EP2170780A2

EP2170780A2 - Mechanically resistant member for castings, and method for the production thereof

Info

Publication number: EP2170780A2
Application number: EP08801057A
Authority: EP
Inventors: Eberhard Ambos
Original assignee: Josch Strahlschweisstechnik GmbH
Current assignee: Josch Strahlschweisstechnik GmbH
Priority date: 2007-07-30
Filing date: 2008-07-28
Publication date: 2010-04-07
Also published as: WO2009015642A2; DE102008032271A1; DE102008032271B4; WO2009015642A3

Abstract

The invention relates to a mechanically resistant member for castings that are to be designed with wear-resistant effective surfaces in the area of the contours thereof as well as a method for producing a mechanically resistant member. The obtained mechanically resistant member (2) has an open-cell metalloceramic structure, has a contour area that corresponds to the contour of the effective surface of the casting (1) to be produced, and is composed of powdery components of metallic and non-metallic materials. Said mechanically resistant member is mainly composed of 92 to 80 percent by weight of one or more carbides of the strong carbide formers W, Ti, Ta, Nb, V, Mo, and Cr, and 8 to 20 percent by weight of Co, or 85 to 60 percent by weight of said carbides and 15 to 40 percent by weight of Ni.

Description

Hard material body for molded parts and method for its production

The invention relates to a hard material body for molded cast parts to be produced, which are to be formed with wear resistant active surfaces in at least a portion of their contours and a method for producing such Hartstoffkörper, which are used in the mold cavity of the mold casting corresponding mold arresting and molded parts / components are produced, the high and subject to shock loads and high wear.

Numerous methods for producing a molded part having a wear-resistant active surface in at least one region of its contour are known from the prior art. So z. B. in WO 0032335 A 1 a composite casting with a metallic matrix and at least one located in the matrix, purely metallic, produced by fusion metallurgy hard material in the form of an insert described. The hard material body, which preferably consists of a wear-resistant metal or a wear-resistant metal alloy, has at least in part an open-pore sponge structure, the pores being substantially completely filled by the material of the matrix during the casting process. As a casting process z. B. the known investment casting, Schwerkraftgieß-, Niederdruckgieß- and die casting are used.

The production of the hard material body requires a very complex multi-stage process. In this process difficulties are to be expected in the destruction of the ceramic mold for the hard body and the removal of mold residues.

The hard material body should, according to the information in WO 0032335 A 1, be able to be produced in virtually any shape, without, however, making any statements regarding the shaping of the initially produced PUR foam body. These polyurethane foam bodies are coated with ceramic slip; after subsequent burning out of the PUR foam, the ceramic mold is fired for the hard material body. The stated possibilities of internal design of the hard material body are therefore doubted for manufacturing reasons. From DE 4322113 Al a brake disc is known in which a consisting of a conventional cast iron or cast steel disk-shaped support body serving as a friction surface layer of a ceramic material, which consists of micro- or macroscopic broken down areas of at least two different materials. The regions of the one material consist of an at least approximately pure ceramic material and the regions of the other material or of the other materials of a metal, metal sintered or Metallkeramiksinter- material. The said layer preferably consists of an open-pored ceramic sponge with metal filling, the pore size of which may amount to approximately 5 to 10 mm. The support body and the metal filling may consist of the same metal material. To produce the brake disk, one or more hard material bodies formed from open-pored ceramic sponge are inserted into the casting mold for the support body per friction surface, which fill with the metal during casting of the support body. Alternatively, in the mold for the support body per friction surface one or more of metal-filled ceramic sponge existing hard material body can be inserted, which are poured during the casting process of the support body in this.

From DE 10122886 B4, a casting having at least one wear-resistant effective surface formed by a composite material for comminuting a feedstock is known. The composite consists here of at least one open-pore hard material body in a casting matrix of a metallic casting material. The hard material body consists of a ceramic material from the group of carbides, oxides and nitrides or a combination of several of these materials. Ceramic bodies in the form of commercially available cast filters for cast iron material and with a structure known from such cast filters may be used as the hard material body. As the metallic casting material, a wear-resistant iron-base alloy is preferred, for example, a molybdenum-alloyed and / or chromium-alloyed cast iron. This solution is because of the use of commercially available casting filter, which are present only as disc-shaped body, only for geometrically simple hard body with flat surfaces (eg grinding plates) usable. Other disadvantages are the limited strength due to the lack of material composite between matrix and hard body and the risk of destruction of the hard body by different expansion coefficients of the materials of hard material and matrix and thus by tensions as a result of heat treatment processes.

Solutions are also known which relate to the formation of wear resistant surfaces of components and consist of metal-matrix composites (MMC) reinforced with minute inclusions of another material to inhibit crack growth and improve performance 695 34 107 T2. It is further stated in this document that the invention described relates to all types of metal-ceramic composites, including ceramic matrix composites (CMC), and the invention is particularly applicable to metal-matrix composites (MMC) having a larger volume fraction on metal as a ceramic. It is then stated that these MMCs can be made from many different components of matrix material and reinforced particles in order to realize a comprehensive application as far as possible.

The basis for these composites are the materials aluminum, magnesium, copper, titanium and so-called superalloys molybdenum and tungsten. Such formed composites are very expensive to manufacture and have only very limited strength and wear properties.

Reference is further made to DE 101 13 590 A1, with which a method for producing a structural part has become known, in which a porous precursor molded body is produced from a metal oxide ceramic material and with a metal melt made from aluminum, magnesium or an aluminum or magnesium alloy is infiltrated.

According to the invention, the porous precursor shaped body is produced by sintering by means of local heating, wherein the local heating in this case takes place in particular by laser beams, electron beams, plasma jets or one or more arcs, whereby a fast sintering process is to be ensured. A disadvantage of this solution is the not inconsiderable expense for sintering and the limitation of the proposed method to the fact that the metal oxide ceramic grains aurweisen a reducible of aluminum metal oxide compound, which are unsuitable for the production of highly loaded components.

The invention has for its object to provide a hard material body and a method for its production, which can be used in molds for the production of molded parts and so wear-resistant active surfaces are formed on the outer contours of the molded parts.

Erfϊndungsgemäß this object is achieved with the features of claims 1 and 4.

In the subclaims advantageous embodiments and particular solutions of the invention are given.

Recognizing that carbide alloys with embedded NiSF hard phases (producing nickel-based metal powders) and WSC (producing ceramic tungsten carbide-based ceramic parts) for wear reduction by plasma powder build-up welding or laser-assisted plasma powder deposition welding can be applied to steel and ferrous materials and also the pouring of porous ceramic bodies (eg casting filter made of various ceramic materials) for reducing wear of castings and the associated disadvantages is known: namely the high nickel content in the hard material alloys with embedded hard phases and the lack of material bond between porous ceramic bodies and the metallic matrix with the restriction of the use of cast filters on flat body, the invention proposes that the use / the use These hard alloys for the generation of porous Eingießkör- pern / Hartstoffkörpeni, these are produced by the generative electron beam melting technique. In this case, the pouring of porous bodies from the hard material alloys with embedded hard phases, whereby it is possible to produce almost any hard material body having the shaped surface of the molded part, this is adapted and a solid material bond with the matrix material is achieved.

Thus, a hard material body was created, which is formed as an open-pored metalloceramic hard material body, which is insertable as insert into a casting mold and from the main components 92 to 80 mass% of one or more carbides of the strong carbide formers W, Ti, Ta, Nb, V, Mo and Cr and 8 to 20% by mass of Co or 85 to 60% by mass of the above carbides and 15 to 40% by mass of Ni.

In a preferred embodiment of the open-pored metalloceramic hard material body, it is also possible to use oxides or nitrides of the abovementioned materials instead of the carbides, an essential feature of the invention being that the hard material body (s) is produced by means of electron beam melting of metallic and non-metallic powdery components of the abovementioned materials. This in such a way that is formed by a suitable electron beam guidance of the hard material body generative by electron beam melting of metallic and non-metallic powdery components of these materials, taking into account the surface structure of the molded part to be produced or a portion of the outer contour of the molded part.

The shape and dimensions of the hard material body to be produced, its porosity, the geometry of the cavities and the wall thicknesses of the hard material body are adapted to the stresses of the molded part to be cast.

It also belongs to the invention that the porosity and the geometry of the cavity structure of the hard material body are formed so that a uniform infiltration of the casting material / matrix material in the entire volume of the hard material body is given.

With the following embodiment, the invention will be explained in more detail. The features disclosed in the exemplary embodiment form the subject of the invention individually and in any combination of features. The accompanying drawing shows in 1 shows the formation of a hard material body and its use in a casting mold with inserted molded part in a principle arrangement,

FIG. 2 shows a honeycomb structure of the cavities of the hard material body in FIG

Sectional views A - A of Figure 1,

FIG. 3 shows a diamond-shaped structure of the cavities of the hard material body in FIG

Sectional views A - A of Figure 1.

Figure 4: the formation and arrangement of a hard body on the wear-stressed surface of a component.

The illustration shown in FIG. 1 clarifies, on the one hand, the formation of the hard material body 2, which corresponds to the surface structure of the molded part 1 to be formed. The reference number T denotes the part of the hard material body 2 which has not yet been infiltrated with the casting material / casting matrix 3. In contrast, the reference numeral 4 denotes the region of the hard material body 2, which is already infiltrated with the casting material, the casting matrix 3.

A molded part 1 to be produced in this way can be used, for example, as a metallic component for conveying and / or processing, for example, soil, coal, overburden, cement, ore, mineral salt, rock and other substances, as well as for recycling valuable materials and the like. The filling of the required mold is carried out by gravity over the sprue 5. For the purpose of density feed of the casting 1 die 6 are arranged. From the illustration of Figure 1 also shows that the molded part to be produced

3 is connected on its curved and partially planar active surface with the hard material body 2, which can be formed both with a uniform layer thickness of 15 to 25 mm, but also on particularly stressed areas with a reinforcement of the layer. As already stated, the surface layer of the molded part 1 to be produced is formed by the inserted hard material body 2 whose cavity structure has been formed by a large number of cavities 8, which are completely penetrated by the casting material / casting matrix 3. Thus, the hard material body 2 is largely embedded in this casting matrix 3 and forms with the casting material / the casting matrix 3 the active surfaces 7 of the molded part 1 produced.

The cavities 8 of the cavity structure of the hard material body 2 are formed with Öffhungsmaßen in the range of 1.0 to 8.0 mm and designed with different cross-sectional shapes.

Thus, the cavities 8 may have a square, rectangular, honeycomb-like, diamond-shaped, latticed, spongy or organic cells similar structures and a so executed cavity structure of the Hartstoflkörpers 2 ensures complete filling of the cavities 8 with the casting matrix 3 - Figures 2 and 3 -. A hard material body 2 thus created consists of metalloceramic materials, as stated above, which are kept in their structure with molten metals or metal alloys, such as nickel and cobalt or only one of these elements, and retain these during casting. In this case, the hard material body 2 is fastened in the mold with pins customary in foundry practice (also referred to as "core nails") and secured in position against displacement by flow pressure of the inflowing casting metal, the casting matrix 3.

In the described embodiment, the hard material body 2 is formed by electron-beam-melted hard material. The dimensioning of the cavities 8 of the hard material body 2 is carried out in dependence on the casting metal in such a way that always a complete penetration of the cavities 8 of the hard material body 2 is ensured. It is desirable in the casting process that there is a solid material bond between the hard material body 2 and the metallic casting matrix 3 of the casting material, which counteracts the breaking out of hard material parts in the external stress by the substances to be conveyed or processed.

FIG. 2 shows a hard material body 2 with a honeycomb-shaped structure of the cavities 8 in two different cut-out enlargements. This design allows a very low flow resistance during penetration of the liquid metal and thus promotes complete penetration. The honeycomb-like structure also ensures a very uniform distribution of hard material over the entire active surface 7. The technique of electron beam melting used for the production of the hard material body 2 also allows the targeted reinforcement of the wall thicknesses within the hard material body 2 under particularly strong local stress. In addition to the honeycomb-like structure, further suitable hollow structures for the hard material bodies 2 are available. These are, for example, the diamond-shaped structures shown in FIG. 3 or structures similar to lattice-shaped, spongy or organic cells. It is also possible to make the size of the cavities 8 within a Hartstofϊkörpers 2 according to the requirements.

If the dimensions of the hard material bodies 2 exceed the dimensions of the working spaces of the electron beam systems, then it is possible to bring the hard material body 2 to the required level by mechanical or thermal joining of individual pieces.

The casting matrix 3 is formed, for example, by the material GS - 42 CrMo 4. The following table indicates, in addition to this material for the exemplary embodiment, further preferred materials for the casting matrix 3 in other castings according to the invention.

The production of a hard material body 2 is effected by the layered construction of the materials used from the powdered components of the metallic and non-metallic materials, which are melted by means of electron beam melting, wherein the electron beam is guided on the basis of three-dimensional CAD data models, thereby the immediate overall shape of the hard material body 2 is formed including its Hohlraurnstruktur. Depending on the size and structure of the hard material body 2 to be produced with its cavities 8, the electron beam, which has a specific power density distribution, has a beam deflection with a frequency of 10 ⁶ Hz and the deflection amplitude of the electron beam is determined by the size of the hard material body 2 to be produced ,

The production of the hard material body 2 is carried out under vacuum and the pulverförmi- materials are applied with layer thicknesses in the range of 0.1 to 0.3 mm on a platform and then fused together by means of an electron beam.

FIG. 4 shows a further exemplary embodiment of the invention. Shown is a molded part 1, which is formed on a partial surface, the surface, which is subject to high and shock loads, with a hard material body 2. The hard material body 2 is designed in accordance with the invention and adapted in its outer structure and shape of the wear-stressed surface of the molded part 1, whose cavity structure is completely penetrated by the casting material / casting matrix 3 during the casting process and the hard material body 2 is largely penetrated into the Casting matrix 3 is embedded.

The material of the hard impact body 2 consists of hard material alloys with embedded hard phases of the type WSC / NiSF in a ratio of 70: 30 and as cast matrix a material GS-42 CrMo 4 is used.

Of particular advantage in the design and arrangement of a hard material body 2 to be produced castings 1 is that the hard material body 2 is inserted into the corresponding mold that the finished molded part 1, the active surface 7 of the hard body 2 with a slight layer, for example in the range of 1 to 2 mm, is covered by the casting matrix 3, thus the different characteristics of the materials used in the curing-solidification process is met. The following embodiments relate to the material composition of hard bodies according to the invention 2.

First embodiment variant:

Material composition of the hard material body: 88% by mass of WC and 12% by mass of Co.

Second embodiment variant:

Material composition of the hard material body: 78% by mass of WC and 22% by mass of Co.

Third embodiment:

Material composition of the hard material body: 80% by mass of WC and 20% by mass of Ni.

The material composition of the hard material bodies 2 to be produced is not limited to those in the abovementioned embodiments, but rather there are further material-related embodiments of the hard material bodies 2 which lie in the ranges of the stated mass% components, in particular taking into account the stresses on the molded cast parts to be produced.

Claims

claims

1. hard body for molded parts, designed as an insert and used in a mold, the hard material body has an open-pored structure, which is infiltrated during the casting of matrix material, characterized in that

the hard material body (2) has an open-pore metalloceramic structure, the hard material body (2) having a contour with the contour of the active surface of the molded part (1) matching contour area, consists of powdered components of metallic and non-metallic materials whose main components 92 to 80% by mass or more carbides of the strong carbide formers W, Ti, Ta, Nb, V, Mo and Cr, and 8 to 20 mass% Co or 85 to 60 mass% of the above carbides and 15 to 40 mass% Ni.

2. hard material body according to claim 1, characterized in that

whose open-pore structure is formed by cavities (8) whose opening dimensions are in the range of 1.0 to 8.0 mm and the hard material body (2) is formed with a thickness of 5 to 25 mm, the cavities (8) have different cross-sectional shapes, which have a square, rectangular honeycomb-like, diamond-shaped, lattice-shaped, spongy or organic cells similar structure.

3. hard material body according to claims 1 and 2, characterized in that

the hard material body (2) with respect to the porosity, the geometry, including the wall thickness and the HobJraumstruktur is designed so as to correspond to the stresses of the molded part to be formed (1).

, A process for producing a hard material body according to claim 1, characterized in that

the hard material body (2) is produced by layered construction of the powdered components of the metallic and non-metallic materials used, which are applied in layer thicknesses in the range of 0.1 to 0.3 mm on a platform and fused together by means of an electron beam, wherein the beam is guided so that an open-pore hard material body (2) with preselectable cavities (8) in size and structure is produced and the hard material body (2) has the shape or a partial shape, the contour of the active surface (7) or a Teilwirkfiäche of the molded part ( 3) corresponds.

5. The method according to claim 1, characterized in that

the electron beam has a specific power density distribution, has a beam deflection with a frequency of 10 ⁶ Hz, is characterized by a deflection amplitude in size of the hard material body (2) and the formation of the hard material body (2) takes place under vacuum.

6. Process according to claims 4 and 5, characterized in that

the porosity and the geometry of the cavity structure of the hard material body (2) are formed so that a uniform infiltration of the casting material / casting matrix (3) in the entire cavity volume of the hard material body (2) is ensured.

7. Process according to claims 1 to 3, characterized in that

the hard material body (2) is arranged at a small distance from the surface of the wear-stressed casting.

8. The method according to any one of claims 4 to 6, characterized in that

the hard material body (2) during the casting process for producing a molded part (1) is connected to this, such that the hard material body (2) in the mold cavity of a mold casting (1) adapted mold is inserted and locked so that between the surface of the hard material body (2) and the mold is a slight distance, preferably between 1 to 2 mm, is given, so that subsequently, after filling the mold cavity of the mold with molten metal or a molten metal alloy, the active surface (7) of the inserted hard material body (2) with the casting material, the casting matrix (3) is coated, so the hard material body (2) is arranged at a small distance from the surface of the wear-molded part (1).