阅读说明：本技术 用于制造由金属制成的开孔成型体的方法和使用该方法制造的成型体 (Method for producing open-porous molded bodies made of metal and molded body produced using said method ) 是由 T·布特内尔 G·沃尔特 汉斯-迪特里希·博姆 T·韦斯加伯尔 B·基巴克 克里斯蒂安·I 于 2018-09-14 设计创作，主要内容包括：本发明涉及一种用于制造由金属制成的开孔成型体的方法。所述成型体用作半成品部件,在由金属制成的开孔成型体的表面上,涂覆与也制成半成品的金属相同的金属的颗粒、或制成半成品的金属的化合物的颗粒,其中该化合物可以在热处理中还原或热分解或化学分解,并通过热处理产生相应金属的颗粒,所述颗粒通过化学还原或热分解或化学分解获得。在涂覆过程之后,进行热处理,在该热处理中,颗粒连接至半成品的表面和/或相邻颗粒,使得所获得的开孔成型体的比表面积增大到至少30m<Sup>2</Sup>/l,和/或与起始材料相比增大到至少5倍。在涂覆后的开孔成型体的热处理期间,保持合适的气氛。(The invention relates to a method for producing an open-porous molded body made of metal. The shaped body is used as a semi-finished part, on the surface of an open-porous shaped body made of metal, particles of the same metal as the metal from which the semi-finished part is also made, or particles of a compound of the metal from which the semi-finished part is made, wherein the compound can be reduced or thermally or chemically decomposed in a thermal treatment, and by the thermal treatment particles of the respective metal are produced, which are obtained by chemical reduction or thermal or chemical decomposition. After the coating process, a heat treatment is carried out in which the particles are connected to the surface of the semifinished product and/or to adjacent particles, so that the specific surface area of the open-porous shaped body obtained is increased to at least 30m 2 /l, and/or increased by at least a factor of 5 compared to the starting material. During the heat treatment of the coated open-porous shaped body, a suitable atmosphere is maintained.)

1. A method for manufacturing a metal-containing open-porous molded body, wherein particles of the same metal as that forming a semi-finished part are coated on the surface of the metal-containing open-porous molded body as the semi-finished part, or

Coating an open-porous shaped body comprising a metal as a semi-finished component with particles of a compound formed from the metal from which the semi-finished component is made, the compound being capable of being reduced or thermally decomposed or chemically decomposed in a heat treatment and forming particles of the corresponding metal obtained by chemical reduction or thermal decomposition or chemical decomposition;

and

after the coating, at least one heat treatment is carried out, in which the particles are bonded to the surface of the semifinished part and/or to adjacent particles by sintering necks or sintering bridges, so that

The specific surface area of the open-celled shaped body obtained is increased to at least 30m²And/or increased by a factor of at least 5 in comparison with the starting material of the uncoated semi-finished metal part, wherein,

maintaining a metal reducing atmosphere or an atmosphere suitable for decomposition in the heat treatment of the open-porous shaped body coated with particles of a reducible or thermally or chemically decomposable compound formed from the metal from which the semi-finished part is made, at least until reduction or thermal or chemical decomposition of the compound to form the metal is completed.

2. The method according to claim 1, wherein particles of a metal or of a compound of said metal are used as a powder, a powder mixture and/or a suspension/dispersion.

3. Method according to claim 1 or 2, characterized in that the application of the particles of the metal or of the compound of the metal as a powder, powder mixture, suspension and/or dispersion is effected by dipping, spraying, in a pressure-assisted manner, electrostatically and/or magnetically.

4. A method according to any one of claims 1 to 3, characterized in that an organic and/or inorganic binder is used in the form of a solution, suspension/dispersion or in the form of a powder to improve the adhesion of the particles.

5. The method according to any one of claims 1 to 4, characterized in that the application of the particles of the metal or of the specific compound of the metal is repeated a plurality of times, in particular at least three times.

6. The method according to any one of claims 1 to 5, characterized in that in the case of multiple coating with particles of the metal or of the compound of the metal, when using a binder, the application of the binder is repeated multiple times, in particular at least three times.

7. Method according to any one of claims 1 to 6, characterized in that the application of the binder and the application of the particles of the metal or of the compound of the metal are carried out using different amounts on different sides of the surface of the semi-finished part, in particular on surfaces facing each other, in order to obtain different porosities, pore sizes and/or specific surface areas.

8. Method according to any of the preceding claims, characterized in that Ni, Fe, Cr, Al, Nb, Ta, Ti, Mo, Co, B, Zr, Mn, Si, L a, W, Cu, Ag, Au, Pd, Pt, Zn, Sn, Bi, Ce or Mg are used as metal for the semi-finished part and particles to be applied, or

Compounds of Ni, Fe, Cr, Al, Nb, Ta, Ti, Mo, Co, B, Zr, Mn, Si, L a, W, Cu, Ag, Au, Pd, Pt, Zn, Sn, Bi, Ce or Mg, in particular salts, oxides, nitrides, hydrides, carbides, sulfides, sulfates, fluorides, chlorides, bromides, iodides, phosphates, azides, nitrates, amines, amides, metal-organic complexes or metal-organic complexes are used as particles of the metal and the reducible, thermally decomposable or chemically decomposable compounds of the metal for the semifinished part.

9. Method according to any one of the preceding claims, characterized in that a semi-finished component obtained by electrochemical coating of open-porous bodies of polymer material with a corresponding metal is used as semi-finished component.

10. Open-porous shaped body produced by the method according to any one of the preceding claims, characterized in that the shaped body with metal particles bonded by sintering necks or sintering bridges to the surface of the semi-finished component and/or to the surface of adjacent particles has at least 30m²Specific surface area/l.

11. Shaped body according to the preceding claim, characterized in that the pore size in the coated and sintered open-pored shaped body corresponds to at most 10000 times the particle size used.

12. Shaped body according to any of the two preceding claims, characterized in that no more than 3 mass%, preferably no more than 1 mass% of oxygen is present in the material of the shaped body.

Technical Field

The invention relates to a method for producing an open-porous molded body or a molded body comprising metal, and to a molded body produced by said method.

Background

In particular, it is known to coat the surface of a porous metal shaped body in order to improve its properties. For this purpose, use is generally made of a pulverulent material which is applied to the surface of the shaped body by means of a binder or suspension and in a heat treatment removes organic constituents and can then form a coating or surface region on the surface of the shaped body at elevated temperature, which coating or surface region has a different chemical composition than the material from which the shaped body is produced.

The specific surface area of the shaped bodies can also be increased by these known possibilities, but this can only be achieved to a limited extent by the known possibilities.

However, very large specific surface areas are advantageous for many industrial applications and are highly desirable in electrodes, for example in catalytic assisted processes, filtration or electrochemical applications.

Disclosure of Invention

It is therefore an object of the present invention to provide an open-porous shaped body which is composed of a metal material and has an increased specific surface area.

According to the invention, this object is achieved by a method having the features of claim 1. Claim 10 relates to a shaped body produced by the process. Advantageous embodiments and further developments can be achieved by means of the features indicated in the dependent claims.

In the present invention, an open-pore formed body composed of a metal material is used as a semi-finished member. These open-porous shaped bodies can be metal grids, metal meshes, metal fabrics, metal foams, metal wool or semi-finished parts comprising metal fibers.

However, the semifinished part can also be an open-pored shaped body such as: in the open-porous shaped body, the polymer material has been electrochemically coated with a metal. The semifinished parts produced in this way can be subjected to a heat treatment in which the organic and volatile constituents of the polymer are removed as a result of pyrolysis. However, this removal of the organic components of the polymer may also occur later in time with the removal of other organic or volatile components, as will be discussed in more detail below.

In one embodiment of the present invention, the open-porous molded body is coated with metal particles composed of the same metal material as that of which the open-porous semi-finished part is made, before or after the heat treatment. In this case, the particles should also be introduced into the interior of the shaped body, i.e. into the pores or interstices of the semifinished part.

In a further embodiment of the invention, the particles of the compound of the chemical element present in the open-porous shaped body as the semi-finished component are applied by coating before or after the heat treatment. The particles consist of the following compounds: the compounds can be converted in the heat treatment by chemical reduction or thermal decomposition or chemical decomposition into the corresponding chemical elements which make up the semifinished parts.

Metal particles of the same metal material as the metal material that has been made into the open-celled semifinished part, or particles of a compound of a chemical element that can be converted into a chemical element that has been made into the open-celled shaped body as the semifinished part, may be used as the powder, powder mixture, suspension or dispersion for the coating operation. The coating of the surface of the semifinished part with the powder, powder mixture and/or suspension/dispersion can be carried out by dipping, spraying, pressure-assisted, electrostatically and/or magnetically.

In a further alternative according to the invention, the powder, powder mixture, suspension or dispersion for coating the open-porous semifinished part may comprise not only metal particles or metal compound particles, but also inorganic and/or organic binders which are mixed into the powder, powder mixture, suspension or dispersion as solid powder in the form of fine particles or which are present in dissolved form in the liquid phase of a solution, suspension/dispersion of metal particles or metal compound particles.

The coating of the surface of the semi-finished part with the binder in the form of a solution or a suspension/dispersion can be achieved by dipping or spraying. The open-porous semifinished part which has been wetted with the binder is subsequently coated with a powder or a powder mixture of metal particles.

The distribution of the powder particles on the surface which has been wetted with the liquid binder and the adhesion of the particles to the surface can be improved by the action of mechanical energy, in particular vibration.

The application of the particles as powder, powder mixture and/or suspension/dispersion can be repeated a plurality of times, preferably at least three times, particularly preferably at least five times. This also applies in each case to the vibrations to be carried out and optionally to the application of the adhesive.

It is also possible to coat the surface of the semifinished part before the heat treatment in which the organic constituents of the polymer material by means of which the semifinished part has been manufactured are removed. After the application of the material containing the particles, a thermal treatment is carried out in which the organic and volatile constituents of the polymer material are removed and at the same time any binder used is removed.

After the heat treatment and the application of the particles, a sintering is carried out in which sintering necks or sintering bridges are formed between the metal particles or from the metal particles obtained by thermal or chemical decomposition (e.g. chemical reduction) to the metal surface of the open-porous metal shaped body.

Here, the specific surface area of the open-porous shaped body which has been coated and sintered in this way should be increased to at least 30m²The specific surface area is increased by a factor of at least 5 compared to the starting material of the uncoated metal shaped body as a semifinished part.

Here, depending on the application, has a value of 450 μPore size in the range of m to 6000 μm and 1m²/l-30m²The porous basic skeleton of the specific surface area/l should be filled with particles from one side (porosity gradient) or completely (particle size d)₅₀In the range of 0.1 μm to 250 μm) or the pillars of the porous metal shaped body should have been coated on the surface.

In order to obtain different porosities, pore sizes and/or specific surface areas in each case, the particle coating can be carried out with different amounts on different sides of the surface, in particular on surfaces of the semifinished part which are arranged opposite one another. This can be achieved, for example, by applying different amounts of particles (with or without the use of a binder) as a powder, a powder mixture or in the form of a suspension/dispersion on surfaces arranged on different sides. In this way, it is also possible to achieve a gradually changing form of the shaped bodies produced according to the invention.

The pore size in the applied particle layer of the coated and sintered open-porous shaped body should correspond to not more than 10000 times the particle size used. This may also be additionally influenced by the maximum sintering temperature and the holding time at this temperature, since with increasing temperature and holding time the mass transfer through diffusion and thus sintering, which is associated with a reduction in the pore volume, is promoted.

The material from which the shaped bodies produced according to the invention are made should contain not more than 3 mass%, preferably not more than 1 mass%, of O₂. For this purpose, an inert or reducing atmosphere is preferably provided while carrying out a heat treatment for removing organic constituents, sintering and/or optionally a chemical reduction to be carried out.

For thermal or chemical decomposition, a suitable atmosphere should be selected in the heat treatment used for this purpose. In the case of thermal decomposition, the atmosphere may be an inert atmosphere, such as an argon atmosphere. In the case of reduction, for example, a hydrogen atmosphere may be employed.

For chemical decomposition by oxidation, atmospheres containing oxygen, fluorine, chlorine, any mixture of these gases, and any mixture of inert gases such as nitrogen, argon, or krypton are particularly useful.

In the case of chemical decomposition, the metal cations may be reduced to form elemental metals. However, the anionic component may be oxidized. It is also contemplated to chemically decompose a compound of a relatively noble metal in air (i.e., in a relatively oxidizing atmosphere) to yield the elemental metal (Au, Pt, Pd). Disproportionation according to illustrative equation 2GeI < - > Ge(s) + GeI (g) may also be performed for aluminum, titanium, zirconium, and chromium. It is also possible to use crystals, metal-organic complexes or salts thereof in which the metal center is already in the oxidation state 0.

The method can also comprise the following steps: (i) the use of such open-porous shaped bodies produced according to the invention in the filtration field, (ii) the use of such open-porous shaped bodies produced according to the invention as catalysts (for example in the synthesis of ethylene oxide using Ag foam catalysts coated with Ag particles), (iii) the use of such open-porous shaped bodies produced according to the invention as electrode materials, or (iv) the use of such open-porous shaped bodies produced according to the invention as supports for catalytically active substances.

In the case of application (i), increasing the specific surface area leads to better filtration performance, since the adsorption tendency and the absorption capacity increase significantly.

In application (ii), the increase in specific surface area leads to a greater proportion of the catalytic activity, since not only the number of active centers increases, but the surface also has a distinctly faceted structure. The resulting increased surface energy also leads to a significant increase in catalytic activity compared to the non-faceted surface of the starting open-celled shaped body.

In the case of application (iii), the increase in the specific surface area likewise leads to an increase in the active centers, which, in combination with the faceted structure of the surface, leads to a significant reduction in the electrical overvoltage compared with commercial electrodes (e.g. nickel or carbon). As a specific application, electrolysis may also be mentioned, for example using Ni or Mo foam coated with Ni or Mo particles. In particular, in this application, sintered metal open-porous shaped bodies coated on one side with metal particles can also be used advantageously, since in this case the gradual change in the pore size ensures good transport away of the gas bubbles.

In the case of application (iv), the increase in specific surface area leads to better adhesion of the active ingredient (e.g. catalytic coating) to the support surface, which significantly improves the mechanical, thermal and chemical stability of the catalytic material.

Suitable metals for the shaped bodies produced according to the invention are Ni, Fe, Cr, Al, Nb, Ta, Ti, Mo, Co, B, Zr, Mn, Si, L a, W, Cu, Ag, Au, Pd, Pt, Zn, Sn, Bi, Ce or Mg. so that particles of these elements (corresponding to the individual chemical elements making up the semifinished part) can be used in the process according to the invention for coating the semifinished part.

As compounds of the metals Ni, Fe, Cr, Al, Nb, Ta, Ti, Mo, Co, B, Zr, Mn, Si, L a, W, Cu, Ag, Au, Pd, Pt, Zn, Sn, Bi, Ce, Mg, V, which can be converted into particles of the corresponding metal by thermal or chemical decomposition in a thermal treatment, in particular the oxides, nitrides, hydrides, carbides, sulfides, sulfates, phosphates, fluorides, chlorides, bromides, iodides, azides, nitrates, amines, amides, metal-organic complexes, salts of metal-organic complexes or decomposable salts thereof can be used for the material formed from the particles, the surface of the open-porous shaped body present as semifinished part being coated with these materials in a second alternative according to the invention.

During thermal or chemical decomposition of the compound to produce the corresponding metal, an atmosphere suitable for decomposition (which may be inert, oxidative or reductive) is maintained until thermal or chemical decomposition of the compound to the metal has occurred. In order to chemically reduce the compound to the corresponding metal, preferably, the heat treatment causing the chemical reduction may be carried out in a reducing atmosphere, in particular in a hydrogen atmosphere, for at least a period of time until the chemical reduction has been carried out.

The porosity, pore size and specific surface area may be substantially influenced by the morphology of the particles used for the coating. In order to achieve a high specific surface area and a fine pore structure, particles (e.g., electrolyte powder) having a small size and a dendritic shape are advantageous. Due to their irregular geometry, which does not allow a gapless arrangement, adjacent particles form voids that partially connect to form channels between the contact points and the particle bodies. Furthermore, when particles of the compounds are used, additional micropore space left by volatile components is formed in thermal or chemical decomposition. The greater the proportion of volatile constituents of the compound, the higher the proportion of micropore space in the total pore volume. For coatings with metal oxide particles, it is therefore advantageous to use oxides having a high oxidation state and therefore a high proportion of oxygen. Since the sintering activity of the structure increases with increasing specific surface area, the sintering temperature in relation to the material is chosen to be just high enough to sinter the particles to each other and to the semifinished part in a mechanically stable manner without significantly densifying the pores.

Detailed Description

The invention will be illustrated below by means of an example.

Working example 1

An open-porous shaped body made of silver, having an average pore diameter of 450 μm, a porosity of about 95%, and a size of 70mm × 63mm, and a thickness of 1.6mm, which is produced by electrolytic deposition of Ag on a polyurethane foam, as a semi-finished component is subjected to a heat treatment at a temperature of at least 400 ℃ in order to remove organic constituents, in particular of the polyurethane.

In order to increase the specific surface area, a total amount of 2g of metal powder is used, i.e. having a particle diameter d in the range of 3 μm to 9 μm₅₀The Ag metal powder of (1).

The coating of the surface of the metal open-porous shaped body as a semifinished part was carried out using 0.6g of a stearamide wax having a particle size of <80 μm and 6ml of a 1% strength aqueous solution of polyvinylpyrrolidone in volume as binder. The surface of the semi-finished part (including the inside of the pores) was sprayed with the binder solution before applying the silver powder to the surface coated with the binder.

The silver powder and stearamide wax were mixed for 10 minutes using a Turbula mixer.

After this application of the adhesive, the coated open-porous shaped body was fixed in a vibrating device and silver powder was scattered on both sides. By vibration, the powder is uniformly distributed in the open-cell network. The particles only adhere to the pillar surface so that the pillar is completely covered by the powder particles and the open porosity of the foam is retained. This process was repeated four times.

Subsequently, a further heat treatment is carried out in a hydrogen atmosphere to effect removal of the binder and sintering. For this purpose, the furnace is heated at a heating rate of 5K/min. The removal of the binder started at about 300 ℃ and ended at 600 ℃ with a holding time of about 30 minutes. The sintering process is carried out at a temperature ranging from 550 ℃ to 850 ℃ for a holding time ranging from 1 minute to 60 minutes.

During this further heat treatment, Ag diffuses out of the powder particles into the pillar material until the powder particles are firmly bonded to the pillars of the surface of the semi-finished component by the sintered necks or bridges formed thereby.

After this further heat treatment, the open-porous shaped body consists of 100% silver. The porosity was about 94%.

The surface of the pillar has high roughness. The reason for this is that the applied powder particles only bridge the metal supporting foam bonded to the semi-finished part through the sintering neck or sintering, so that the original particle morphology is retained. The internal specific surface area (measured by the BET method) of the finished open-cell shaped body can be from the initial 10.8m²Increase to the subsequent 99.3m²L (state after coating).

Working example 2

As in working example 1, an open-cell shaped body having an average pore diameter of 450 μm, a porosity of 95%, a size of 70mm × 63mm, and a thickness of 1.6mm, which was obtained by electrochemical coating of a porous foam composed of polyurethane, was subjected to a heat treatment to remove organic components, the open-cell shaped body being made of silver, as a semi-finished member.

Subsequently, the surface of the semifinished part from which the organic constituents have been removed is coated by spraying a suspension having the following composition:

-48% of<5 μm of Ag₂O a metal oxide powder, and a metal oxide powder,

-1.5% of a polyvinylpyrrolidone (PVP) binder,

49.5% of water as solvent,

-1% of a dispersant.

For this purpose, the pulverulent binder was first dissolved in water, then all the other ingredients were added and mixed in a Speedmixer at 2000rpm for 2 × 30 seconds to give a suspension.

The prepared powder suspension is sprayed on both sides of the semifinished part several times by a wet powder spraying process. Here, the suspension is atomized in a spraying device and applied to the surfaces on both sides of the semifinished part. The suspension is distributed evenly in the porous network of the semifinished part by the outlet pressure from the nozzle. The suspension adheres only to the surface of the pillars, so that the pillars are completely covered with the suspension and the open porosity of the semifinished part is largely retained. Subsequently, the semifinished parts coated in this way are dried in air at room temperature.

For binder removal, reduction and sintering, heat treatment is carried out under a hydrogen atmosphere and subsequently in a furnace. For this purpose, the furnace is heated at a heating rate of 5K/min. The reduction of silver oxide started below 100 ℃ and ended at 200 ℃ with a holding time of about 30 minutes under hydrogen. The remaining binder removal and sintering process may then be performed in an oxygen-containing atmosphere (e.g., air) at a temperature range of 200 ℃ to 800 ℃ for a time period of 1 minute to 180 minutes.

During this further heat treatment, the silver oxide is first reduced to metallic silver, which is present in the form of nanocrystals. As the residual binder is removed and the metallic silver particles are then partially sintered onto the silver foam struts, the particles grow to form larger, coarser crystal agglomerates, and secondly Ag also diffuses out of the powder particles and into the strut material until the powder particles are firmly bonded to the struts of the surface of the open-celled shaped body by the formed sintered necks or bridges.

After this further heat treatment, there is a homogeneous open-porous shaped body formed from 100% silver.

The porosity was about 93%.

The surface of the pillar has high roughness. The reason for this is that the applied powder particles are only bonded to the surface of the semi-finished component by the sintering neck/sintering bridge, so that the original particle morphology is retained. By carrying out this process, the internal specific surface area (measured by the BET method) of the open-celled shaped body of the finished product can be from the first 10.8m²Increase to the following 82.5 m/l (uncoated state)²L (state after coating).

Working example 3

An open-porous shaped body consisting of copper (produced by electrolytic deposition of Cu on a polyurethane foam) with an average pore diameter of 800 μm, a porosity of about 95%, a size of 200mm × 80mm, and a thickness of 1.6mm was used as a semi-finished part.

FF L type electrolytic copper powder having a dendrite shape, the FF L type electrolytic copper powder having an average particle size < 63 μm and a mass of 20g was used as a powder for coating the surface of a semi-finished part.

A1% strength aqueous polyvinylpyrrolidone solution of 20ml volume was used as binder.

The binder solution is sprayed on both sides of the semifinished part consisting of copper. The semi-finished part coated with adhesive is then fixed in a vibrating device and copper powder is sprinkled on both sides. By means of vibration, the powder is distributed in the porous network of the semi-finished component. The application of the binder and powder was repeated three times so that the pore space was completely filled.

The removal and sintering of the binder are performed in a heat treatment under a hydrogen atmosphere. For this purpose, the furnace is heated at a heating rate of 5K/min. The removal of the binder started at about 300 c and ended at 600 c with a holding time of about 30 minutes. Heating was then continued to a sintering temperature of 950 ℃ and held at this temperature for 30 minutes.

During this heat treatment, the powder particles consisting of copper sinter to each other and to the pillar material until the powder particles are openThe over-formed sintered necks or bridges are firmly bonded to the surface of the semi-finished component, maintaining a high porosity and achieving an increase in the specific surface area. The open-porous shaped body treated in this way had a porosity of 54% and a specific surface area of 67m²/l。

Working example 4

Open-porous shaped bodies made of cobalt (made by electrolytic deposition of Co on polyurethane foam) with an average pore diameter of 580 μm, a porosity of about 95%, a size of 70mm × 65mm, and a thickness of 1.9mm were used as semi-finished parts, Co metal powder with an average particle diameter of <45 μm and a mass of 10g, and stearamide wax with a particle size of <80 μm and a mass of 0.1g were used as powders, and a volume of 6ml of a 1% strength aqueous solution of polyvinylpyrrolidone was used as binder.

Cobalt powder and stearamide wax were mixed for 10 minutes using a Turbula mixer.

The binder solution was sprayed on one side of the semifinished part consisting of cobalt. The semi-finished part is then fixed in a vibrating device and cobalt powder is sprinkled on both sides. As a result of the vibration, the powder is distributed uniformly in the porous network of the semi-finished component. The particles only adhere to the pillar surface so that the pillars are completely covered by the powder particles and the open porosity of the foam is initially retained. In a second step, the adhesive solution is sprayed onto the surface of the first side of the semi-finished part, so that the previously opened holes are closed on one side by the adhesive and the hole spaces close to this surface are completely filled by the subsequent further application of powder. On the opposite side of the semi-finished part, only the struts are coated on the surface. Thus, the powder loading is gradually varying from the first side to the opposite side of the semi-finished part, and thus the porosity in the foam is gradually varying from the first side to the opposite side of the semi-finished part.

To remove the binder and sinter, a heat treatment is performed in a hydrogen atmosphere. For this purpose, the furnace is heated at a heating rate of 5K/min. The removal of the binder started at about 300 ℃ and ended at 600 ℃ with a holding time of about 30 minutes. Then heated to a sintering temperature of 1300 c and held at this temperature for 30 minutes.

During this heat treatment, Co diffuses out of the powder particles and into the pillar material of the semi-finished component until the powder particles are firmly bonded to the pillars and (in the fully filled areas) to each other by the formed sintering necks or bridges.

The Co content of the open-cell shaped article was 100%. The porosity is gradually varied over the total thickness of the shaped body from the first side to the side opposite the first side, being about 54% on one side and about 93% on the other side of the foam. The specific surface area of the open-cell shaped article was 69m²/l。

Working example 5 (expanded Ni Metal mesh + Ni powder → Uniform coating + sintering)

1. Material

An expanded open-pored nickel metal mesh (made by drawing slotted Ni sheets initially 0.25mm thick) with a cell size of about 0.7mm × 2mm and a size of 75mm × 75mm, a thickness of about 1mm was used as a semi-finished part, Ni metal powder with an average particle size of <10 μm and a mass of 8g, stearamide wax with an average particle size of <80 μm and a mass of 0.2g was used as the metal powder, and 4ml volume of 1% strength aqueous polyvinylpyrrolidone solution was used as the binder.

The powder and stearamide wax were mixed for 10 minutes using a Turbula mixer.

An extended nickel metal mesh was sprayed from opposite sides using a binder solution. The nickel wire mesh was then fixed in a vibrating device and nickel powder was scattered on both sides. The nickel powder is uniformly distributed on the nickel mesh due to vibration. The particles only adhere to the surface of the mesh struts so that the mesh struts are completely covered by the powder particles and the open porosity of the expanded metal mesh is retained. This process was repeated five times.

The removal and sintering of the binder are performed in a heat treatment under a hydrogen atmosphere. For this purpose, the furnace is heated at a heating rate of 5K/min. The removal of the binder started at about 300 ℃ and ended at 600 ℃ with a holding time of about 30 minutes. Heating was then continued up to a sintering temperature of 1280 ℃ and held at this temperature for 30 minutes.

During the heat treatment, Ni diffuses out of the powder particles and into the mesh strut material until the powder particles are firmly bonded to the mesh struts by the formed sintered necks or bridges.

The open-porous shaped bodies obtained in this way consist of 100% nickel.

The surface of the struts has a high roughness, since the applied powder particles are bonded to the support network of the semifinished part and to one another only by sintering necks or bridges, so that the original particle morphology is largely retained. The high porosity nickel layer applied on the pillars has a thickness of 1 μm to 300 μm. The porosity in the applied layer was 40%.