carried out at a temperature of 950 to 1430 degrees Celsius. Figure 1 (f) Schematically shows the final object 24 as a unit.

[0080] Figure 2 Schematically shows a similar Figure 1 The method can be used to manufacture an object 24 by joining a first component 25 and a second component 26, wherein the first component 25 and the second component 26 have uneven first and second joining surfaces 27, 28, respectively, such as Figure 2 (a). In this figure, the first and second joining surfaces 27, 28 are shown as having similar profiles, but the profiles may be different. A mixture 29 of a dissolved third binder and a metal powder having a third alloy composition is disposed between the first joining surface 27 and the second joining surface 28; Figure 2 (b) is shown. The third alloy composition is composed of a plurality of chemical elements, and the chemical elements are selected so that for each chemical element present in the mixture in an amount greater than 0.5% by weight of the metal powder: for a chemical element present in the third alloy composition in an amount of up to 5.0% by weight, the amount of the chemical element differs by at most 1 percentage point between the first and third alloy compositions; for a chemical element present in the third alloy composition in an amount greater than 5.0% by weight, the amount of the chemical element differs by at most 3 percentage points between the first and third alloy compositions. If it is found necessary, a solvent (not shown) may be applied to dissolve the first joining surface 27 and / or the second joining surface 28 before providing the mixture 29 of dissolved third binder and metal powder.

[0081] Then, if Figure 2 As shown in (c), the first and second bonding surfaces 27, 28 are arranged as close together as possible, while sandwiching the dissolved third adhesive and metal powder mixture 29 between them, and the first and second bonding surfaces 27, 28 are kept in contact with the dissolved third adhesive and metal powder mixture 29 for a period of time to allow at least some of the solvent to evaporate. Figure 2 As shown in (d), this step may involve applying an external force F.

[0082] In the same manner as described above, the first and second components 25, 26 are then sintered together while keeping the first and second joining surfaces 27, 28 as close as possible to obtain the object. Figure 2 In the embodiment shown in (e), the sintering is carried out in a reducing atmosphere 33 in a furnace 34, for example, to produce an object 24 such as Figure 2 (f) as shown.

[0083] exist Figure 2 In the embodiment of FIG. 2 , the mixture 29 is shown as being disposed over the entire first engagement surface 27. However, as described above, for some applications, it would be advantageous to dispose the mixture 29 in a predetermined pattern, such as by using 3D printing. Different examples of such patterns are described in Figure 3 , which shows a top view of a mixture 29 disposed at one end of a first component 25. As can be seen, the mixture 29 can be, for example, in the form of a straight line, a curve, a circle, a dot, or a combination thereof. Depending on the method used to place the mixture, the line may not be completely straight, the size of the dots may not be exactly the same, and the line may not be exactly as expected.

[0084] FIG4( a) shows a side view of an embodiment in which the mixture 29 is provided as a plurality of layers. This can be used, for example, to take into account the mutual shape of the first and second joining surfaces 27, 28 or simply to ensure that more mixture 29 is provided in certain areas than in other areas. The application of the mixture 29 as a plurality of layers can also be used to establish a relatively thick joining area, for example to obtain a specific distance between the non-contacting areas of the first and second parts 25, 26 after joining. FIG4( a) is an example of such an object with three layers of mixture 29. FIG4( b) shows an object with a first part 25 and a second part 26 joined by the mixture 29.

[0085] exist Figure 1 In any of the methods shown in -4, the first and second components 25, 26 can be manufactured by powder extrusion, powder injection molding, additive manufacturing or tape casting.

[0086] With regard to embodiments according to the present invention including the use of a mixture disposed between the first and second joining surfaces 27, 28, some examples of potential problems can be given in the event that the third alloy composition of the mixture differs too much from the first alloy composition. As a first example, FeCrAl can be used for heating elements, but if there is too little Al in the metal powder of the mixture, the surface of the connection area will not be able to protect due to the formation of AlO, and therefore cannot withstand as much heat as the area of ​​the components being joined. Therefore, during the use of the object, the connection area may fail. As a second example, the corrosion resistance of 316L is the same. If the Cr content in the third alloy composition of the mixture is too little, the connection area will not have the same corrosion resistance, resulting in an undesirable weak area.

[0087] The material composition of the first and second components 25, 26 can be the same, but can also be different. Figure 5 schematically shows examples of different cross-sectional combinations of components containing ceramic particles. In Figure 5, the ceramic particles are shown in black, even though they are white in the actual components. Figure 5(a) shows an example in which the first component has no ceramic and the second component has ceramic. Figure 5(b) shows another example in which both the first and second components contain ceramic particles, but at different volume fractions. Figure 5(c) shows a third example in which the size of the ceramic particles is different in the first and second components.

[0088] Depending on the desired final shape or size, the object 24 can be manufactured by connecting the first and second parts 25 , 26 according to the method of the invention. Figure 6 (a) shows an embodiment in which first and second parts 25, 26 in the form of block-like elements including longitudinally extending channels 22 are arranged side by side and adjacent to each other, so that the object 24 has a certain number of channels 22, which is the sum of the number of channels 22 in the first part 25 and the number of channels 22 in the second part 26. Figure 6 (b) shows another embodiment in which the first and second components 25, 26 are arranged so that the channels 22 of the first and second components 25, 26 are continuous with each other. The present invention can also be used to join a component having a channel with a component without a channel (eg, a solid component).

[0089] During the development of the present invention, parts made of FeCrAl and 316L have been joined and sintered. The binders were methylcellulose and water. By using a scanning electron microscope (SEM), it has been demonstrated that the transitions between the material phases from the joined parts are almost imperceptible. Figure 7 shows two microscope images of an object obtained by joining three parts at different magnifications. The parts were made from the same FeCrAl metal powder material. Analysis of the joined area with SEM and energy dispersive X-ray spectroscopy showed that there was no clear separation or interface between the joined parts in the SEM pictures. The only difference between the three parts was a slightly higher porosity in the outer parts compared to the middle part, while any minor changes in the material composition on the cross section could not be distinguished. The object in Figure 7 has channels; they are large dark areas in the image.

[0090] Although the present invention has been described in conjunction with specific embodiments, it should not be interpreted as being limited in any way to the examples presented. The scope of the present invention is defined by the appended claims. In the context of the claims, the terms "comprise" or "comprising" do not exclude other possible elements or steps. Furthermore, references such as "one" or "an" should not be interpreted as excluding pluralities. The use of reference symbols in the claims with respect to elements indicated in the drawings should also not be interpreted as limiting the scope of the present invention. Furthermore, the individual features mentioned in different claims may be advantageously combined, and the mention of these features in different claims does not exclude that a combination of features is impossible and advantageous.

Claims

1. A method for manufacturing an object (24) by joining a first component (25) and a second component (26), the method comprising the following steps: - providing a first component (25), the first component comprising a metal powder having a first alloy composition and a first soluble binder, the first component having a first joining surface (27), - providing a second component (26), the second component comprising a metal powder having a second alloy composition and a second soluble binder, the second component (26) having a second joining surface (28) to be joined with the first joining surface (27); wherein the first alloy composition and the second alloy composition are each composed of a plurality of chemical elements, and wherein the chemical elements are selected such that for each chemical element present in an amount greater than 0.5 weight percent in each alloy composition, the chemical element is contained in both the first alloy composition and the second alloy composition, and - for a chemical element present in an amount of up to 5.0 wt. % in the first alloy composition, the amount of said chemical element differs between the first alloy composition and the second alloy composition by at most 1 percentage point, and - for a chemical element present in the first alloy composition in an amount greater than 5.0 wt. %, the amount of said chemical element differs by at most 3 percentage points between the first alloy composition and the second alloy composition; and wherein the adhesive of the first and second components (25, 26) is soluble in water; The method achieves the bonding by the following steps: - at least partially dissolving the first joining surface (27) and / or the second joining surface (28) by applying a solvent, and - bringing the first engaging surface (27) into contact with the second engaging surface (28) and maintaining the contact for a period of time to allow at least some of the solvent to evaporate; as well as sintering or oxidizing the first and second components (25, 26) together while maintaining the first and second joining surfaces (27, 28) in contact to obtain the object (24); The binders of the first and second components are selected from at least one of the following: methyl cellulose, polyethylene oxide, polyvinyl alcohol, sodium carboxymethyl cellulose, alginate and ethyl cellulose.

2. A method for manufacturing an object (24) by joining a first component (25) and a second component (26), the method comprising the following steps: - providing a first component (25), the first component comprising a metal powder having a first alloy composition and a first soluble binder, the first component having a first joining surface (27), - providing a second component (26), the second component comprising a metal powder having a second alloy composition and a second soluble binder, the second component (26) having a second joining surface (28) to be joined with the first joining surface (27); wherein the first alloy composition and the second alloy composition are each composed of a plurality of chemical elements, and wherein the chemical elements are selected such that for each chemical element present in an amount greater than 0.5 weight percent in each alloy composition, the chemical element is contained in both the first alloy composition and the second alloy composition, and - for a chemical element present in an amount of up to 5.0 wt. % in the first alloy composition, the amount of said chemical element differs between the first alloy composition and the second alloy composition by at most 1 percentage point, and - for a chemical element present in the first alloy composition in an amount greater than 5.0 wt. %, the amount of said chemical element differs by at most 3 percentage points between the first alloy composition and the second alloy composition; and wherein the adhesive of the first and second components (25, 26) is soluble in water; The method achieves the bonding by the following steps: - a mixture (29) comprising a dissolved third binder and a metal powder having a third alloy composition is arranged between the first joining surface (27) and the second joining surface (28), wherein the third alloy composition consists of a plurality of chemical elements and wherein the chemical elements are selected such that for each chemical element present in the mixture in an amount greater than 0.5% by weight of the metal powder: - for a chemical element present in an amount of up to 5.0 wt. % in the third alloy composition, the amount of said chemical element differs by at most 1 percentage point between the first alloy composition and the third alloy composition, and - for a chemical element present in the third alloy composition in an amount greater than 5.0 wt. %, the amount of said chemical element differs by at most 3 percentage points between the first alloy composition and the third alloy composition; - placing the first and second joining surfaces (27, 28) as close together as possible while sandwiching the dissolved third binder and metal powder mixture (29) therebetween, and maintaining the first and second joining surfaces (27, 28) in contact with the dissolved third binder and metal powder mixture (29) for a period of time to allow at least part of the solvent to evaporate; and sintering or oxidizing the first and second components (25, 26) together while keeping the first and second joining surfaces (27, 28) as close together as possible to obtain the object (24); The binders of the first and second components are selected from at least one of the following: methyl cellulose, polyethylene oxide, polyvinyl alcohol, sodium carboxymethyl cellulose, alginate and ethyl cellulose.

3. The method according to claim 2, wherein the mixture (29) is arranged in a predetermined pattern. The method according to claim 3 , wherein the predetermined pattern is selected from the group consisting of straight lines, curves, circles, dots, and combinations thereof.

5. The method according to any one of claims 2 to 4, wherein the mixture (29) is arranged as a plurality of layers in at least some areas.

6. The method according to claim 2, wherein the step of providing the mixture (29) is performed by 3D printing.

7. The method according to claim 2, wherein one of the following steps is performed before the step of providing the mixture (29) and at least one of the steps of providing the first and second engagement surfaces (27, 28): - at least partially dissolving the first joining surface (27) and / or the second joining surface (28) by applying a solvent, or - providing at least one of the first component (25) and the second component (26) in a wet state.

8. The method of claim 2, wherein the mixture (29) comprising the dissolved third binder and the metal powder further comprises a ceramic powder.

9. A method according to claim 8, wherein the amount of ceramic powder in the mixture (29) is varied during the step of providing the mixture so that the composition of the mixture varies between the first and second joining surfaces (27, 28).

10. The method of claim 2, wherein the first soluble binder, the second soluble binder, and the third binder have similar or identical solubilities.

11. The method of claim 2, wherein after sintering or oxidation, the previous interface between the first component (25), the second component (26) and the mixture (29) is not identifiable or barely perceptible by analysis using scanning electron microscopy.

12. A method for manufacturing an object (24) by joining a first component (25) and a second component (26), the method comprising the steps of: - providing a first component (25), the first component comprising a metal powder having a first alloy composition and a first soluble binder, the first component having a first joining surface (27), - providing a second component (26), the second component comprising a metal powder having a second alloy composition and a second soluble binder, the second component (26) having a second joining surface (28) to be joined with the first joining surface (27); wherein the first alloy composition and the second alloy composition are each composed of a plurality of chemical elements, and wherein the chemical elements are selected such that for each chemical element present in an amount greater than 0.5 weight percent in each alloy composition, the chemical element is contained in both the first alloy composition and the second alloy composition, and - for a chemical element present in an amount of up to 5.0 wt. % in the first alloy composition, the amount of said chemical element differs between the first alloy composition and the second alloy composition by at most 1 percentage point, and - for a chemical element present in the first alloy composition in an amount greater than 5.0 wt. %, the amount of said chemical element differs by at most 3 percentage points between the first alloy composition and the second alloy composition; and wherein the adhesive of the first and second components (25, 26) is soluble in water; The method achieves the bonding by the following steps: - placing at least one of the first component (25) and the second component (26) in a wet state, bringing the first joining surface (27) into contact with the second joining surface (28) and maintaining the contact for a period of time to allow at least some of the solvent to evaporate; as well as sintering or oxidizing the first and second components (25, 26) together while maintaining the first and second joining surfaces (27, 28) in contact to obtain the object (24); The binders of the first and second components are selected from at least one of the following: methyl cellulose, polyethylene oxide, polyvinyl alcohol, sodium carboxymethyl cellulose, alginate and ethyl cellulose.

13. The method according to any of the preceding claims 1-2 and 12, wherein the first and second components (25, 26) are manufactured by powder extrusion, powder injection molding, additive manufacturing or tape casting.

14. The method according to any of the preceding claims 1-2 and 12, wherein the alloy composition of the first and second components (25, 26) includes one or more of the following: iron, chromium, aluminum, cobalt, nickel, manganese, molybdenum, vanadium, and silicon.

15. The method according to any one of claims 1-2 and 12, wherein the first and / or second component (25, 26) comprises a ceramic material.

16. The method according to any one of the preceding claims 1-2 and 12, wherein each of the first and second components (25, 26) comprises a plurality of nearly parallel or parallel channels (22), the channels (22) extending in the longitudinal direction of the first and second components (25, 26).

17. The method according to claim 16, wherein the first and second components (25, 26) are configured as follows: - are arranged adjacent to each other so that the object has a number of channels (22) which is the sum of the number of channels (22) in the first part (25) and the number of channels (22) in the second part (26), or - making the channels (22) of the first and second parts (25, 26) continuous with each other.

18. The method of claim 1 or 12, wherein after sintering or oxidation, the previous interface between the first component (25) and the second component (26) is not identifiable or barely perceptible by analysis using scanning electron microscopy.

19. The method according to any one of the preceding claims 1-2 and 12, wherein there is a debinding step before the sintering or oxidation step.

20. The method of claim 19, wherein the debinding step comprises heating the first and second components (25, 26) to a temperature at which at least some of the binder is burned off.

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