DE102021120273A1 - Process for the production of a cemented carbide material with a reinforced binder phase - Google Patents

Abstract

The invention relates to a sintered carbide material, in particular hard metal, with 70-95% by weight, preferably with 80-95% by weight, tungsten carbide in dispersed form and a binder phase, the binder phase having metallic binder material, the metallic binder material having Co , wherein the binder phase comprises intermetallic phase material and/or the dissolved elements Ni and Al, the intermetallic phase material, if present, being formed according to the structural formula (M,Y)3 (AI,X), where M=Ni, Y=Co and/or another component and X=tungsten and/or another component, the binder phase having the following chemical element composition: Ni > 25% by weight, Al > 4% by weight, remainder Co and dissolved binder components, for example W and/or C. Such a sintered carbide material is characterized by high wear resistance and, at the same time, high fracture toughness.

Description

The invention relates to a sintered carbide material, in particular a hard metal, with 70-95% by weight of tungsten carbide in dispersed form and a binder phase, the binder phase having a metallic binder material, in particular Co.

Out of EP 2 691 198 B1 describes such a sintered carbide material, namely a hard metal body, and a method for its production. According to this known method, a powder is mixed comprising coarse-grain tungsten carbide, a superstoichiometric proportion of carbon and cobalt powder. In addition, tungsten in powder form was added to the powder. The tungsten powder and the cobalt powder had an average particle size of about 1 μm. The coarse grain tungsten carbide had an average particle size of 40.8 microns.

Then, this powder was ground in a ball mill, and hexane and paraffin wax were added thereto. A green compact was pressed from this mixture and this green compact was then sintered. Subsequent to the sintering process, the obtained cemented carbide material was subjected to a heat treatment. It was heated to 600°C and held at this temperature for 10 hours.

After a subsequent cooling process, the sintered carbide material was subjected to an analysis. It has been shown that the sintered carbide material has nanoparticles in the binder phase, with the nanoparticles having a size of less than 10 nm. The nanoparticles were formed by the eta phase (Co ₃ W ₃ C) or (Co ₆ W ₆ C) or theta phase (Co ₂ W ₄ C). The grain size of the nanoparticles was less than 10 nm.

It has been shown that the nanoparticles are accompanied by a strengthening of the binder phase. The hardness of the sintered carbide material can thus be increased. The disadvantage of these materials is the lack of thermal stability of the nanoparticles. As a result, they are only suitable to a limited extent for high-temperature applications or for applications in which a high temperature input occurs.

Very high temperatures occur on the tool surface due to friction when working rock and milling asphalt and concrete. The hard material tungsten carbide has a high hot hardness at these temperatures and is not very affected by it. However, the strength of the metallic binder drops dramatically at these temperatures. The reduced strength of the metallic binder leads to increased abrasive wear and/or extrusion of the binder phase as a result of the stresses caused by use. As a result, the tungsten carbide grains can no longer be held in the hard metal.

It is the object of the invention to provide a sintered carbide material, in particular a hard metal, which has improved wear resistance and, at the same time, high fracture strength.

This object is achieved with the features of claim 1. Accordingly, a sintered carbide material, in particular a hard metal, is proposed with 70-95% by weight, preferably with 80-95% by weight, tungsten carbide in dispersed form, and a binder phase, the binder phase having metallic binder material, the metallic binder material Co wherein the binder phase comprises intermetallic phase material and/or the dissolved elements Ni and Al, the intermetallic phase material, if present, being formed according to the structural formula (M,Y) ₃ (AI,X), where M=Ni,Y= Co and/or another component and X=tungsten and/or another component, the binder phase having the following chemical element composition: Ni > 25% by weight, Al > 4% by weight, remainder Co and dissolved binder components, e.g. W and/or C.

According to the invention, a sintered carbide material, in particular hard metal, is therefore proposed which either has a reinforced binder phase and/or is prepared in order to form a reinforced binder phase. In both cases, the binder phase is strengthened via the intermetallic phase material.

If the intermetallic phase material is already present in the binder phase, it immediately reinforces it.

If the sintered carbide material in the binder phase contains the dissolved elements Ni and Al, thermal treatment of the sintered carbide material forms intermetallic phase material, which then leads to a strengthening of the binder phase.

During the thermal treatment, the elements Ni, Co, W and Al from the binder phase combine to form the intermetallic phase material. This intermetallic phase material is again formed according to the structural formula (M,Y) ₃ (AI,X), where M=Ni, Y=Co and/or other component and X=tungsten and/or other component.

The thermal treatment of the sintered carbide material can take place in different ways that are suitable for forming the intermetallic phase material as intended.

This can in particular be a thermal heat treatment, in particular an external introduction of heat into the sintered carbide material. The thermal heat treatment can be effected, for example, in that an active source generates heat or cold and that this heat or cold is introduced into or withdrawn from the material. For example, the intermetallic phase material can correspondingly be formed in a furnace into which the sintered carbide material was introduced. It is also conceivable that at least part of the surface of the sintered carbide material is acted upon by a heating device, for example a burner.

Alternatively, it is conceivable that an excitation source is present, which introduces energy into the cemented carbide material in order to generate heat therein. This can be an induction coil or a laser device, for example.

Alternatively, it is also conceivable that the heat is generated by passive heating, i.e. by using the sintered carbide material in a preferably intended operating state or in the course of a method step in which the sintered carbide material is processed, in particular installed.

For example, heat is generated in the sintered carbide material by friction, as occurs, for example, during the intended use, in particular the intended use, in particular the use of tools, of the sintered carbide material. If it is a tool, it is moved relative to the object to be machined (e.g. in the case of a road milling bit, this road milling bit relative to a road surface), this creates frictional energy that leads to heat generation in the sintered carbide material. The resulting heat can be used to achieve a self-reinforcing effect of the binder phase through the at least partial formation of intermetallic phase material in the sintered carbide material.

It is also conceivable that the sintered carbide material is passively heated in the course of a method step in which the sintered carbide material is applied to a carrier, for example a tool base body or carrier. The resulting heat can be used to form the intermetallic phase material. A conceivable joining method is a welding method, for example a friction welding method, an electron beam welding method, a soldering method, for example a hard soldering method, a furnace soldering method, an inductive soldering method, a diffusion soldering method, a plating method, for example explosive plating.

In order to achieve the above effects, it is provided according to the invention that the binder phase has the following chemical element composition: Ni > 25% by weight, Al > 4% by weight, remainder Co and dissolved binder components, for example W and/or C .

The intermetallic phase material forms a crystalline intercalation in the metallic binder.

This intermetallic phase material has a significantly higher strength, especially at higher temperatures, compared to the metallic binder material in which it is embedded. At the surface of the cemented carbide material that is exposed to wear attack, the intermetallic phase material reduces erosion or extrusion of the metallic binder material when it is used, for example in a tillage tool.

The movement of the tillage tool and the loosened soil material as well as the remaining soil material creates an abrasive and mechanical load on the sintered carbide material. The tungsten carbide grains counteract this wear attack with sufficient wear resistance. In the prior art, the problem here is the binding material, which has a significantly lower strength than tungsten carbide. Since, according to the invention, the intermetallic phase material is integrated in the binder phase or is formed therein, rapid erosion or extrusion of the metallic binder material is prevented.

In addition, it has surprisingly been shown that the intermetallic phase material can also reinforce the internal structure of the cemented carbide material. If severe, sudden stresses occur, the crystals of the intermetallic phase material reduce or prevent the tungsten carbide particles from sliding in the area of the binder phase connecting them, and thus excessive plastic deformation of the binder phase. In particular, the individual crystals of the intermetallic phase material support one another. This has a significant advantage, particularly at high tool application temperatures, since the strength of the Co in the binder phase is reduced at such temperatures, but the intermetallic phase material still reliably provides sufficient support for the binder material.

Overall, it has been shown that a significant increase in the wear resistance of the sintered carbide material can be achieved with the solution according to the invention. Experiments have shown that, for example, the use of the sintered carbide material according to the invention in the form of a cutting tip of a pick for road milling machines results in up to 50% higher wear resistance! It has been shown that such a significant increase in wear resistance can be achieved both when milling asphalt and concrete road surfaces.

With the sintered carbide material according to the invention, the working areas of tools for machining, loosening, conveying and processing vegetable or mineral materials or building materials can be designed, in particular in the field of agriculture or forestry or road, mining or tunnel construction.

If intermetallic phase material is present in the sintered carbide material, it can be provided according to a variant of the invention that the proportion of metallic binder material in the sintered carbide material is 1-28% by weight, preferably 1-19% by weight. In addition to unavoidable impurities, the entire proportion or almost the entire proportion of this metallic binder material can be formed by Co. Such a choice of material leads to a particularly tough binder phase, which can be effectively reinforced by the existing or the forming intermetallic phase material.

According to a variant of the invention, it can be provided that the sum of the elements Ni and Al in the sintered carbide material is 1-28% by weight, preferably 1.5-19% by weight, at least in one area of the sintered carbide body. These ranges take into account both Ni and Al from intermetallic phase material that may be present and dissolved Ni or Al in the binder phase. With such compositions, it is possible in particular to create sophisticated hard metal tools for tilling the soil.

If there is little or no intermetallic phase material in the sintered carbide material, it can be provided according to a variant of the invention that the proportion of the binder phase in the sintered carbide material is 5-30% by weight, preferably 5-20% by weight. In this case, the binder phase can be predominantly formed by the metallic binder material Co. In addition, Al and Ni can be dissolved in the binder phase as metallic binder material. Finally, other elements and unavoidable impurities can also be present in the binder phase.

According to the invention, it can also be provided that, in addition to unavoidable impurities, the binder phase has other components, in particular dissolved W, C and/or Fe, in addition to Co, Ni, Al.

According to the invention, the intermetallic phase material optionally present in the binder phase is formed according to the structural formula (M,Y) ₃ (AI,X), or the intermetallic phase material can be formed according to this structural formula, due to the element composition in the finished sintered carbide material where M=Ni, Y=Co and/or other component and X=tungsten and/or other component.

If the intermetallic phase material is present in the binder phase, it is preferably the case that at least for the majority of the crystals of the intermetallic phase material Y=Co and X = W. Accordingly, the composition of the dissolved components in the binder phase in the cemented carbide material is selected in such a way that the intermetallic phase material can form as a result of heat treatment or exposure to heat (see above).

Additionally, some or all of the crystallites of the intermetallic phase material (Al,X) may be such that X is in the form of W as well as Mo and/or Nb and/or Ti and/or Ta and/or Cr and/or V is present. Correspondingly, the composition of the dissolved components in the binder phase in the finished cemented carbide material can be selected in such a way that the intermetallic phase material can be formed by heat treatment or exposure in this way (see above).

According to the invention, it can be provided that the binder phase has two or more intermetallic phase materials or only a single intermetallic phase material and/or that the sintered carbide material is prepared in such a way that two or more intermetallic phase materials or only forms a single intermetallic phase material.

• Ni > 35 Gew.%, AI > 5 Gew.%, Rest Co und gelöste Binderbestandteile, beispielsweise W und/oder C,
• besonders bevorzugt Ni >40, AI > 6,5 Gew. %, Rest Co und gelöste Binderbestandteile, beispielsweise W und/oder C,

According to a preferred embodiment of the invention, it can be provided that the binder phase has the following chemical element composition:

• Ni > 35% by weight, Al > 5% by weight, remainder Co and dissolved binder components, for example W and/or C,
• particularly preferably Ni>40, Al>6.5% by weight, remainder Co and dissolved binder components, for example W and/or C,

This information relates to the total content of the respective substances in the binder phase. The information therefore takes into account the respective elements in dissolved form and also the respective elements as they are bound in the intermetallic phase material.

It has been shown that an optimal reinforcing effect for the binder phase is achieved with the specified values.

In order to be able to bring about an optimal reinforcement of the binder phase with the intermetallic phase material, it can be provided within the scope of the invention that the ratio of the mass fractions Al to Ni is >0.10, preferably >0.12.

It can preferably also be provided that the ratio of the mass fractions Al to Ni is ≦0.46, preferably ≦0.18, particularly preferably ≦0.16.

The above information, which relates the ratio of the mass fractions Al to Ni, takes into account the total mass fraction, ie both the dissolved elements Al and Ni and Al and Ni in the intermetallic phase material (if present). The mass fractions of Al and Ni can be verified using a standard ICP measurement.

A conceivable variant of the invention is such that the sintered carbide material has at least two volume areas, the relative proportion of intermetallic phase material, based on a volume unit, being greater in the first volume area than in the second volume area. By designing at least two volume areas, the properties, in particular the tool properties, of the sintered carbide material can be influenced in a targeted manner. For example, a zone subject to high abrasive wear may have the volume region with a higher relative proportion of intermetallic phase material. A zone which, in contrast, has to meet special toughness requirements can have the volume range with a lower relative proportion of intermetallic phase material. For the sake of completeness, it should be pointed out at this point that the second volume area, which has a lower relative proportion of intermetallic phase material compared to the first volume area, that this second volume area can also have no intermetallic phase material.

A conceivable alternative of the invention is such that the first volume region, which has the high relative proportion of intermetallic phase material, is delimited by at least one region of the surface of the sintered carbide material. In this way, a high resistance to abrasion is created on the surface of the cemented carbide material there. The second volume region is preferably not arranged adjacent to a surface of the cemented carbide material, but is located in the interior of the cemented carbide material. Here he ensured a high fracture resistance.

Alternatively, it can also be provided that the second volume area, which compared to the first volume area has a lower relative proportion of intermetallic phase material or no intermetallic phase material, is delimited by at least one area of the surface of the sintered carbide material and preferably the first volume area is not bounded by a surface of the cemented carbide material. In this way, a tool can be created that adapts its cutting contour to the cutting task in an optimal manner while the tool is being used, in order to achieve an optimal service life. In particular, a so-called re-sharpening effect can be realized as a result.

A conceivable variant of the invention is such that the binder phase, in particular the metallic binder material and/or the intermetallic phase material, Nb and/or Ti and/or Ta, and/or Mo and/or V and/or Cr, preferably one or more of these materials is in the dissolved form in the binder phase and/or in the carbide form. In this way, an increase in the solvus temperature and the strength of the intermetallic phase that is present and/or that is formed as a result of thermal action or treatment can be achieved. As a result, less intermetallic phase material is required while the strength of the sintered carbide material remains the same. Or the binder strength increases as a result of the addition and thus the high-temperature strength.

However, it is also conceivable that one or more of the aforementioned components is/are integrated into the crystal lattice of at least part of the intermetallic phase material or can be integrated into the crystal lattice of the intermetallic phase material by the thermal treatment (heat treatment or exposure to heat). For example, the titanium atom (or another material from the aforementioned group) in the crystal lattice of the intermetallic phase material primarily occupies the lattice site of Al or W and, like W, increases the precipitation temperature for the intermetallic phase material.

As a result, if present in the sintered carbide material, the intermetallic phase material can be precipitated more effectively during the sintering process, since the precipitations start at higher temperatures and since the diffusion rate is significantly higher here.

On the other hand, this measure achieves high heat resistance, since, as mentioned, the solvus temperature of the sintered carbide material is increased. In other words, the temperature required to redissolve the intermetallic phase material in the cemented carbide material increases.

According to the invention, it can also be provided that the proportion of Mo and/or Nb and/or Ti and/or Ta and/or Cr and/or V in the binder phase is ≦15 at%. The elements mentioned above basically form carbides. In the context of the invention, it can now be provided that the material composition is selected such that these elements, depending on the solubility product and their affinity for carbon, are dissolved in small amounts in the binder phase and they can thus be incorporated into the crystal lattice of the intermetallic phase material and/or dissolved in the metallic binder phase. If a cemented carbide material is desired that has a high toughness of the binder phase, then the proportion of the carbide form should be kept small. The materials should then be present in a total proportion of ≦15 at%.

Furthermore, it is advantageous that the powder mixture for the production of the sintered carbide material can be set stoichiometrically with regard to the carbon content, since the titanium (and/or Mo and/or Nb and/or Ti and/or Ta and/or Cr and/or V ) takes over the task of tungsten.

According to a design variant of the invention, it can be provided that the proportion of carbon is set stoichiometrically or sub-stoichiometrically. With this measure, graphite precipitations in the sintered material are prevented or minimized due to the over-stoichiometric carbon content. The inventors have recognized that such inclusions have an adverse effect on the breaking strength of the sintered carbide material.

vorzugsweise im Bereich zwischen: $$\begin{array}{l}{\text{C}}_{\text{st}\ddot{\text{o}}\text{ch}}\left(\text{Gew}\text{.\%}\right)-\mathrm{0,005}\text{ mal Bindergehalt }\left(\text{Gew}\text{.\%}\right){\text{ und C}}_{\text{st}\ddot{\text{o}}\text{ch}}\left(\text{Gew}\text{.\%}\right)-\mathrm{0,01}\text{ mal}\\ \text{Bindergehalt Gew}\text{.\% betr}\ddot{\text{a}}\text{gt}\text{.}\end{array}$$

According to the invention, it can be provided in particular that the proportion of carbon in the sintered carbide material is in the range between: $$\begin{array}{l}{\text{C}}_{\text{St}\ddot{\text{O}}\text{ch}}\left(\text{weight}\text{.\%}\right)-0.003\text{times binder content}\left(\text{weight}\text{.\%}\right){\text{and c}}_{\text{St}\ddot{\text{O}}\text{ch}}\left(\text{weight}\text{.\%}\right)-0.012\text{times}\\ \text{binder content wt}\text{.\% re}\ddot{\text{a}}\text{>}\text{,}\end{array}$$

preferably in the range between: $$\begin{array}{l}{\text{C}}_{\text{St}\ddot{\text{O}}\text{ch}}\left(\text{weight}\text{.\%}\right)-0.005\text{times binder content}\left(\text{weight}\text{.\%}\right){\text{and c}}_{\text{St}\ddot{\text{O}}\text{ch}}\left(\text{weight}\text{.\%}\right)-0.01\text{times}\\ \text{binder content wt}\text{.\% re}\ddot{\text{a}}\text{>}\text{.}\end{array}$$

In the context of the invention, the advantageous effects described above are particularly pronounced in the case of coarse-grain hard metal. In a preferred embodiment of the invention, it is therefore provided that the dispersed tungsten carbide in the sintered carbide material is in grain form with an average particle diameter, measured according to DIN ISO 4499 Part 2, in the range between 1 and 15 μm, preferably in the range between 1.3 and 10 μm, particularly preferably in the range between 2.5 and 6 μm.

Provision is preferably made for the maximum proportion of Fe in the binder phase to be 5% by weight and/or for other unavoidable impurities to be present in the binder material.

If it is provided that the intermetallic phase (M,Y) ₃ (Al,X) present or resulting from heat treatment or exposure has a crystal structure L1 ₂ (space group 221) according to ICSD (Inorganic Crystal Structure Database), then results A microstructure develops in the binder phase in which the crystals of the intermetallic phase can effectively support each other in the metallic binder material when the sintered carbide body is subjected to heavy loads.

It is preferably provided for the purpose of use, preferably soil preparation tools, that the intermetallic phase material that is present or that results from heat treatment or heat treatment has a maximum size of 1500 nm, preferably a maximum size of 1000 nm.

According to a preferred embodiment variant of the invention, it can be provided that the sintered carbide material is free or as free as possible of eta phase and/or Al ₂ O ₃ . The inventors have recognized that the maximum proportion of the eta phase or the maximum proportion of Al ₂ O ₃ should be a maximum of 0.6% by volume based on the total sintered carbide material. If both substances are present in the sintered carbide material, it is advantageous if the sum of eta phase material and Al ₂ O ₃ . is a maximum of 0.6% by volume.

The particle size of Al ₂ O ₃ and / or the eta phase material is advantageously a maximum of 5 times the average WC grain size, the average WC grain size and the particle size of Al ₂ O ₃ and / or the eta phase material using the line intersection method DIN ISO 4499, Part 2 can be determined.

The toughness of the sintered carbide material can be negatively influenced by the eta phase or Al ₂ O ₃ . With higher eta phase proportions, the sintered carbide material is only conditionally suitable for use in demanding tillage tools. The same also applies to Al ₂ O ₃ .

The above-mentioned object of the invention is also achieved with a tool, in particular a comminuting, soil-working tool, preferably for a road milling machine, a recycler, a stabilizer, an agricultural or forestry soil-working machine, with a base body that has a working area, with at least a working element consisting of a sintered carbide material according to one of Claims 1 to 17, preferably with a material connection, in particular a soldered connection, in particular a hard-soldered connection, is held.

The cemented carbide material preferably forms a cutting body with a cutting tip or a cutting edge or a cutting edge or a working edge in the working area. It is also conceivable that the sintered carbide material is an armored coating.

As mentioned above, it can be provided according to the invention that the working element is in the form of a cutting element, preferably with at least one cutting edge and/or at least one cutting tip, or in the form of a wear protection element, in particular a protective plate, a protective strip, a protective pin, a Protective projection or a protective bolt is formed.

A particularly preferred application of the invention results when it is provided that the tool is a cutting tool, a milling tool, in particular a road milling or mining tool, a ploughshare, a cultivator tip, a drilling tool, in particular an earth auger, a crushing tool, for example a crushing chisel or a crushing bar, a mulching tool, a wood chipping tool or a shredding tool, a fractionating tool, for example a sieve.

A further particularly preferred application of the invention is such that the milling chisel has a chisel head and a chisel shank directly or indirectly connected thereto, and that the working element is held on the chisel head.

For example, it can also be provided that the working element is formed from the sintered carbide material according to the invention, with this working element forming a carrier for a super-hard cutting tip, which consists, for example, of PCD material.

As described above, the cemented carbide material may be a hard metal with a reinforced binder phase. This reinforcement can take place through the precipitation of intermetallic phase material during cooling in the sintering process and/or it is such that the intermetallic phase material is formed in a thermal process subsequent to the sintering process, in which the cemented carbide material is brought to a temperature that allows precipitation of the intermetallic phase material in the cemented carbide material.

For the production of a cemented carbide according to the invention, a nominal composition of 70-95% by weight of WC, 1-28% by weight of metallic binder and 1-28% by weight of intermetallic phase can be selected when the raw materials are weighed. The metallic binder can contain the elements Co and optionally Fe and/or other components. The intermetallic phase is Ni ₃ Al when weighed out.

• Ni > 25 Gew.%, AI > 4 Gew.%, Rest Co und gelöste Binderbestandteile, beispielsweise W und/oder C,
• wobei in einem weiteren Verfahrensschritt das Vorstufen-Sinterkarbid-Material einer Wärmebehandlung unterzogen wird, um ein Sinterkarbid-Material zu bilden, das intermetallisches Phasenmaterial in der Binderphase aufweist, wobei das intermetallische Phasenmaterial nach der Strukturformel (M,Y)₃(Al,X) gebildet ist,
• wobei M = Ni, Y=Co und/oder ein sonstiger Bestandteil ist und X=Wolfram und/oder ein sonstiger Bestandteil ist.

The object of the invention is also achieved with a method for creating a sintered carbide material, with a preliminary sintered carbide material, in particular a hard metal, being created in a first method step, which contains 70-95% by weight, preferably 80-95 % by weight, tungsten carbide in dispersed form, and having a binder phase, the binder phase having metallic binder material, the metallic binder material having Co, the binder phase having the dissolved elements Ni and Al, the binder phase having the following chemical element composition:

• Ni > 25% by weight, Al > 4% by weight, remainder Co and dissolved binder components, for example W and/or C,
• in a further process step the precursor cemented carbide material is subjected to a heat treatment to form a cemented carbide material having intermetallic phase material in the binder phase, the intermetallic phase material having the structural formula (M,Y) ₃ (Al,X) is formed
• where M=Ni, Y=Co and/or other component and X=tungsten and/or other component.

The thermal treatment can include at least one heating step or at least one cooling step.

According to the invention, provision can preferably be made for at least some of the crystals of the intermetallic phase material (M,Y) ₃ (Al,X) to have the crystal structure L12 (space group 221) according to ICSD (Inorganic Crystal Structure Database) after the heat treatment.

In order to be able to achieve a particularly effective reinforcement of the binder phase, in particular with coarse-grain hard metal as the sintered carbide material, it can advantageously be provided that at least part of the intermetallic phase material has a maximum size of 1500 nm, preferably a maximum size of 1000 nm (measured according to the line intersection method at a micrograph).

vorzugsweise $$\text{HcM }\left[\text{kA}/\text{m}\right]>\left(\mathrm{1,5}+\mathrm{0,04}*\text{B}\right)+\left(\mathrm{12,5}-\mathrm{0,5}*\text{B}\right)/\text{D}+6\left[\text{kA}/\text{m}\right],$$

besonders bevorzugt $$\text{HcM }\left[\text{kA}/\text{m}\right]>\left(\mathrm{1,5}+\mathrm{0,04}*\text{B}\right)+\left(\mathrm{12,5}-\mathrm{0,5}*\text{B}\right)/\text{D}+10\left[\text{kA}/\text{m}\right],$$

wobei B der Anteil der Binderphase im Sinterkarbid-Material in Gew% ist und D die Korngröße des dispergierten WC, ermittelt nach dem Linienschnittverfahren gemäß DIN ISO 4499, Teil 2 ist.It can advantageously be provided that the coercive field strength HcM of at least one region, preferably a region in which intermetallic phase material is present, of the sintered carbide material produced using the method according to the invention is: $$\text{HcM}\left[\text{no}/\text{m}\right]>\left(1.5+0.04*\text{B}\right)+\left(12.5-0.5*\text{B}\right)/\text{D}+4\left[\text{no}/\text{m}\right],$$

preferably $$\text{HcM}\left[\text{no}/\text{m}\right]>\left(1.5+0.04*\text{B}\right)+\left(12.5-0.5*\text{B}\right)/\text{D}+6\left[\text{no}/\text{m}\right],$$

particularly preferred $$\text{HcM}\left[\text{no}/\text{m}\right]>\left(1.5+0.04*\text{B}\right)+\left(12.5-0.5*\text{B}\right)/\text{D}+10\left[\text{no}/\text{m}\right],$$

where B is the proportion of the binder phase in the sintered carbide material in % by weight and D is the particle size of the dispersed WC, determined using the line intersection method in accordance with DIN ISO 4499, part 2.

With common hard metals, with Co in the binder phase and without intermetallic phase material, the coercive field strength is usually used to indirectly determine the average grain size of the WC for a given binder content.

According to the invention, the intermetallic phase material brings about a significant increase in the coercive field strength. The coercive field strength can thus be evaluated indirectly as a measure of the strengthening of the binder phase as a result of the embedded intermetallic phase material. The higher the coercivity, the larger the total interface between metallic binder material, intermetallic phase material and WC. A high number of precipitated intermetallic phase material leads to a good support of the individual crystals of the intermetallic phase material against each other in the binder phase, especially at high temperatures (especially at high tool application temperatures).

Coercive field strengths of at least one area of the sintered carbide material HCM [kA/m]>(1.5+0.04*B)+(12.5-0.5*B)/D+4 [kA/m] can primarily be used are, for the wear protection applications mentioned above, for example for wear armor.

Coercive field strengths of at least one area of the sintered carbide material, preferably HCM [kA/m] > (1.5 + 0.04*B) + (12.5-0.5*B)/D + 6 [kA/m] can primarily be used for the above-mentioned demanding tillage tools.

Coercive field strengths of at least one area of the sintered carbide material, preferably HCM [kA/m] > (1.5 + 0.04*B) + (12.5-0.5*B)/D + 10 [kA/m] can primarily be used for the high-performance tools mentioned above.

According to one embodiment variant of the invention, it can also be provided that the coercive field strength of at least one area of the sintered carbide material is 20% higher than the coercive field strength of a hard metal body that has the same composition and WC grain size as the sintered carbide material, with the binder phase alone is formed of metallic Co binder; however, this has no intermetallic phase material.

A cemented carbide body having the same composition is therefore a cemented carbide body with 70-95% by weight of tungsten carbide in dispersed form and a binder phase, the binder phase having metallic binder material without intermetallic phase material, the proportion of metallic binder material in the sintered carbide material is 5-30% by weight and the binder material otherwise has the same or approximately the same composition as the binder material of the sintered carbide material according to the invention.

As mentioned above, the coercivity indirectly gives an indication of the proportion of intermetallic phase material in the binder phase. Thus, the degree of reinforcement of the binder phase is indirectly indicated with the coercive field strength.

Within the scope of the invention, the sintered carbide material can be designed in such a way that the hot compressive strength of the sintered carbide material produced using the method according to the invention is ≧1650 [MPa] at a temperature of 800° C. and a strain rate of 0.001 [1/s] and/ or that the hot compressive strength of the cemented carbide material at a temperature of 800 °C and a strain rate of 0.01 [1/s] ≥ 1600 [MPa] (measurement for a cylindrical specimen with a diameter of 8 mm and a height of 12 mm). Such a sintered carbide material can be used, in particular, to manufacture cutting tips for road milling tools in which the proportion of metallic binder material in the binder phase is 5-7% by weight and the proportion of WC is in the range of 93-95% by weight, with preference being given to here WC is present in coarse grain form with an average particle size in the range between 2-5 μm.

Production (with description of the measurement methods)

Manufacturing:

The following describes the manufacturing method by which a cemented carbide material with intermetallic phase material in the binder phase can be manufactured via a powder metallurgical process routine. The latter is divided into the process steps of producing a compressible powder mixture, shaping and finally sintering to form compact and dense sintered carbide bodies.

WC powders of different grain sizes can be used as starting materials for the production of the powder mixture, in particular coarse-grain WC with a particle size FSSS > 25 µm. Starting powders for the binder phase are extra-fine cobalt powder (FSSS 1.3 µm) and nickel-aluminum powder, for example Ni-13AI powder with an aluminum content of approx. 13.3% by weight. The particle size of the Ni-Al powder is FSSS<70 μm, preferably less than FSSS 45 μm. W metal powder (FSSS < 2 µm) and lamp black are used to set and adjust a specific carbon content. To alloy the binder phase with alloying elements such as Ti, Ta, Mo, Nb, V, Cr, their carbide powder or their W-containing mixed carbides with particle sizes < 3 µm are used.

The powder mixture is produced according to the state of the art by wet grinding, preferably in a ball mill fitted with hard metal balls. Ethanol and hexane are used as grinding media. Other possible grinding media would be acetone or aqueous media with suitable inhibitors.

When producing powder mixtures for sintered carbide material with a binder content of >15%, a single grinding process is sufficient due to the high binder content and promoted recrystallization. With binder contents of up to 15%, on the other hand, a multi-stage wet grinding process is advantageous in order to effectively crush the Ni-Al powder and minimize the formation of oxides during the grinding process.

In the first step, the Ni-Al powder is intensively mixed with grinding liquid and coarse-grain tungsten carbide with an average particle size FSSS>20 µm, preferably between 30 and 60 µm. If necessary, pressing aids, small amounts of alloying components and cobalt powder can also be added here.

The grinding parameters (duration, ratio of grinding balls to material to be ground, grinding medium) and the ratio of WC to Ni-Al powder are based on the WC grain size to be set in the sintered carbide material.

In the second step, between 50 and 80% by weight WC raw material(s) of defined grain size(s) are added to this pre-grinding and mixed, with the main focus being on reducing agglomerates and obtaining a mixture that is as homogeneous as possible.

If the alloy adjustment and the addition of the pressing aid have not already been carried out in the first grinding step (pre-grinding VM), this can also be done in the second step.

The slip obtained during wet grinding is dried according to the state of the art and converted into a powder ready for pressing. This is preferably done by the process of spray drying.

Shaping is preferably done directly, by axial pressing on mechanical, hydraulic or electromechanical presses.

Sintering takes place between 1350 and 1550 °C in a vacuum, preferably in industrial sinter-HIP furnaces, in which, following liquid-phase sintering, an overpressure is created by means of an inert gas inlet, with any residual porosity being able to be eliminated.

In 1 the phase diagram WC-Co-Ni ₃ Al for 3% by weight Co and 3% by weight Ni ₃ Al is shown as an example, which shows the formation of these precipitates.

After the melt has solidified, initially only WC and a mixed crystal of Co, Ni, Al, W and C are present. Only below the solvus temperature does the intermetallic phase material separate from this mixed crystal, the intermetallic phase material being formed according to the structural formula (M,Y) ₃ (Al,X), where M=Ni, Y=Co and/or a other component is and X=tungsten and/or a other component is. These intermetallic phase materials can be visualized with a scanning electron microscope.

In 2 and 3 two different sintered carbide materials according to the invention, in the form of hard metals, are illustrated on the basis of such scanning electron microscope images. The binder phase of such a hard metal can be clearly seen, in which the intermetallic phase material (lighter phase) 10 and the metallic binder material 30 (dark) can be seen. The WC grains 20 are connected to one another via the binder phase.

There is a uniform distribution of the intermetallic phase material in the binder phase, with the crystals of the intermetallic phase material having a cubic shape and preferably being smaller than 1500 nm. The crystals of the intermetallic phase material (M,Y) ₃ (Al,X) have a crystal structure L1 ₂ (space group 221) according to ICSD (Inorganic Crystal Structure Database).

Such cemented carbide material can be bonded to a steel body to form a working element of a tool, e.g. a crusher, tillage tool, preferably for a road milling machine, a recycler, a stabilizer, an agricultural or forestry tillage machine. In this case, this working element is then arranged in the working area of the tool. The connection to the base body is made with a soldered connection, in particular a hard-soldered connection. Heat is introduced into the tool to create the soldered joint. The tool is then quenched, e.g. in a water-oil emulsion.

During the soldering process, the intermetallic phase material is at least partially dissolved again, so that components of the intermetallic phase material are present as dissolved components in the sintered carbide material after quench hardening. Thus, a precursor cemented carbide material is formed in this way.

This precursor sintered carbide material is then subjected to a thermal treatment, as has already been described several times above. It can be the case that heat is introduced into the sintered carbide material via the thermal treatment, with the temperature being below the solvus temperature and preferably above 400 degrees Celsius. The treatment duration, ie the time within which the thermal treatment takes place, is in the range between 0.25 and 24 hours. During the thermal treatment, intermetallic phase material forms again, at least in some areas in the sintered carbide material, in order to strengthen the binder phase.

The thermal treatment can be an active process in which heat is introduced into the sintered carbide material in a targeted manner by means of a heat source. It is preferably the case that the heat treatment takes place passively, with the precursor cemented carbide material coming into contact with the workpiece to be machined, for example a road surface of a road, for example during use of the tool. This contact introduces heat into the precursor cemented carbide material to bring it to a temperature at which the intermetallic phase material forms. In this way, the tool is automatically strengthened according to the invention, with the sintered carbide material according to the invention being formed in the area subject to wear.

It is also conceivable that a sintered carbide material designed in the manner described above is manufactured in a sintering process in which intermetallic phases are formed. This product can then be brought to a temperature, preferably above the solvus temperature, at which the intermetallic phase material at least partially dissolves again. Then this material is quenched to form the precursor cemented carbide material. Then, the precursor cemented carbide material is subjected to a heat treatment to form the cemented carbide material of the present invention.

In order to be able to easily separate the intermetallic phase material in the binder phase, it can preferably be provided that the (M,Y) ₃ (Al,X) content in the binder phase is ≧40% and the carbon balance is adjusted to be stoichiometric or substoichiometric.

It has been shown that a higher tungsten solution in the binder stabilizes the precipitation of the intermetallic phase material. This is due to the incorporation of "Co3W" into the crystal structure of the intermetallic phase material and the shift of the precipitation range towards higher temperatures.

The elements Mo, Nb, Cr, V and in particular Ti, Ta, which can be alloyed in small amounts (<15 at.% in the binder), also show a similar effect here.

The amount of alloy that can be used depends on the respective solubility product of the metal carbides. Even if these seem negligible in terms of their magnitude, there are surprisingly clear effects that cannot be attributed to a grain-refining effect.

Due to the increased stability and the better precipitation behavior through the alloying of other elements, the proportion of intermetallic phase material in the binder can be reduced and even be below 40%. Furthermore, in the presence of Ti or Ta, for example, the carbon balance no longer has to be substoichiometric, because these elements take over the role of tungsten as a stabilizer.

The effect of the precipitation of the intermetallic phase material on the high-temperature strength can be impressively demonstrated by means of high-temperature compression tests. 4 shows the hot compressive strength of hard metals with 6% binder each at different test temperatures and strain rates. Especially at a test temperature of 800°C, the strength is increased by about 40-50% due to the intermetallic phase material.

Physical parameters are determined on the sintered carbide material samples according to the invention, which help to characterize the material and its properties.

In the case of hard metals, the determination of the coercive field strength H _cM and the specific magnetic saturation 4ps have established themselves as non-destructive testing methods.

Both measured variables are also determined for the characterization of the sintered carbide material according to the invention on a Koerzimat® 1.097 from Förster.

Another parameter for characterizing the material is the density, which is determined by weighing according to the Archimedean principle.

The hardness of the material is determined according to the standard applicable to hard metals on metallographically prepared polished samples. The Vickers HV10 hardness test with a test load of 10 kp is preferably used (ISO 3878).

The porosity of the sintered material (standard DIN-ISO 4499-4) and aluminum oxide particles are also determined and assessed using a light microscope on polished samples. To estimate the percentage by volume of aluminum oxide in the structure, comparison images for A and B porosity can be used, with A08 and B08 approximately corresponding to a volume percentage of 0.6% by volume. For light microscopic examination of the eta phase, this is etched with Murakami solution in accordance with the standard (DIN-ISO 4499-4). The average WC grain sizes are determined according to DIN ISO 4499-2. Here, REM (scanning electron microscope) images are evaluated using the line intersection method.

The proportions of the intermetallic phase in the binder and the maximum size of the separated particles are also determined using SEM images, but using an in-lense BSE detector. For this purpose, recordings are made at several points on the sample and the evaluation is carried out on a representative section by means of image processing and determination of the surface areas through tonal value delimitation.

Examples:

The following table shows examples of cemented carbide bodies according to the invention. In principle, the examples shown in this table can be manufactured using the same process as described above: 1 6% binder, of which approx. 50% is intermetallic phase, raw materials without carbon correction 2 6% binder, of which approx. 50% is intermetallic phase, addition of tungsten metal powder 3 6% binder, of which approx. 50% is intermetallic phase, addition of carbon black 4 6% binder, of which approx. 40% is intermetallic phase, raw materials without carbon correction 5 6% binder, of which approx. 50% is intermetallic phase, addition of WTiC 6 8.5% binder, of which approx. 40% is intermetallic phase, raw materials without carbon correction 7 15% binder, of which approx. 50% is intermetallic phase, raw materials without carbon correction 8th Small series with 6% binder, of which approx. 50% is intermetallic phase, addition of tungsten metal powder Reference, not according to the invention 6% binder, only cobalt, milling conditions comparable to Examples 1-8 6-50 6-50 C 6-50C+ 6-40 6-50 ti 8:5-40 15-50 6-50 C-S 6-0 designation example 1 example 2 Example 3 example 4 Example 5 Example 6 Example 7 example 8 reference pre-grinding material size [kg] [kg] [kg] [kg] [kg] [kg] [kg] [kg] [kg] weight Ni-13Al -325 mesh 0.120 0.120 0.120 0.096 0.120 0.240 0.240 9,000 co FSSS 1.3µm 0.120 0.120 0.120 0.144 0.120 9,000 0.240 WC FSSS 25µm 0.760 0.760 0.760 0.760 0.740 0.760 0.760 57,000 0.760 WTiC 50:50 FSSS 1.7µm 0.020 In total 1 1 1 1 1 1 1 75 1 grinding parameters grinding time [H] 24 24 24 24 24 24 24 7 24 Ratio of grinding ball to material to be ground 5:1 5:1 5:1 5:1 5:1 5:1 5:1 6.7:1 5:1 finish grind material [kg] [kg] [kg] [kg] [kg] [kg] [kg] [kg] [kg] weight VM 0.25 0.25 0.25 0.25 0.25 0.142 0.313 37.5 0.25 co FSSS 1.3µm 0.051 0.075 WC FSSS 25µm 0.75 0.745 0.75 0.75 0.75 0.807 0.612 111.7 0.75 W metal FSSS 2µm 0.005 0.8 soot 0.0003 In total 1 1 1 1 1 1 1 150 1 grinding parameters grinding time [H] 8th 8th 8th 8th 8th 8th 8th 6 10 Ratio of grinding ball to material to be ground 5:1 5:1 5:1 5:1 5:1 5:1 5:1 3.3:1 5:1 parameters Sinter-HIP vacuum furnace system: vacuum dewaxing, vacuum sintering/argon partial pressure, sintering temperature 1430°C 1h +30' high pressure 50 bar, cooling under pressure, cooling time in the temperature interval 900-600° approx. 40 min coercivity _HcM [came] 21:9 25.5 15.1 11.5 25.3 11.7 20.4 28.7 5.2 spec magn. saturation 4πσ [µTm ³ /kg] 5.8 5.1 6.6 7.1 5.4 10.0 13.9 4.9 11.5 hardness HV10 1200 1220 1170 1160 1205 1080 910 1250 1150 density ρ [g/cm ³ ] 14.83 14.87 14.82 14.85 14.83 14.53 13.75 14.82 14.91 porosity ISO 4499-4 <A02, B00, C00 <A02, B00, C00 <A02, B00, C00 <A02, B00, C00 <A02, B00, C00 <A02, B00, C00 <A02, B00, C00 <A02, B00, C00 <A02, B00, C00 Grain size WC ISO 4499-2 3 2.9 3.1 3.2 2.9 3 3.1 2.4 3.1 hot compressive strength* [MPa] 1930 1380 eta phase no no no no no no no no aluminum oxide no no no no no no <0.1vol% <0.05 vol% Binder content in the carbide (weight) [m%] 6 6 6 6 6 8.5 15 6 6 share interm. phase to binder** [%] 46% 48% 39% 35% 49% 35% 47% 52% - maximum size of the intermetallic phase [nm] <150 <150 <150 <150 <150 <150 <150 <100 - * Non-standard comparison test with samples ⌀8×12mm, test temperature 800°C, strain rate 0.0011/s
** Evaluation of surface areas based on tonal value delimitation in the micrograph. Calibration with solution annealed and isothermally aged at 700°/10h samples of the same composition.

Accordingly, the invention relates to a sintered carbide material, in particular hard metal, with 70-95% by weight, preferably with 80-95% by weight, tungsten carbide in dispersed form, and a binder phase, the binder phase having metallic binder material, wherein the metallic binder material comprises Co, dissolved Ni and dissolved Al, wherein the binder phase may optionally comprise intermetallic phase material, the intermetallic phase material, if present, being formed according to the structural formula (M,Y) ₃ (Al,X), where M=Ni , Y=Co and/or another component and X=tungsten and/or another component, the binder phase having the following chemical element composition: Ni> 25% by weight, AI> 4% by weight, remainder Co and dissolved binder components, e.g. W and/or C.

• 5 einen Vertikalschnitt durch eine Meißelspitze,
• 6 die Meißelspitze gemäß 5 entlang des in 5 mit VI-VI markierten Schnittverlaufs und
• 7 bis 12 die Meißelspitze 50 gemäß den 5 bis 6 im Vertikalschnitt, jedoch mit einer veränderten Gefüge-Zusammensetzung.

The invention is described below with reference to the 5 until 12 embodiments shown explained in more detail. Show it:

• 5 a vertical section through a chisel tip,
• 6 the chisel tip according to 5 along the in 5 with VI-VI marked cutting course and
• 7 until 12 the chisel point 50 according to the 5 until 6 in vertical section, but with a different structure.

In the 5 until 12 chisel tips 50 in the form of a cemented carbide material 40 are shown. These chisel tips 50 are advantageously used on a cutting tool, in particular a cutting chisel, a pick, a road milling chisel, a mining chisel or the like.

The chisel tip 50 is designed and prepared to be connected, preferably soldered, to a steel body. For this purpose, the steel body usually has a head on which a shank, preferably a round shank, is integrally formed. Away from the shank, the head has a receptacle for the chisel tip 50 . The chisel tip 50 can be fastened in or on this receptacle.

The chisel tip 50 is made in one piece and has a base part 51 . The chisel point 50 can be connected to the steel body with the base part 51 . The base part 51 preferably has a connecting surface 51.1. To attach the chisel point 50 to the steel body, the soldering material of a hard-soldered connection can be arranged between the connecting surface 51.1 and the steel body.

In order to keep the thickness of the solder gap between the chisel point 50 and the steel body as constant as possible, it can be provided that in the area of the connecting surface 51.1 spacers 51.2 are formed on the chisel point 50, which protrude beyond the connecting surface 51.1 and which are designed to Put on steel body, such that the connecting surface 51.1 is kept for the soldering process at a distance from a counter-surface of the steel body.

Provision can furthermore be made for one or more indentations 52 to be present in the area of the connecting surface 51.1. In this case, the indentation can preferably be such that it transitions via a convex rounding from the connecting surface 51.1 into a recessed section which is advantageously designed as a concave trough. The material requirement for the chisel tip 50 can be reduced with the indentation 52 . In addition, the depression 52 forms a reservoir for excess solder material in the area of the connecting surface 51.1.

The base part 51 has a preferably circumferential edge 51.3, which can be designed as a convex shape at least in some areas. The edge 51.3 can be designed as a transition between the base part 51 and a transition section 53.

The transition section 53 has a first area which is designed as a concave area 53.1. Alternatively, a truncated cone-shaped geometry or a combination consisting of a concave area 53.1 and a truncated cone-shaped geometry, at least in some areas, can also be provided. With the first.

The chisel point 50 is tapered in the direction of the base part 51 towards a tip 54 of the chisel point 50 in the area.

The transition section 53 can furthermore also have a cylindrical area 53.2, which adjoins the first area opposite the base part 51. Preferably, the transition, at least in areas of the chisel tip 50, between the first area and the cylindrical area is continuous, preferably continuously differentiable in the direction of the central longitudinal axis of the chisel tip, so that jumps in continuity are avoided, such as the 5 indicates.

The chisel tip 50 can preferably have indentations 53.3 in the region of the transition section 53. These are used to reduce material and to optimize the removal of soil material that is removed during tool use.

The chisel tip 50 has a tip 54 which adjoins the transition section 53, preferably the cylindrical area 53.2. The connecting section 54.1 can be designed as a convex curvature. The connecting section 54.1 is followed by a tapering section 54.2, which merges into an end section 54.3. The end section 54.3 is preferably in the form of a convex curvature, particularly preferably in the form of a spherical cap.

6 shows the chisel tip 50 in section and in a top view. The indentations 53.3 are arranged evenly distributed over the circumference of the chisel tip 50 and can be clearly seen.

The chisel tip 50 has at least one 1st volume area 70 and at least one 2nd volume area 60 .

In the second volume region 60, the sintered carbide material 40 has tungsten carbide grains (WC grains) 20, which are connected to one another via metallic binder material 30 of a binder phase. Provision can be made for no intermetallic phase material 10 or intermetallic phase material 10 to be present in the 2nd volume region 60, preferably in a concentration of less than 30% by weight/volume unit, preferably less than 25% by weight/volume unit, particularly preferably less than 15% by weight .% / volume unit, is present.

In the 1st volume region 70 the sintered carbide material 40 has tungsten carbide grains (WC grains) 20 which are connected to one another via metallic binder material 30 of a binder phase. In the 1st volume region 70 is intermetallic phase material 10, preferably in a concentration ≥ 30% by weight/volume unit, preferably in the range between 30-70% by weight/volume unit, particularly preferably in the range between 35-60% by weight/volume unit, more preferably in the range between 40-50% by weight/volume.

The intermetallic phase material is formed according to the structural formula (M,Y) ₃ (Al,X), where M=Ni, Y=Co and/or other component and X=tungsten and/or other component. The binder phase has the following chemical element composition: Ni > 25% by weight, Al > 4% by weight, remainder Co and dissolved binder components, for example W and/or C.

The relative proportion Y of intermetallic phase material, based on a unit volume, in the first volume region 70 is greater than in the second volume region 60.

As the drawings show, the first volume region 70 and the second volume region 60 may be bounded by at least a portion of the surface of the cemented carbide material 40 .

The first volume region 70, which has the relatively higher proportion of intermetallic phase material 10, forms part of the surface of the chisel tip 50, in particular at the tip 54 at the tapering section 54.2 and/or at the end section 54.3.

Starting from the tip 54 it can then continue to be the case that the 1st volume region 70 extends up to the base part 51 . Preferably, the area of the base part 51 can also be formed by the second volume area 60 . The 2nd volume region 60 with the relatively lower content of intermetallic phase material 10 or without intermetallic phase material 10 is preferably arranged in the area of the transition section 53 . As 6 illustrated, it can also be the case that both the 1st Volume area 70 and the second volume area 60 in the area of the transition section 53 adjoin the surface of the chisel tip 50 .

• Dadurch, dass die Spitze 54 von dem 1. Volumenbereich 70 gebildet ist, wird hier in dem besonders verschleißgefährdeten Bereich eine hohe Abrasion-Festigkeit geboten.

The arrangement of the 1st and 2nd volume area 70, 60 according to the embodiment according to the 5 and 6 has the following technical advantages:

• Due to the fact that the tip 54 is formed by the 1st volume area 70, a high abrasion resistance is offered here in the area particularly at risk of wear.

In the area that is not at risk of wear, there is increased toughness and thus greater fracture stability.

Furthermore, it is conceivable that forms of wear can be set in a targeted manner with the volume areas 60, 70, which, for example, support resharpening of the chisel tip.

the 7 until 12 show further embodiment variants of a chisel point 50. The chisel point 50 is constructed essentially identically to the chisel point 50 according to FIGS 5 and 6 . In this respect, to avoid repetition, reference is made to the above statements and only the differences are discussed. The chisel tips 50 according to 7 until 12 differ in particular in the arrangement and design of the 1st and 2nd volume areas 70, 60.

As 7 As illustrated, the first volume region 70 is arranged in the region of the tip 54 and preferably partially in the cylindrical region 53.2 of the transition section 53. However, it is also conceivable that the 1st volume area 70 is only arranged in the area of the tip 54 . The first volume area 70 effectively protects against abrasive wear in the area of the tip 54 .

8th 1 illustrates that the 1st volume region 70 may be located wholly or partially within the chisel tip 50 . The first volume area 70 can be designed in such a way that it preferably extends in the direction of the central longitudinal axis of the chisel tip 50 over the entire area of the transition section 53 . As has already been mentioned above, the first volume region 70 is distinguished by a particularly high shearing strength as a result of the presence of intermetallic phase material 10 . In this way, the transition area 53 that is in danger of breaking is effectively reinforced with the first volume area 70 .

Conversely, it can also be like this 9 shows that the 2nd volume region 60 can be arranged completely or partially within the chisel point 50 . The 1st volume area 70 then preferably completely surrounds the 2nd volume area 60 . The 1st volume area completely or almost completely forms the surface of the chisel tip 50 in order to protect it particularly effectively from abrasion and to prevent the chisel tip 50 from breaking in the area of the transition section 53 . Due to the large extent transverse to the central longitudinal axis of the chisel tip 50, the 1st volume region 70 also offers a high equatorial section modulus against bending.

10 illustrates that it is in accordance with the variant in a further development 7 It can also be such that the 1st volume region 70 with its relatively high proportion of intermetallic phase material 10 can extend over the region of the tip 54 and the transition section 53 so that it preferably completely forms the surface of the tip 54 and the transition section. The 1st volume area 70 is brought up to the base part 51 or also out into the base part 51, as shown in FIG 10 illustrated.

11 shows that the 1st volume area 70 can also extend within the chisel tip 50 in such a way that it forms a continuous volume area, from the end section 54 3 of the tip 54 to the base part 51.

12 illustrates that it is the reverse of the embodiment according to FIG 5 and 6 it can also be provided that the 1st and the 2nd volume area 70, 60 are exchanged with one another.

The above drawings are to be understood as schematic representations. In particular, it is the case that the 1st or the 2nd volume area 70, 60 do not form exactly sharply delimited, as shown in the drawings, but rather form transition sections between the two volume areas 70, 60.

• Ni > 25 Gew.%, AI > 4 Gew.%, Rest Co und gelöste Binderbestandteile, beispielsweise W und/oder C.

For the production or formation of the 5 until 12 Sintered carbide materials 40 shown, a method is used according to the invention, with a preliminary sintered carbide material, in particular a hard metal, being created in a first method step, which contains 70-95% by weight, preferably 80-95% by weight, tungsten carbide in dispersed form, and having a binder phase. The binder phase has at least Co as the metallic binder material and the dissolved elements Ni and Al. The binder phase has the following chemical element composition:

• Ni > 25% by weight, Al > 4% by weight, remainder Co and dissolved binder components, for example W and/or C.

In a further process step, the precursor cemented carbide material is subjected to a heat treatment as explained above in order to form the cemented carbide material 40 which has intermetallic phase material 10 in the binder phase at least in the 1st volume region 70 . The intermetallic phase material 10 is formed according to the structural formula (M,Y) ₃ (Al,X), where M=Ni, Y=Co and/or other component and X=tungsten and/or other component.

For this purpose, in the further process step, the precursor cemented carbide material can be kept in a temperature range between 400° C. and the solvus temperature for a period in the range between 0.25 to hours during the heat treatment. For the specific formation of the individual volume areas 60, 70, for example, specific heating can be carried out by means of a laser or an induction coil.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 2691198 B1 [0002]

Claims (27)

Cemented carbide material (40), in particular hard metal, with 70-95% by weight, preferably with 80-95% by weight, tungsten carbide in dispersed form, and a binder phase, the binder phase having metallic binder material (30), the metallic binder material Co, wherein the binder phase has intermetallic phase material (10) and/or the dissolved elements Ni and Al, the intermetallic phase material (10), if present, being formed according to the structural formula (M,Y) ₃ (AI,X), where M=Ni, Y=Co and/or another component and X=tungsten and/or another component, the binder phase having the following chemical element composition: Ni > 25% by weight, Al > 4% by weight , remainder Co and dissolved binder components, for example W and/or C. cemented carbide material (40). claim 1 , characterized in that the binder phase has the following chemical element composition: Ni > 35% by weight, Al > 5% by weight, remainder Co and dissolved binder components, for example W and/or C, particularly preferably Ni > 40, Al > 6 .5% by weight, remainder Co and dissolved binder components, for example W and/or C. cemented carbide material (40). claim 1 or 2 , characterized in that the ratio of the mass fractions Al to Ni > 0.10, preferably > 0.12. Cemented carbide material (40) according to one of Claims 1 until 3 , characterized in that the proportion of Co in the sintered carbide material (40) is 1-28% by weight, preferably 1-19% by weight. Cemented carbide material according to any of Claims 1 until 4 , characterized in that the sum of the elements Ni and Al in the sintered carbide material (40) is 1-28% by weight, preferably 1.5-19% by weight, at least in a region of the sintered carbide body. Cemented carbide material according to any of Claims 1 until 5 , characterized in that the sintered carbide material (40) has at least two volume areas (60, 70), wherein the relative proportion of intermetallic phase material (10), based on a volume unit, is greater in the first volume area (70) than in the second volume area (60). cemented carbide material (40). claim 6 , characterized in that the first volume region (70) is delimited by at least one region of the surface of the cemented carbide material (40) and preferably the second volume region (60) does not border on a surface of the cemented carbide material (40), or that the second volume region (60) is bounded by at least a portion of the surface of the cemented carbide material (40) and preferably the first volume region (70) is not adjacent to a surface of the cemented carbide material (40). Cemented carbide material (40) according to one of Claims 1 until 7 , characterized in that the binder phase, in particular the metallic binder material (30) and/or the intermetallic phase material (10), Nb and/or Ti and/or Ta, and/or Mo and/or V and/or Cr, wherein preferably one or more of these materials is present in the dissolved form in the binder phase. Cemented carbide material (40) according to one of Claims 1 until 8th , characterized in that the proportion of carbon in the cemented carbide material (40) is adjusted to be stoichiometric or sub-stoichiometric. cemented carbide material (40). claim 9 , characterized in that the proportion of carbon in the sintered carbide material (40) is in the range between: Cstöch (% by weight) - 0.003*binder content (% by weight) and Cstöch (% by weight) - 0.012*binder content by weight, preferably in the range between: Cstöch (wt%) - 0.005*binder content (wt%) and Cstöch (wt%) - 0.01*binder content wt%. Cemented carbide material (40) according to one of Claims 1 until 10 , characterized in that the proportion of Mo and/or Nb and/or Ti and/or Ta and/or Cr and/or V in the binder phase is ≦15 at%. Cemented carbide material (40) according to one of Claims 1 until 11 , characterized in that the dispersed tungsten carbide (WC grains 20) in the sintered carbide material (40) in grain form with an average particle diameter, measured according to DIN ISO 4499 Part 2, in the range between 1 and 15 µm, preferably in the range between 1 3 and 10 μm, particularly preferably in the range between 2.5 and 6 μm. Cemented carbide material (40) according to one of Claims 1 until 12 , characterized in that the maximum proportion of Fe in the binder phase is <5% by weight and/or that other unavoidable impurities are present in the binder phase. Cemented carbide material (40) according to one of Claims 1 until 13 , characterized in that at least part of the crystals of the intermetallic phase material (M,Y) ₃ (AI,X) (10) has a crystal structure L12 (space group 221) according to ICSD (Inorganic Crystal Structure Database). Cemented carbide material (40) according to one of Claims 1 until 14 , characterized in that at least part of the intermetallic phase material (10) has a maximum size of 1500 nm, preferably a maximum size of 1000 nm (measured according to the line-intersection method on a micrograph). Cemented carbide material (40) according to one of Claims 1 until 15 , characterized in that the maximum proportion of the eta phase or the maximum proportion of Al ₂ O ₃ is a maximum of 0.6% by volume based on the entire cemented carbide material (40) or that the sum of eta phase material and Al ₂ O ₃ is a maximum of 0.6% by volume. Cemented carbide material (40) according to one of Claims 1 until 16 , characterized in that the average particle size of Al ₂ O ₃ and/or the eta phase material is at most 5 times the average WC grain size. Cemented carbide material (40) according to one of Claims 1 until 17 , characterized in that the coercive field strength HcM of at least one region of the sintered carbide material (40) produced by the method according to the invention is: $$\text{HcM}\left[\text{no}/\text{m}\right]>\left(1.5+0.04*\text{B}\right)+\left(12.5-0.5*\text{B}\right)/\text{D}+4\left[\text{no}/\text{m}\right]$$

preferably $$\text{HcM}\left[\text{no}/\text{m}\right]>\left(1.5+0.04*\text{B}\right)+\left(12.5-0.5*\text{B}\right)/\text{D}+6\left[\text{no}/\text{m}\right]$$

particularly preferred $$\text{HcM}\left[\text{no}/\text{m}\right]>\left(1.5+0.04*\text{B}\right)+\left(12.5-0.5*\text{B}\right)/\text{D}+10\left[\text{no}/\text{m}\right]$$

where B is the proportion of the binder phase in the sintered carbide material in % by weight and D is the particle size of the dispersed WC, determined using the line intersection method in accordance with DIN ISO 4499, part 2. Tool, in particular crushing, soil processing tool, preferably for a road milling machine, a recycler, a stabilizer, an agricultural or forestry soil processing machine, with a base body which has a working area, wherein at least one working element consisting of a sintered carbide material (40th ) after one of the Claims 1 until 18 , is preferably held with an integral connection, in particular a soldered connection, in particular a brazed connection. tool after claim 19 , characterized in that the working element is in the form of a cutting element, preferably with at least one cutting edge and/or at least one cutting tip or in the form of a wear protection element, in particular a protective plate, a protective strip, a protective pin, a protective projection or a protective bolt. tool after one of claims 19 or 20 , characterized in that the tool is a cutting tool, a milling tool, in particular a road milling or mining tool, a ploughshare, a cultivator point, a drilling tool, in particular an auger, a breaking tool, for example a breaking chisel or a breaking bar, a mulching tool, a wood chipping tool or a shredding tool, a fractionating tool, e.g. a sieve. tool after Claim 21 , characterized in that the milling tool has a tool head and a tool shaft directly or indirectly connected thereto, and in that the working element is held on the tool head. A method for creating a sintered carbide material (40), wherein initially in a first method step a precursor sintered carbide material, in particular a hard metal, is created which contains 70-95% by weight, preferably 80-95% by weight, of tungsten carbide in dispersed form, and having a binder phase, the binder phase having metallic binder material (30), the metallic binder material (30) having Co, the binder phase having the dissolved elements Ni and Al, the binder phase having the following chemical element composition: Ni > 25% by weight, Al > 4% by weight, remainder Co and dissolved binder components, for example W and/or C, with the preliminary stage sintered carbide material being subjected to a heat treatment in a further method step in order to produce a sintered carbide material (40) to form, the intermetallic phase material (10) in the binder phase, wherein the intermetallic phase material (10) is formed according to the structural formula (M,Y) ₃ (AI,X), wobe i M = Ni, Y=Co and/or other component and X=tungsten and/or other component. procedure after Claim 23 , characterized in that at least part of the crystals of the intermetallic phase material (M,Y) ₃ (AI,X) (10) has a crystal structure L12 (space group 221) according to ICSD (Inorganic Crystal Structure Database). Procedure according to one of Claims 23 or 24 , characterized in that at least part of the intermetallic phase material (10) has a maximum size of 1500 nm, preferably a maximum size of 1000 nm (measured according to the line intersection method on a micrograph). Procedure according to one of Claims 23 until 25 , characterized in that the precursor cemented carbide material is held in a temperature range in the range between 400°C and the solvus temperature for a period in the range between 0.25 - 24 hours during the heat treatment. Procedure according to one of Claims 23 until 26 , characterized in that the precursor cemented carbide material as cemented carbide material (40) according to one of Claims 1 until 18 is trained.

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