Composite wear part

Abstract

The invention relates to a graded wear part comprising a reinforcing portion comprising zirconia or alumina-zirconia alloy, said reinforcing portion further comprising a centimeter insert having a predetermined geometry, said insert comprising microparticles of a metal carbide, nitride, boride or intermetallic compound bound by a first metal matrix, said insert being inserted into a reinforcing structure infiltrated by a second metal matrix, the reinforcing structure comprising periodically alternating millimeter regions of high and low concentrations of microparticles of zirconia or alumina-zirconia alloy, the second metal matrix being different from the first metal matrix.

Description

TECHNICAL FIELD

[0001] Subject matter of the invention

[0002] The present invention relates to a cast wear part. It relates more particularly to a graded wear part comprising a reinforcement on the side of the part where the stresses are the most important. This reinforcement is obtained by placing in the mould, at the time of preparing the casting of the wear part, a reinforcement consisting of an aggregate of millimetric particles with millimetric interstices. This reinforcement also comprises centimetric inserts made of ceramic and manufactured beforehand according to a predetermined geometry. The inserts comprise micrometric ceramic particles incorporated in a first metal matrix and the millimetric interstices of the reinforcement are infiltrated with a second metal matrix during the casting. The first metal matrix is independent of the second metal matrix.

[0003] The invention also proposes a method for obtaining said wear part with its reinforcement. BACKGROUND

[0004] State of the art

[0005] Mining and crushing equipment, in particular grinding and crushing devices, are subject to many constraints in terms of impact and wear resistance.

[0006] In the field of aggregates, cements and ore processing, wear parts include ejectors and anvils of vertical shaft crushers, hammers and battos of horizontal shaft crushers, cones for crushers, tables and rollers of vertical grinders, liners and elevators of ball or rod grinders. With regard to mining equipment, mention can be made in particular of oil sand pumps or drills, mining pumps and digging teeth.

[0007] It is known in the prior art to manufacture composite wear parts by casting by casting parts comprising a portion reinforced by ceramic and infiltrated during the casting.

[0008] Document EP 0 575 685 A1 (Sulzer, 1996) describes a moulded part having a wear surface reinforced by porous ceramic bodies integrated in a metal phase, each ceramic body having a structure in the form of a porous three-dimensional network.

[0009] Document WO 981 5373 A1 (Magotteaux, 1997) discloses a composite wear part manufactured by a casting process. It comprises a metal matrix with a reinforcement formed by a three-dimensional structure of agglomerated particles comprising a homogeneous phase of 20-80% of AI2O3 and 80-20% of ZrO2.

[0010] Document WO2016008967A1 (Magotteaux, 2015) discloses sintered ceramic particles comprising 3-55 wt% of alumina and 40-95 wt% of zirconia, combined with inorganic components such as rare earth metal oxides or alkaline earth metal oxides.

[0011] However, the documents according to the prior art do not make it possible to obtain a high concentration of ceramic in the most stressed parts of the component, since the millimetric three-dimensional aggregate structure of grains requires a sufficient interstice proportion to allow the complete infiltration of the reinforcing structure by the ferrous alloy during casting, which limits the concentration of available ceramic in the reinforced zone. SUMMARY

[0012] Object of the invention

[0013] The present invention aims to overcome the drawbacks of the prior art, in particular the difficulty of obtaining a reinforced zone comprising very high concentrations of ceramic particles. The object of the present invention is also to integrate a zone with a high concentration of ceramic particles within a three-dimensional structure of aggregated millimetric grains mainly based on alumina-zirconia, comprising millimetric interstices that can be infiltrated by the cast ferrous alloy. The reinforcing structure of millimetric grains also makes it possible to position a preformed insert in the mold of a wear part, the insert having a defined geometry and being enriched with carbide, nitride, boride or intermetallic element type ceramic particles. The insert comprises a first metal matrix acting as a binder for the ceramic particles, the first metal matrix being independent of the cast alloy constituting a second metal matrix.

[0014] Summary of the invention

[0015] The present invention discloses a graded wear part comprising a reinforced portion comprising zirconia or an alumina-zirconia alloy, said reinforced portion further comprising a centimetric insert having a predetermined geometry, said insert comprising micrometric particles of metallic carbide, nitride, boride or intermetallic compound bound by a first metal matrix, said insert being inserted into a reinforcing structure infiltrated by a second metal matrix, the reinforcing structure comprising millimetric zones of periodically alternating high and low concentrations of micrometric particles of zirconia or an alumina-zirconia alloy, the second metal matrix being different from the first metal matrix.

[0016] The preferred embodiments of the present invention comprise at least one or any suitable combination of the following features:

[0017] - the reinforcing portion also comprises millimetric regions of ceramic-metal composite comprising microparticles of titanium carbide, titanium nitride or titanium carbonitride in a binder constituting a third metallic matrix, independent of the first and second metallic matrices, in a proportion of less than 50% by volume, preferably less than 40% by volume, particularly preferably less than 30% by volume, relative to the millimetric regions of microparticles of high-concentration zirconia or alumina-zirconia alloy;

[0018] - the insert comprises a concentration of microparticles of intermetallics or of metal carbides, nitrides, borides or intermetallics of elements of between 20 and 95% by volume, and at least 30% by volume, preferably at least 40% by volume, particularly preferably at least 50% by volume;

[0019] - the first metallic matrix used as a binder for the microparticles of the insert is mainly composed of nickel, a nickel alloy, cobalt, a cobalt alloy or an iron alloy different from the cast alloy;

[0020] - the third metallic matrix used as a binder for the microparticles of titanium carbide, titanium nitride or titanium carbonitride in the millimetric regions that are part of the reinforcement is mainly composed of nickel, a nickel alloy, cobalt, a cobalt alloy or an iron alloy different from the cast alloy;

[0021] - the millimetric regions of the insert or of the reinforcement, when they comprise a ceramic-metal composite, comprise particles of intermetallics or microparticles of metal carbides, nitrides, borides with an average size D50 of less than 80 pm, preferably less than 60 pm and particularly preferably less than 40 pm;

[0022] - the insert and the regions reinforced with zirconia or alumina-zirconia alloy comprise micrometric interstices comprising a different metallic matrix.

[0023] The application also discloses a method for manufacturing a wear part according to the application, comprising the following steps:

[0024] - providing a mold comprising a cavity of the wear part with a predetermined geometry of the region to be reinforced;

[0025] - introducing and positioning a compacted mixture of powder in the form of zirconia or alumina-zirconia millimetric granulés in said region to be reinforced, at least partially surrounding one or more prefabricated inserts with a defined geometry and enriched with microparticles of metal carbides, nitrides, borides or intermetallics bound by a first metallic matrix;

[0026] - casting an iron alloy into the mold, said liquid iron alloy infiltrating into the three-dimensional structure comprising the particles of zirconia or alumina-zirconia alloy at least partially surrounding the prefabricated inserts.

[0027] According to a preferred embodiment of the method of the application, the insert having a predetermined geometry, manufactured before casting the wear part, is manufactured by powder metallurgy.

[0028] The application further discloses the application in the form of an impactor, an anvil, a cone or a grinding roller. BRIEF DESCRIPTION OF DRAWINGS

[0029] Brief description of the drawings

[0030] Figure 1 A wear part having a zone reinforced by a reinforcement comprising a preformed cylindrical insert surrounded by a structure of infiltrated metal into zirconia or alumina-zirconia based aggregated millimetric particles is schematically shown.

[0031] Figure 2 Details of the reinforcement according to the application are schematically shown, consisting of a preformed cylindrical insert made of ceramic fixed in a structure of millimetric particles of zirconia or alumina-zirconia.

[0032] Figure 3 A beater of a horizontal shaft crusher having a predetermined zone reinforced by a preformed cylindrical ceramic insert surrounded by a structure of millimetric particles of zirconia or alumina-zirconia having infiltrable porosity and millimetric interstices is schematically shown.

[0033] Figure 4 A grinding roller of a vertical mill having a predetermined zone reinforced by a preformed cylindrical ceramic insert surrounded by a structure of millimetric particles of zirconia or alumina-zirconia having infiltrable porosity and millimetric interstices is schematically shown.

[0034] Figure 5 An anvil of a vertical shaft crusher having a predetermined zone reinforced by a preformed cylindrical ceramic insert surrounded by a structure of millimetric particles of zirconia or alumina-zirconia having infiltrable porosity and millimetric interstices is schematically shown.

[0035] Figure 6 A method for measuring the Feret diameter (minimum and maximum Feret diameter) is schematically shown. The Feret diameter is used in this method to obtain the average size of the ceramic-metal particles (as explained below).

[0036] List of symbols

[0037] 1 : Composite wear part reinforced by a ceramic composition at the site most exposed to wear.

[0038] 2: Reinforcing structure of predetermined geometry infiltrated by a cast metal (second metal matrix) comprising alumina-zirconia millimetric particles with infiltrable porosity and millimetric interstices.

[0039] 3: Prefabricated ceramic-metal composite insert comprising a first metal matrix different from the cast metal, as binder of ceramic particles based on carbides, nitrides, borides and intermetallic elements, which is integrated into the infiltrable structure, which is placed as a whole in the mould before casting.

[0040] 4: Detail of the reinforcing structure showing millimetric interstices with areas of low concentration of ceramic particles. This interstice is mainly occupied by the second metal matrix (cast metal).

[0041] 5: Detail of the reinforcing structure showing millimetric areas with high concentration of ceramic particles, which originate from the aggregates of millimetric particles infiltrated by the second metal matrix (cast metal).

[0042] 6: Cast metal (second metal matrix).

[0043] 7: Alumina in the millimetric particles forming the infiltrable porous structure.

[0044] 8: Zirconia in the millimetric particles forming the infiltrable porous structure.

[0045] References 7 and 8 show the alloy of alumina-zirconia particles.

[0046] 9: Prefabricated ceramic particles, which can occupy up to 90% of the total volume of the insert. These inserts can be manufactured by any technique, but preferably by powder metallurgy.

[0047] 10: First metal matrix dedicated to the ceramic insert. This metal matrix, which acts as binder of particles of carbides, nitrides, borides and intermetallic elements, is independent of the second metal matrix resulting from the casting, which infiltrates the infiltrable structure based on zirconia and / or alumina-zirconia.

[0048] 13: Beater of a horizontal shaft crusher comprising a reinforcing structure according to the present application.

[0049] 14: Roller of a vertical mill comprising a reinforcing structure according to the present application.

[0050] 15: Anvil of a vertical shaft crusher comprising a reinforcing structure according to the present application. DETAILED DESCRIPTION

[0051] Detailed description of the invention

[0052] The present invention discloses a wear part of conventional foundry manufacture with enhanced wear resistance. The invention more particularly relates to a wear part comprising a reinforcing portion in a predetermined geometry, having ceramic inserts of a few centimetres in size (cylindrical, polygonal, conical, etc.) manufactured beforehand, which are inserted in a permeable three-dimensional structure consisting of agglomerated millimetric particles, and forming a periodic alternation of particles and millimetric gaps.

[0053] The particles used to manufacture the three-dimensional structure mainly comprise zirconium oxide ZrO2, or alumina-zirconia, the composition of which can range from 5 to 95% by weight of alumina and from 95 to 5% by weight of zirconia, preferably from 10 to 90% and from 90 to 10% by weight, and particularly preferably from 20 to 80% and from 80 to 20% by weight. In addition to these constituents, the particles can comprise a stabiliser such as a rare earth oxide, in particular yttrium oxide or cerium oxide as a stabiliser for the zirconia.

[0054] The millimetric particles used to manufacture the three-dimensional reinforcing structure can also comprise, in a third metallic matrix, independently of the first two matrices (not shown in the figure), titanium carbide, titanium nitride or titanium carbonitride in a proportion of less than 50% by volume, preferably less than 40% by volume and particularly preferably less than 30% by volume. The third metallic matrix used as a binder for these millimetric particles preferably contains an iron alloy, a nickel alloy or a molybdenum alloy. The volume proportion of the metallic binder (third metallic matrix) is generally from 5 to 60%, preferably from 7 to 45% and particularly preferably from 10 to 35%. The titanium carbide, titanium nitride or titanium carbonitride has a size of from 0.05 to 75 μm, preferably from 0.2 to 40 μm and more preferably from 0.5 to 15 μm.

[0055] The permeable structure is thus constituted by a three-dimensional structure of agglomerates of millimetric particles having an average size of from 0.5 to 10 mm, preferably from 0.7 to 6 mm and particularly preferably from 1 to 4 mm. The gaps between the particles depend on the degree of compaction and the size of the particles, but are of the order of one millimetre or a fraction of one millimetre. There is thus a "periodic" alternation of particles and gaps, as opposed to a "random" alternation.

[0056] The millimetric particles comprise a homogeneous mixture containing zirconium oxide or alumina-zirconia and can be agglomerated / compacted together by means of a binder (glue), or held in a metallic container, thus defining the reinforcing area of the wear part in terms of geometry.

[0057] The use of a binder that solidifies by the addition of a catalyst makes it possible to produce the permeable structure without solidification, which can be a preferred solution in certain cases where no suitable solidification measures are available. The nature of the binder is then organic or mineral type, preferably organic type, more preferably phenolic type.

[0058] The use of a solidified binder by curing enables the use of more high-temperature resistant binders. The nature of the binder is then of the mineral type, preferably of the silicate type, more preferably of the sodium silicate type.

[0059] The amount of binder (glue) used to produce the infiltrable structure is between 0.5 and 10% by weight, preferably between 1 and 8% by weight, more preferably between 1.5 and 7% by weight. The amount of binder is adjusted to provide sufficient intra-particle cohesion, limit the production of gas during the liquid cast metal infiltration process, and minimize the residual thickness of the binder around each particle forming the porous three-dimensional structure.

[0060] The ceramic inserts held by the three-dimensional structure of agglomerated particles can have any shape, but are preferably cylindrical, polygonal or conical. In the case of cylinders, these ceramic inserts have a diameter of about 3-50 mm, preferably 6-30 mm, more particularly 8-20 mm, and their length ranges from 5 to 300 mm, preferably from 10 to 200 mm, in particular from 10 to 150 mm.

[0061] The present invention thus describes a wear part reinforced on one or more of its sides of maximum stress and obtained by infiltration of a three-dimensional ceramic structure of agglomerated millimetric particles periodically alternating with millimetric gaps, which has integrated a prefabricated ceramic geometry insert of the ceramic-metal composite type, generally obtained by powder metallurgy, in which ceramic particles are embedded in a first metal matrix completely independent of a second metal matrix for casting, mainly consisting of steel or liquid cast iron.

[0062] This technology enables the convenient and secure positioning of an insert having a defined geometry and enriched with metal carbides, nitrides, borides or intermetallic alloys, which contains a metal matrix independent of the metal matrix produced by casting. This first metal matrix, which is present before casting the wear part, is present from the outset in the ceramic-metal composite insert. The pre-existing insert is integrated into an infiltrable structure containing agglomerated millimetric particles (filling) of zirconia, alumina-zirconia or ceramic-metal composite infiltrated during the casting of the wear part. The infiltrable three-dimensional structure can also contain a proportion of millimetric particles of titanium carbide, titanium nitride or titanium carbonitride in a third metal matrix independent of the first two metal matrices.

[0063] In contrast to the practice in the prior art, ceramic-metal composite inserts, such as cylindrical or frustoconical inserts, are used in this part. Such inserts can consist, for example, of a minimum concentration of 40% by volume of titanium carbide, titanium nitride or chromium carbide in a first metal matrix comprising, for example, iron, manganese, nickel or cobalt, which is "encased" in an infiltrable structure made, for example, of an aggregate of millimetric particles comprising zirconia or alumina-zirconia. For certain conditions of use, this infiltrable structure can further comprise millimetric particles of metal carbides, nitrides, borides or intermetallic elements, preferably titanium carbide, titanium nitride or titanium carbonitride.

[0064] Alumina is known for its high hardness and for its low load wear properties compared to the hardness of the main natural minerals. Alumina also benefits from a low density and a low implementation cost, whether by melting or by powder sintering.

[0065] For pure zirconia, it is generally used in the presence of a stabilizer. Zirconia in its tetragonal crystalline form has mechanical properties that are beneficial for reinforcing wear stress parts. The addition of 0.3-8% of rare earth oxides such as yttrium oxide or cerium oxide can stabilize zirconia in its tetragonal phase.

[0066] Zirconia has a higher bending strength and higher toughness than alumina. The transition of tetragonal zirconia into a less dense monoclinic crystalline form and thus the ability to close the crack front when necessary gives the material a high toughness and mechanical strength. The wear resistance of zirconia is particularly good in the case of high surface stresses induced by abrasive particles. On the other hand, its lower hardness compared to certain natural minerals, including quartz or free silica, limits its use when the ore containing said minerals exerts stresses on it.

[0067] The production of alumina-zirconia composites makes it possible to improve the properties of the two compounds used alone, in particular their mechanical strength and toughness. The evolution of these properties is illustrated in the following diagram. The choice of the proportion of zirconia in alumina is used to optimize the hardness / toughness-mechanical property pair according to the wear stresses to which the material is subjected, to obtain the best performance of the thus reinforced parts.

[0068]

[0069] Thus, the application not only makes it possible to achieve very high concentrations of ceramics (generally greater than 40% by volume and up to 95% by volume) in preformed geometric inserts or in millimetric particles of pre-existing ceramic-metal composites, but also makes it possible to select specific metal matrices (first and third metal matrices) for these elements and thus independently of the casting metal of the wear part (second metal matrix), which is generally cast iron or chromium steel.

[0070] The present invention improves the performance of the casted reinforced wear part compared to the wear parts of the prior art, due to a local increase in the wear resistance of the zones, enhanced by the presence of a greater number of wear-resistant particles and / or particles of different nature (by means of a more suitable metal matrix). The present invention also provides a better performance manufactured wear part by increasing the zones with defined geometry and enriched in metal carbides, nitrides, borides or intermetallic alloys and the metal matrix present before casting the wear part, by having a structure of compact zones with fine ceramic particles in the millimeter size alternating with zones substantially free of fine ceramic particles in the metal matrix of the part in the vicinity of the "package" structure of the pre-existing ceramic inserts, avoiding the preferential wear of the ferrous alloy of the wear part around these zones, while improving the cohesion of these inserts with the ferrous alloy of the reinforced wear part.

[0071] Measurement method

[0072] Average size of particles of metal carbide, nitride, boride or intermetallic alloy particles

[0073] The average size d of the particles of metal carbides, nitrides, borides or intermetallic alloys is calculated by the following steps 50 .

[0074] First, a microphotographic panoramic view of the polished cross section of the sample is made so that there are at least 250 complete particles in the entire field of view. This panoramic view is achieved by stitching (process of combining a series of digital images of different parts of an object into a panoramic view of the entire object to maintain good clarity) using a computer program and an optical microscope (such as the generic field of view panorama obtained from Alicona InfiniteFocus).

[0075] Then an appropriate thresholding is performed to segment the image into the features of interest (particles) and the background in different gray levels.

[0076] If the thresholding is not consistent due to poor image quality, a manual step of drawing the particles, the scale (if any) and the image frame on a tracing paper is added, as well as a step of scanning the tracing paper.

[0077] The Feret diameter of each particle (corresponding to the distance between two parallel tangents placed perpendicularly to the measurement direction so that the entire projection of the particle lies between the two tangents) is measured in all directions by the image analysis software (such as ImageJ). An example is shown in Figure 6 .

[0078] The minimum and maximum Feret diameters of each particle in the image are then determined. The minimum Feret diameter is the smallest diameter in the set of Feret diameters measured for the particle. The maximum Feret diameter is the largest diameter in the set of Feret diameters measured for the particle. Particles touching the edge of the image are ignored in the calculation.

[0079] The average of the minimum and maximum Feret diameters of each particle is taken as the equivalent diameter x. The volume distribution q3(x) of the particle size is then calculated from a sphere of diameter x.

[0080] The average particle size d 50 is the volume-weighted average size according to standard ISO 9276-2:2014

[0081] Examples

[0082] Comparative examples

[0083] In this example, the resistance of a reinforced wear part according to the prior art was measured. The wear part was manufactured similarly to the method disclosed in prior art WO9815373A1 (Magotteaux, 1997).

[0084] The wear part was a vertical shaft impactor part, reinforced with a porous and infiltrable three-dimensional structure of agglomerated millimetric particles. The volume of the wear part was 10.27 dm 3 and the weight was 74.16 kg.

[0085] To evaluate the degree of wear, the overall weight loss of the vertical shaft impactor part was measured. In practice, this is the only method of determining the wear, which depends on a series of factors, in particular the positioning geometry in the impactor. Although the impactor wears mainly on the side of the reinforcement, depending on the positioning, the impactor also wears outside of the reinforcement.

[0086] In the three-dimensional structure according to the prior art, there is an alternation between millimetric particles and interstices. These particles consist of fused alumina-zirconia agglomerated using a mineral binder of the sodium silicate type at 3.5% by weight. The composition of the fused alumina-zirconia particles is as described above.

[0087]

[0088] This infiltrable structure comprises agglomerates of millimetric particles of average size of approximately 2.5 mm. Said particles are agglomerated in a three-dimensional structure according to a predetermined shape using sodium silicate in a resin mould. In this three-dimensional structure, there is an alternation between millimetric particles and interstices.

[0089] This comparative example thus comprises a reinforced portion comprising alumina-zirconia on the side of the wear part where the stresses are the greatest, without initially comprising a centimetre insert of ceramic-metal composite material, for example of cylindrical type, previously positioned in a metal matrix different from the ferrous alloy used for casting. At the end of these steps, a three-dimensional structure is manufactured having a total reinforced volume of 0.857 dm 3 The weight loss observed during the wear test on the wear part of the vertical shaft impactor is 6.795 kg per 100 hours of operation (kg / 100h).

[0090] Examples according to the invention

[0091] Example 1 :

[0092] The reinforced part according to the application comprises a reinforced zone having a predetermined geometry and a cylindrical ceramic insert, which is previously manufactured in a size of several centimetres and is previously inserted into an infiltrable structure comprising particles of electrofused alumina-zirconia containing a composition as described below. It is noted that these particles have the same characteristics as in the comparative example.

[0093]

[0094] This infiltrable structure comprises aggregates of millimetric particles having an average size of approximately 2.5 mm. The particles are aggregated in a three-dimensional structure according to a predetermined shape in a resin mould using a sodium silicate glue. In this three-dimensional structure, there is an alternation between millimetric particles and interstices.

[0095] The previously manufactured ceramic insert has a cylindrical geometry, composed on average of 70-80% of titanium carbide microparticles bound by a first metal matrix of austenitic steel type.

[0096] The diameter of the previously manufactured ceramic insert is 20 mm. The height is 30 mm.

[0097] Before the addition of the millimetric particles of alumina-zirconia, the 25 previously manufactured ceramic inserts are positioned vertically with respect to the filling face in a predetermined manner in the resin mould, which defines the reinforced zone by the cut-outs in the resin mould.

[0098] According to these steps, a three-dimensional structure is manufactured by casting AFNOR Z 270C 27-M cast iron having a total volume of 0.857 dm 3 similar to Figure 2 The cast iron of this type forming the second metal matrix is used in all the examples.

[0099]

[0100] Example 2 :

[0101] Example 1 was repeated, but this time the pre-manufactured 25 ceramic inserts were positioned in the same manner as Example 1, but the inserts were composed of an average of 70-80% titanium carbide microparticles and a first metal matrix of nickel alloy.

[0102]

[0103] Example 3 :

[0104] Example 1 was repeated using 25 inserts, but this time, the pre-manufactured ceramic-metal composite inserts contained an average of 75-85% titanium carbonitride microparticles and a first metal matrix containing a molybdenum alloy.

[0105]

[0106] Example 4:

[0107] Example 1 was repeated, again using 25 inserts of the same size, but the pre-manufactured ceramic inserts contained an average of 80-90% chromium carbide microparticles, bound in a first metal matrix containing nickel.

[0108]

[0109] Example 5 :

[0110] Example 4 was repeated, again using 25 inserts of the same size, and the pre-manufactured ceramic inserts contained an average of 80-90% chromium carbide microparticles, bound in a first metal matrix containing nickel.

[0111] This time, the three-dimensional structure around the centimeter inserts contained 25% by volume of millimeter particles containing an average of 80-85% titanium carbonitride microparticles, in a third metal matrix containing a molybdenum alloy.

[0112]

[0113] Summary table and interpretation of results

[0114] The table below shows the weight loss of the worn parts of the 74.16 kg vertical shaft impactor in the new state, with an enhanced volume of approximately 0.857 dm 3 . The weight loss was measured after 438 hours of operation and reduced to 100 hours of operation.

[0115]

[0116] Explanation of results

[0117] The above examples show that, compared to the state of the art, by adding centimetric inserts with a predetermined geometry in a porous three-dimensional structure composed of millimetric particles, the wear performance of the vertical shaft impactor wear parts is improved.

[0118] The wear mechanism of vertical shaft impactor wear parts is a complex mix of material tearing due to wear, micro-exfoliation due to micro-crack propagation and impact erosion by the processed particles.

[0119] Under such complex operating conditions, the wear behavior of the material depends on a large number of interdependent parameters. Among the most important parameters are hardness, toughness, elastic modulus, average free path between different particles at different scales (microns, millimeters, centimeters) depending on the size and shape of the processed particles, elastic limit, fatigue resistance and ductility.

[0120] In a simplified approach, the higher the hardness*toughness product, the better the wear resistance of the material. For the same class of materials, these two properties are closely linked, as shown in the following graph.

[0121]

[0122] The development of composite materials makes it possible to advantageously move this curve to higher hardnesses for the same toughness.

[0123]

[0124] The optimization of the geometric distribution of the materials forming the composite, combined with their properties and thus with their intrinsic properties, thus makes it possible to further increase the overall hardness of the material while maintaining sufficient toughness, thus obtaining better wear performance.

Claims

1. A wear part (1) comprising a reinforced portion (2) comprising zirconia or alumina-zirconia alloy, said reinforced portion further comprising a centimeter insert (3) having a predetermined geometry, said insert (3) comprising microparticles (9) of a metal carbide, nitride, boride or intermetallic compound bound by a first metallic matrix (10), said insert (3) being inserted into the reinforced portion (2) infiltrated by a second metallic matrix (6) different from the first metallic matrix (10) and comprising millimeter areas of periodically alternating high and low concentrations of microparticles of zirconia or alumina-zirconia alloy (7, 8), the insert (3) comprising microparticles (9) of a metal carbide, nitride, boride or intermetallic element in a concentration of 20-95% by volume.

2. The wear part (1) according to claim 1, wherein the reinforced portion (2) further comprises millimeter areas of a ceramic-metal composite comprising microparticles of titanium carbide, titanium nitride or titanium carbonitride in a binder constituting a third metallic matrix, the proportion of these areas relative to the millimeter areas of high concentration of microparticles of zirconia or alumina-zirconia alloy (7, 8) being less than 50% by volume, the third metallic matrix being independent of the first (10) and second (6) metallic matrices.

3. The wear part (1) according to any one of the preceding claims, wherein the insert (3) comprises microparticles (9) of a metal carbide, nitride, boride or intermetallic element in a concentration of at least 30% by volume.

4. The wear part (1) according to claim 1 or 2, wherein the first metallic matrix (10) of the binder used as microparticles (9) of the insert (3) mainly comprises nickel, a nickel alloy, cobalt, a cobalt alloy or a ferrous alloy different from the second metallic matrix (6).

5. The wear part (1) according to claim 1 or 2, wherein the third metallic matrix of the binder used as microparticles of titanium carbide, titanium nitride or titanium carbonitride in the millimeter areas that are part of the reinforced portion (2) mainly comprises nickel, a nickel alloy, cobalt, a cobalt alloy or a ferrous alloy different from the second metallic matrix (6).

6. The wear part (1) according to claim 1 or 2, wherein the millimetre region of the insert (3) or of the reinforcing portion (2) comprises, when it comprises a ceramic-metal composite material, particles of intermetallic alloy or of metal carbide, nitride, boride (9) having an average size D 50 less than 80 pm.

7. The wear part (1) according to claim 1 or 2, wherein the insert (3) and the millimeter areas of high concentration of microparticles of zirconia or alumina-zirconia alloy comprise intermicronic gaps comprising different metallic matrices (6, 10).

8. The wear part (1) according to claim 1 or 2, manufactured in the form of an impactor, anvil, cone or mill roller.

9. A method of manufacturing a wear part (1) according to any one of the preceding claims, comprising the following steps: - providing a mold comprising a cavity of the wear part (1) having a predetermined geometry of the area to be reinforced; - filling the cavity with a mixture of microparticles of a metal carbide, nitride, boride or intermetallic compound and a binder constituting a first metallic matrix (10) of the insert (3); - infiltrating the mixture with a second metallic matrix (6) different from the first metallic matrix (10) and comprising millimeter areas of periodically alternating high and low concentrations of microparticles of zirconia or alumina-zirconia alloy (7, 8); and - removing the insert (3) from the mold. - introducing and positioning in said area to be reinforced a compact mixture of powders in the form of zirconia or alumina-zirconia millimetric granules, at least partially surrounding one or more preformed inserts (3) having a defined geometry and enriched with microparticles of metal carbides, nitrides, borides or intermetallics bound by a first metal matrix (10); - casting a liquid ferrous alloy into a mould, said liquid ferrous alloy infiltrating into the three-dimensional structure comprising zirconia or alumina-zirconia alloy granules at least partially surrounding the preformed inserts (3).

10. Method for manufacturing a wear part (1) according to claim 9, wherein the inserts (3) having a predefined geometry, manufactured prior to casting the wear part, are manufactured by powder metallurgy.

11. Wear part (1) according to any one of claims 1 to 10, wherein the first metal matrix (10) is a metal alloy comprising at least one of the following metals: iron, nickel, cobalt, chromium, molybdenum, tungsten, vanadium, titanium, aluminium, copper, silicon, manganese, boron, carbon, phosphorus, sulphur, selenium, tellurium, zinc, tin, antimony, bismuth, lead, arsenic, cadmium, indium, gallium, germanium, thallium, cesium, rubidium, strontium, barium, radium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and mixtures thereof.

12. Wear part (1) according to any one of claims 1 to 11, wherein the second metal matrix (20) is a metal alloy comprising at least one of the following metals: iron, nickel, cobalt, chromium, molybdenum, tungsten, vanadium, titanium, aluminium, copper, silicon, manganese, boron, carbon, phosphorus, sulphur, selenium, tellurium, zinc, tin, antimony, bismuth, lead, arsenic, cadmium

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