WO2015103670A1

WO2015103670A1 - Wear member incorporating wear resistant particles and method of making same

Info

Publication number: WO2015103670A1
Application number: PCT/AU2015/000014
Authority: WO
Inventors: Anthony Milne ROWETT; David William John Elwell
Original assignee: Bradken Uk Limited; Bradken Resources Pty Limited
Priority date: 2014-01-09
Filing date: 2015-01-09
Publication date: 2015-07-16

Abstract

A method of manufacturing a wear resistant member, such as a ground-engaging tool or dredge point, is disclosed where wear particles are confined to a region of a mould in which the wear member is formed by casting of a liquid metal into the mould. The method may be employed in applications such as the mining and dredging industries to form a highly abrasion resistant material. A wear resistant member is also disclosed, the wear resistant member having a metal matrix containing wear particles. The wear particles are concentrated to a region within the hardened metal matrix.

Description

WEAR MEMBER INCORPORATING WEAR RESISTANT PARTICLES AND

METHOD OF MAKING SAME

TECHNICAL FIELD

A wear resistant member and a method for manufacturing such member is disclosed. The wear resistant member may be used in many applications, for example may take the form of a wear pad, ground-engaging tool, dredge point or a mineral processing part. The method may be employed in applications such as the mining industry and the disclosure is herein described in that context. However, it is to be appreciated that the disclosure is not limited to that use and may be applied to other industries that require highly abrasion resistant materials.

BACKGROUND ART

Conventional tools for use in the mining and dredge industries include wear parts that are subject to abrasion during operation of the tools and are designed to be regularly replaced. In some applications, for example in dragline excavation operations, the peripheral region of the ground engaging tool is exposed to extreme abrasion. This leads to rapid wear of the wear parts, which then requires replacement. Since replacement of the wear parts is interraptive to operations, it is advantageous to improve the wear performance of the parts to reduce the frequency of replacement.

It is known to cast abrasion resistant wear particles, such as tungsten carbide bonded with cobalt, with a parent matrix of metal to form the wear parts of ground engaging tools. With this arrangement the abrasion resistant wear particles are distributed in the matrix. To provide more localised wear resistance, it is also known to form a wear part by bonding a protective layer of abrasion resistant wear particles to a metal surface of a tool to form a multilayer composite.

The use of multilayer composite materials has a number of drawbacks. Although the process of bonding hard materials to the surface of ground engaging tools does increase their service life, wear still occurs, relatively slowly at the start while the hard surface remains intact and then quickly when the hard surface is itself damaged. A further drawback of this type of structure is that the required protective surface hardening is time consuming, awkward and the layer is often not uniform in thickness. The variation in thickness of the protective layer may accentuate localised wear. Further, the process of arc welding a hard protective surface to ground engaging tools is expensive and requires skilled labour.

The above references to the background art do not constitute an admission that the art forms part of the common general knowledge of a person of ordinary skill in the art. The above references are also not intended to limit the application of the disclosure as disclosed herein.

SUMMARY OF THE DISCLOSURE

In some forms, a method of manufacturing a wear resistant member is disclosed. The method may comprise the steps of casting a combination containing liquid metal and wear particles in a mould, confining at least some of the wear particles to a region of the mould, and providing conditions suitable to harden the liquid metal to form the member with a hardened matrix, the confined wear particles forming a concentrated region of wear particles in the hardened matrix.

In some forms, a wear resistant member is disclosed. The wear resistant member may include one or more wear regions having a concentration of wear particles interspersed in the metal matrix as compared to other regions of the member.

The foregoing summaiy is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Further embodiments of the method and additive will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which:

Fig. 1 illustrates a process flow diagram of the method of manufacturing a wear resistant member; Fig. 2 illustrates a container for confining the wear resistant particles for use in the method of Fig. 1;

Fig. 3 illustrates a cast and hardened wear resistant member;

Fig. 3 illustrates a section through the cast and hardened wear resistant member;

Fig. 4 illustrates an electron image through the wear resistant member;

Fig. 5 illustrates another electron image through the wear resistant member; and

Fig. 6 illustrates another electron image through the wear resistant member.

Fig. 7 illustrates another container for confining the wear resistant particles for use in sand casting.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

In the following detailed description, reference is made to accompanying drawings which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilised, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the Figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein.

The disclosure is directed generally towards ground-engaging and dredge tools for use in the mining and dredging industries, including wear parts that are subject to abrasion during operation of the tools and are designed to be regularly replaced. Ground-engaging tools include teeth, adaptors and rippers for loaders, dozers, compactors, scrapers, graders and excavators. These tools are subject to rapid wear and therefore require regular replacement.

It is known to cast abrasion resistant wear particles, such as tungsten carbide bonded with cobalt, with a parent matrix of metal to form ground engaging tools. It is also known to form tools by bonding plates to the metal surface of a tool such that it provides a protective layer of abrasion resistant wear particles. The use of protective plates does increase the service life of ground engaging tools, however, they also have a number of disadvantages. Variation in the thickness of the protective coating causes irregular wear characteristics. Further, bonding protective coatings to ground engaging tools requires specialist technicians and is time consuming, which increases the overall cost of production. When casting the wear particles into a metal matrix, it is difficult to control the settled location of the wear particles. Again, this results in varied wear characteristics of ground engaging tools.

In some forms, the confined wear particles are disposed within a container. In some forms, the liquid metal infiltrates the container during casting. In some forms, the container is foraminous to allow the container to be is infiltrated by the liquid metal during casting.

In some forms, the confined wear particles are disposed loosely within the container such that when the container is infiltrated by the liquid metal, the confined wear particles become interspersed within the liquid metal.

In some forms, the container is a package formed from metal or ceramic such that during casting the package forms part of the hardened matrix. In some forms, the container is at least partly destroyed during manufacturing of the wear materials. In some forms, the container remains largely intact in the hardened matrix. In some forms, the wear particles are formed from a highly abrasion resistant material.

In some forms, the wear particles include carbide particles with a nominal diameter of between 0.05 and 10mm. In some forms, the wear particles include ceramic particles with a nominal diameter of between 0.05 and 10mm. In some forms, the wear particles include both carbide and ceramic particles. In some forms, the container within which the wear particles are confined is located within a second container.

In a further aspect, a wear resistant member having a metal matrix containing wear particles is disclosed, wherein the member includes one or more wear regions having a concentration of wear particles interspersed in the metal matrix as compared to other regions of the member. The wear resistant member may be formed in a mould by casting. In at least one embodiment, the wear resistant member has an abrasion resistant face formed from a wear region of the hardened matrix.

In at least one embodiment, the one or more wear regions are defined by one or more containers that confined the wear particles during manufacture of the member.

In at least one embodiment, the container is foraminous to allow for liquid metal infiltration into the container during forming of the member.

In at least one embodiment, the confined wear particles are disposed loosely within the container such that infiltration of the container by the liquid metal during casting causes the wear particles to be interspersed within the region of the matrix.

In at least one embodiment, the container is at least partially destroyed during forming of the member so that the container forms part of the metal matrix.

In at least one embodiment, the wear particles are formed from a highly abrasion resistant material.

In at least one embodiment, the wear particles include carbide particles with a nominal diameter of between 0.05 and 10mm.

In at least one embodiment, the wear particles include ceramic particles with a nominal diameter of between 0.05 and 10mm.

In at least one embodiment, the wear particles include both carbide and ceramic particles.

In at least one embodiment, the wear resistant member is a ground engaging tool or dredge tool.

Referring firstly to Fig. 1, a process flow chart for a method 1 of casting a wear resistant member 10 (see Fig. 3) is shown. The method involves the confinement of wear particles 1 1 in the casting process so as to provide one or more regions 15 of wear particle concentrations in the member 10.

In a first step 3, wear particles are introduced into a mould 21 in at least one container. The container, which may be in the form of an open mesh package 13 (as shown in Fig. 2), may be located in position by being located on a surface of the mould, suspended in the mould or by being placed in an outer supporting container or frame (not shown). In one form the wear particles may be in the form of tungsten carbide particles and are loosely packed in the container so as to allow infiltration by liquid metal. At step 5, molten metal is introduced into the mould to cast the wear member. At this step the molten metal infiltrates the container(s) and the loosely packed wear particles so that those particles are dispersed in the liquid metal (yet are still confined to the area defined by the container) so as to maintain a concentration of the wear particles.

At step 7, conditions are provided that are suitable/conducive to harden the liquid metal to form the wear member 10 with a hardened matrix. During this step 7 or the previous step 5, the container may be at least partially destroyed so as to form part of the member matrix or may retain its structure throughout the process.

The contained wear particles form a concentrated region in the hardened matrix. The concentrated region of wear particles forms the region of the wear member that is highly abrasion resistant. This is a result of the region containing a relatively high concentration of wear particles. Outside this region, the matrix of the member 10 may be predominately metal and may not include a localised concentration of wear particles (see for example as shown in region 17 as shown in Fig. 3).

Confining the wear particles to specific areas of the member 10 has considerable benefit. Typically, such members have predictable wear characteristics that are dependent on their use. Using the disclosed method allows for the wear particles in the member 10 to be confined to the regions that undergo the greatest abrasion. The benefits of confining the wear particles to a specific region of a mould, and the resultant wear member, include that the service life of the wear member is increased and savings are generated in wear resistant material, time, specialist labour and overall manufacturing cost. This arrangement also provides for a maximum benefit from an optimum quantity of hard particles by locating them in the wear area. In many instances the wearing section of a component is a small volume fraction of the whole component. Therefore, the disclosed wear resistant member avoids the need to have a general dispersion of hard particles throughout the wear component.

Referring now to Fig. 2, the package 13 used to confine the wear particles is as illustrated foraied from metal or ceramic and is foraminous. The walls of the package 13 have an open, woven or mesh-like structure to allow the liquid metal to enter the package during casting. Any foraminous structure (e.g. slits, square holes, round holes) may be used provided that it adequately allows for the liquid metal to infiltrate the package during casting, while confining the wear particles to a specified region of the mould 21. The foraminious structure also allows the package to become integrated in the hardened matrix, even if the package is not fully destroyed thereby reducing the likelihood of weakened regions in the resulting member.

The confined wear particles 1 1 are disposed loosely within the package 13. As previously mentioned this facilitates infiltration by the liquid metal during casting and ensures that the confined wear particles 11 become interspersed within the liquid metal.

Fig. 3 shows a cross-section of the hardened matrix of a sample cast member 10 in the mould 21. As is apparent from the cross section distinct regions are formed in the member with a wear region 15 being formed containing the high concentration of wear particles in the hardened metal matrix and a surrounding region 17 being formed without wear particles. Further in the wear member 10 as shown, the wear region may extend to a surface of the member to form an abrasion resistant face 19 (Fig. 3). Further, the region 15 of the hardened matrix that forms the face 19 also extends away from the face 19. Therefore, as the face 19 of the wear member breaks down / is worn during use, the newly exposed surface of the wear member becomes the abrasion resistant wear surface of the ground-engaging tool. This allows for an increased service life relative to a tool to which a protective coating or plate is applied.

The wear particles 11 are typically formed from a highly abrasion resistant material such as ceramic or carbide particles. In at least one embodiment, the wear particles are tungsten carbide, which is known to be an abrasion resistant material. The volume and size of the particles is dependent on the size and application of the ground engaging tool. Usually, a higher volume fraction of hard particles is used in a small casting, whereas a relatively low volume fraction is used in a larger casting.

Referring now to Figs. 4-6, the matrix of the member 10 is shown in further detail. Fig. 4 shows a first electron image through the wear resistant member 10 (noting the scale showing 1mm). Fig. 5 shows a greater magnified image of the matrix (noting the scale showing scale of 400μηι). In both Figs. 4 and 5, a clear distinction between the regions of high concentration of wear particles 15 and other regions 17 (without wear particles) can be seen. Also the larger wear particles (given reference 1 1 A) can be seen in combination with the small wear particles near the boundary with region 17. Fig. 6 shows an even more magnified region (noting the scale showing 30 μιη). In Fig. 6 the dispersion of the small wear particles in the metal matrix can be more easily seen.

Spectral analysis of the wear member at various points gave the following results: • spectrum marked 23 in region 17 (Fig. 5) has a weight percentage of 3% carbon, 3% silicon, 1% chromium, 2% manganese and 91% iron

• Spectrum marked 25 in region 15 (Fig. 5) has a weight percentage of 5%

carbon, 18% iron, 5% cobalt and 72% tungsten.

• Spectrum marked 27 in region 15 (Fig. 5) has a weight percentage of 5%

carbon, 35% iron, 5% cobalt and 55% tungsten.

• Spectrum marked 29 in region 15 (Fig. 6) has a weight percentage of 5%

carbon, 25% iron, 5% cobalt, 5% rhenium and 60% tungsten.

• Spectrum marked 31 in region 15 (Fig. 6) has a weight percentage of 5%

carbon, 5% silicon, 1% chromium, 2% manganese, 10% cobalt, 5% tungsten and 72%o iron.

• Spectrum marked 33 in region 15 (Fig. 6) has a weight percentage of 5%

carbon and 95% tungsten; and

• Spectrum marked 35 in region 15 (Fig. 6) has a weight percentage of 5%

carbon, 5% cobalt, 70% tungsten and 20%> iron.

It has been found that 0.85 x 0.6mm, 1.7 x 1.18mm, 3.2 x 4.8mm and 6.4 x 7.9mm tungsten carbide particles are a useful size and adequately allow liquid metal to infiltrate during casting. While the size of the holes in the package 13 may be uniform for all particle sizes, the holes can also be varied to be as large as possible while still being able to confine the wear particles to a specified region of the mould 21. In an embodiment not illustrated, the package 13 includes multiple compartments. The compartments allow for wear particles of differing diameter to be confined to segments within the region of the mould 21. The compartments may have different size holes (i.e. as large as possible while still confining the wear particles within the compartments).

Referring now to Fig. 7, a further embodiment of the wear resistant member is illustrated. In this embodiment, confinement of wear particles 1 1 takes place in a sand casting process so as to provide one or more regions of wear particle concentrations. The container is a perforated steel tube that is open ended and is inserted into the bottom of a sand casting mould typically to a depth of 50mm so that is held in the sand. The tube extends into the sand as a method of location and the portion of the tube in the sand does not contain any hard particles. The perforations in the steel tube are smaller in diameter relative to the wear resistant particles so as to restrain the wear particles (e.g. tungsten carbide) within the tube. In the illustrated example (Fig, 7), the tube is filled with tungsten carbide granules up to approximately 12mm of the top of the tube 37. A number of these tubes may be inserted into the sand mould 39 to produce a wear surface with multiple regions of wear particle concentrations. When the casting is removed from the sand the excess length of tube which extends from the cast surface is removed by cutting or grinding

Accordingly methods of manufacturing wear members and resultant wear members are disclosed that confine the wear particles to a specific region(s), allowing the service life of the wear member to increase and savings are generated in wear resistant materi al, time, specialist labour and overall manufacturing cost. This arrangement also provides for a maximum benefit from an optimum quantity of hard particles by locating them in the wear area. In many instances the wearing section of a component is a small volume fraction of the whole component. Therefore, the disclosed wear resistant member avoids the need to have a general dispersion of hard particles throughout the wear component.

In the claims which follow and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e., to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the process or product.

Claims

1. A method of manufacturing a wear resistant member comprising the steps of;

casting a combination containing liquid metal and wear particles in a mould;

confining at least some of the wear particles to a region of the mould; and

providing conditions suitable to harden the liquid metal to form the member with a hardened matrix, the confined wear particles forming a concentrated region of wear particles in the hardened matrix.

2. A method according to claim 1, wherein the confined wear particles are disposed within a container.

3. A method according to claim 2, wherein the liquid metal infiltrates the container during casting.

4. A method according to claims 2 or 3, wherein the container is foraminous to allow the container to be is infiltrated by the liquid metal during casting.

5. A method according to any one of claims 2 to 4, wherein the confined wear particles are disposed loosely within the container such that when the container is infiltrated by the liquid metal, the confined wear particles become interspersed within the liquid metal.

6. A method according to any one of claims 2 to 5, wherein the container is a package formed from metal or ceramic such that during casting the package forms part of the hardened matrix.

7. A method according to any one of the preceding claims, wherein the wear particles are formed from a highly abrasion resistant material.

8. A method according to any one of the preceding claims, wherein the wear particles include carbide particles with a nominal diameter of between 0.05 and 10mm.

9. A method according to any one of the preceding claims, wherein the wear particles include ceramic particles with a nominal diameter of between 0.05 and 10mm.

10. A method according to any one of the preceding claims, wherein the wear particles include both carbide and ceramic particles.

1 1. A method according to any one of claims 2 to 10, wherein the container within which the wear particles are confined is located within a second container.

12. A wear resistant member having a metal matrix containing wear particles, wherein the member includes one or more wear regions having a concentration of wear particles interspersed in the metal matrix as compared to other regions of the member.

13. A wear resistant member according to claim 12, wherein the wear resistant member is formed in a mould by casting.

14. A wear resistant member according to claim 12 or 13, the wear resistant member has an abrasion resistant face formed from a wear region of the hardened matrix.

15. A wear resistant member according to claim 13 or 14, wherein the one or more wear regions are defined by one or more containers that confined the wear particles during manufacture of the member.

16. A wear resistant member according to claims 15, wherein the container is foraminous such that when the liquid metal infiltrates the container during casting, it forms part of the part of the matix and concentrates the wear particles to the region of the matrix.

17. A wear resistant member according to claim 16 or 17, wherein the confined wear particles are disposed loosely within the container such that infiltration of the container by the liquid metal during casing causes the wear particles to be interspersed within the region of the matrix.

18. A wear resistant member according to any one of claims 15 to 17, wherein the container is at least partially melted during forming of the member so that the container forms part of the metal matrix.

19. A wear resistant member according to any one of claims 12 to 18, wherein the wear particles are formed from a highly abrasion resistant material.

20. A wear resistant member according to any one of claims 12 to 19, wherein the wear particles include carbide particles with a nominal diameter of between 0.05 and 10mm.

21. A wear resistant member according to any one of claims 12 to 20, wherein the wear particles include ceramic particles with a nominal diameter of between 0.05 and 10mm.

22. A wear resistant member according to any one of claims 12 to 21, wherein the wear particles include both carbide and ceramic particles.

23. A wear resistant member according to any one of claims 12 to 22, wherein the wear resistant member is a ground engaging tool, dredge point, wear pad, or a wear part of mineral processing apparatus.