WEAR RESISTANT COMPONENT AND DEVICE FOR MECHANICAL DECOMPOSITION OF A MATERIAL PROVIDED WITH SUCH A COMPONENT
20170043347 ยท 2017-02-16
Inventors
Cpc classification
B02C2210/02
PERFORMING OPERATIONS; TRANSPORTING
B02C13/28
PERFORMING OPERATIONS; TRANSPORTING
B02C4/08
PERFORMING OPERATIONS; TRANSPORTING
C23C24/085
CHEMISTRY; METALLURGY
B22F7/08
PERFORMING OPERATIONS; TRANSPORTING
C23C28/027
CHEMISTRY; METALLURGY
B22F2005/001
PERFORMING OPERATIONS; TRANSPORTING
International classification
B02C4/30
PERFORMING OPERATIONS; TRANSPORTING
B02C13/28
PERFORMING OPERATIONS; TRANSPORTING
B22F1/00
PERFORMING OPERATIONS; TRANSPORTING
Abstract
A wear resistant component for comminution of particulate material includes a steel body and a leading portion of cemented carbide attached to a front portion of the steel body. The wear resistant component includes a wear resistant coating of a metal matrix composite attached to at least one face of the steel body connected to the leading portion.
Claims
1. A wear resistant component for comminution of particulate material, comprising: a steel body having a front portion and a leading portion of cemented carbide attached to the front portion of said steel body; and a wear resistant coating of a metal matrix composite attached to at least one face of said steel body connected to said leading portion, wherein the wear resistant coating is formed by consolidation of a powder mixture and by metallurgically bonding said powder mixture to the steel body by means of Hot Isostatic Pressing.
2. A wear resistant component according to claim 1, wherein said metal matrix composite is selected from a nickel-based metal matrix composite, a cobalt-based metal matrix composite, and an iron-based metal matrix composite.
3. A wear resistant component according to claim 1, wherein particles of tungsten carbide are distributed as discrete non-interconnecting particles in the matrix of metal-based alloy.
4. A wear resistant component according to claim 1, wherein said metal matrix composite includes particles of tungsten carbide and a matrix of a nickel-based alloy, wherein the nickel-based alloy consists of: 0-1.0 wt % C; 5-14.0 wt % Cr; 0.5-4.5 wt % Si; 1.25-3.0 wt % B; 1.0-4.5 wt % Fe; balance Ni and unavoidable impurities.
5. A wear resistant component according to claim 1, wherein the metal matrix composite includes particles of tungsten carbide and a matrix of a cobalt-based alloy, wherein the cobalt-based alloy consists of: 20-35 wt % Cr, wt % W, 0-15 wt % Mo, wt % Fe, 0-5 Ni, 0.05-4 wt % C and balance Co and unavoidable impurities.
6. A wear resistant component according to claim 1, wherein the metal matrix composite includes particles of tungsten carbide and a matrix of a cobalt-based alloy, wherein the cobalt-based alloy comprises: 26-29 wt % Cr, 4.5-6 wt % Mo, 0.20-0.35 wt % C, 2-3 wt % Ni, and balance Co and unavoidable impurities.
7. A wear resistant component according to claim 1, wherein the metal matrix composite includes particles of tungsten carbide and a matrix of an iron-based alloy, wherein the iron-based alloy consists of: 0,5-3 wt % C; wt % Cr; 0-3 wt % Si; wt % Mo; wt % W; wt % Co; 0-15 wt % V; 0-2 wt % Mn; balance Fe and unavoidable impurities
8. A wear resistant component according to claim 1, wherein said leading portion has a tapering cross-section and forms a tip or edge at said front portion of the steel body.
9. A wear resistant component according to claim 1, wherein said steel body includes a bottom face and a top face opposite said bottom face, said wear resistant coating of the metal matrix composite being attached to said top face.
10. A wear resistant component according to claim 9, wherein, between said bottom face and said top face, said steel body includes opposing lateral faces, said wear resistant coating of the metal matrix composite being attached to at least parts of said lateral faces.
11. A wear resistant component according to claim 8, wherein said steel body has the shape of a truncated cone, said leading portion forming a nose on said truncated cone and said face being a mantle surface of said truncated cone, and the wear resistant coating of a metal matrix composite being attached to at least parts of said mantle surface.
12. A wear resistant component according to claim 1, wherein the wear resistant component is selected from an impact hammer; a roll crusher tooth; a crusher tooth for secondary and/or tertiary crushers; a wear segment for crushers; a wear plate for crushers; and a component for a slurry handling system.
13. A device for mechanical decomposition of material comprising a wear resistant component according to claim 1.
14. A device for mechanical decomposition of material according to claim 13, further comprising at least a first rotary element and a second element, wherein there is a gap between the first rotary element and said second element, wherein at least one wear resistant component is disposed on an outer peripheral surface of said first rotary element, such that, upon rotation of the first rotary element, the at least one wear resistant component is arranged to move into said gap with its leading portion, first to mechanically decompose particulate matter present in said gap.
15. A device for mechanical decomposition of material according to claim 14, wherein the second element is a second rotary element and that on an outer peripheral surface of said second rotary element, there is provided at least one wear resistant component, and that, upon rotation of the second rotary element, the wear resistant component thereon is arranged to move into said gap with its leading portion first, to mechanically decompose particulate matter present in said gap.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Embodiments of the disclosure will now be presented with reference to the annexed drawing, on which:
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DEFINITIONS
[0043] The term comminution as used herein is intended to include any process meaning a reduction of solid materials from one average particle size to a smaller average particle size. Example of, but not limited tocomminution is milling, cruching, grinding and pulverization.
[0044] The term wt % is intended to mean weight % and the term vol % is intended to mean volume %.
[0045] The term metal matrix composite (MMC) is intended to mean a material consisting of a metallic matrix containing a dispersion of ceramic material, examples of but not limiting of the shape of ceramic material are particles, fibers, whiskers which consist of carbides, nitrides, oxides and/or borides. Furthermore, the ceramic material is not a result of a chemical reaction between the alloying elements of the metallic matrix but is added to the metal matrix composite.
[0046] Cemented carbide is a MMC material usually comprising a Co or Co-alloy matrix with WC particles. The metallic matrix may also comprise Ni or Ni-alloys. In addition to the WC carbides, other carbides or nitrides may also be present in the cemented carbide e.g. TiC, Cr-carbides, TaC, and/or HfC.
DETAILED DESCRIPTION
[0047]
[0048] The wear resistant components 4 shown in
[0049]
[0050] The wear resistant coating 8 comprises a metal matrix composite comprised by particles of tungsten carbide and a metal matrix of any one of a nickel-based alloy, a cobalt-based alloy or an iron-based alloy. The wear resistant coating has been formed through consolidation of a powder mixture by means of Hot Isostatic Pressing (HIP). According to one embodiment, the particles of tungsten carbide are distributed as discrete non-interconnecting particles in the matrix of metal-based alloy. Examples of preferred metal matrix alloys will be presented later.
[0051] The wear resistant component 4 shown in
[0052]
[0053] As in the previous embodiment, the leading portion 17 consists of cemented carbide, and the wear resistant coating 18 comprises a metal matrix composite which in turn comprises particles of tungsten carbide and a metal matrix of any one of a nickel-based alloy, a cobalt-based alloy or an iron-based alloy.
[0054] The steel body 16 comprises a bottom face 19 aimed to bear on a holder like one of the holders 5 shown in
[0055] The wear resistant component 15 shown in
[0056]
[0057] The wear resistant component 23 presents a said steel body 25 that at least partially, in a front portion thereof, has the shape of a truncated cone. The steel body 25 also comprises a rear portion aimed for insertion into and attachment to a holder 24. At a foremost part of the front portion of the steel body 25, there is provided a leading portion 26 forming a nose on said truncated cone. A wear resistant coating 27 of a metal matrix composite is attached to a mantle surface 28 of said truncated cone. When the wear resistant component 23 is inserted into and attached to the holder 24, there are no surfaces of the steel body 25 exposed to the exterior. In other words, all faces of the steel body 25 that are not housed by the holder 24 are covered by the wear resistant coating 27 and the leading portion 26.
[0058] The wear resistant component shown in
[0059] The wear resistant components 4, 15, 23, described with reference to
[0060] The wear resistant coating 8, 18, 27 is formed and attached to the steel body 6, 16, 25 by means of Hot Isostatic Pressing, wherein a powder mixture comprising the constituents of the wear resistant coating is arranged on the face or faces of the steel body 6, 16, 27 which are to be covered by the coating and encapsulated in that position, for example by means of a glass encapsulation or a metal encapsulation, wherein the steel body and the encapsulation forms a mould in which the powder mixture is housed. Thereafter, temperature and pressure is increased in a heatable pressure chamber, normally referred to as a Hot Isostatic Pressing-chamber (HIP-chamber) in accordance with a predetermined HIP cycle. The elevated temperature and pressure applied, as well as the duration of the application of elevated temperature and pressure is adapted to the specific composition and possible other relevant features, such as particle size and geometry, and amount of the powder mixture to be consolidated.
[0061] The heating chamber is pressurized with gas, e.g. argon gas, to an isostatic pressure in excess of 500 bar. Typically the isostatic pressure is 900-1200 bar. The chamber is heated to a temperature below the melting point of the metal-based alloy powder. The closer to the melting point the temperature is, the higher is the risk for the formation of melted phase and unwanted streaks of brittle carbide networks. Therefore, the temperature should be as low as possible in the furnace during HIP:ing. However, at low temperatures the diffusion process slows down and the material will contain residual porosity and the metallurgical bond between the particles becomes weak. Therefore, the temperature is preferably 100-200 C. below the melting point of the metal-based alloy, for example 900-1150 C., or 1000-1150 C. for a cobalt-based or nickel-based alloy. The filled mould is held in the heating chamber at the predetermined pressure and the predetermined temperature for a predetermined time period. The diffusion processes taking place between the powder particles during HIP:ing are time dependent so long times are preferred. However, too long times could lead to excessive WC dissolution. Preferable, the form should be HIP:ed for a time period of 0.5-3 hours, such as 1-2 hours, such as 1 hour.
[0062] During HIP:ing, the particles of the metal-based alloy powder will deform plastically and bond metallurgically through various diffusion processes to each other and the tungsten particles so that a dense, coherent component of diffusion bonded metal-based alloy particles and tungsten carbide particles is formed. In metallurgic bonding, metallic surfaces bond together flawlessly with an interface free of defects such as oxides, inclusions or other contaminants.
[0063] After consolidation of the powder mixture, possible parts of the encapsulation that are not wanted on the finally produced wear resisting component are removed from the wear resistant component with its wear resistant coating.
[0064] In a powder mixture for HIP:ing, a wear resistant coating according to the present disclosure, the amounts of the included powders are selected such that a first, WC powder constitutes 30-70 vol % of the total volume of the powder mixture and a second, metal-based alloy, powder constitutes 70-30 vol % of the total volume of the powder mixture. For example, if 30 vol % of the total volume of the powder mixture is constituted by WC, the remainder is 70 vol % metal-based alloy powder WC powder. By WC is meant either pure tungsten carbide or cast eutectic carbide (WC/W2C). The use of macro crystalline, pure, WC as opposed to the eutectic WC/W.sub.2C carbide, is preferred. The WC phase of tungsten carbide resists dissolution much better than W.sub.2C. The eutectic tungsten carbide consists of 80-90 vol % W.sub.2C and is therefore much more sensitive to dissolution than pure tungsten carbide.
[0065] The metal-based matrix composite forming the wear resistant coating 8, 18, 27 on the steel body 6, 16, 25 of the wear resistant component 4, 14, 23 is a nickel-based metal matrix composite or a cobalt-based metal matrix composite, or an iron-based metal matrix composite. The particles of tungsten carbide may be distributed as discrete non-interconnecting particles in the matrix of metal-based alloy.
Nickel-Based Metal Matrix Composites
[0066] Examples of suitable compositions (in weight %) of a nickel-based alloy within the scope of the present disclosure and suitable for consolidation by means of HIP are:
C: 0.1; Si: 2.3; B: 1.25; Fe 1.25; balance Ni and unavoidable impurities.
C: 0.1; Si: 2.3; B: 1.75; Fe 1.25; balance Ni and unavoidable impurities.
C: 0.1; Si: 3.2; B: 1.25; Fe 1.25; balance Ni and unavoidable impurities.
C: 0.25; Cr: 5.0; Si: 3.25; B: 1.25; Fe: 1.0; balance Ni and unavoidable impurities.
C: 0.35; Cr: 8.5; Si: 2.5; B: 1.25; Fe: 1.0; balance Ni and unavoidable impurities.
C: 0.35; Cr: 9.5; Si: 3.0; B: 2.0; Fe: 3.0; balance Ni and unavoidable impurities.
C: 0.5; Cr: 11.5; Si: 4.0; B: 2.5; Fe: 3.0; balance Ni and unavoidable impurities.
C: 0.75; Cr: 14.0; Si: 4.0; B: 2.0; Fe: 4.5; balance Ni and unavoidable impurities.
[0067] The nickel-based alloy particles have a substantially spherical shape, alternatively a deformed spherical shape. An increased content of alloying elements will result in a harder and more brittle material. The above-mentioned examples range from a hardness (Rc) of approximately 14 to a hardness (Rc) of approximately 62. Hardness of the metal alloy is to a certain degree an important property for obtaining a wear resistant metal matrix composite. However, certain ductility is also a requested property of the alloy since this makes the metal matrix composite less prone to cracking. A metal matrix composite that is not prone to cracking has been proven to have a better wear resistance than a corresponding metal matrix composite being more prone to cracking.
[0068] In the case of a nickel-based metal matrix composite, a nickel-based alloy having a hardness (Rc) in the range of 30-40, preferably 33-37, has proven to be particularly advantageous while resulting in a sufficiently hard and yet ductile metal matrix composite. Among the above-mentioned examples of possible nickel-based alloys within the scope of the present disclosure, the following composition (in weight %) has proven to result in a metal matrix composite with very good wear resistant properties due to its combination of hardness and ductility, and is therefore preferred:
TABLE-US-00001 0.35 C 8.5 Cr 2.5 Si 1.8 B 2.5 Fe
[0069] Balance Ni and unavoidable impurities.
[0070] In order to generate said metal matrix composite, a powder of the above-mentioned composition with a particle size of d90=22 m is used in a powder mixture to be HIP:ed, i.e 90% of the powder particles have a size less than 22 m.
[0071] The preferred tungsten carbide has a particle size in the range of 105-250 m. A metal matrix composite with approximately 50 vol. % tungsten carbide is preferred. This corresponds to approximately 67 wt % tungsten carbide. Accordingly, the wear resistant coating is formed by a metal matrix composite in which 33 wt % is metal matrix and 67 wt % is tungsten carbide.
Cobalt-Based Metal Matrix Composites
[0072] As an alternative to a nickel-based metal matrix composite, a cobalt-based metal matrix composite may be used as the wear resistant coating. The main advantage of using cobalt-based alloys in a metal matrix composite is that these alloys have low stacking fault energy which leads to a suitable deformation hardening behaviour of the alloy. This is, without being bond to any theory, believed to be one reason for cobalt-based alloys good resistance to erosion at high impinging angles of the erosive media.
[0073] According to one embodiment, the metal matrix composite comprises particles of tungsten carbide and a matrix of a cobalt-based alloy, wherein the cobalt-based alloy consists of: 20-35 wt % Cr, 0-20 wt % W, 0-15 wt % Mo, 0-10 wt % Fe, 0-5 Ni wt %, 0.05-4 wt % C and balance Co and unavoidable impurities. Chromium is added for corrosion resistance and to ensure that hard chromium carbides are formed by reaction with the carbon in the alloy. Also tungsten and/or molybdenum are may be included in the cobalt based alloy for carbide formation and solid solution strengthening. The carbides, i.e. chromium carbides, tungsten carbides and/or molybdenum rich carbides will increase the hardness of the ductile cobalt phase and thereby its wear resistance. However, too high amounts of the alloy elements Cr, W and Mo may lead to excessive amounts of carbide precipitation which will reduce the ductility of the metal matrix. Iron is added to stabilize the FCC crystal structure of the alloy and thus increases the deformation resistance of the alloy. However, too high amounts of iron may affect mechanical, corrosive and tribological properties negatively.
[0074] According to a further embodiment, the cobalt-based alloy may comprise 27-32 wt % Cr, 0-2 wt % W, 4-9 wt % Mo, 0-2 wt % Fe, 2-4 wt % Ni, 0,1-1.7 wt % C and balance Co.
[0075] According to an alternative embodiment, the cobalt-based alloy may comprise: 26-30 wt % Cr, 4-8 wt % Mo, 0-8 wt % W, 0-4 wt % Ni, 0-1.7 wt % C and balance Co.
[0076] According to yet another embodiment, the cobalt-based alloy may comprise: 26-29 wt % Cr, 4.5-6 wt % Mo, 2-3 wt % Ni, 0.20-0.35 wt % C and balance Co.
[0077] For the enablement of the present disclosure, a preferred metal matrix composite comprises approximately 50 vol % WC particles and 50 vol % of a cobalt-based alloy having a composition of: 26-29 wt % Cr, 4,5-6 wt % Mo, and 0,2-0,35% C and balance Co and unavoidable impurities. This composition will be consolidated by means of HIP. Thereby, a WC-powder having a mean size of 100-200 m and a cobalt-based alloy powder having a mean size of 45-95 m may preferably form a powder mixture to be consolidated by means of HIP.
Iron-Based Metal Matrix Composites
[0078] As an alternative to a nickel-based or a cobalt-based metal matrix composite, an iron-based metal matrix composite may be used as the wear resistant coating. Preferably, the iron-based alloy comprises, in weight %: 0,5-3 wt % C; 0-30 wt % Cr; 0-3 wt % Si; 0-10 wt % Mo; 0-10 wt % W; 0-10 wt % Co; 0-15 wt % V; 0-2 wt % Mn; balance Fe and unavoidable impurities. According to a preferred embodiment, the iron-based alloy comprises, in weight %: 1-2.9 wt % C; 4-25 wt % Cr; 0,3-1.5 wt % Si; 4-8 wt % Mo; 4-8 wt % W; 0-8 wt % Co; 3-15 wt % V; 0,4-1.5 wt % Mn; balance Fe and unavoidable impurities.
[0079] For the enablement of the disclosure, a preferred iron-based metal matrix composite comprises approximately 50 vol % WC particles and 50 vol % of an iron-based alloy having a composition of: in weight %: 1,9-2.1 wt % C; 26 wt % Cr; 0,6-0.8 wt % Si; 0,4-0.6 wt % Mn remainder Fe and unavoidable impurities. This composition is consolidated by means of HIP. Thereby, a WC-powder having a mean size of 100-200 m and an iron-based alloy powder having a mean size of 45-95 m may preferably form a powder mixture to be consolidated by means of HIP.