KR20200127966A - Method for manufacturing an open pore molded article made of metal and a molded article manufactured using the method - Google Patents

Abstract

The present invention relates to a method of manufacturing an open pore molded article made of metal. The surface of the open-pore molded body, made of metal and used as a semi-finished product, is coated with particles of the same metal from which the semi-finished product is produced or particles of a chemical compound of the metal from which the semi-finished product is produced. The compound can be reduced in heat treatment or thermally or chemically decomposed, each particle of metal is prepared by heat treatment, and the particles are obtained by chemical reduction or thermal or chemical decomposition. After the coating process, heat treatment is performed so that the particles are connected to the surface of the semi-finished product and/or adjacent particles, so that the specific surface area of the obtained open pore compact is increased by at least 30 m²/l and/or by at least 5 times compared to the starting material. Performed. During the heat treatment of the coated open pore green body, a suitable atmosphere is maintained.

Description

Method for manufacturing an open pore molded article made of metal and a molded article manufactured using the method

The present invention relates to a method for manufacturing an open pore molded article or a molded article containing a metal, and to a molded article manufactured by the method.

In particular, it is known to coat the surface with a porous metal compact in order to improve its properties. To this end, a pulverulent material is usually used on the surface of the molded body using a binder or suspension, the organic component is removed from the heat treatment, and the coating or surface area having a chemical composition different from the material from which the molded body is manufactured is then It can be formed at high temperatures on the surface.

The specific surface area of the shaped body can also be increased by this known possibility, but this was only possible to a limited extent by the known possibilities.

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

Accordingly, it is an object of the present invention to provide an open pore formed body composed of a metallic material and having an increased specific surface area.

This object is achieved according to the invention by a method having the features of claim 1. Claim 10 relates to a molded article produced by the method. Advantageous embodiments and further developments can be realized by the features indicated in the dependent claims.

In the present invention, an open pore body made of a metallic material is used as a semifinished part. They may be semi-finished products comprising metal grids, metal meshes, woven metal fabrics, metal foams, metal wool or metal fibers.

However, the semi-finished product may also be an open pore molded body in which a polymeric material is electrochemically coated with a metal. Semi-finished products made in this way can be subjected to heat treatment in which organic and volatile components of this polymer are removed as a result of pyrolysis. However, this removal of the organic component of the polymer can also occur later in the simultaneous removal of other organic or volatile components, which will be discussed in more detail below.

In one embodiment of the present invention, this heat treatment is performed prior to or subsequent to coating the open pore body with metal particles composed of the same metal material from which the open pore semi-finished product was produced. Here, the particles must also be introduced into the interior of the shaped body, ie into the pores or voids of the semi-finished product.

In a further embodiment of the invention, particles of chemical compounds of chemical elements present in the open pore molded body as semi-finished products are applied by coating before or after such heat treatment. The particles are composed of chemical compounds that can be converted into respective chemical elements from which a semi-finished product is made in heat treatment by chemical reduction or thermal or chemical decomposition.

Metal particles of the same metal material from which the open pore semi-finished product is made, or particles of chemical compounds of chemical elements that can be converted into the chemical elements from which the open pore molded article is made as semi-finished products are used as powders, powder mixtures, suspensions or dispersants for coating operations I can. Coating the surface of the semi-finished product with powders, powder mixtures and/or suspensions/dispersants can be carried out by dipping, spraying, pressure assisted methods, electrostatic and/or magnetism.

In another alternative according to the invention, the powder, powder mixture, suspension or dispersant used to coat the open pore semi-finished product is fine as a solid powder into a powder, powder mixture, suspension or dispersant, as well as particles of metal particles or chemical compounds of metals. It may contain mixed inorganic and/or organic binders in a divided form, or it is dissolved in a liquid phase of a solution, a suspension/dispersant of metal particles, or a particle of a chemical compound of a metal.

Coating the surface of the semi-finished product with a binder in the form of a solution or suspension/dispersant can be carried out by dipping or spraying. The open pore semi-finished product moistened with a binder is then coated with a powder or a powder mixture of metal particles.

The distribution of the powder particles on the surface moistened 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 powders, powder mixtures and/or suspensions/dispersants can be repeated several times, preferably at least 3 times, particularly preferably at least 5 times. This also applies to the vibration carried out in each case and, optionally, to the application of the binder.

The coating of the surface of the semi-finished product can also be carried out prior to heat treatment in which the organic components of the polymeric material from which the semi-finished product is made are removed. After application of the particle-containing material, a heat treatment is performed in which the organic and volatile components of the polymeric material and any binder used are simultaneously removed.

After heat treatment and application of the particles, a sinter neck or sinter bridge is formed between the metal particles or from the metal particles obtained by thermal or chemical decomposition, i.e. by chemical reduction, to the metal surface of the open pore metal compact. The sintering to be formed is carried out.

Here, the specific surface area of the open pore compact coated and sintered in this way should be increased to at least 30 m²/l, but by at least 5 times compared to the starting material of the uncoated metal compact as a semi-finished product.

Here, the porous basic skeleton with a pore size of 450 μm to 6000 μm and a specific surface area of 1 m²/l to 30 m²/l is from one side (porosity gradient) or completely particles (particle size in the range of 0.1 μm to 250 μm) d ₅₀ ), or a strut of a porous metal molded body must be coated on the surface.

The coating of the particles can be carried out using different amounts on different sides of the surface, in particular on the surface of the semi-finished products arranged opposite to each other, in order to obtain in each case different porosity, pore size and/or specific surface area. This can be achieved, for example, by application of different numbers of particles as powders, powder mixtures or suspensions/dispersants with or without a binder on surfaces arranged on different sides. The graded formation of a shaped body made according to the invention can also be achieved in this way.

The pore size in the applied particle layer of the coated and sintered open pore green body should correspond to not more than 10,000 times the particle size used. Since mass transfer by sintering associated with diffusion and reduction in void volume is promoted with an increase in temperature and holding time, this can be additionally affected by the maximum sintering temperature and the holding time at this temperature.

The material from which the molded article produced according to the invention is produced should contain not more than 3 mass %, preferably not more than 1 mass% O ₂ . For this purpose, an inert or reducing atmosphere is preferred during heat treatment to remove organic components, chemical reduction and/or sintering, which are optionally performed.

For thermal or chemical decomposition, an appropriate atmosphere must be selected in the heat treatment used for this purpose. This can be an inert atmosphere in the case of thermal decomposition, for example an argon atmosphere. In the case of reduction, it is possible, for example, to use a hydrogen atmosphere.

In the case of chemical decomposition by oxidation, atmospheres containing oxygen, fluorine, chlorine, mixtures of these gases and mixtures with inert gases, for example nitrogen, argon or krypton, are particularly useful.

In the case of chemical decomposition, metal cations can be reduced to form elemental metals. However, it is possible to oxidize the anionic component. Chemical decomposition of compounds of relatively noble metals may also be considered in order to provide elemental metals (Au, Pt, Pd) in air, ie in a relatively oxidizing atmosphere. The imbalance according to the exemplary equation (2 GeI <-> Ge (s) + GeI (g)) is also possible for aluminum, titanium, zirconium and chromium. It is also possible to use crystalline metal organic complexes or salts thereof in which the metal center is already in the oxidation state 0.

(i) in the field of filtration (ii) as a catalyst (e.g. in the synthesis of ethylene oxide using an Ag foam catalyst coated with Ag particles), (iii) an electrode material or (iv) as a support for a catalytically active material, It is also possible to use such open pore shaped bodies produced according to the invention.

Increasing the specific surface area, in the case of application (i), significantly increases the adsorption tendency and absorption capacity, resulting in better filtration performance.

In application (ii), the increase in specific surface area is greater than a proportional increase in catalytic activity, since not only the number of active centers increases, but the surface also has a distinct faceted structure. The resulting increased surface energy significantly increases the catalytic activity compared to the unfaceted surface of the open pore starting shaped body.

In application (iii), an increase in the specific surface area likewise leads to an increase in the active center, which is combined with the cotton structure of the surface to significantly reduce the electrical overvoltage compared to commercial electrodes (eg nickel or carbon). As a specific application, mention may be made of electrolysis using, for example, Ni or Mo foams coated with Ni particles or Mo particles. In the present application, in particular, it may be advantageous to use a sintered metal open-pore molded body coated with metal particles on one side, because in this case, a gradation of the pore size ensures that gas bubbles move well.

For application (iv), the increase in specific surface area leads to good adhesion of the active ingredient, for example to the supporting surface of the catalytic wash coat, which greatly increases the mechanical, thermal and chemical stability of the catalytic material.

Metals suitable for the molded body manufactured according to the present invention are Ni, Fe, Cr, Al, Nb, Ta, Ti, Mo, Co, B, Zr, Mn, Si, La, W, Cu, Ag, Au, Pd, Pt , Zn, Sn, Bi, Ce or Mg. The particles of these elements, corresponding to each chemical element from which the semi-finished product is made, can thus be used in the method of the present invention for coating semi-finished products.

Metals that can be converted into individual metal particles by thermal or chemical decomposition in heat treatment Ni, Fe, Cr, Al, Nb, Ta, Ti, Mo, Co, B, Zr, Mn, Si, La, W, Cu, Chemical compounds of Ag, Au, Pd, Pt, Zn, Sn, Bi, Ce, Mg, V, especially their oxides, nitrides, hydrides, carbides, sulfides, sulfates, phosphates, fluorides, chlorides, bromide, iodine Cargoes, azides, nitrates, amines, amides, metal-organic complexes, salts of metal-organic complexes or decomposable salts for substances formed from particles, wherein the surface of the open pore molded body present as a semi-finished product is a second according to the present invention. Should be coated in the alternative. Particularly suitable chemical compounds are those of Ni, Fe, Ti, Mo, Co, Mn, W, Cu, Ag, Au, Pd or Pt.

In thermal or chemical decomposition of a chemical compound to provide each metal, an atmosphere suitable for decomposition that can be inert, oxidized or reduced is maintained until thermal or chemical decomposition of the chemical compound to the metal occurs. In order to chemically reduce the chemical compound to the respective metal, the heat treatment leading to the chemical reduction may preferably be carried out in a reducing atmosphere, in particular a hydrogen atmosphere, for at least some time until the chemical reduction is performed.

Porosity, pore size and specific surface area can be substantially influenced by the shape of the particles used in the coating. In order to achieve a high specific surface area and microporous structure, particles having a small size and dendritic shape, for example electrolyte powder, are advantageous. As a result of the irregular geometry that does not allow for a gapless arrangement, adjacent particles form partially connected voids to provide a channel between the contact point and the particle body. In addition, additional microporous spaces left by the volatile components are formed in thermal or chemical decomposition when using particles of chemical compounds. The larger the proportion of volatile components in the chemical compound, the higher the proportion of microporous spaces in the total pore volume. Thus, the use of oxides having a high oxidation state and consequently a high proportion of oxygen is advantageous for coating with metal oxide particles. As the sintering activity of the structure increases with increasing specific surface area, the material-dependent sintering temperature is chosen so that the particles are sufficiently high to sinter to each other and to the semi-finished product in a mechanically stable manner without significantly densifying the micropores.

The invention will be described below with the aid of examples.

<Example 1>

As a semi-finished product, an open pore molded body composed of silver with a porosity of about 95% and a dimension of 70 mm x 63 mm, a thickness of 1.6 mm (produced by electrolytic deposition of Ag on a polyurethane foam) and an average pore size of 450 μm, has an organic component, In particular, it is heat treated at a temperature of at least 400 °C to remove the organic components of the polyurethane.

In order to increase the specific surface area, a metal powder having a particle size d ₅₀ in the range of 3 μm to 9 μm, that is, Ag metal powder is used in a total amount of 2 g.

The coating of the surface of the metal open pore molded article as a semi-finished product was coated using 0.6 g of stearamide wax having a particle size of less than 80 µm and a 1% strength aqueous solution of polyvinylpyrrolidone having a volume of 6 ml as a binder. .

The surface of the semi-finished product is sprayed with a binder solution contained inside the pores before the silver powder is applied to the surface coated with the binder.

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

After coating with a binder, the open pore-coated molded body was fixed to a vibration device and silver powder was sprinkled on both sides. The powder is evenly distributed in the open pore network by vibration. Since the particles adhere only to the strut surface, the strut is completely covered with powder particles and the open porosity of the foam is maintained. The procedure is repeated four times.

Then, in order to perform binder removal and sintering, an additional heat treatment is performed in a hydrogen atmosphere. To this end, the furnace is heated at a heating rate of 5 K/min. Binder removal begins at about 300° C. and ends with a hold time of 600° C. and about 30 minutes. The sintering process is carried out in a temperature range of 550° C. to 850° C. with a holding time of 1 minute to 60 minutes.

During further heat treatment, Ag diffuses from the powder particles into the strut material until the powder particles are firmly bonded to the struts of the semi-finished surface through the sintered neck or sintered bridge.

After further heat treatment, the open pore green body consisted of 100% silver. The porosity was about 94%.

The surface of the strut has high roughness. The reason is that the applied powder particles are bonded to the metal support foam of the semi-finished product only through the sintered neck or sintered bridge, so that the original particle shape is maintained. The internal specific surface area (measured using the BET method) of the finished open pore molded body can be increased from 10.8 m²/l initially (uncoated state) to 99.3 m²/l later (coated state).

<Example 2>

As a semi-finished product, an open pore molded article composed of silver, having an average pore size of 450 μm, a porosity of 95%, a dimension of 70 mm x 63 mm, a thickness of 1.6 mm, obtained by electrochemical coating of a porous foam made of polyurethane, is an Example As in 1, heat treatment is performed to remove organic components.

The surface of the semi-finished product without organic components was subsequently coated by spraying with a suspension having the following composition:

-48% Ag ₂ O metal oxide powder <5 μm,

-1.5% polyvinylpyrrolidone (PVP) binder

-As a solvent, 49.5% water

-1% dispersant.

To this end, a pulverulent binder was first dissolved in water, then all other ingredients were added and mixed in a speed mixer at 2000 rpm for 2 x 30 seconds to form a suspension.

The prepared powder suspension was sprayed several times on both sides by a wet powder spraying process on the semi-finished product. Here, the suspension is sprayed in a spraying device and applied to both surfaces of the semi-finished product. By the outlet pressure from the spray nozzle, the suspension is evenly distributed over the porous network of semi-finished products. Since the suspension adheres only to the strut surface, the strut is completely covered with the suspension and the open porosity of the semi-finished product is kept large. The semi-finished product coated in this way was then dried in air at room temperature.

For binder removal, reduction and sintering, heat treatment was carried out under a hydrogen atmosphere and then in a furnace. For this purpose, the furnace was heated at a heating rate of 5 K/min. The reduction of silver oxide started at less than 100° C. and completed at 200° C. and holding time of about 30 minutes under hydrogen. Thereafter, the residual binder removal and sintering process may be performed in an oxygen-containing atmosphere, for example, in air in a temperature range of 200°C to 800°C at a waiting time of 1 minute to 180 minutes.

During further heat treatment, silver oxide was first reduced to metallic silver, which is present in nanocrystalline form. As a result of removal of residual binder and partial sintering of metallic silver particles onto silver foam struts, the particles grow to form larger and coarser crystalline aggregates, and secondly, Ag also allows powder particles to form struts on the surface of the open pore compact. It diffuses from the powder particles into the strut material until it is firmly bonded through the sintered neck or sintered bridge that is formed in the.

After further heat treatment, there is a homogeneous open pore shaped body formed by 100% silver. The porosity is about 93%. The surface of the strut has a high roughness. The reason is that the applied powder particles are bonded to the surface of the semi-finished product only through the sintered wood/sintered bridge, so that the original particle shape is maintained. The internal specific surface area (measured by the BET method) of the finished open-pore molded body could be increased from the initial (uncoated state) 10.8 m²/l to the later (coated state) 82.5 m²/l by the process performed. .

<Example 3>

Open pore molded body composed of copper and having an average pore size of 800 μm, a porosity of about 95%, a dimension of 200 mm x 80 mm and a thickness of 1.6 mm (generated by electrolytic deposition of Cu on PU foam) Is used as a semi-finished product.

As the powder for coating the surface of the semi-finished product, an electrolytic copper powder of the FFL type having a dendritic form, an average particle size of less than 63 μm and a mass of 20 g was used.

A 1% strength aqueous solution of polyvinylpyrrolidone having a volume of 20 ml was used as a binder.

The semi-finished product composed of copper was sprayed with a binder solution on both sides. The binder-coated semi-finished product was then fixed in a vibrating device and sprinkled on both sides with copper powder. The powder is distributed in the porous network of the semi-finished product by vibration. The binder and powder coating were repeated 3 times so that the pore space was completely filled.

Binder removal and sintering were performed in a heat treatment under a hydrogen atmosphere. To this end, the furnace was heated at a heating rate of 5 K/min. Binder removal starts at about 300[deg.] C. and completes at 600[deg.] C. and a hold time of about 30 minutes. Then, heating was continued until the sintering temperature of 950° C. and this temperature was maintained for 30 minutes.

During heat treatment, the powder particles composed of copper are sintered to each other and to the strut material until the powder particles are firmly bonded through a sinter neck or sinter bridge formed on the surface of the semi-finished product, and the high porosity Is maintained and an increase in specific surface area is achieved. The open pore compact treated in this way has a porosity of 54% and a specific surface area of 67 m²/l.

<Example 4>

An open pore molded body consisting of cobalt, having an average pore size of 580 μm, a porosity of about 95%, a dimension of 70 mm x 65 mm and a thickness of 1.9 mm (generated by electrolytic deposition of Co on PU foam) Co metal powder having an average particle size of less than 45 μm and a mass of 10 g and also a stearamide wax having a particle size of less than 80 μm and a mass of 0.1 g was used as a semi-finished product, and poly A 1% strength aqueous solution of vinylpyrrolidone was used as the binder.

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

The semi-finished product composed of cobalt was sprayed with a binder solution on one side. Then, it was fixed to the vibrating device and sprinkled on both sides with cobalt powder. As a result of the vibration, the powder is evenly distributed in the porous network of the semi-finished product. Since the particles adhere only to the strut surface, the strut is completely covered with powder particles and the open porosity of the foam is initially maintained. In a second step, the surface of the semi-finished product is sprayed with a binder solution on the first side, so that the previously open pores are closed on one side by the binder, and the pore space close to the surface is completely filled by the subsequent application of additional powder. On the opposite side of the semi-finished product, only struts are coated on the surface. As a result, the powder loading and thus the porosity of the foam gradients from the first side of the semi-finished product to the opposite side.

To remove the binder and sinter, heat treatment was performed in a hydrogen atmosphere. For this purpose, the furnace was heated at a heating rate of 5 K/min. Binder removal starts at about 300[deg.] C. and completes at 600[deg.] C. and a hold time of about 30 minutes. It was then heated to a sintering temperature of 1300° C. and held this temperature for 30 minutes.

During heat treatment, Co diffuses from the powder particles into the semi-finished strut material until the powder particles are tightly bonded through the struts and sintered necks or sintered bridges that form each other (in the fully filled area). The Co content of the finished open pore molded body was 100%. The porosity is gradated from the first side to the side opposite the first side over the total thickness of the molded body and is about 54% on one side and about 93% on the other foam side. The specific surface area of the finished open pore compact is 69 m²/l.

<Example 5> (Ni expanded metal mesh + Ni powder → uniform coating + sintering)

1. Material

An open pore nickel expanded metal mesh having a cell size of about 0.7 mm x 2 mm, dimensions of 75 mm x 75 mm, and a thickness of about 1 mm (originally created by stretching a 0.25 mm thick slotted Ni sheet) was used as a semi-finished product. Ni metal powder with a particle size of less than 10 μm and a mass of 8 g, stearamide wax with an average particle size of less than 80 μm and a mass of 0.2 g was used as the metal powder, and a volume of 4 ml polyvinylpyrrolidone An aqueous solution of 1% strength was used as a binder.

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

The nickel expanded metal mesh was sprayed with a binder solution from two opposite sides. The mesh was then fixed to the vibrating device and nickel powder was sprinkled on both sides. As a result of the vibration, the nickel powder is evenly distributed on the mesh. Since the particles adhere only to the surface of the mesh strut, the mesh strut is completely covered with the powder particles and the open porosity of the expanded metal mesh is maintained. The procedure was repeated 5 times.

Binder removal and sintering were performed in a heat treatment under a hydrogen atmosphere. For this purpose, the furnace was heated at a heating rate of 5 K/min. Binder removal starts at about 300[deg.] C. and completes at 600[deg.] C. and a hold time of about 30 minutes. Then, heating was continued until the sintering temperature of 1280° C. was maintained and this temperature was maintained for 30 minutes.

During heat treatment, Ni diffuses from the powder particles into the mesh strut material until the powder particles are firmly bonded through the sintered neck or sintered bridge forming the mesh strut.

The open pore compact obtained in this way consisted of 100% nickel.

The surface of the strut has a high roughness since the applied powder particles are bonded to the support mesh of the semi-finished product and to each other only through a sintered neck or sintered bridge, so that the original particle shape remains large. The thickness of the highly porous nickel layer applied on the strut is between 1 μm and 300 μm. The porosity in the applied layer is 40%.

Claims (12)

In the method of manufacturing an open pore molded article containing a metal,
The open pore molded body containing metal as a semi-finished product is coated with particles of the same metal on which the semi-finished product is formed, or is coated with particles of a chemical compound of the metal from which the semi-finished product has been prepared, and the chemical compound is reduced in heat treatment or Can be thermally or chemically decomposed and formed by particles of each of the above metals obtained by chemical reduction or thermal or chemical decomposition; And
After the coating, at least one heat treatment in which the particles are bonded to the surface of the semi-finished product and/or adjacent particles through a sinter neck or sinter bridges is performed, and the specific surface area of the obtained open pore molded body Is increased to at least 30 m²/l and/or is increased by at least 5 times compared to the starting material of the uncoated metal semi-finished product, and the metal reducing atmosphere or an atmosphere suitable for decomposition is at least the chemical composition for forming the metal. The method, wherein until the reduction or thermal or chemical decomposition of the compound is complete, the semi-finished product is maintained in the heat treatment of an open pore molded body coated with particles of a reducing or thermally or chemically degradable chemical compound of the metal produced. In claim 1,
A method, characterized in that said particles of metal or particles of chemical compounds of said metal are used as powders, powder mixtures and/or suspensions/dispersants. The method according to claim 1 or 2,
The application of particles of the metal or particles of chemical compounds of the metal as powders, powder mixtures, suspensions and/or dispersants is carried out by dipping, spraying, pressure assisted methods, electrostatic and/or magnetic The method characterized in that. According to any one of claims 1 to 3,
A method, characterized in that organic and/or inorganic binders are used in a solution, suspension/dispersant or as a powder to improve the adhesion of the particles. The method according to any one of claims 1 to 4,
A method, characterized in that the application of the metal particles or particles of the specific chemical compound of the metal is repeated several times, in particular at least three times. The method according to any one of claims 1 to 5,
In the case of multiple coatings with the metal particles or particles of the metal chemical compound, the application of the binder is repeated several times, in particular at least three times, when the binder is used. The method according to any one of claims 1 to 6,
The application of the binder and the application of the particles of the metal or the particles of the chemical compound of the metal are carried out on different sides of the surface, in particular the semi-finished products using different amounts to obtain different porosities, pore sizes and/or specific surface areas. A method, characterized in that it is carried out on surfaces located opposite each other. The method according to any one of claims 1 to 7,
Ni, Fe, Cr, Al, Nb, Ta, Ti, Mo, Co, B, Zr, Mn, Si, La, W, Cu, Ag, Au, Pd, Pt, Zn, Sn, Bi, Ce or Mg Used as a metal for semi-finished products and particles to be applied, or
Ni, Fe, Cr, Al, Nb, Ta, Ti, Mo, Co, B, Zr, Mn, Si, La, W, Cu, Ag, Au, Pd, Pt, Zn, Sn, Bi, Ce or Mg Of chemical compounds, 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 A method, characterized in that the salt is used as a metal for said semi-finished product and for particles of a reducing, thermally or chemically degradable compound of this metal. The method according to any one of claims 1 to 8,
A method, characterized in that a semi-finished product obtained by electrochemical coating the open pores of a polymer material with respective metals is used as a semi-finished product. In the open pore molded body produced by the method according to any one of claims 1 to 9, through a sinter neck or a sinter bridge, on the surface of the semi-finished product and/or on the surface of adjacent particles. A molded article, characterized in that the molded article having bonded metal particles has a specific surface area of at least 30 m²/l. In claim 10,
A molded article, characterized in that the pore size in the coated and sintered open pore molded article corresponds to 10,000 times or less of the particle size used. In claim 10 or 11,
A shaped article, characterized in that 3% by mass or less, preferably 1% by mass or less of oxygen is present in the material of the shaped article.