RU2798861C9 - Composite material based on in_situ produced alloys reinforced with tungsten carbide and methods for its production - Google Patents

Abstract

FIELD: powder metallurgy.

SUBSTANCE: present invention relates to a composite material based on alloys produced in situ, in particular iron-based alloys, reinforced with tungsten carbide in the form of crystals and/or particles. It can be used for the manufacture of wear parts of machines. A composite material based on iron-based alloys reinforced with tungsten carbide in the form of crystals and/or particles is obtained in the form of a composite layer or composite zone of a cast structural element. The composite material is formed by applying to the cavity or core of the mould a liquid reactive casting coating comprising a mixture of powders comprising tungsten in the range from 90 to 97 wt.% and carbon in the range from 3 to 10 wt.%, and a carrier, or introducing into the mould cavity of at least one casting liner obtained by pressing a mixture comprising tungsten and carbon. An iron-based alloy of high temperature at the same time, the heat coming from the liquid alloy in the form of high temperature is then poured into the mould cavity to provide the energy needed to initiate the in-situ reaction of the ceramic phase in the form of at least one type of tungsten carbide or tungsten carbide with other types of carbides added, which undergo a self-propagating high temperature fusion reaction and are a catalyst for the tungsten carbide synthesis reaction. The microstructure of the composite material comprises faceted crystals and/or faceted particles of tungsten carbide, providing a uniform macroscopic and microscopic distribution, which comprise nano- and/or microregions of irregular and/or round and/or oval shape, filled with a metal-based alloy.

EFFECT: high hardness and resistance to abrasive wear within the working surfaces.

18 cl, 19 dwg, 2 tbl, 8 ex

Description

The present invention relates to a composite material based on alloys produced in situ , in particular, iron-based alloys reinforced with tungsten carbide particles with increased wear resistance. This material is especially suitable for the manufacture of wear parts. The subject of the present invention is a method for producing said composite material in the form of a composite layer and in the form of a composite zone by using reactive components, that is, pressing and liquid casting coating.

One of the significant problems associated with the frequency of replacement of machine parts is excessive wear of their surfaces. Such wear leads to loss of original dimensions and shape, causing deterioration or complete loss of the functional properties of a given structural element. This requires frequent replacement of these elements, which reduces the profitability of users of such machines and devices. This common phenomenon initiates the design of functional elements of machines with a hardened outer layer. The thickness and shape of the wear area depend on the operating conditions of the part and can even amount to several tens of millimeters. This problem mainly concerns such industrial sectors as mining, cement industry, metallurgy, energy, agriculture, offshore industry, recycling, processing industry, where abrasion is the main physical phenomenon that allows this process, for example, crushing, grinding, milling, drilling, drilling, loading, transmission, including energy generated by wind and tides, transportation of solid or liquid substances and their mixtures.

There are many known solutions in the art regarding materials that make it possible to protect structural elements by increasing wear resistance. These solutions mainly include various types of casting alloys and metal forming alloys. More often they use solutions aimed at obtaining functional castings, i.e. having a hard and wear-resistant outer layer and a more plastic core. This sector is dominated by materials deposited using welding, laser and plasma technologies. A distinctive feature of abrasive materials that are most resistant to wear is the high content of ceramic phases, mainly carbides, located inside a properly selected matrix based on metal or metal alloys. The most wear-resistant materials contain in their microstructure ceramic phases in the form of titanium carbide (TiC), tungsten carbide (WC) and their mixtures in an amount not exceeding 50% by volume. The high volume fraction of these types of carbides results in materials deposited on semi-finished machine parts exhibiting better wear resistance compared to the most abrasion-resistant casting alloys or alloys developed for metal forming.

However, the use of modern technologies is expensive and time-consuming due to the costs of using two or more processes and a number of intermediate steps to produce the final part. Another important disadvantage of metal deposition and alloying technologies known in the art is the virtual inability or difficulty in applying layers or coatings that are resistant to abrasion wear in hard-to-reach places or on areas of complex shape, for example, curved pipes, castings with complex internal and external form. The deposited surfaces have a relatively high roughness, which in many cases actually limits the use of this group of methods in the production of wear-resistant elements of machines and devices. Another significant drawback in the manufacture of a layer resistant to abrasive wear using welding technologies is the need for preliminary preparation of the surface on which the specified layer is to be applied. An improperly prepared surface leads to embrittlement of the applied material. At the same time, when applied by impact, one can often observe the embrittlement of fragments of the applied materials, which actually leads to a reduction in service life.

There are other solutions known in the art that increase the abrasive wear resistance of the outer layer of machine elements and devices, in which composite layers reinforced with ceramic phases, for example TiC, are produced in situ directly during the casting process. Such solutions consist of applying a coating containing a mixture of powders, TiC reaction substrates and a liquid, ie alcohol, to a mold cavity, and then the mold is dried and filled with a liquid iron-based alloy. This method is described in Polish patent application PL414755 A. Such solutions make it possible to create a composite layer inside the casting, reinforced with oval crystals or TiC particles, however, this layer obtained using this method is not continuous and homogeneous and may have numerous defects in the form of roughness caused by the presence of gas. This problem arises due to the fragmentation and gas evolution phenomena that accompany the synthesis reaction of pure TiC. The problem of gas evolution during SHS reactions (self-propagating high-temperature synthesis) is discussed in the article by Shchukin (Shchukin AS, Savchenko SG (2015). International Journal of Self-Propagating High-Temperature Synthesis , 24, pp. 227-30), in which it is proven that As part of the first SHS reaction with the formation of TiC, rapid degassing of the pressed Ti and C powders occurs along with the release of significant volumes of gases. This leads to encapsulation of the released gases during crystallization of the alloy in the form of bubbles, forming roughness in the area of the composite layer. The increase in the temperature of the alloy in the reaction zone is the result of the release of thermal energy that accompanies the highly exothermic reaction of TiC synthesis; the enthalpy of formation of such a phase is -187 kJ/mol. For comparison, the enthalpy of formation of WC is -32 kJ/mol, copper (Cu) is only -13 kJ/mol. The detrimental phenomenon of fragmentation is discussed in international patent application WO 2017081665 concerning the in situ production of TiC reinforced composite zones within castings. This application describes that reaction infiltration during the synthesis of TiC in the presence of a liquid alloy leads to the separation of fragments of the composite zone, which are then displaced into the mold cavity. In extreme cases, this affects the complete destruction of the local reinforcement zone or leads to an increase in the volume of the matrix due to TiC particles. This phenomenon is defined as fragmentation of composite zones. The presence of roughness and uneven displacement of phases reinforced within the area of the composite layer affects the deterioration of hardness and resistance to abrasive wear.

The existing state of the art also includes European patent application EP 2334836 B1, which describes a composite material of a hierarchical structure containing an iron-based alloy reinforced with oval TiC particles in accordance with a given geometry, wherein the reinforced part includes an alternating macrostructure of millimeter zones enriched with micrometer ones. agglomerates of spherical TiC particles separated by millimeter-sized zones substantially free of zones of micrometric spherical TiC particles, wherein such enriched micrometric spherical TiC particles form a microstructure in which the micrometric gaps between said spherical particles are also filled with an iron-based alloy. In addition, the above application describes a method for producing a hierarchical structure composite material by casting.

International patent application PCT/IB 2016/056825 describes a material and a method for its production, which consists of producing composite zones in situ in castings by using SHS reaction substrates, including a regulator in the form of a mixture of metal powders. With this solution, the regulator acts as a stabilizer and prevents the destructive phenomenon of fragmentation of TiC-reinforced composite zones, and allows the creation of a composite matrix with specific structural properties. This solution makes it possible to obtain a composite zone with a uniform macroscopic distribution of particles of the reinforcing phase, high wear resistance and relatively low roughness. However, the addition of a regulator introduced into the reaction substrates that form carbides undergoing the SHS reaction leads to a decrease in their volume in the resulting zone, which, in turn, actually leads to a decrease in resistance to abrasive wear. In addition, in the case of the WC formation reaction, the addition of a regulator containing Fe causes the formation of a brittle eta phase, for example of the Fe ₂ W ₂ C type. Thus, in the method according to the invention, unexpectedly, results were achieved confirming the possibility of obtaining stable composite zones based on WC in situ in castings, without the need to add a regulator. The material according to the invention contains a stable zone or composite layer reinforced with WC carbide particles and/or crystals of unexpected characteristic morphology. This atypical morphology is the reason for the very good bonding of the carbide particles to the matrix, as evidenced by the presence of an irregular oval shaped region containing the alloy. Such regions are formed during crystal and/or particle growth in situ in a liquid alloy and are encapsulated, absorbed by the growing crystal and/or particle and associated with the production of liquid solutions of a certain composition during the WC synthesis reaction. The absence of the addition of a Fe-containing regulator sharply limits the proportion of brittle phases of the eta type, which affects the very high wear resistance and toughness of such a material. At the same time, the material obtained according to the invention has a very low level of microporosity, amounting to 2% by volume, compared to other methods known in the field. This means that the composite material according to the invention has unexpectedly high flexural strength and abrasion resistance.

An object of the present invention is to provide a tungsten carbide particle-reinforced composite material that can exhibit increased hardness and abrasion resistance within the working surfaces by providing uniformly distributed hard and wear-resistant tungsten carbide crystals/particles therein. At the same time, the present invention solves the problem of fragmentation and high infiltration that accompanies the TiC in situ synthesis reaction. Both such phenomena can cause damage to the composite layer in the event of complete fragmentation or significantly reduce the content of TiC particles in the zone due to a high degree of infiltration, which cannot be physically avoided due to the highly exothermic nature of the TiC synthesis reaction. During in situ synthesis of TiC, the degree of infiltration of liquid alloy into the composite zone can be limited by the use of certain techniques, but the final volume of TiC carbide will never reach the level that can be achieved using the compounds and methods of the present invention in the case of tungsten carbide. This is a technical advance in the field of obtaining abrasion-resistant composite layers and zones reinforced with tungsten carbide, resistant to wear parts of machines, devices and semi-finished products.

The present invention also provides methods for producing composite materials reinforced with tungsten carbide particles of a specific morphology. The solution according to the present invention is to obtain in situ , i.e. directly in the mold in a one-step process, composite materials reinforced with uniformly distributed particles and/or crystals of tungsten carbide or a mixture of different types of tungsten carbides, which eliminates the disadvantages listed above.

The object of the present invention is a composite material based on in situ alloys, in particular iron-based alloys reinforced with tungsten carbide in the form of crystals and/or particles, which can be characterized by the fact that the microstructure of said composite material within the composite layer and/or composite zone contains faceted crystals and/or particles of tungsten carbide, providing uniform macroscopic and microscopic distribution, while such crystals and/or particles of tungsten carbide contain nano- and/or micro-regions of irregular and/or round and/or oval shape, filled with a metal-based alloy .

Nano- and/or microzones of irregular and/or round and/or oval shape, filled with a metal-based alloy, are preferably located in the inner part of the tungsten carbide crystals and/or particles, and in the outer part, near the walls, their structure is uniform, with wherein said crystals and/or particles are formed in situ within the liquid alloy and are present in a matrix, said matrix being formed after the alloy crystallization process.

The volume of at least one type of tungsten carbide in the composite material is preferably from 15 to 90% by volume, in particular from 25 to 75% by volume.

The size of the crystals and/or particles of tungsten carbide in the composite material according to the present invention is preferably from 0.5 to 30 μm.

In the tungsten carbide region of the composite material according to the present invention, the size of the regions filled with metal or alloy is preferably from 0.1 to 4.5 μm.

The composite material of the present invention preferably includes additional types of tungsten carbide or borides undergoing a self-propagating high temperature synthesis reaction, in particular TiC, MoC, NbC, ZrC, VC, TaC, TaB, TiB ₂ or mixtures thereof, except for SiC, which is thermodynamically is unstable in iron-based alloys and dissolves in them.

The subject of the present invention is also a mixture of powders for obtaining a composite material according to the present invention, containing tungsten in the range from 90 to 97% by weight. and carbon, in particular in the form of high purity carbon or other high carbon content carrier or mixtures thereof, in the range of 3 to 10 wt.%, preferably tungsten in the range of 93 to 95 wt.%, and carbon in the range of 5 to 95 wt.% 7% wt., preferably tungsten in an amount of about 94% wt. and carbon in the form of graphite in an amount of about 6% by weight.

The present invention also includes a mixture of powders for obtaining a composite material according to the present invention, containing:

a) tungsten powder, in particular in the form of microcrystalline powder or nanoparticle agglomerates or other carrier with a high tungsten content,

b) carbon powder, in particular in the form of graphite or other high carbon content carrier or mixtures thereof, and

c) a catalyst in the form of substrates for carbon formation reactions other than WC or boride which undergo a self-propagating high temperature synthesis reaction, in particular TiC, MoC, NbC, ZrC, VC, TaC, TaB, TiB ₂ or mixtures thereof, excluding SiC .

According to such an aspect, the present invention also provides a method for producing a composite material in the form of a composite layer, comprising the following steps:

a) applying to the mold cavity or core, in particular the sand core, a reactive liquid casting coating containing a mixture of powders according to the present invention and a carrier,

b) drying, in particular at a temperature equal to or above 100°C,

c) filling the cavity of the casting mold with an alloy, in particular an iron-based alloy, wherein the heat supplied from the liquid alloy in the form of high temperature provides the energy necessary to initiate an in situ reaction of a ceramic phase in the form of tungsten carbide of at least one type or tungsten carbide with the addition of other types of carbides, which undergo a self-propagating high-temperature synthesis reaction and constitute a catalyst for the tungsten carbide synthesis reaction.

In the method of the present invention, the carrier is preferably a solvent solution with added polymer, more preferably the solvent is an alcohol, in particular ethyl alcohol, and most preferably the polymer is a low gassing resin, in particular rosin.

In the method of the present invention, the surface density of the reactive cast coating is preferably 0.29 to 2 g/cm ² , more preferably 0.29 to 0.6 g/cm ² , most preferably it is 0.5 g/cm ² .

In the method of the present invention, the percentage of the powder mixture representing the reaction substrates forming tungsten carbide relative to the support is preferably 6:1 to 1:1, more preferably 4:1.

According to another aspect, the present invention also provides a method for producing a composite material in the form of a composite zone, comprising the following steps:

a) obtaining a powder mixture according to the present invention,

b) pressing the powder mixture into the form of a forming plate, which can have various shapes, preferably granules, briquettes, preforms or compacts,

c) introducing at least one casting compact into the cavity of the casting mold using fasteners,

d) filling the cavity of the casting mold with an alloy, in particular an iron-based alloy, wherein the heat supplied from the liquid alloy in the form of high temperature provides the energy necessary to initiate an in situ reaction of a ceramic phase in the form of tungsten carbide of at least one type or tungsten carbide with the addition of other types of carbides, which undergo a self-propagating high-temperature synthesis reaction and constitute a catalyst for the tungsten carbide synthesis reaction.

The pressing pressure of the reactants is preferably from 100 to 650 MPa, preferably from 250 to 600 MPa, most preferably from 460 to 550 MPa, in particular by ensuring said pressure by using pressing methods, in particular by using cold isostatic pressing, single or biaxial cold pressing.

The present invention also relates to a cast structural member containing a composite material according to the present invention or obtained according to the present invention.

One of the most common methods for producing composites in situ is self-propagating high-temperature synthesis (SHS). This method is the main method for producing composite materials in powder metallurgy. However, despite many advantages, including low energy input required to initiate the synthesis of ceramic phases and high yield, the resulting products are characterized by a high degree of porosity, which significantly impairs the mechanical and performance properties of industrial products. Therefore, studies were carried out aimed at linking the SHS method with traditional casting technologies, in which the factor initiating the synthesis reaction is the high temperature of the liquid casting alloy poured into the mold cavity. The use of such combined methods makes it possible to obtain products free of casting defects, which can be characterized by very good binding at the interface of the ceramic and matrix phases, free of inclusions, roughness and good mechanical properties, and at the same time produced in a single-stage technological process. As a result of such research work, a composite material reinforced with tungsten carbide particles was unexpectedly produced by the method of the present invention by using liquid reactive coatings and reactive casting compacts.

In the case of composite layers, the technological method for their production involves the production of a reactive cast coating containing reagents that form a ceramic phase in the form of tungsten carbide or tungsten carbide with the addition of other reagents that undergo an SHS reaction. The heat supply required for the in situ synthesis reaction of the ceramic phase is provided by introducing a liquid casting alloy into the mold cavity. The high temperature of the liquid metal promotes the SHS reaction of tungsten carbide in the area of the composite layer/coating. The composite reinforcement zone, obtained in situ in the form of a composite layer, can be characterized by a microstructure in the form of particles or crystals of tungsten carbide with a characteristic morphology. They are separated from each other by sections of the matrix formed after crystallization of the liquid alloy poured into the cavity of the mold. This phenomenon is the result of reaction infiltration of a reactive coating applied to the mold cavity using liquid casting alloy.

According to the present invention, there is also a method for producing a composite material reinforced with tungsten carbide particles by using reactive casting compacts. At least one compact is inserted into the mold cavity, which in actual conditions will serve as a casting zone, locally reinforced with a composite zone. The synthesis reaction of the ceramic phase in the form of tungsten carbide particles is initiated by high temperature of the casting alloy. The supply of a sufficient amount of heat helps initiate the SHS reaction of tungsten carbide in the pressing area. A composite reinforcement zone fabricated in situ in the form of a composite zone may be characterized by a uniform microstructure in the form of tungsten carbide particles or crystals of characteristic morphology located within an alloy-based matrix, in particular an iron-based alloy with carbon and other elements. However, the volume of the ceramic phase is significantly larger compared to the composite layer. Such a layer is obtained by applying a liquid reactive coating without the use of high pressure, which leads to an increase in the density of the reagent powder. This affects a smaller proportion of WC crystals after the synthesis reaction and crystallization of the alloy in the composite layer according to the present invention. The composite zone, reinforced with tungsten carbide or other types of carbides and/or borides undergoing the SHS reaction, contains a matrix, wherein said matrix is formed after crystallization of the alloy and is a consequence of the controlled process of reaction infiltration that occurs during the synthesis reaction. The controlled infiltration process according to the present invention is carried out by appropriately selecting the pressure and method of pressing the powders, their shape and the chemical composition of the powder mixture. Within the composition of this mixture, the catalyst in the form of reaction substrates forming carbides and borides of other types is added to the reaction substrates forming tungsten carbide in a suitable stoichiometry. Parameters such as the pressing pressure of the powders, the shape of the pressed powders, and the chemical composition of the powder mixture are parameters that make it possible to create composite zones in situ in cast parts of machines, devices and semi-finished products of various shapes and weights.

A mixture of powders representing reaction substrates that form tungsten carbide is obtained at a given stoichiometry. Preferred is a mixture of powders in which the mass fraction of tungsten is from 90 to 96%, and the remainder is in the form of graphite or a carrier with a high carbon content or mixtures thereof. More preferably, the mixture of powders representing substrates for the production of tungsten carbide contains approximately 94% of the mass. tungsten and approximately 6% wt. carbon in the form of graphite or other high carbon content carrier or mixtures thereof. The resulting powder mixtures are subjected to a homogenization process to ensure uniform properties throughout the entire volume of the mixture. In the next step, they are dried, preferably at a temperature of at least 100°C, to remove alcohol and moisture absorbed on the surface of the powders. Depending on the chosen method for producing material reinforced with WC particles, they represent the base material for the production of reactive casting coatings and casting compacts.

The term "reactive cast coating" means a mixture of powders containing substrates of carbide and/or boride formation reactions that undergo a SHS reaction, the components of which are in the form of graphite and tungsten powders and a carrier. In addition to tungsten and graphite powders and the carrier, the reactive coating may preferably contain other additives in the form of reaction substrates forming titanium carbide or other carbides and/or borides other than SiC. The technological process for producing a composite material with the application of reactive cast coatings includes: preparing a sample of powdered substrates forming the ceramic phase, homogenized throughout the entire volume; then an alcohol solution with the addition of a polymer, for example rosin, is added to the powder mixture, which is used as an air-drying adhesive and which affects the physical, chemical and technological properties of the coatings; then at least one layer of the resulting composition, which is a cast coating, is applied to the cast core or into the cavity of the casting mold by brush, dipping or spraying, while at the initial stage of the process each of the applied layers or all of them is dried to remove products thermal decomposition of the used solvent and additives. The cavity of the casting mold, without or with a casting core, is then filled with a selected material from a group of iron-based alloys containing carbon and other elements, preferably with the chemistry of cast irons and cast steels, but the synthesis reaction is conditioned by a suitable temperature of the base alloy and a suitable filling device design. Likewise, instead of using iron-based alloys, other alloys can be used, including preferred casting alloys, for example, cobalt-based or nickel-based, in which the synthesis reaction can be initiated. A key parameter in such a process is the heat balance between the reactive casting coating applied to the mold cavity and/or core containing the WC reaction substrate powders and the liquid alloy in the casting and its selection so that the amount of heat is sufficient to initiate the reaction. If there is insufficient heat in the mold cavity, the WC synthesis reaction does not begin and a WC-reinforced composite layer does not form in the casting. The heat balance parameter should be determined experimentally or empirically for a given type of casting of the specified mass and shape. The use of a catalyst in the form of TiC formation reaction substrates at a given percentage is intended to keep the WC synthesis reaction going, increasing the amount of energy generated during the reaction, which effectively allows for thicker layers and better bonding to structural components through infiltration. The amount of TiC-forming reaction substrates as a WC-forming reaction catalyst must be selected experimentally or empirically for a given casting shape or weight. The role of a catalyst can be played by reaction substrates that form a carbide other than TiC, or a boride that undergoes a self-propagating high-temperature synthesis reaction, in particular TiC, MoC, NbC, ZrC, VC, TaC, TaB, TiB ₂ . Of the carbides, SiC cannot be a catalyst because, among other things, it is thermodynamically unstable for the group of iron-based alloys.

The parameter that determines the amount of cast coating applied to the cavity or core of a casting mold is the areal density, which should be understood as the mass of cast coating to area, expressed in g/cm ² . The area density of the applied reactive cast coating according to the present invention is from 0.29 g/cm ² to 2 g/cm ² , preferably from 0.29 to 0.6 g/cm ² , most preferably 0.5 g/cm ² .

The mass fraction of the powder mixture representing the substrates for the formation of tungsten carbide is from 1 to 6 parts by weight per 1 part by weight of the carrier. More preferably, the weight ratio of the mixture representing the tungsten carbide formation reaction substrates to the support is 4:1.

This carrier was developed to increase the adhesion of the coating to the cavity of the casting mold. The carrier may be a solution of a binder in the form of a low-gassing polymer in a solvent in the form of an alcohol with a percentage concentration of from 1 to 10% by weight. The best results were achieved with a carrier consisting of a 10% solution of rosin with ethyl alcohol. The use of materials characterized by a low degree of gas evolution during thermal decomposition prevents the formation of porosity in the area of the composite layer.

The forming plate is a pressure-pressed mixture of tungsten carbide substrates in the form of graphite or tungsten. The technological process for producing a composite material using an insert includes: preparing a sample of substrate powders forming a ceramic phase of the MeC type, homogenized throughout the entire volume, where Me is metal, C is carbon, then such a sample of powders is subjected to cold pressing using uniaxial presses or a method isostatic pressing, in which a manufactured at least one molding plate of suitable dimensions is inserted into the cavity or core of a casting mold using elements of a fastening system in the form of nails, bolts, metal mesh, which leads to the integration of the entire system during the casting process. Finally, the resulting casting mold without/with a core is filled with a selected casting alloy, most preferably from the Fe-based group, while the synthesis reaction is conditioned using a suitable temperature and a suitable structure of the filling device. The use of additives in the form of TiC forming substrates is intended to support the WC synthesis reaction by supplying additional energy in the form of heat of the TiC synthesis reaction. The choice of the amount of additives depends on the mass, shape of the casting and the base alloy and must be determined experimentally each time to provide the required energy within the casting necessary to initiate the fusion reaction. According to the present invention, the casting mold together with the compact installed therein after filling with liquid alloy is considered as an in situ carbide synthesis reactor.

The present invention is presented in embodiments that do not limit the scope of the protective action of the present invention, and is depicted in the following figures, in which:

In fig. 1 shows a layer (a) of a composite material (b) with tungsten carbide crystals/particles within an iron-based alloy matrix of characteristic morphology (c), containing an alloy-filled region located in the interior of the crystal (region I), and a region free of alloy-filled areas in the outer part of the crystal (region II), obtained using an in situ reactive cast coating,

In fig. Figure 2 shows a cross-section of a rod representing an element of a casting mold for the manufacture of a casting of a pump casing with an applied reactive casting coating (a), and a diagram of a pump casing (b) with a composite layer obtained in situ , reinforced with tungsten carbide of a characteristic morphology, as well as diagrams , related to the T-beam (c, d),

In fig. Figure 3 shows the characteristic morphology of a faceted tungsten carbide crystal within the layer, including irregular oval shaped areas filled with a metal-based alloy;

In fig. Figure 4 shows histograms of the size distribution of tungsten carbide particles/crystals, as well as the sizes of the alloy-filled regions within the region of individual tungsten carbide particles/crystals.

In fig. Figure 5 shows the cross-sectional microstructure of an in situ cast composite layer reinforced with tungsten carbide particles/crystals, along with selected enlarged areas.

In fig. Figure 6 shows typical microstructures of a layer with a composite with a certain surface content of the ceramic phase, i.e. tungsten carbide, the matrix of the composite layer and the surface content of graphite, which is a component of gray cast iron used to produce the casting.

In fig. Figure 7 shows the microstructure of the composite layer, as well as the average particle size of tungsten carbide, defined as its two diagonals intersecting at right angles,

In fig. 8 shows photographs of a gray iron casting with an in situ composite layer produced using various surface densities of the casting reactive coating according to the present invention.

In fig. Figure 9 shows the microstructure of a composite layer in situ obtained using a mixture of reaction reagents forming two types of carbide (tungsten and titanium) undergoing a self-propagating high-temperature synthesis reaction.

In fig. Figure 10 shows the surface content of individual phases representing the microstructure of a composite layer in situ , obtained using a mixture of reaction substrates that form two types of carbide (tungsten and titanium), undergoing self-propagating high-temperature synthesis,

In fig. 11 shows photographs of casting mold cavities with reactive casting coatings applied to their surfaces for in situ synthesis of tungsten carbide reinforced composite layers.

In fig. Figure 12 shows the effect of the surface density of the reactive cast coating on the macrostructure of the in situ produced tungsten carbide reinforced composite layer when casting slabs of different thicknesses.

In fig. 13 shows the microstructure of a composite material when using a reactive compact (a) in a cast steel casting containing carbide crystals of a characteristic morphology (b), containing areas of irregular oval shape filled with the alloy and areas not containing them.

In fig. 14 shows the microstructure of a composite material containing tungsten carbide crystals/particles, along with a graph showing the following surface content: ceramic phase in the form of various types of tungsten carbide and a metal composite matrix,

In fig. 15 shows the microstructure of particles/crystals of various types of tungsten carbide structure, including WC type carbide,

In fig. 16 shows the results of a comparison of the hardness of the composite zones according to the present invention with the hardness of a wear-resistant reference casting alloy made of reinforced manganese cast steel, as well as a composite material reinforced with titanium carbide (TiC) particles produced in situ within the casting.

In fig. 17 shows the results of a comparison of the composite abrasive wear zones of the present invention with a wear-resistant reference casting alloy of reinforced manganese cast steel, as well as with a composite material reinforced with titanium carbide (TiC) particles produced in situ within the casting.

In fig. 18 shows typical diagrams of structural elements and their cross sections with in situ produced zones containing a composite material with tungsten carbide crystals and/or particles of a certain morphology according to the present invention.

In fig. 19 shows a schematic process for producing a composite material according to the present invention in a casting layer (a) and a casting zone (b).

Example 1

According to one embodiment, the core 1 of a casting mold for producing a casting of a pump housing 4 or a T-beam is coated with a reactive coating 2 using a spray gun 3, as shown in FIG. 2a and 2c. The result was a casting of a pump housing 4 or a T-beam with a layer 5 containing a composite material (Fig. 2b, 2d), obtained in situ , with a visible morphology of faceted tungsten carbide 6, consisting of two shapes, one in the internal part of the particle containing areas irregular, round, oval shaped, filled with alloy, and another in the outer part of the particle, not containing areas filled with alloy 6, as shown in Fig. 3. A flow diagram of the coating manufacturing process is shown in FIG. 19a.

To form a layer 5 of WC-reinforced composite material, subject to intense wear, in the inner surface of the pump housing 4 or T-beam, a casting mold core 1 was made. The reactive casting coating 2 was applied directly to the surface of the rod 1, made of quartz sand and furan resin. Coating 2 was prepared by mixing tungsten powder with a particle size of approximately 5 μm and graphite powder with a particle size of approximately 5 μm. This mixture of powders was obtained using 94% of the mass. tungsten and 6% wt. graphite Then, weighed portions of the powders were added to a liquid solution of resin in alcohol, which was a carrier and an air-drying adhesive agent. The relative ratio of the mixture of tungsten and graphite powders to the liquid solution of the adhesive agent in both cases was 4:1 parts by weight. The entire mixture was mixed to ensure a uniform reaction consistency of the cast reactive coating 2. The mixed reactive cast coating 2 was applied using a spray gun 3 onto a casting core 1 having an internal T-beam shape. 4. The coating was applied layer by layer until a surface density of 0.5 g/cm ² and 0.45 g/cm ² was achieved. Then rod 1 was installed in the mold cavity and then each of the molds was assembled and filled with liquid alloy with a temperature of 1380°C. Using the method described above, a pump housing 4 or a T-beam was obtained.

The area of the pump body 4 rod manufactured by this method was approximately 3789 cm ² . For this purpose, powder mixtures of two different compositions were used, with one of the compositions containing 96 at. % W and 4% wt. C, and the other composition contained 94% wt. W and 6 wt% C. In both cases, the resulting castings contained a base alloy with a microstructure characteristic of gray cast iron with scattered flake graphite, the outer surface of which was reinforced with a composite layer 5 containing particles of tungsten carbide 6. The use of cast rods 1 of the same area and surface density similar to that of Reactive Cast Coating 2 was assumed and performed to demonstrate the effect of the powder mixture stoichiometry used on the integrity of the composite layer. The results are presented in Fig. 8 A.1-A.3 and B.1-B.3. Studies have shown that the application of a reactive casting coating 2 containing a mixture of powders consisting of 96 at. % W and 4% wt. C, made it possible to ensure the integrity of the layer at a level of approximately 80%, and in the case of a mixture consisting of 94% of the mass. W and 6% wt. C, specified in the patent application as a mixture developed to produce a composite layer in situ , such a layer was characterized by 100% integrity. In both types of pump casings 4, the composite layers were reinforced with WC using reactive cast coatings 2 with the area density given in Table 1 to provide 100% to 80% integrity of the pump internal surface. The results obtained showed that, along with an increase in the proportion of atomic tungsten in the powder mixture, the synthesis reaction deteriorates, which leads to the absence of a continuous composite layer. However, for some industrial applications, a layer integrity of 80% may be acceptable.

As a result of the synthesis reaction, localized composite reinforcement zones reinforced with at least one type of tungsten carbide particles were formed in the cast steel casting. Casting rod 2 after the crystallization process had a microstructure characteristic of this grade of cast steel, however, inside the surface of the casting formed crystals 6in situ. Such crystal 6 had a morphology consisting of two different regions. One of the regions was in the interior of the tungsten carbide crystal 6 and contained oval-shaped micro-regions 7 filled with a metal-based alloy, and the other region was a surrounding rim 8 containing no oval alloy-filled micro-regions, as shown in FIG. . 3. The average particle size was preferably 4 to 18 µm, the average size of the base alloy filled areas was 0.05 to 0.45 µm, as shown in FIG. 4.

The ball-on-disc wear rate of tungsten carbide-reinforced composite layer 5 in gray cast iron pump housing 4 casting with flake graphite as the base alloy ranged from 5 to 8×10 ^-6 mm ³ / N×m, and in the housing of 4 pumps made of gray cast iron with flake graphite, which is the main alloy, without a reinforcing layer, was 37.6×10 ^-6 mm ³ /N×m. Those. the layer with the composite material according to the present invention wore out 4.7 to 7.5 times less compared to a pump made of gray cast iron.

Example 2

In the example of a wear-resistant casting with a layer of composite material, the coating was prepared by mixing tungsten powder with a particle size of approximately 5 microns and graphite powder with a particle size of less than 5 microns. This mixture of powders was obtained using 96% of the mass. tungsten and 4% wt. graphite Then, weighed portions of the powders were added to a liquid solution of resin in alcohol, which was a carrier and an air-drying adhesive agent. The relative ratio of the mixture of tungsten and graphite powders to the liquid solution of the adhesive agent in both cases was 4:1 parts by weight. The entire mixture was mixed to ensure a uniform reaction consistency of the cast reactive coating 2. The mixed reactive cast coating 2 was sprayed using a spray gun 3 onto the cavity of the casting mold. Coating 2 was applied layer by layer until a surface density of at least 0.5 g/cm ² was achieved. The mold was then assembled and filled with a liquid alloy having the composition of manganese cast steel, with the following content of the main alloying elements: 1.3% C, 0.6% Si, 12.2% Mn and the remainder Fe.

The composite layer shown in FIG. 1, with a hardness of 724 HV30 (1253 HV1), while the hardness of the base alloy was approximately 247 HV30 (517 HV1). The obtained parameters indicate the achievement of a hardness almost three times higher than in the case of wear-resistant manganese cast steel.

Example 3

To obtain the in situ WC-reinforced composite layer 5, a sand core of a casting mold 1 based on quartz sand and soluble glass was prepared and blown with CO ₂ . The cavity of the casting mold 1 was coated with a reactive casting coating 2. The coating 2 was prepared by mixing tungsten powder with a particle size of 5 μm and graphite powder with a particle size of approximately 5 μm. This mixture of powders was obtained using 94% of the mass. tungsten and 6% wt. graphite The powders were then added to a liquid solution of rosin in alcohol, which was a carrier and air-drying adhesive. The ratio of the mixture of tungsten and graphite powders to the liquid adhesive agent was 4:1 parts by weight. The entire mixture was mixed to ensure a uniform reaction consistency of the cast reactive coating 2. The mixed reactive cast coating 2 was applied by spraying using a spray gun 3. Coating 2 was applied layer by layer until a surface density of 0.29 g/cm ² or 0.4 g was achieved /cm ² . The mold cavity was then dried to remove residual alcohol and moisture, followed by filling with liquid alloy at a temperature of approximately 1400°C. The casting after the crystallization process had a microstructure of gray cast iron with flake graphite, however, within the composite layer region, crystals 6 and/or WC particles were formed in situ , having a structure formed by two different regions. One of the regions was in the interior of the WC crystal 6 or particle and contained oval-like micro-regions 7 filled with a metal-based alloy, and the other region was a surrounding rim 8 containing no oval alloy-filled micro-regions. A cross section of the layer with selected enlarged areas is shown in FIG. 5. To estimate the proportion of the reinforcing phase, the surface content of the phases identified in the microstructure was determined, that is, flake graphite and the base alloy, which is the matrix of the composite layer, and tungsten carbide, which is the reinforcing phase. Typical microstructures with a certain surface fraction and the obtained results are presented in Fig. 6. The surface fraction of tungsten carbides in this case was 25% and the matrix was 70%, the remainder being graphite, which is a component of the base alloy used to produce the casting. In addition, the average particle size of tungsten carbide was evaluated, which was determined as the average of two measurements of diagonals intersecting at right angles. The results showed a bimodal size distribution of tungsten carbide in the composite layer, which reached a first distribution maximum in the range of 0.5 to 6 μm, and another maximum in the range of 7 to 30 μm. The results are presented in the form of a histogram as shown in FIG. 7.

Example 4

To obtain the inner layer of the pump casing 4 subject to intense wear, layers 5 containing a composite material reinforced with ceramic phases/particles such as tungsten and titanium carbides, a mold core 1 was produced. The reactive casting coating 2 was applied directly to the surface of the rod 1, made of quartz sand and liquid glass, and blown with CO ₂ . Coating 2 was made by mixing 80% of the mass. reaction substrates forming tungsten carbide, and 20% of the mass. reaction substrates forming titanium carbide. A mixture of reaction substrate powders forming tungsten carbide was prepared at a W:C mass ratio of 94:6 wt%. Reaction substrates forming TiC were prepared at a Ti:C atomic ratio of 55:45%. In this case, the following powders were used: tungsten of microcrystalline morphology with a particle size of approximately 4.5 μm, titanium of spongy morphology with a particle size of 44 μm, and graphite of flake morphology with a particle size of less than 5 μm. The resulting mixture of powders was introduced into a liquid solution of rosin in ethyl alcohol, which was a carrier and air-drying adhesive agent. The relative ratio of tungsten and graphite powders to liquid adhesive agent was 4:1 parts by weight. The casting coating was prepared on the basis of 600 g of a mixture of powders and 150 g of solution. The entire mixture was mixed to ensure a homogeneous reaction consistency of the cast reactive coating 2. The mixed reactive cast coating 2 was applied by spraying with a spray gun 3. Then the rod 1 along with the applied reactive cast coating 2 was dried at a temperature above 100°C to remove residues alcohol and moisture. The rod 1 was installed inside the cavity of the casting mold, after which the mold was assembled and filled with liquid alloy. Casting 4 after the crystallization process had a microstructure of gray cast iron with flake graphite, however, in the area of the composite layer 5, particles of tungsten and titanium carbides were formed in situ (Fig. 9). The resulting microstructure was used to determine the surface fraction of individual phases representing the microstructure of the in situ obtained composite layer. The results are shown in Fig. 10 taking into account the phase separation present in the area of the matrix and the composite layer. The presence of uncut TiC particles in the microstructure indicates the addition of a percentage of pure substrates for the TiC formation reaction. Hardness tests carried out according to the Vickers method (HV1) with a load of 1 kg, i.e. 9.81 N, in the area of the base alloy and composite layer showed values at the level of 312.3 HV1 and 767.1 HV1, respectively. The results obtained indicate a more than twofold increase in the hardness of the outer layer of the casting produced together with the composite layer in situ .

Example 5

In this example, the goal was to relate the areal density of the composite coating and the thickness of the cast wall as a parameter influencing the progress and efficiency of the tungsten carbide synthesis reaction. Studies have shown that the use of a W:C powder ratio of 96:4 wt% is less effective than 94:6 wt%, so in another experiment a W:C composition corresponding to 94:6 wt% was used. Powders with this composition were introduced into a liquid solution of rosin in alcohol, which was a carrier and air-drying adhesive agent. The ratio of the mixture of tungsten and graphite powders to the liquid adhesive agent was 4:1 parts by weight. The entire mixture was mixed to ensure a uniform reaction consistency of the cast reactive coating 2. The mixed reactive cast coating 2 was applied by spraying using a spray gun 3.

To obtain castings of slabs with a thickness of 10 and 90 mm, casting molds were made, with each of the cavities being divided into three equal parts. Each of the separated areas of the sand mold was coated with a cast coating to achieve a surface density of 0.3 g/ ^cm2 , 0.4 g/ ^cm2 , 0.5 g/ ^cm2 , 0.6 g/ ^cm2 , 0.7 g/cm ² and 0.8 g/cm ² as shown in FIG. 11. In turn, in FIG. Figure 12 shows the macrostructure of castings with composite layers obtained in situ . Studies of the macrostructure of castings have shown that with a surface density of 0.3 g/cm ² , 0.4 g/cm ² and 0.5 g/cm ² it is possible to obtain a casting with a continuous working surface, reinforced with a composite layer, without any significant impact casting wall thickness. By increasing the amount of applied coating to 0.6 g/cm ² , 0.7 g/cm ² and 0.8 g/cm ² , respectively, in the case of a thin-walled casting with a wall thickness of 10 mm, no synthesis reaction could be observed - the absence of a composite layer on the surface of the casting. In the case of a casting with a wall thickness of 90 mm, there were areas in the macrostructure that did not contain a composite layer, characterized by a “shell”-like structure. The use of a surface density of reactive cast coating 2 in the range from 0.6 g/cm ² to 0.8 g/cm ² resulted in a lack of complete infiltration due to the lack of energy required for the in situ WC synthesis reaction to occur. It should be noted that this result applies to castings of small size and low mass, which should not limit the cases of castings with larger mass, in which the use of higher surface densities of reactive cast coatings 2 made it possible to obtain a continuous composite layer.

Example 6

In an embodiment using reactive compaction, localized composite reinforcement zones reinforced with at least one type of crystal/particle tungsten carbide were produced. For this purpose, a mixture of tungsten and carbon powders was prepared with a mass fraction of W:C equal to 90:10 wt%. The tungsten and graphite particle sizes were 4.5 μm and less than 5 μm, respectively. The prepared powder samples were stirred for 60 minutes and then dried at a temperature of 175°C to evaporate the absorbed moisture. Prepared samples of powders of a given mass were pressed under a pressure of 500 MPa using the cold uniaxial pressing method. The prepared reactive molding plates were inserted into the casting mold and secured to it at a predetermined location using bolts. This mold was then filled with an iron-based casting alloy - cast steel containing 0.28% C, 1.85% Cr, 0.6% Mn, 1.58% Si, with the remainder being Fe (GS30), at a temperature of 1580°C. The reaction between tungsten and carbide was initiated by supplying thermal energy through the liquid casting alloy. The synthesis reaction produced a composite zone reinforced with at least one type of tungsten carbide particles/crystals. The casting rod after the crystallization process had a microstructure characteristic of this grade of cast steel, but in situ crystals formed in the area of the forming plate. Crystals 6 and/or particles had a morphology consisting of two different regions. One of the regions was in the interior of the crystal 6 and/or tungsten carbide particles and contained micro-regions 7 with a similar oval shape filled with a metal-based alloy, and the other region was a thin rim 8 surrounding it, containing no oval micro-regions filled with an alloy , as shown in Fig. 13b.

Example 7

Another experiment similar to example 6 was carried out, however, the mass fraction of tungsten powders to graphite was 94:6 wt%, while the filling temperature was 1560°C and the compaction pressure was 500 MPa. After the synthesis reaction in the casting mold, the volume of the reinforced phase at the maximum level was obtained, which was approximately 74% (Fig. 14). As shown in FIG. 15, the microstructure of the composite zone region may be characterized by the presence of tungsten carbide WC with the characteristic morphology shown in FIG. 13b, and carbide type W ₂ Fe ₂ C. To confirm the chemical composition, tests were carried out by energy dispersive X-ray microanalysis. When applying this accepted method of investigation, the mass fraction of carbon should be considered only qualitatively and not quantitatively. The measurement results for individual castings are presented in Table 2. The mass of the resulting casting was approximately 1.5 kg.

A composite zone with a hardness greater than 1100 HV30 was obtained (Fig. 16, WC - type 2), while the hardness of the base alloy was approximately 250 to 300 HV30. The obtained parameters indicate the achievement of a hardness comparable to solutions known in the art, which consist of synthesis within castings, with composite zones obtained based on titanium carbide, with a hardness of such a zone ranging from approximately 500 to 1200 HV30 (Fig. 16 ), however, the solution according to the present invention surprisingly provided a uniform distribution of hardness throughout the entire zone, as evidenced by the low standard deviation value shown in FIG. 16.

As a result of the experiments, a material of exceptional wear resistance was unexpectedly obtained, the abrasive wear index of which, determined by the “ball on disk” method, was 0.16×10 ^-6 mm ³ /N×m (Fig. 17, WC - type 2), according to compared with materials known in the art, obtained through in situ synthesis technology in castings using reactive components, while in the case of the selected materials, the abrasive wear rate ranged from 2.7 to 3.83×10 ^-6 mm ³ /N× m (Fig. 17).

Example 8

In this case, the goal was to obtain localized composite reinforcement zones within the slab casting. To do this, a mixture of powders containing reagents for the synthesis of WC was prepared, which was pressed under a pressure of 450 MPa. The chemical composition of the mixture was obtained with a percentage of W:C equal to 94:6 wt%. The slab dimensions were 300 mm, thickness approximately 30 mm and width 75 mm. Forming plates with a thickness of 5 mm were installed in the cavity of the casting mold in areas of greatest wear, using metal elements representing a fastening system. To initiate the WC synthesis reaction, the cavity of the finished casting mold was filled with alloy cast steel with a high manganese content. The result was a cast slab locally reinforced with Fe-based composite zones.

A composite zone was obtained with a hardness above approximately 750 HV30 (Fig. 16, WC - type 1), while the hardness of the base alloy was approximately 250 to 300 HV30, and after hardening from 400 to 500 HV30 (data not shown in Fig. 16) . The obtained parameters indicate the achievement of a hardness comparable to solutions known in the art, which consist of synthesis within castings, with composite zones obtained based on titanium carbide, with a hardness of such a zone ranging from approximately 500 to 1200 HV30 (Fig. 16 ), however, the solution according to the present invention surprisingly provided a uniform distribution of hardness throughout the entire zone, as evidenced by the low standard deviation value shown in FIG. 16.

As a result of the experiments, a material of exceptional wear resistance was unexpectedly obtained, the abrasive wear index of which, determined by the “ball on disk” method, was 0.58×10 ^-6 mm ³ /N×m (Fig. 17, WC - type 1), according to compared with materials known in the art, obtained through in situ synthesis technology in castings using reactive components, while in the case of the selected materials, the abrasive wear rate ranged from 2.7 to 3.83×10 ^-6 mm ³ /N× m (Fig. 17).

Typical diagrams of structural elements containing an in situ produced composite zone containing a composite material according to the present invention, in which crystals and/or particles of tungsten carbide of a certain morphology are present, are shown in FIG. 18. The presented diagrams do not limit the scope of application in the production of other cast structural elements.

Claims (32)

1. A method for producing in situ a composite material based on iron-based alloys reinforced with tungsten carbide in the form of crystals and/or particles, where the microstructure of said composite material in the form of a composite layer of a cast structural element contains faceted crystals (6) and/or faceted carbide particles tungsten, providing a uniform macroscopic and microscopic distribution, while said crystals (6) and/or particles of tungsten carbide contain nano- and/or micro-regions of irregular and/or round and/or oval shape, filled with a metal-based alloy, including the following stages: a) applying to the cavity or core of the mold, in particular the sand core, a liquid reactive casting coating (2) containing a mixture of powders containing tungsten in the range from 90 to 97 wt. % and carbon in the range from 3 to 10 wt. %, and carrier, b) drying, in particular at a temperature equal to or above 100°C, c) filling the mold cavity with an iron-based alloy, wherein the heat supplied from the liquid alloy in the form of high temperature provides the energy necessary to initiate an in situ reaction of a ceramic phase in the form of at least one type of tungsten carbide or tungsten carbide with the addition of carbides of other types, which undergo a self-propagating high-temperature synthesis reaction and constitute a catalyst for the synthesis reaction of tungsten carbide. 2. The method according to claim 1, characterized in that the carrier is a solution of a solvent with the addition of a polymer, the solvent is preferably an alcohol, in particular ethyl alcohol, and the polymer is preferably a resin with low gas-forming ability, in particular rosin. 3. The method according to claim 1, characterized in that the surface density of the reactive cast coating is from 0.29 to 2 g/ ^cm2 , more preferably from 0.29 to 0.6 g/ ^cm2 , most preferably 0.5 g /cm ² . 4. The method according to claim 1, characterized in that the percentage of the mixture of powders to the carrier is from 6:1 to 1:1, preferably 4:1. 5. A method for producing in situ a composite material based on iron-based alloys reinforced with tungsten carbide in the form of crystals and/or particles, where the microstructure of said composite material in the form of a composite zone of a cast structural element contains faceted crystals (6) and/or faceted carbide particles tungsten, providing a uniform macroscopic and microscopic distribution, while said crystals (6) and/or particles of tungsten carbide contain nano- and/or micro-regions of irregular and/or round and/or oval shape, filled with a metal-based alloy, including the following stages: a) obtaining a mixture of powders containing tungsten and carbon; b) pressing the mixture of powders into a casting insert, which can take various forms, in particular granules, briquettes, preforms or compacts. c) introducing at least one casting insert into the mold cavity using fasteners, d) filling the mold cavity with an iron-based alloy, wherein the heat supplied from the liquid alloy in the form of high temperature provides the energy necessary to initiate an in situ reaction of a ceramic phase in the form of at least one type of tungsten carbide or tungsten carbide with the addition of carbides of other types, which undergo a self-propagating high-temperature synthesis reaction and represent a catalyst for the synthesis reaction of tungsten carbide, characterized in that said mixture of powders contains tungsten in the range from 90 to 97 wt. % and carbon in the range from 3 to 10 wt. %. 6. The method according to claim 5, characterized in that the compaction pressure of the powder mixture is from 100 to 650 MPa, preferably from 250 to 600 MPa, most preferably from 460 to 550 MPa, in particular, when ensuring the specified pressure by using pressing methods, in particular through the use of cold isostatic pressing, single- or biaxial cold pressing. 7. The method according to any of the previous paragraphs, characterized in that the mixture of powders contains tungsten in the range from 93 to 95 wt. % and carbon in the range from 5 to 7 wt. %. 8. The method according to any of the previous paragraphs, characterized in that the mixture of powders contains tungsten in an amount of 94 wt. % and carbon in the form of graphite in an amount of 6 wt. %. 9. The method according to any of the previous paragraphs, characterized in that the mixture of powders contains a) tungsten powder, in particular in the form of microcrystalline powder or nanoparticle agglomerates, b) carbon powder, in particular in the form of graphite and c) a catalyst in the form of precursors for the formation of carbides other than WC, which undergo a self-propagating high-temperature synthesis reaction, in particular TiC, MoC, NbC, ZrC, VC, TaC or mixtures thereof, excluding SiC. 10. Reactive cast coating, including: a) a mixture of powders containing tungsten in the range from 90 to 97 wt. % and carbon in the range from 3 to 10 wt. %, b) carrier; And c) a catalyst in the form of precursors for the formation of carbides other than WC, which undergo a self-propagating high-temperature synthesis reaction, in particular TiC, MoC, NbC, ZrC, VC, TaC or mixtures thereof, excluding SiC. 11. Reactive casting coating according to claim 10, characterized in that said mixture of powders contains tungsten in the range from 93 to 95 wt. % and carbon in the range from 5 to 7 wt. %. 12. Reactive casting coating according to claim 10, characterized in that said mixture of powders contains tungsten in an amount of 94 wt. %. and carbon in the form of graphite in an amount of 6 wt. %. 13. A cast structural element containing a composite material based on an alloy reinforced with tungsten carbide in the form of crystals and/or particles, where the microstructure of said composite material in the form of a composite layer obtained according to any one of claims. 1-4, and/or a composite material in the form of a composite zone obtained according to any one of paragraphs. 5-9, contains faceted crystals (6) and/or faceted particles of tungsten carbide, providing uniform macroscopic and microscopic distribution, while said crystals (6) and/or particles of tungsten carbide contain nano- and/or microregions of irregularity, and/or round and/or oval, filled with a metal-based alloy. 14. Cast structural element according to claim 13, characterized in that nano- and/or microzones (7) of irregular and/or round and/or oval shape, filled with a metal-based alloy, are located in the inner part of the crystals (6) and/or particles of tungsten carbide, and in the outer part, near the walls, the structure of crystals (6) and/or particles of tungsten carbide is homogeneous (8), while these crystals (6) and/or particles are formed in situ inside the liquid alloy and are present inside the matrix, while the specified matrix is formed after the process of crystallization of the alloy. 15. Cast structural element according to claim 13 or 14, characterized in that the composite material contains at least one type of tungsten carbide in an amount of from 15 to 90% by volume, preferably from 25 to 75% by volume. 16. Cast structural element according to claim 13 or 14, characterized in that the size of the particles and/or crystals (10) of tungsten carbide is preferably from 0.5 to 30 μm. 17. Cast structural element according to claim 13 or 14, characterized in that inside the region of the tungsten carbide crystal (6) the size of the areas filled with metal or alloy ranges from 0.1 to 4.5 μm. 18. Cast structural element according to claim 13 or 14, characterized in that the composite material additionally contains carbides or borides undergoing a self-propagating high-temperature synthesis reaction, in particular TiC, MoC, NbC, ZrC, VC, TaC, TaB, TiB ₂ or their mixture, excluding SiC.