Composite Material Based On Alloys, Manufactured In Situ, Reinforced With Tungsten Carbide And Methods Of Its Production

Abstract

A composite material is disclosed based on in situ produced alloys, especially iron based alloys, reinforced with tungsten carbide in the form of crystals and/or particles, that can be characterized by the fact that the microstructure of the composite material within the composite layer and/or the composite zone comprises faceted crystals and/or faceted particles tungsten carbide that provide uniform macroscopic and microscopic distribution, wherein the crystals and/or particles of tungsten carbide include irregular and/or round and/or oval nano and/or micro-areas filled with alloy based on metal. Compositions of powders used to produce the composite material and methods of its production as well as to cast working element made of such composite materials or using the method are disclosed.

Claims

1. Composite material based on in situ produced alloys reinforced with tungsten carbide in the form of at least one of crystals and particles, wherein a microstructure of the composite material within at least one of a composite layer and a composite zone comprises at least one of faceted crystals and faceted particles of tungsten carbide that provide uniform macroscopic and microscopic distribution, wherein the at least one of crystals and particles of tungsten carbide include at least one selected from the group consisting of irregular, round, oval nano, and micro-areas filled with alloy based on metal.

2. The composite material according to claim 1 wherein at least one of the irregular, oval, round nano and micro zones filled with an alloy based on metal are located within a internal part of the at least one of faceted crystals and particles of tungsten carbide, and within a external part near walls their structure is uniform, and the at least one of faceted crystals and particles are formed in situ within liquid alloy and are present within a matrix, the matrix is formed after a alloy crystallization process.

3. The composite material according to claim 1, wherein a volume of at least one type of tungsten carbide is from 15 to 90% by volume.

4. The composite material according to claim 1, wherein a size of the least one of particles and crystals of tungsten carbide amounts between 0.5 and 30 μm.

5. The composite material according to claim 1, wherein within a area of crystal of tungsten carbide, a size of areas filled with metal or alloy is from 0.1 to 4.5 μm.

6. The composite material according to claim 1, wherein the composite material comprises additional types of carbides or borides subject to self-propagating high-temperature synthesis reaction, TiC, MoC, NbC, ZrC, VC, TaC, TaB, TiB.sub.2 or their mix, except for SiC.

7. The composite according to claim 1 wherein a mix of powders for producing the composite material comprises tungsten with a range 90-97% wt. and carbon, in the form of high purity carbon or other carrier of its high content of the mixes thereof within a scope of 3-10% wt.

8. The composite according to claim 6, wherein a mix of powders for producing the composite material comprising tungsten carbide in a composite layer or zone of a wear part comprises: a. tungsten powder, in a form of at least one of microcrystalline powder, nanoparticles agglomerates, and other carrier of high tungsten content, b. carbon powder, in a form of at least one of graphite, other carrier of high carbon content, and their mixtures, and c. catalyst in a form of substrates of carbon forming reactions, other than WC or boride, which are subject to self-propagating high temperature synthesis reaction, TiC, MoC, NbC, ZrC, VC, TaC, TaB, TiB.sub.2, or mixtures thereof, except for SiC.

9. Method of producing a composite material based on in situ produced alloys reinforced with tungsten carbide in the form of at least one of crystals and particles, wherein a microstructure of the composite material within at least one of a composite layer and a composite zone comprises at least one of faceted crystals (6) and faceted particles of tungsten carbide that provide uniform macroscopic and microscopic distribution, wherein the at least one of crystals (6) and particles of tungsten carbide include at least one selected from the group consisting of irregular, round, oval nano, and micro-areas filled with alloy based on metal in the form of composite layer, including the following stages: a) covering the mould cavity or core with liquid reactive casting coating including a mix of powders and the carrier, i. wherein the mixture of powders includes at least one of tungsten and carrier powder of high tungsten content between 90-97% wt. and carbon in the form of high purity carbon or other carrier of high carbon content or their mixes, within the range from 3 to 10% wt. or, ii. wherein the mixture of powders includes a. tungsten powder in the form of at least one of microcrystalline, nanocrystalline powder, and agglomerates of nanoparticles, and other carrier of high tungsten content, b. carbon powder in the form of at least one of graphite, other carrier of high carbon content, and mixtures thereof, and c. catalyst in the form of carbide reactants other than WC or boride, which are subject to self-propagating high temperature synthesis reaction, TiC, MoC, NbC, ZrC, VC, TaC, TaB, TiB2 or the mixtures thereof, except for SiC; b) drying at temperature equal to or above 100° C., c) pouring the mould cavity with an alloy wherein heat supplied by the liquid alloy in the form of high temperature provides energy necessary to initiate the in situ reaction of a ceramic phase in a form of at least one type of tungsten carbide or tungsten carbide with addition of other types of carbides that are subject to self-propagating high temperature synthesis reaction and represent a catalyst of a tungsten carbide synthesis reaction.

10. The method according to claim 9, wherein the carrier is a solution of a solvent with addition of a polymer, the solvent is alcohol, and the polymer is a resin of low gas producing potential.

11. The method according to claim 9, wherein a surface density of the reactive cast coating is within a range of 0.29 to 2 g/cm.sup.2.

12. The method according to claim 9, wherein a percentage ration of the powders mixture to the carrier is 6:1 to 1:1.

13. A method of producing the composite material based on in situ produced alloys reinforced with tungsten carbide in the form of at least one of crystals and particles, wherein a microstructure of the composite material within at least one of a composite layer and a composite zone comprises at least one of faceted crystals (6) and faceted particles of tungsten carbide that provide uniform macroscopic and microscopic distribution, wherein the at least one of crystals (6) and particles of tungsten carbide include at least one selected from the group consisting of irregular, round, oval nano, and micro-areas filled with alloy based on metal in the form of the composite zone, comprising the following steps: a) preparation of the powders mix i. wherein the mixture of powders includes at least one of tungsten and carrier powder of high tungsten content between 90-97% wt. and carbon in the form of high purity carbon or other carrier of high carbon content or their mixes, within the range from 3 to 10% wt., or ii. wherein the mixture of powders includes a. tungsten powder in the form of at least one of microcrystalline, nanocrystalline powder, and agglomerates of nanoparticles, and other carrier of high tungsten content, b. carbon powder in the form of at least one of graphite, other carrier of high carbon content, and mixtures thereof, and c. catalyst in the form of carbide reactants other than WC or boride, which are subject to self-propagating high temperature synthesis reaction, TiC, MoC, NbC, ZrC, VC, TaC, TaB, TiB2 or the mixtures thereof, except for SiC; b) pressing the powders mix in a form of a casting mould compacts, which can have different forms, especially granules, briquettes, preforms or compacts, c) insertion of at least one casting compact within the mould cavity using installation elements, d) pouring the mould cavity with an alloy, wherein heat supplied by the liquid alloy in a form of high temperature provides energy necessary to initiate the in situ reaction of a ceramic phase in a form of at least one type of tungsten carbide or tungsten carbide with addition of other types of carbides that are subject to self-propagating high temperature synthesis reaction and represent a catalyst for the tungsten carbide synthesis reaction.

14. The method according to claim 13, wherein pressure of the reagent pressing is between 100 and 650 MPa, wherein when the pressure is obtained using at least one of compaction methods, cold isostatic pressing, one or two-axis cold pressing.

15. The composite material according to claim 1 in the form of a cast structural element.

16. The composite material according to claim 1, wherein a volume of at least one type of tungsten carbide is from 25 to 75% by volume.

17. The composite according to claim 1 wherein a mix of powders for producing the composite material comprises tungsten within a range of 93-95% wt., and carbon within a scope 5-7% wt.

18. The composite according to claim 1 wherein a mix of powders for producing the composite material comprises tungsten in the amount of 94% wt. and carbon in the form of graphite in amount about 6% wt.

19. The method according to claim 9, wherein a surface density of the reactive cast coating is from 0.29 to 0.6 g/cm.sup.2.

20. The method according to claim 9, wherein a surface density of the reactive cast coating is 0.5 g/cm.sup.2.

Description

[0043] The invention is presented in embodiments that do not limit the protective scope of the invention and on the following figure, wherein:

[0044] FIG. 1 presents a layer (a) of composite material (b) with tungsten carbide crystals/particles within the matrix based on the iron based alloy of characteristic morphology (c) comprising the area filled with an alloy present within the internal part of the crystal (area I) and area deprived of the areas filled with alloy within external part of the crystal (area II), manufactured using the reactive in situ cast coating,

[0045] FIG. 2 presents a cross-section of the core representing an element of the casting mould for producing a casting of a pump body with the applied reactive casting coating (a) and diagram of a pump body (b) with the in situ produced composite layer reinforced with tungsten carbide of characteristic morphology as well as diagrams concerning tee-section (c, d),

[0046] FIG. 3 presents the characteristic morphology of faceted tungsten carbide crystal within layer including irregular oval areas filled with an alloy based on metal;

[0047] FIG. 4 presents histograms of the tungsten carbide particles/crystals size distribution as well as sizes of areas filled with the alloy within the area of individual particles/crystals of tungsten carbide,

[0048] FIG. 5 presents the microstructure of the composite layer cross-section produced in situ in the casting, reinforced with tungsten carbide particles/crystals together with selected, magnified areas,

[0049] FIG. 6 presents exemplary microstructures of the layer with the composite with determined surface area content of the ceramic phase, i.e. tungsten carbide, matrix of the composite layer and graphite surface area content being the component of grey cast iron used to produce the cast,

[0050] FIG. 7 presents the microstructure of the composite layer as well as average size of tungsten carbide particles determined as its two diagonals intersecting at the right angle,

[0051] FIG. 8 presents photos of the grey iron cast with the composite layer made in situ, obtained with the use of different surface densities of the casting reactive coating according to the invention,

[0052] FIG. 9 presents the microstructure of the in situ composite layer produced using the mix of reactants of the reaction forming two types of carbide (tungsten and titanium), subject to self-propagating high-temperature synthesis reaction,

[0053] FIG. 10 presents the surface area content of individual phases representing the microstructure of the in situ composite layer produced using the mix of substrate mix of the reaction forming two types of carbide (tungsten and titanium), subject to self-propagating high-temperature synthesis reaction,

[0054] FIG. 11 presents photos of the casting mould cavities with the reactive casting coatings applied on their surfaces for the in situ synthesis of composite layers reinforced with tungsten carbide,

[0055] FIG. 12 presents the effect of surface density of the reactive cast coating on the macrostructure of the in situ produced composite layer reinforced with tungsten carbide in the casting of slabs of different thickness,

[0056] FIG. 13 presents a microstructure of the composite material using the reactive compact (a) in the cast of cast steel comprising carbide crystals of characteristic morphology (b) comprising irregular oval areas filled with an alloy and areas deprived of them,

[0057] FIG. 14 presents a microstructure of the composite material having crystals/particles of tungsten carbide together with the graph presenting the following surface area content of: ceramic phase in the form of different types of tungsten carbide and metal composite matrix,

[0058] FIG. 15 presents a microstructure of particles/crystals of different types of tungsten carbide structure, including WC type carbide,

[0059] FIG. 16 presents comparative results of hardness of composite zones according to the invention with the wear resistant reference casting alloy of reinforced manganese cast steel as well as composite material reinforced with titanium carbide (TiC) particles made in situ within the casting,

[0060] FIG. 17 presents comparative results of abrasive wear composite zones according to the invention with the wear resistant reference casting alloy of reinforced manganese cast steel as well as composite material reinforced with titanium carbide (TiC) particles made in situ within the casting,

[0061] FIG. 18 presents exemplary diagrams of structural elements and their cross-sections with the in situ produced zones comprising the composite material with crystals and/or particles of tungsten carbide of specific morphology according to the invention,

[0062] FIG. 19 presents schematic process of manufacture the composite material according to the invention within the layer of casting (a) and zone of casting (b).

EXAMPLE 1

[0063] According to one embodiment, the core 1 of the casting mould to produce the pump body 4 cast or Tee-section is coated with the reactive coating 2 using a sprayer 3, as shown in the FIGS. 2a and 2c. As a result, pump body 4 cast or Tee-section with the layer 5 comprising composite material (FIG. 2b, 2d) made in situ in produced with visible morphology of faceted tungsten carbide 6 consisting of two forms, one in the internal part of a particle containing irregular, round, oval areas filled with the alloy and another in the external part of a particle deprived of areas filled with the alloy 6, as shown in the FIG. 3. Diagram of the process of producing the coating is presented in FIG. 19a.

[0064] To form the layer 5 of WC reinforced composite in the internal surface of the pump body 4 or Tee-section subject to intense wear, core 1 of the casting mould was prepared. The reactive casting coating 2 is applied directly on the surface of the core 1 made of quartz sand and furan resin. The coating 2 is made by mixing tungsten powder of particle size ca. 5 μm and graphite powder of particle size ca. 5 μm. The mixture of the powders was made using 94% wt. of tungsten and 6% wt. of graphite. Then, the weighed amounts of powders were introduced into liquid solution of resin in the alcohol representing the carrier and air dried gluing agent. Mutual ratio of the tungsten and graphite powders mixture to liquid solution of gluing agent in both cases was 4:1 parts by weight. The whole was subject to mixing in order to obtain uniform reactive consistency of the cast reactive coating 2. The mixed reactive cast coating 2 was applied by means of a spray gun 3 on the casting core 1, representing the internal shape of the Tee-section 4. The coating was applied in layers until obtaining surface density 0.5 g/cm.sup.2 and 0.45 g/cm.sup.2. Then, the core 1 was installed within the mould cavity, and then each of the moulds was assembled and filled with liquid alloy of temperature 1380° C. Using the aforementioned method, a body 4 of the pump or Tee-section was made.

[0065] Body 4 of the pump manufactured using this method had the core area equal to ca. 3789 cm.sup.2. In order to do that, a powder mixes of two different compositions were used, wherein one comprised 96% at. W and 4% wt. C, and the other one 94% wt. W and 6% wt. C. In both cases, the produced casts had base alloy with a microstructure characteristic for grey cast iron with separated flake graphite whose outer surface was reinforced with the composite layer 5 comprising tungsten carbide particles 6. Application of the cast cores 1 of the same area and similar surface density of the applied reactive cast coating 2 was intended and performed in order to show the impact of the applied stoichiometry of the powders mix on the continuity of the composite layer. The results are presented in the FIGS. 8 A.1-A.3 and B.1-B.3. The performed observations showed that the application of reactive casting coating 2 comprising the mixt of powders 96% at. W to 4% wt. C allowed for obtaining the continuity of the layer at the level ca. 80%, and in case of the mixture 94% wt. W to 6% wt. C specified in the patent application as designed for producing the in situ composite layer, characterized with the continuity at the level of 100%. In both types of pumps bodies 4, composite layers were made reinforced with WC, using reactive cast coatings 2 of surface density given in Table 1, in order to obtain continuity at the level between 100% and 80% of the pump internal surface. This shows that together with the increase of share of atomic tungsten in the powders mixture, the synthesis reaction deteriorates resulting in lack of continuous composite layer. However, continuity of the layer at the level of 80% may be acceptable under certain industrial applications.

TABLE-US-00001 TABLE 1 Mass fraction, Surface density of Weight of Layer Core surface [% wt.] the reactive cast the applied Protective continuity No. [cm.sup.2] W C coating [g/cm.sup.2] coating [g] coating [%] 1. 3247.52 94 6 0.29 1000 not 100 available 2. 3247.52 94 6 0.4 1300 not 100 available 3. 3789.62 94 6 0.29 1100 not 100 available 4. 3789.62 94 6 0.4 1500 not 100 available 5. 3789.62 94 6 0.5 1894.5 not 100 available 6. 3247.52 96 4 0.29 1000 not 100 available 7. 3247.52 96 4 0.4 1300 not 100 available 8. 3789.62 96 4 0.29 1100 not available 100 9. 3789.62 96 4 0.4 1500 not available 100 10. 3789.62 96 4 0.5 1894.5 not available 90 11. 3247.52 96 4 0.5 1623.76 not available 90 12. 3247.52 96 4 0.5 1623.76 applied 80 13. 3247.52 96 4 0.6 1623.76 not available 80

[0066] As a result of the synthesis reaction, local composite reinforcements reinforced with particles of a t least one tungsten carbide type, are formed in the cast steel casting. The core 2 of the casting, after the crystallization process had the microstructure characteristic for the given grade of the cast steel, however the in situ crystals 6 are formed within the casting surface area. Such a crystal 6 has a morphology consisting of two different areas. One of the areas is within the internal part of the crystal 6 of tungsten carbide and comprises micro-areas 7 of shape similar to oval, filled with an alloy based on metal, and the other one is a rim 8 surrounding it deprived of oval micro-areas filled with alloy, as showed in the FIG. 3. Average particle size preferably is within the range from 4 to 18 μm, average size of areas filled with the base alloy is from 0.05 to 0.45 μm, as showed in the FIG. 4.

[0067] The wear index—determined using the Ball-on-disk method—of the layer 5 with composite material reinforced with tungsten carbide in the pump body 4 casting of grey cast iron with flake graphite, representing the base alloy, is from 5 to 8*10.sup.−6 mm.sup.3/N*m, and in the pump body 4 of grey cast iron with flake graphite representing the base alloy without the reinforcement layer is 37.6*10.sup.−6 mm.sup.3/N*m. I.e. the layer with the composite material according to the invention wear from 4.7 to 7.5 times less comparing to the pomp made of grey cast iron.

EXAMPLE 2

[0068] In the example of the wear resistant casting with the layer of composite material, the coating is made by mixing tungsten powder of particles size about 5 μm and graphite powder of particles size below 5 μm. The mixture of the powders was made using 96% wt. of tungsten and 4% wt. of graphite. Then, the weighed amounts of powders were introduced into liquid solution of resin in the alcohol representing the carrier and air dried gluing agent. Mutual ratio of the tungsten and graphite powders mixture to liquid solution of gluing agent in both cases was 4:1 parts by weight. The whole was subject to mixing in order to obtain uniform reactive consistency of the cast reactive coating 2. The mixed reactive cast coating 2 was applied by spraying with a spray gun 3 onto the casting mould cavity. The coating 2 was applied in layers until obtaining surface density at least 0.5 g/cm.sup.2. Them the mould was assembled and filled with liquid alloy of manganese cast steel composition of the following content of the main alloying elements, 1.3% C, 0.6% Si, 12.2% Mn and the remaining of Fe.

[0069] The composite layer presented in the FIG. 1 of hardness 724 HV30 (1253 HV1), with the hardness of the basic alloy amounting ca. 247 HV30 (517 HV1) was obtained. The obtained parameters indicate achievement of hardness almost three-times higher than of wear resistant manganese cast steel.

EXAMPLE 3

[0070] In order to produce the in situ composite layer 5 reinforced with WC, the sand core of the casting mould 1 was prepared, based on quartz sand and water glass blown with CO.sub.2. The casting mould 1 cavity was coated with reactive casting coating 2. The coating 2 is made by mixing tungsten powder of particle size 5 μm and graphite powder of particle size ca. 5 μm. The mixture of the powders was made using 94% wt. of tungsten and 6% wt. of graphite. Then, the powders were introduced into liquid solution of colophony in the alcohol representing the carrier and air dried gluing agent. Mutual ratio of the tungsten and graphite powders mixture to liquid gluing agent was 4:1 parts by weight. The whole was subject to mixing in order to obtain uniform reactive consistency of the cast reactive coating 2. The mixed reactive casting coating 2 was applied by spraying with a spray gun 3. The coating 2 was applied in layers until obtaining surface density 0.29 g/cm.sup.2 or 0.4 g/cm.sup.2. Then, the casting mould cavity was dried in order to remove residues of alcohol and moisture follow by filling with liquid alloy at temperature ca. 1400° C. The cast, after the crystallization process had the microstructure of grey cast iron with flake graphite, however within the area of composite layer, the in situ crystals 6 and/or WC particles were formed, having a structure formed of two different areas. One of the areas is within the internal part of the crystal 6 or WC particle and comprises micro-areas 7 of shape similar to oval, filled with an alloy based on metal, and the other one is a rim 8 surrounding it deprived of oval micro-areas filled with alloy. The cross-section of the layer with the selected magnified areas is presented in the FIG. 5. In order to assess the share of the reinforcing phase, one determined surface area content of phases identified within microstructure, i.e. flake graphite and base alloy representing the matrix of the composite layer and tungsten carbide representing the reinforcement phase. Exemplary microstructures with determined surface share and the obtained results are presented in the FIG. 6. Surface share of tungsten carbides in this case is 25% and of the matrix 70%, the rest is graphite being the component of the basic alloy used to produce the cast. Moreover, average tungsten carbide particle size was estimated and it was determined as an average of two measurements of diagonals intersected at the right angle. The results show to bimodal size distribution of tungsten carbide within the composite layer that achieves the first distribution maximum for the distribution from 0.5 to 6 μm, and the other from 7 to 30 μm. The results are presented in the form of a histogram, as showed in the FIG. 7.

EXAMPLE 4

[0071] In order to produce internal layer of the pump body 4 that is subject to intense wear, the layers 5 comprising the composite material reinforced with ceramic phases particles, such as tungsten and titanium carbides, the mould core 1 was prepared. The reactive casting coating 2 was applied directly on the surface of the core 1 made of quartz sand and water glass and blown with CO.sub.2. The coating 2 was made based on mixing 80% wt. of reaction substrates forming tungsten carbide and 20% wt. of reaction substrates forming titanium carbide. The mixture of powders of reaction substrates forming tungsten carbide was made in the weight ratio W:C equal to 94:6% wt. Reaction substrates forming TiC were prepared in atomic ratio of Ti:C equal to 55:45%. In this case, the following powders were used: tungsten of micro-crystalline morphology and particle size ca. 4.5 μm, titanium of spongy morphology of particle size 44 μm and graphite of flake morphology of particle size below 5 μm. The prepared mixture of powders was introduced into liquid solution of colophony resin in ethyl alcohol representing the carrier and air dried gluing agent. Mutual ratio of the tungsten and graphite powders to liquid gluing agent was 4:1 parts by weight. The casting coating was prepared based on 600 g of powders mixture and 150 g of solution. The whole was subject to mixing in order to obtain uniform reactive consistency of the cast reactive coating 2. The mixed reactive casting coating 2 was applied by spraying with a spray gun 3. Then, the core 1 together with the applied reactive casting coating 2 was dried at temperature above 100° C. in order to remove residues of alcohol and moisture. The core 1 was installed inside the casting mould cavity, and then the mould was assembled and filled with liquid alloy. The casting 4, after the crystallization process had the microstructure of grey cast iron with flake graphite, however within the composite layer 5 area, the in situ particles of tungsten and titanium carbides were formed (FIG. 9). The obtained microstructure were used to determine the surface share of individual phases representing microstructure of the produced in situ composite layer. The results are showed in the FIG. 10 considering the division of phases present within the area of the matrix and composite layer. The presence of non-faceted particles of TiC within the microstructure indicates the addition of percentage share of pure TiC formation reaction substrates. Hardness test performed using Vickers method (HV1) under the load of 1 kG i.e. 9.81 N within the area of the base alloy and the composite layer showed the values at the level of 312.3 HV1 and 767.1 HV1 respectively. The obtained results indicate over twice increase of hardness of the outer layer of the cast made together with the in situ composite layer.

EXAMPLE 5

[0072] In this example, the purpose was to bind the composite coating surface density and thickness of the cast wall as a parameter affecting the course and effectiveness of the tungsten carbide synthesis reaction. The performed observations indicated that application of mutual ratio of powders W:C amounting 96:4% wt. is less favourable than 94:6% wt. therefore, within another experiment, one used the composition of W:C equal to 94:6% wt. Powders, with such a composition, were introduced into liquid solution of colophony in the alcohol representing the carrier and air dried gluing agent. Mutual ratio of the tungsten and graphite powders mixture to liquid gluing agent was 4:1 parts by weight. The whole was subject to mixing in order to obtain uniform reactive consistency of the cast reactive coating 2. The mixed reactive casting coating 2 was applied by spraying with a spray gun 3.

[0073] Casting moulds were prepared to produce casts of slabs of thickness 10 and 90 mm, wherein each of the cavities was divided to three equal parts. Each of the separated areas of the sand mould was covered with the cast coating until obtaining the surface density 0.3 g/cm.sup.2, 0.4 g/cm.sup.2, 0.5 g/cm.sup.2, 0.6 g/cm.sup.2, 0.7 g/cm.sup.2 and 0.8 g/cm.sup.2, as showed in the FIG. 11. In turn, FIG. 12 presents macrostructure of the castings with in situ produced composite layers. The observations of the casts macrostructure indicate that in case of surface density 0.3 g/cm.sup.2, 0.4 g/cm.sup.2 and 0.5 g/cm.sup.2 it is possible to obtain a cast of continuous operating surface reinforced with a composite layer without any significant impact of the cast wall thickness. In case of increasing the amount of the applied coating to 0.6 g/cm.sup.2, 0.7 g/cm.sup.2 and 0.8 g/cm.sup.2 respectively for the thin-walled cast of wall thickness 10 mm, one may observe no synthesis reaction—lack of the composite layer on the cast surface. In case of the cast of wall thickness 90 mm, the macrostructure has areas deprived of the composite layer, which characterized with a structure similar to a “shell”. Application of surface density of the reactive cast coating 2 between 0.6 g/cm.sup.2-0.8 g/cm.sup.2 results in lack of full infiltration due to missing enough energy for the in situ WC synthesis reaction to take place. It is to be noted that this result is related to casts of small dimensions and low weight, which should not limit the cases of casts with higher weight, wherein the use of higher surface densities of the reactive cast coatings 2 allows for obtaining continuous composite layer.

EXAMPLE 6

[0074] In the embodiment using the reactive compact, local composite reinforcements were provided, reinforced with at least one type of tungsten carbide in the form of crystals/particles. In order to do that, a mix of powders of tungsten and carbon was prepared with the mass fraction of W:C equal to 90:10% wt. The size of tungsten and graphite particles was 4.5 μm and below 5 μm respectively. The prepared weighed amount of powders was mixed for 60 minutes and then dried at temperature 175° C. to evaporate the absorbed moisture. The prepared weighed amounts of powders of predetermined weight were pressed under pressure of 500 MPa using cold one-axis compaction. The prepared reactive casting pads were inserted into the casting mould and fixed to it at predetermined place using bolts. Then, it was filled with a casting iron based alloy—cast steel comprising 0.28% C, 1.85% Cr, 0.6% Mn, 1.58% Si and the rest was Fe (GS30) at temperature 1580° C. The reaction between tungsten and carbide is initiated by supplying heat energy via the liquid casting alloy. Due to the synthesis reaction, the composite zone was formed reinforced with particles/crystals of at least one type of tungsten carbide. The core of the casting, after the crystallization process had the microstructure characteristic for the given grade of the cast steel, however the in situ crystals are formed within the casting pad area. Crystals 6 and/or particles have morphology composed of two different areas. One of the areas is within the internal part of the crystal 6 and/or particle of tungsten carbide and comprises micro-areas 7 of shape similar to oval, filled with an alloy based on metal, and the other one is a thin rim 8 surrounding it deprived of oval micro-areas filled with alloy, as showed in the FIG. 13b.

EXAMPLE 7

[0075] Another experiment was performed that was similar to example 6, however the mass fraction of tungsten to graphite powders was 94:6% wt., and the temperature of filling was 1560° C. and the pressure of pressing 500 MPa. After the synthesis reaction in the casting mould, one obtained the volume of the reinforced phase at the maximum level amounting ca. 74% (FIG. 14). As presented in the FIG. 15, the microstructure of the composite zone area can be characterized by the presence of tungsten carbide WC of characteristic morphology presented in the FIG. 13b and carbide type W.sub.2Fe.sub.2C. In order to verify the chemical composition, tests were performed using an energy dispersive x-ray microanalysis. In case of the accepted research method, the mass fraction of carbon must be treated qualitatively only, not quantitatively. The results of measurements within individual items are presented in Table 2. The produced cast weighed ca. 1.5 kg.

TABLE-US-00002 TABLE 2 Chemical composition, % wt. Point C Cr Fe W Mn Si 11 — 1.2 91.0 7.1 0.6 — 12 — 1.2 91.9 5.1 0.6 1.2 13 1.8 — 3.3 94.9 — — 14 2.1 — 2.5 95.4 — — 15 0.8 1.1 24.5 73.6 — — 16 0.8 1.1 25.7 72.4 — —

[0076] One obtained the composite zone of hardness above 1100 HV30 (FIG. 16, WC—type 2), with the hardness of the base alloy amounting ca. 250-300 HV30. The obtained parameters indicate the achievement of harness comparable to solutions known in the art that consist in synthesis within the castings, wherein composite zones are produced based on titanium carbide, wherein the zone have hardness from ca. 500 to 1200 HV30 (FIG. 16), however, in the solution according to the invention, a uniform distribution of hardness within the whole zone was unexpectedly achieved, as manifested by low value of standard deviation showed in the FIG. 16.

[0077] As result of the performed experiments, a material of exceptional wear resistance was unexpectedly obtained, where the abrasive wear index, determined using the Ball-on-disk method was 0.16*10 mm.sup.3/N*m (FIG. 17, WC—type 2) in relation to materials known in the art manufactured using the in situ synthesis technique in castings using reactive components, wherein in case of the selected materials, the abrasive wear index was 2.7 to 3.83*10.sup.−6 mm.sup.3/N*m (FIG. 17).

EXAMPLE 8

[0078] In this case, the purpose was to form local composite reinforcements within the slab casting. In order to do that, a mix of powders was prepared comprising WC reagents, which was pressed under pressure 450 MPa. The chemical composition of the mix was prepared with the percentage share W:C amounting 94:6% wt. Dimensions of the slab 300 mm, thickness ca. 30 mm and width 75 mm. The casting pads of thickness 5 mm were installed within the casting mould cavity at the locations of the highest wear using metal elements representing an installation system. To initiate the WC synthesis reaction, the ready casting mould cavity was filled with alloying cast steel of higher manganese content. As a result, slab cast locally reinforced with composite zones based on Fe were obtained.

[0079] One obtained the composite zone of hardness above ca. 750 HV30 (FIG. 16, WC—type 1), with the hardness of the basic alloy ca. 250-300 HV30, and after hardening 400-500 HV30 (data not included in the FIG. 16). The obtained parameters indicate the achievement of harness comparable to solutions known in the art that consist in synthesis within the castings, wherein composite zones are produced based on titanium carbide, wherein the zone have hardness from ca. 500 to 1200 HV30 (FIG. 16), however, in the solution according to the invention, a uniform distribution of hardness within the whole zone was unexpectedly achieved, as manifested by low value of standard deviation showed in the FIG. 16.

[0080] As result of the performed experiments, a material of exceptional wear resistance was unexpectedly obtained, where the abrasive wear index, determined using the Ball-on-disk method was 0.58*10.sup.−6 mm.sup.3/N*m (FIG. 17, WC—type 1) in relation to materials known in the art manufactured using the in situ synthesis technique in castings using reactive components, wherein in case of the selected materials, the abrasive wear index was 2.7 to 3.83*10.sup.−6 mm.sup.3/N*m (FIG. 17).

[0081] Exemplary diagrams of the structural elements comprising the in situ produced composite zone, wherein the zone comprises the composite material according to the invention, wherein crystals and/or particles of tungsten carbide of specific morphology are present, are showed in the FIG. 18. The presented diagrams do not limit the area of application in case of producing other cast structural elements.