AT14986U1 - Component of a metalworking machine - Google Patents

Abstract

The invention describes a component of a metal processing machine made of a refractory metal (RM) selected from the group consisting of tungsten (W), W alloy, molybdenum (Mo) and Mo alloy, wherein at least one surface of the component at least partially a layer which is formed, at least in regions, from at least one compound of at least one element selected from the group consisting of carbon (C), boron (B) and nitrogen (N) with at least one element selected from the group consisting of W and Mo.

Description

description

COMPONENT OF A METAL PROCESSING MACHINE

The invention relates to a component of a metal processing machine made of a refractory metal (RM) selected from the group consisting of tungsten (W), W alloy, molybdenum (Mo) and Mo alloy. Furthermore, the invention relates to a method for producing such a component.

Metal processing machines, such as extrusion presses and forming units, contain components such as matrices, dies, foundry molds, mandrels, etc.

These components are exposed during operation of the metal processing machine high thermal and abrasive loads by the metal melts processed therewith or heated to forming temperature metals. Component damage occurs as a result of thermal stress as well as chemical and mechanical erosion. In addition, alloying or the formation of intermetallic phases between the components and the processed metal may occur. This leads to material removal on the surface of the components and it can lead to contamination of the metals to be processed or damage to the components of the machine.

The challenges in the operation of metal processing machines consist in the reduction of the wear of the components. Developments are therefore aimed at increasing the resistance of the components to the prevailing conditions in order to achieve longer operating times. An increase in operating times also reduces, among other things, the operating costs of a metal processing machine.

Some ways to increase the life of such components have already been described in the relevant literature.

For the processing of metals such as aluminum or copper are often used as a base material for corresponding components steels, but also refractory metals or their alloys. The processing of metals such as aluminum or copper takes place at temperatures of about 500-700'C or 750-1000 ° C and therefore exerts not only a purely thermal stress, but also a high chemical load on the materials used. The lifetime of components of metal processing machines, for example for aluminum or copper is therefore often greatly reduced.

Other problems that occur in the processing of metals and often lead to failure of components of metal processing machines are, for example, the formation of intermetallic, often brittle phases, the formation of low-melting eutectics or alloying.

For example, JP2007038251A discloses a method for increasing the life of a forging mandrel made of iron by diffusion coating with carbon.

Further known from the prior art by means of gas phase reactions, such as chemical vapor deposition (CVD) or gas phase nitriding, on corresponding base materials of corresponding components deposited hard material layers to increase the wear resistance of the respective components.

However, the solutions known from the prior art often have poor adhesion to the base material, which can lead to material removal and contamination of the metals to be processed or damage to the components of the machine.

Furthermore, it is often desirable not to provide the entire surface of the base material with a wear protection layer, which is very poorly possible, for example, in deposited by a CVD method layers.

The object of the invention is therefore to provide a solution, whereby the disadvantages described above can be avoided. In particular, it is an object of the invention to provide a solution in which the components of a metal processing machine have a higher resistance to the aforementioned loads and thereby the service life of the components and thus the metal processing machine is increased. In particular, the present invention is intended to reduce material removal of components, thereby reducing contamination or damage to the metals to be processed.

This object is solved by the independent claims. Preferred embodiments are given in the subclaims.

A component of a metal processing machine according to the invention is made of a refractory metal (RM) selected from the group consisting of tungsten (W), W alloy, molybdenum (Mo) and Mo alloy and is characterized in that at least one surface of the component at least in some areas has a layer which at least partially from at least one compound at least one element selected from the group consisting of carbon (C), boron (B) and nitrogen (N) with at least one element selected from the group consisting of W and Mo. , is formed.

The component according to the invention is preferably a die, a die a mandrel or a foundry mold.

The component is made of a refractory metal, wherein the refractory metal is selected from the group consisting of tungsten (W), W alloy, molybdenum (Mo) and Mo alloy. W, W alloys, Mo and Mo alloys are also abbreviated to RM in the following text. Therefore, an RM component is a component made of W, a W alloy, Mo, or a Mo alloy.

A surface of the RM component has at least partially on a layer which at least partially from at least one compound of at least one element selected from the group consisting of carbon (C), boron (B) and nitrogen (N), with at least one element selected from the group consisting of W and Mo is formed.

In the solution according to the invention, both the base body / the base material, as well as the layer on RM. In the context of the invention, the basic bodies are the areas of the component which have no layer or no layer yet.

It has now been shown that by the execution of the invention layer adhesion problems, as can be observed in the prior art, do not occur. Furthermore, the components according to the invention are also significantly more resistant to a broad field of use conditions compared to uncoated components of W, W alloys, Mo or Mo alloys.

Particularly advantageous compounds are the carbides, borides and nitrides to mention. However, it is also excellent compounds that contain at least two elements of the group consisting of C, B and N in addition to W and / or Mo. For example, with compounds containing both C and B, excellent lifetime results could be achieved.

Preferably, the layer as RM that element which also forms the majority of the main body. So it is advantageous if, for example, the base body is made of molybdenum or a molybdenum alloy, that the layer is formed by a compound of molybdenum. For example, excellent results could be obtained if the main body of the component is made of Mo and the layer comprises M02B, MoB, MoC, M02C, M02N or MoN.

It is particularly advantageous if, in the production of the layer, the compound formation takes place by reaction of C, B and / or N with the W and / or Mo of the main body, since an excellent layer adhesion can be achieved thereby.

The layer can completely cover the base body or can also be applied only in places of highest stress. In addition, the layer may be single-layered or multi-layered and / or made up of mixed phases of varying composition. If a Mo-W alloy is used as the base body for the component, which represents an advantageous embodiment, then the compound may have Mo and W as metallic constituents. Therefore, in the list of advantageous borides, carbides and nitrides listed below, without adversely affecting the properties, W may be partially replaced by Mo or Mo in part by W.

Particularly advantageous binary compounds W2B, WB, W2B5, Wi xBa, WB4, WC, W2C, WN, W2N, W3N2, M02B, MoB, M03B2, M0B4, MoC, M02C, MoN, M02N and M03N2 mentioned. In particularly advantageous ternary and quaternary compounds, the non-metallic constituent of the aforementioned binary compounds is partially replaced by one (for ternary compounds) or two (for quaternary compounds) further element (s) from group C, B and N. For example, for WC, the ternary compounds W (C, N) and W (C, B) and as the quaternary compound W (C, B, N).

In addition to the respective stoichiometric compositions of the compound, these may additionally contain other elements, for example C, B, N, W and / or Mo, in dissolved form.

A further advantageous embodiment is a composite layer. A com-posite layer is a layer which is composed of at least two phase regions. A particularly advantageous embodiment of the invention should be emphasized when the layer contains the phases WC and / or W2C. Another particularly advantageous embodiment is given if the layer contains WB and / or W2B. The combination of WC and / or W2C and WB and / or W2B represents a particularly advantageous embodiment of the invention. Thus, for example, the outermost region of the layer of WC and / or WB be formed, followed by an area, the W2B- and / or W2C phase. W2B and / or W2C are adjacent to the main body of W or a W alloy. In an analogous manner, for example, the outermost region of the layer can be formed from MoC and / or MoB, followed by a region which has M02B and / or M02C phases. M02B and / or M02C are adjacent to the main body of Mo or a Mo alloy.

In a further advantageous embodiment, the layer is interlocked with the adjoining region of the base body. This gearing effect is achieved in a simple manner by the reaction of C, B and / or N with Mo and / or W of the main body. For this purpose, C and / or B and / or compounds of C, B and / or N are applied to the surface of the base body. By heating C, B and / or N now diffuse into the main body, where it comes to the compound formation. The toothing is advantageously formed by grains of the layer (for example and advantageously by W2B, W2C, M02B and / or M02C grains). When applying C and B to tungsten or molybdenum, for example, a carbide forms as the top layer layer, which is particularly resistant to wear. The introduction of N into the layer is preferably carried out by annealing in an N-containing atmosphere (reaction annealing). NH 3 or a mixture of at least two gases of the group consisting of NH 3, H 2 and N 2 and also annealing temperatures, for example in the range from 700 to 1300 ° C., are preferably used.

The advantageous average layer thickness can be selected within a wide range, with a preferred range of 1 to 300 pm, preferably 3 to 200 pm to call.

As an advantageous material for the main body are pure W, W - 0.1 to 3 Ma% rare earth oxide, W heavy metal, pure Mo, Mo - titanium (Ti) - zirconium (Zr) - C (common name: TZM), Mo - hafnium (Hf) - C (common name: MHC) or Mo-W alloys. The most suitable rare earth oxide is La203. W - La203 has a significantly improved cutting behavior compared to pure W, whereby the manufacturing cost of the component can be significantly reduced. Pure-W or Rein-Mo are to be understood as meaning the metals of the usual technical purity.

Advantageously, the component has at least one of the following properties: - The compound is selected from the group a or b, with:

Group a: carbides, borides and nitrides;

Group b: compound containing W and / or Mo and at least two elements of the group consisting of C, B and N.

The compound is selected from the group consisting of WgB, WB, W2B5, Wi-xBa, WB4, WC, W2C, WN, W2N, W3N2; M02B, MoB, M03B2, M0B4, MoC, M02C, MoN, M02N and M03N2.

- The layer is designed as a composite layer.

The composite layer has at least one region of a boride and at least one region of a carbide.

The outermost layer layer is at least partially formed by WC or WB.

- The layer is interlocked with the adjoining body.

- The toothing is formed by grains of the layer.

[0038] The RM component has the layer in places of high stress.

At least one compound contains at least one element selected from the group consisting of B, C, N, W and Mo in dissolved form.

The RM component is selected from pure W, W-0.1 to 3% by mass rare earth oxide, W heavy metal, pure Mo Mo-Ti-Zr-C (TZM), Mo-Hf-C (MHC) or a Mo-W alloy.

The object of the invention is also achieved by a method for producing an RM component.

The method has at least the following steps: - Production of the geometry of the RM component by conventional methods; Applying at least one element and / or at least one compound of one

Elements selected from the group consisting of C, B and N, preferably in powder or slurry form; - Heat treatment for forming a compound with at least one RM in Vaku order, inert gas or reactive gas.

Conventional methods for producing the RM component include pressing / sintering methods with subsequent mechanical processing, near net shape pressing / sintering methods, hot pressing, hot isostatic pressing, spark plasma sintering or metal powder injection molding.

After the geometry has been produced, at least one element or at least one compound of an element selected from the group consisting of C, B and N is applied in the regions which are to have the layer in use. The application can be done for example by dumping, by brushing, by dipping or by spraying. Particularly suitable is the application of a slurry to mention, since it is also possible to coat parts with complex geometries in a simple and advantageous manner. After application of C and / or B and / or a C, B and / or N-containing compound, the component is heat treated in vacuum, inert gas or reactive gas. Suitable reactive gases are, in particular, gases or gas mixtures which contain N (for example NH 3 or a mixture of at least two gases of the group consisting of NH 3, H 2 and N 2), C (for example CH 4) and / or B (for example BH 3). The temperature is advantageously 700 to 2,000 ° C. (annealing in vacuum) or 700 to 1,300 ° C. (annealing in reactive gas), whereby the most suitable range for the respective compound can be determined by simple experiments. In the heat treatment, C, B and / or N then diffuse / diffuse into the base material and forms with it the compound according to the invention.

In conventional CVD method, a layer is deposited on the outside of the base material. As a result, it may be that tolerances of the components can no longer be met and the components must be reworked. In the coating according to the invention, this is not necessary since the dimensional stability is ensured in this method.

In contrast, for example, to a gas phase nitration in which the surface of the entire component, i. E. all areas which are achieved by the gas flow, nitrided and it is not possible to selectively expose certain areas, can be masked by the inventive method areas, whereby it is possible to apply the coating, for example, only in tribologically contaminated zones. By means of this targeted masking of the components, it is possible to realize hard or resistant as well as soft or tough regions on the same component.

Another advantage compared to gas-phase nitriding is that layer thicknesses in a wide range of 1 to 300 pm can be achieved with the method according to the invention. In gas phase nitriding only thicknesses of 1 to 15 pm can be achieved. Due to the higher layer thicknesses, the range of use or the duration of use of the coated components can be significantly widened.

The size of the components, which can be coated, is another distinguishing feature for gas phase nitriding. In gas phase nitriding, not only the size of the system, but also the gas flow in this crucial. In the case of uneven gas conduction, as is increasingly the case with large components, it can happen that the components are coated only partially or inadequately. The coating according to the invention can be carried out largely geometry-independent, with only the size of the system for the required heat treatment is limiting.

In the method according to the invention a large scale automation with manageable effort is feasible. This is difficult to carry out in the case of gas phase nitriding, since, in addition to the high manual effort for the charging, the system size also has a strongly limiting effect. By appropriate automation, it is possible to reduce the manufacturing cost per piece and at the same time to achieve an improvement in properties such as hardness and wear properties.

In addition to the methods described above, the layer can also be applied by other conventional methods such as PVD, CVD, thermal spraying or annealing in reactive gas (for example, in the aforementioned gases / gas mixtures).

In the following the invention will be described in more detail by way of example and compared with the prior art.

FIG. 1 shows a two-layered molybdenum boride / diboride layer on Mo. FIG.

Figure 2 shows a multilayer composite layer comprising areas of molybdenum carbide and areas of molybdenum boride.

FIG. 3 shows a GDOES profile of the layer in FIG. 2. FIG. 4 shows a sketch of a matrix with partial coating (thick lines).

FIG. 5 shows a coated part of a matrix.

FIG. 6 shows an EBSD image of a two-layered tungsten boride / tungsten carbide

Layer on W.

Example 1 Basic bodies of W, W - 1 Ma% La203 (WL) and Mo were provided by diffusion processes with different layers. For this purpose, a slurry containing carbon and / or boron was applied by dipping on the surface of the base body. The respective C and B components can be taken from Tables 1 and 2. Thereafter, the samples were subjected to annealing at ISGOO / 10h in vacuum. The constituents C, B and N formed during the heat treatment, the corresponding compounds. As an example, this is reproduced for the sample 19 according to Table 2 in FIG.

The EBSD measurement was performed as follows.

[0064] - 120 pm electron beam stop - high current mode, 20 kV acceleration voltage [0066] - scan area 57 x 24 pm2 - magnification 1500x [0068] - step size 0.05 pm - binning 4x4 [0070] camera -Gain 17.06 [0071] - Camera Exposure 4.50 [0072] Substrate Correction: Static Subtraction Combined with Normalized Intensity Histogram [0073] System: FEG-SEM Zeiss Ultra plus 55 with EDAX Trident XM4 Analysis Package, Hikari EBSD Camera Tables 1 and 2 show an overview of the samples.

Table 1

Table 2

Example 2

Coated template from MHC

A matrix of MHC was cleaned alkaline in an ultrasonic bath. Subsequently, parts of the template were covered with adhesive tape. The thus prepared template was immersed in an aqueous suspension with graphite and boron (in the ratio 20:80 by weight) and dried in air. Still in the green state, the tape was removed. This masking ensured that the coating takes place only at the desired locations of the matrix. A sketch with the coated areas of such a coated matrix (thick lines) is shown in Figure 4.

The heat treatment was carried out under vacuum at 1500 ° C for 4h, forming a multilayer of molybdenum carbides and molybdenum borides. A scanning electron micrograph of a portion of the thus treated matrix is shown in FIG.

Claims (12)

claims 1. component of a metal processing machine made of a refractory metal (RM) selected from the group consisting of tungsten (W), W alloy, molybdenum (Mo) and Mo alloy, characterized in that at least one surface of the component at least partially a Layer, which is at least partially formed of at least one compound of at least one element selected from the group consisting of carbon (C), boron (B) and nitrogen (N) with at least one element selected from the group consisting of W and Mo. , 2. Component according to claim 1, characterized in that the compound is selected from the group a or b, comprising: - Group a: carbides, borides and nitrides; Group b: compounds containing W and / or Mo and at least two elements of the group consisting of C, B and N. 3. Component according to claim 1 or 2, characterized in that the compound from the group consisting of W2B, WB, W2B5, Wi_xBa, WB4, WC, W2C, WN, W2N, W3N2, M02B, MoB, M03B2, M0B4, MoC, M02C, MoN, M02N and M03N2 is selected. 4. Component according to one of the preceding claims, characterized in that the layer is a composite layer having at least a portion of a boride and at least a portion of a carbide. 5. Component according to claim 4, characterized in that WC or WB at least partially forms the outermost layer layer. 6. Component according to one of the preceding claims, characterized in that the layer is interlocked with the adjoining region of RM. 7. Component according to claim 6, characterized in that the toothing is formed by grains of the layer. 8. Component according to one of the preceding claims, characterized in that the RM component has the layer in places of high stress. 9. Component according to one of the preceding claims, characterized in that at least one compound contains at least one element selected from the group consisting of B, C, N, W and Mo in dissolved form. 10. Component according to one of the preceding claims, characterized in that the RM component of pure W, W - 0.1 to 3 Ma% rare earth oxide, W heavy metal, pure Mo, a Mo - titanium (Ti) - zirconium (Zr) - C alloy (TZM), a Mo - hafnium (Hf) -C alloy (MHC) or a Mo-W alloy. 11. Component according to one of the preceding claims, characterized in that it is a die, a die, a mandrel or a foundry mold. 12. A method for producing a component according to one of the preceding claims, characterized in that it comprises the following steps: - Production of the geometry of the RM component by conventional methods; - applying at least one element and / or at least one compound of an element selected from the group consisting of C, B and N, preferably in powder or slurry form; - Heat treatment to form a compound with at least one RM.