WO2021219564A1

WO2021219564A1 - Pre-alloyed powder for sinter-brazing, sinter-brazing material and sinter-brazing method

Info

Publication number: WO2021219564A1
Application number: PCT/EP2021/060865
Authority: WO
Inventors: Ulf Engström; Simon HEDSTRÖM; Torstein GRØSTAD; Zhaoqiang TAN; Chengjiang HUANG; Xin Xu
Original assignee: Höganäs Ab (Publ)
Priority date: 2020-04-29
Filing date: 2021-04-26
Publication date: 2021-11-04
Also published as: WO2021217512A1

Abstract

Disclosed is a new fully pre-alloyed brazing powder material. The pre-alloyed brazing powder contains specified amounts of iron, nickel, manganese silicon, boron and balanced with copper. The pre-alloyed brazing powder material can be mixed with up to 3% by weight of a powdered flux composition, or with a wax, and compacted into preforms to be used as a sinter-brazing material in a sinter-brazing process.

Description

PRE-ALLOYED POWDER FOR SINTER-BRAZING, SINTER-BRAZING MATERIAL AND SINTER-BRAZING METHOD.

FIELD OF THE INVENTION

SUMMARY

Disclosed is a new fully pre-alloyed brazing powder material. The pre-alloyed brazing powder contains specified amounts of iron, nickel, manganese silicon, boron and balanced with copper.

The pre-alloyed brazing powder material can be mixed with up to 3% by weight of a powdered flux, or with a wax, and compacted into preforms to be used as a sinter-brazing material in a sinter-brazing process.

BACKGROUND

Brazing technology is frequently used in metal part production. In powder metallurgy (PM) of ferrous part production, sinter brazing is the most common and cost-effective way to manufacture large and complex parts, by combining sintering and brazing in a single process. The compacted PM metal part can be brazed to another PM metal part or to a wrought metal part. To achieve a qualified brazing joint, the brazing material should have good wetting with substrate and flow sufficiently into the designed joint under the sintering atmosphere and temperature.

However, the compacted PM ferrous part normally has a density 6.0 g/cm³ to 7.2 g/cm³, which means it is porous as full iron density is 7.8 g/cm³. Thus, careful handling should be taken to avoid excessive infiltration of braze alloy into the porous substrate. This is to some extent achieved by an isothermal solidification process, i.e. the desired increase of the melting temperature of the brazing alloy when it enters the pores through the alteration of the chemical composition caused by diffusion.

Excessive infiltration of the porous component by the brazing alloy is however a problem at sinter brazing. US patent application US 3,717,442 to Knopp, proposed a solution to this problem by providing a brazing alloy composition suitable for sinter-brazing at least one ferrous porous part to another part. The proposed brazing alloy comprises a blended mixture of an alloy A and an alloy B in proportions 50(A)/50(B) to 75(A)/25(B). A proposed composition of alloy A consists essentially of 35-70% by weight of copper, 3-20% by weight of nickel and 15-50% by weight of manganese, whereas a proposed composition of alloy B consists essentially of 2.5-5.5% by weight of silicon, 0.75-5.25% by weight of boron and the balance essentially nickel. The blended mixture of the two alloys is preferably mixed to provide an overall composition of 30-50% by weight of copper, 10-20% by weight of manganese, 0.5-3% by weight of silicon, 0.5-1.5% by weight of boron, balance essentially nickel in the range of 30-50% by weight. During the isothermal solidification process, the most important diffusion element is iron from the ferrous substrate, this phenomenon may lead to erosion of substrate resulting in decreased precision and physical properties of finished parts. A solution to this problem is disclosed by Knopp in the US patent US4,029,476, which proposed blending 3-25% by weight of iron powder into an alloy powder having a similar composition as the blended powder disclosed in US 3,717,442. Normally, the brazing material is compacted into preforms such as tablets, which are placed in “pockets” between the parts to be brazed. It is stated in the patent that an additional benefit by having iron powder blended with the brazing alloy is increased green strength of such preforms.

However, physical blending tends to cause segregation between the iron powder particles and the braze alloy powder particles during blending, powder transfer and compaction processes. The isothermal solidification process highly depends on local braze/iron ratio in molten braze, for instance, poor iron area would solidify slowly to cause more infiltration and rich iron area would solidify quickly resulting in no braze flow in designed joint. Due to such inhomogeneity of the blend, different infiltration depths in joints are always found even within each part, causing over-consumption of braze material, unstable dimension and occasionally joint failure.

Figure 1 shows an example of different infiltration depths from 20 pm to 1 800 pm with voids and substrate erosion. The sinter-brazing material used was a mixture between 82% by weight of a brazing alloy powder, 15% by weight of an iron powder and 3% by weight of a flux powder. The brazing alloy powder consisted of 39.6% by weight of Cu, 14.8% by weight of Mn, 1.74% by weight of Si and 1.43% by weight of B and balanced with Ni.

Iron-based PM metal parts are generally produced by mixing graphite (e.g.

0.8% by weight), lubricant (e.g. 0.8% by weight of a wax), iron powder and desired metal alloy components (e.g. 2% by weight copper). The mix is transferred into designed shape mold and pressed into green compacts with the density 6.0 g/cm³ to 7.2 g/cm³. The green compacts are thereafter sintered in a sintering furnace at about 1050°C to 1350°C. During this production process, lubricant is necessarily used, and added to the mix prior to compaction, to get smooth ejection from the mold. Lubricants need to be removed completely before the solidus temperature of the sinter brazing material is reached. Rapid burn off (RBO) is frequently used to remove, or dewax, lubricants by introducing highly oxidizing atmosphere in the dewaxing zone of the furnace. To protect the braze alloy, high amount up to 5% fluoride- and or boride- flux is blended into traditional braze material. Otherwise, the brazing material could be seriously oxidized and cannot flow into the gap, as seen in figure 2. The sinter-brazing material used was a mixture between 84.4% by weight of a brazing alloy powder, 15% by weight of an iron powder and 0.6% by weight of wax. The brazing alloy powder consisted of 39.6% by weight of Cu, 14.8% by weight of Mn, 1.74% by weight of Si and 1.43% by weight of B and balanced with Ni.

Since the particle size of the flux normally is very fine, and the volume to weight ratio is higher compared to the brazing alloy powder, it is difficult to obtain a stable and homogenous mix with e.g. 5% by weight of a flux and 95% by weight of brazing alloy powder. Another drawback is the flux can dramatically increase the wetting of braze alloy causing much higher infiltration depth in substrate, which is not desirable. Thus, the amount of inmixed flux normally has to be adjusted depending on e.g. type of furnace and component to be brazed.

Iron powder has a melting point of 1535°C and a conventionally used brazing alloy has a solidus temperature about 900°C and a liquidus temperature of about 1050°C. The big difference in liquidus temperature of the brazing alloy powder and the melting point of the iron powder increases the risk that residues of brazing material is trapped in the regions where the brazing material is placed, causing inferior quality of the brazed products which entails extensive quality inspection and high scrap rate at mass production. A stable sinter brazing process resulting in good quality brazes, enables a simple visual inspection of the sinter-brazed parts, without any excessive use of destructive inspection such as metallographic inspection of cross sections of the sinter- brazed joints.

DETAILED DESCRIPTION

The present invention provides a solution to some or all of the previously mentioned problems by providing a consistent brazing alloy material to be used in a brazing process, as well as a sinter-brazing process. The new brazing alloy material makes it possible to obtain brazed joints with controlled infiltration depth and reduced substrate erosion, enabling effective mass manufacturing. In a first aspect of the invention there is provided a pre-alloyed powder for sinter-brazing consisting of:

30-45 wt.% Ni;

10-20 wt.% Mn;

3-15 wt.% Fe;

1-3 wt.% Si;

1-3 wt.% B; balanced with Cu; inevitable impurities up to 1 wt.%. In a further embodiment the first aspect there is provided a pre-alloyed powder for sinter-brazing consisting of:

30-45 wt.% Ni;

10-20 wt.% Mn;

3-12 wt.% Fe;

1-3 wt.% Si;

30-45 wt.% Ni;

12-18 wt.% Mn;

3-10 wt.% Fe;

1-3 wt.% Si;

1 -3 wt.% B balanced with Cu; inevitable impurities up to 1 wt.%.

In a further embodiment the first aspect there is provided a pre-alloyed powder for sinter-brazing consisting of: 35-45 wt.% Ni;

12-18 wt.% Mn;

3-9 wt.% Fe;

1-3 wt.% Si;

1 -3 wt.% B balanced with Cu; inevitable impurities up to 1 wt.%.

In a further embodiment the first aspect there is provided a pre-alloyed powder for sinter-brazing consisting of:

36-41 wt.% Ni;

12-16 wt.% Mn;

3-9 wt.% Fe;

1-2 wt.% Si;

1 -2 wt.% B balanced with Cu; inevitable impurities up to 1 wt.%.

In another embodiments the first aspect there is provided a pre-alloyed powder for sinter-brazing consisting of:

36-41 wt.% Ni;

12-16 wt.% Mn;

4-8 wt.% Fe;

1-2 wt.% Si;

1 -2 wt.% B balanced with Cu; inevitable impurities up to 1 wt.%.

In an embodiment of the first aspect the pre-alloyed powder for sinter brazing having a particle size distribution such that: at least 95% by weight is below 425 pm; at most 10% by weight is below 45 pm, measured according to

IS04497:1983.

In an embodiment of the first aspect, the pre-alloyed powder for sinter brazing is produced through water-atomization. In an embodiment of the first aspect, the pre-alloyed powder for sinter brazing has a melting range of at most 150°C, preferably at most 120°C, more preferably at most 100°C.

In a second aspect of the invention there is provided a sinter-brazing material containing of up to 3% by weight of a flux material balanced with a pre-alloyed powder for sinter-brazing according to any the first aspect.

In one embodiment of the second aspect, the flux consists of at least 50% by weight of boric acid.

In one embodiment of the second aspect, there is provided a sinter- brazing material containing of up to 1% by weight of a lubricant balanced with a pre- alloyed powder for sinter-brazing according to the first aspect.

In one embodiment of the second aspect, the lubricant is chosen from the group of waxes, such as ethylene bis stearamide, fatty acid monoamides such as stearic acid amide, oleic acid amide, arachidic acid amide, erucic acid amide, behenic acid amide, palmitic acid amide, or mixtures thereof, amide oligomers, polyamides or mixtures thereof.

In one embodiment of the second aspect, the sinter-brazing material is present in form of a preform such as a tablet.

In a third aspect of the invention there is provided a sinter-brazing-method comprising the steps of: a) providing at least one compacted iron-based component and at least one iron-based component; b) applying a sinter-brazing material containing a pre-alloyed powder for sinter-brazing according to any of claims 1 to 7 to the at least one compacted component or the at least one iron- based component; c) combine the at least one compacted component with the at least one iron-based component to form structure; d) subjecting said structure to brazing procedure at a temperature between 1100°C and 1350°C for a period of time of 10 minutes to 1 hour in an atmosphere of dissociated ammonia, endogas, a mixture of nitrogen and hydrogen or in hydrogen; e) cooling the obtained brazed structure.

In an embodiment of the third aspect the sinter-brazing material is according to the second aspect.

In a fourth aspect of the invention there is provided a sinter-brazed product produced according to the third aspect.

Pre-alloved powder for sinter-brazing The pre-alloyed powder for sinter-brazing consists of Ni, Mn, Fe, Si, B, balanced with Cu and inevitable impurities such as O, C, N, S, P etc.

The pre-alloyed powder for sinter brazing is preferably produced by water atomization. Water atomized powders have an irregular shape which means that the particles are effectively locked with each other after compaction, providing a compacted part or a preform having enough structural integrity or green strength, to be handled. In contrast, gas-atomized powders have a more spherical shape and thus lower green strength after compaction. However, gas- atomized powders may also be of interest, especially if such powders are mixed with substances promoting green strength. A distinguishing feature for the present invention is that all elements are in pre- alloyed form, i.e. not mixed as separate powders. Apart from contributing to homogeneity it has also been noticed that the melting range, i.e. the difference between solidus and liquidus, of the pre-alloyed powder according to the invention is more narrow compared to a powder having the same chemical composition wherein Fe as a separate iron-powder is mixed with the an alloyed powder containing the other alloying elements.

This is an important feature since a common problem in brazing is liquation, which can occur in brazing alloys that melt over a significant temperature range. The first low-melting composition can in presence of narrow gaps such as porosity or tight gap clearances between parts, flow away from the application point of the brazing material by capillary action, increasing the temperature needed to melt the remaining material. This increases the tendency of metallic unmolten residues and leads to brazing defects. With a narrower melting range, the risk of liquation is reduced as the brazing material can be completely melted in a shorter time, reducing the possibility of the low-melting composition flowing away.

The nominal melting range of the conventional sinter-brazing alloy powder as disclosed in US4,029,476 is approximately 150°C, i.e. a solidus temperature of about 900°C and a liquidus temperature of about 1050°C.The liquidus temperature of the sinter-brazing material is further increased by blending in iron powder having a melting temperature of 1535°C.

Opposed to conventional Ni-Cu-Mn-Si-B sinter brazing material where blending in iron powder does not affect the solidus temperature, pre-alloying with Fe can be found to increase the solidus temperature of the resulting alloy, while simultaneously leading to a comparatively smaller increase of the liquidus temperature up to an identified threshold content of about 15 wt.% Fe. Flence, the overall melting range decreases with increasing pre-alloying with Fe up to the identified threshold content. Higher pre-alloying additions than about 10 wt.%, increases the risk of incomplete melting of the sinter-brazing material as the liquidus temperature is too close to the sintering temperature. The preferred pre-alloying with Fe is therefore 3-10 wt.%, preferably 3-9 wt.%, more preferably 4-8 wt.%. Maximum content of Fe below 10 wt.% may contribute to a more robust melting behavior for certain applications. The solidus temperature of a pre-alloyed powder for sinter-brazing according to the present invention pre alloyed with 6 wt.% Fe is 930°C and the liquidus temperature is 1030°C, measured by Differential Scanning Calorimetry (DSC) in N2 atmosphere. The approximately 50°C lower overall melting range compared to the conventional Ni-Cu-Mn-Si-B sinter-brazing material ensures consistently improved melting properties and significantly improved sinter-brazing results.

Thus, the melting range of the new pre-alloyed powder for sinter brazing is less than 150°C, preferably less than 120°C, more preferably less than 100°C.

Flux

In order to avoid detrimental oxidation of the braze alloy, a flux is normally mixed in with the pre-alloyed powder for sinter-brazing, which is especially needed at sinter-brazing processes where RBO is employed. It has been noticed that the flux consumption can be substantially reduced when applying the new pre-alloyed powder for sinter-brazing compared to using a conventional sinter brazing material containing in-mixed iron powder. This is especially advantageous since the difficulties to obtain a homogeneous mix of flux and alloyed powder increases with increased flux content. Boride and fluoride fluxes may be a potential environmental problem, why the possibility of using lower content of such fluxes is very beneficial.

Thus, a suitable amount of flux is up to 3% by weight, preferably up to 2% by weight, most preferably up to 1.5% by weight or up to 1% by weight based on the total weight of the brazing material. When flux is used, a minimum content is 0.1% by weight of the total mix.

A typical boride-based flux contains at least 50% by weight of boric acid, such as 80% by weight of boric acid and 20% by weight of sodium tetraborate- decahydrate. A typical fluoride-based flux may contain mixtures of potassium difluorohydroxyborate, potassium trifluorohydroxyborate, potassium fluoborate, potassium tetrafluoroborate, potassium tetraborate and elemental boron.

Sinter-brazing material in form of preforms

Preferably, the sinter-brazing material containing the pre-alloyed powder for sinter-brazing and the flux, is supplied in the shape of preforms, which are produced by compaction of a mixture of the ingredients. Alternatively, the flux may be replaced by, or combined with, a lubricant, at a content of up to 1% by weight, such as up to 0.8% by weight, or 0.2-0.8% by weight or 0.3-0.6% by, in application wherein the risk of oxidation of the braze alloy is not a problem. Examples of lubricants are waxes, such as ethylene bis stearamide, fatty acid monoamides such as stearic acid amide, oleic acid amide, arachidic acid amide, erucic acid amide, behenic acid amide, palmitic acid amide, or mixtures thereof, amide oligomers, polyamides or mixtures thereof. Preferably the lubricant is chosen from as ethylene bis stearamide or a mixture of behenic acid amide, stearic acid amide and palmitic acid amide. It is important that the lubricants enable a clean delubrication or dewaxing without leaving any residues in form of soot or the like. Thus, lubricants containing metal salts are not suitable. A lubricant facilitates the production of the preforms, which also is the case for the flux, and both contributes to the integrity of the preforms. The sinter-brazing material may be compacted into a preform of any shape depending on the geometry of the target components. Typically, 0.2-0.5 grams braze material per square centimeter of brazed joint is used.

Sinter-brazing method The sinter-brazing method comprising the steps of: a) providing at least one compacted iron-based component and at least one iron-based component; b) applying a sinter-brazing material containing a pre-alloyed powder for sinter-brazing according to any of claims 1 to 7 to the at least one compacted component or the at least one iron- based component; c) combine the at least one compacted component with the at least one iron-based component to form structure; d) subjecting said structure to brazing procedure at a temperature between 1100°C and 1350°C for a period of time of 10 minutes to 1 hour in an atmosphere of dissociated ammonia, endogas, a mixture of nitrogen and hydrogen or in hydrogen. e) cooling the obtained brazed structure.

FIGURE LEGENDS

Figure 1 shows an example of different infiltration depths in a joint, brazed with a conventional brazing material.

Figure 2 shows an oxidized brazed joint brazed with a conventional brazing material without any flux addition.

Figure 3 shows a brazed joint in a planetary carrier, brazed with a brazing material according to the invention.

Figure 4 shows brazed joints in cylinder parts, brazed with a brazing material according to the invention.

Figure 5 shows brazed joints in cylinder parts, brazed with a conventional brazing material with in-mixed iron powder (a) 6 wt.% iron powder; (b) 10 wt.% iron powder; (c) 20 wt.% iron powder.

EXAMPLES EXAMPLE 1

A fully pre-alloyed water-atomized braze powder of Fe-Ni-Cu-Mn-Si-B composed of by weight about 6% iron, 39.4% nickel, 37.6% copper, 13.6% manganese, 1 .6% silicon and 1 .5% boron was used for sequent test. The powder was sieved on a 60 mesh US Standard Screen and the powder passing the screen was admixed with 1% flux as an oxidation-reduction agent, also acting as a lubricant. The flux consisted of 80% by weight of boric acid and 20% by weight of sodiumtetraborate decahydrate. Sinter-brazing preforms were produced by compaction of the mixed powder material at 600 MPa into discs having a diameter of 6 mm and a height of 6 mm, and having sufficient green strength allowing handling.

The substrate material was common Fe-Cu-C system of iron powder, 2% copper and 0.8% graphite by weight at the density of 6.9 g/cm³. The produced sinter-brazing material in shape of tablets were tested at sinter-brazing of the substrate material in the form of a planetary carrier parts.

Figure 3 presents the sinter-brazing quality of a planetary carrier made from the substrate material. RBO was applied and the structure was sintered-brazed at 1130°C in an endogas sintering atmosphere for about 20 min.

Well-controlled infiltration depth of about 0.2 mm and even braze joint without obvious substrate erosion were achieved in combination with minor amounts of residues, allowing effective visual inspection.

Figure 3a shows a part of the planetary carrier having good quality of the brazed joint at visual inspection. Figure 3b shows a cross section after cutting of a part of the planetary carrier having minor amounts of residues. Figure 3c shows a metallographic image of the same part disclosing well-controlled infiltration depth and an even braze joint without obvious substrate erosion.

EXAMPLE 2

The same preforms and the same composition of the substrate material, in the shape of a cylinder and a plate, were used in Example 2. Two different furnaces were used.

The result of the sinter-brazing process is shown in Figure 4, which shows good sinter-brazing quality joint between the substrate material as a cylinder and the substrate material in the shape of a plate.

Figure 4a shows a metallographic image of a cross section of the sinter-brazed joint, sinter-brazed at 1130°C in an atmosphere of endogas for about 20 minutes in a furnace, rapid burn off was applied. Figure 4b shows a metallographic image of a cross section of the sinter-brazed joint, sinter-brazed at 1130°C in an atmosphere of 90%N2/10%H2 for about 20 minutes, a RBO system was not used.

The result shows that well-controlled and uniform sinter-brazing joints were obtained, and that the new braze alloy is robust and suitable for various sintering conditions.

EXAMPLE 3

Example 2 was repeated but with the difference that iron in form of an iron powder, AHC100.29 available from Hoganas AB, Sweden, was mixed to a Ni- Cu-Mn-Si-B water atomized pre-alloyed powder, resulting in a powder having the same chemical composition as the fully pre-alloyed water atomized braze powder of Example 1. Sinter-brazing preforms were produced according to Example 1 and sinter-brazing test according to Example 2 was performed, i.e. the cylinder was sinter-brazed to the plate at 1130°C in an atmosphere of 90%N2/1 0°/OH2 for about 20 minutes, the furnace was not equipped with a RBO system.

Figure 5a shows the result for 6% admixed water atomized iron powder. A comparison with Figure 4b, discloses much worse sinter-brazing joints with insufficient filling, more residue and porosity, compared to fully pre-alloyed braze at content of 6%, fig 4b.

The tests with admixed iron powder were repeated but with 10% and 20% admixed iron powder, keeping the same relation between the other alloying elements as for 6% admixed iron powder.

Figure 5b and Figure 5c represents 10% and 20% iron respectively. The figures show even worse sinter-brazing joints with insufficient filling, more residue and porosity, compared to Figure 5a. Especially when the admixed iron amount is higher than 10%, the braze quality decreased a lot.

In summary, the new fully pre-alloyed powder for sinter-brazing and the new sinter-brazing material, provide consistent and even braze joints with controlled infiltration depth and reduced substrate erosion, and that the new sinter-brazing method is effective for mass production of various parts.

Claims

1. A pre-alloyed powder for sinter-brazing consisting of: 30-45 wt.% Ni;

10-20 wt.% Mn;

3-15 wt.% Fe;

1-3 wt.% Si;

1-3 wt.% B; balanced with Cu; inevitable impurities up to 1 wt.%.

2. A pre-alloyed powder for sinter-brazing consisting of: 30-45 wt.% Ni;

10-20 wt.% Mn;

3-12 wt.% Fe;

1-3 wt.% Si;

1-3 wt.% B; balanced with Cu; inevitable impurities up to 1 wt.%.

3. A pre-alloyed powder for sinter-brazing consisting of 30-45 wt.% Ni;

12-18 wt.% Mn;

3-10 wt.% Fe;

1-3 wt.% Si;

1 -3 wt.% B balanced with Cu; inevitable impurities up to 1 wt.%.

4. A pre-alloyed powder for sinter-brazing consisting of 35-45 wt.% Ni;

12-18 wt.% Mn;

3-9 wt.% Fe;

1-3 wt.% Si;

1 -3 wt.% B balanced with Cu; inevitable impurities up to 1 wt.%.

5. A pre-alloyed powder for sinter-brazing consisting of 36-41 wt.% Ni; 12-16 wt.% Mn;

4-8 wt.% Fe;

1-2 wt.% Si;

1 -2 wt.% B balanced with Cu; inevitable impurities up to 1 wt.%.

6. A pre-alloyed powder for sinter-brazing according to anyone of claims 1 - 4 having a particle size distribution such that: at least 95% by weight is below 425 pm; at most 10% by weight is below 45 pm, measured according to

IS04497:1983.

7. A pre-alloyed powder for sinter-brazing according to anyone of claims 1 -

5 wherein the powder is produced through water atomization.

8. A pre-alloyed powder for sinter-brazing according to anyone of claims 1 -

6 having a melting range of at most 150°C, preferably at most 120°C, more preferably at most 100°C.

9. A sinter-brazing material containing of up to 3% by weight of a flux material balanced with a pre-alloyed powder for sinter-brazing according to any of claims 1 to 7.

10. A sinter-brazing material according to claim 8 wherein the flux consists of at least 50% by weight of boric acid.

11. A sinter-brazing material containing of up to 1% by weight of a lubricant balanced with a pre-alloyed powder for sinter-brazing according to any of claims 1 to 7.

12. A sinter-brazing material according to claim 10 wherein the lubricant is chosen from the group of waxes, such as ethylene bis stearamide, fatty acid monoamides such as stearic acid amide, oleic acid amide, arachidic acid amide, erucic acid amide, behenic acid amide, palmitic acid amide, or mixtures thereof, amide oligomers, polyamides or mixtures thereof..

13. A sinter-brazing material according to any of claims 8 to 11 wherein the brazing material is in form of a tablet.

14. A sinter-brazing-method comprising the steps of: a) providing at least one compacted iron-based component and at least one iron-based component; b) applying a sinter-brazing material containing a pre-alloyed powder for sinter-brazing according to any of claims 1 to 7 to the at least one compacted component or the at least one iron- based component; c) combine the at least one compacted component with the at least one iron-based component to form structure; d) subjecting said structure to brazing procedure at a temperature between 1100°C and 1350°C for a period of time of 10 minutes to 1 hour in an atmosphere of dissociated ammonia, endogas, a mixture of nitrogen and hydrogen or in hydrogen; e) cooling the obtained brazed structure.

15. A method according to claim 13 wherein in step b) said sinter-brazing material is according to any of claims 8 to 12.

16. A sinter-brazed product produced according to claim 12 or 13.