TUNGSTEN CARBIDE AND TITATNIUM CARBIDE REINFORCED MANGANESE STEEL

Abstract

A composite material includes at least one reinforcing zone composed of tungsten carbide (WC) and titanium carbide (W, Ti)C and a manganese steel matrix; a manganese steel zone that surrounds each of the reinforcing zones; and an interface layer positioned between each of the reinforcing zones and the manganese steel zone. The average grain size of the (W, Ti)C particles in each of the reinforcing zone(s) is between 0.2-2 m and the average grains size of the WC particles in each of the reinforcing zone(s) is between 20-30 m.

Claims

1. A composite material comprising: a plurality of reinforcing zone, each of the reinforcing zones comprising core-rim tungsten titanium carbide (W,Ti)C, tungsten carbide (WC) and a manganese steel matrix, wherein a core of the core-rim (W,Ti)C is rich in titanium and a rim core of the core-rim (W,Ti)C is rich in tungsten; a manganese steel zone surrounding each of the reinforcing zones; and an interface layer positioned between each of the reinforcing zones and the manganese steel zone, wherein a distance between two neighbouring reinforcing zones is between 1-5 mm, wherein a wt % of (W,Ti)C in each of the reinforcing zones is between 80-98 and a wt % of WC in each of the reinforcing zones is between 20-30, wherein a hardness of the reinforcing zones is between 900-1400 HV1 and a hardness of the manganese steel zone is between 300-400 HV1 before work hardening, wherein work hardening occurs as manganese steel in the manganese steel zone is subjected to the impact of crushing forces, wherein an average grain size of (W,Ti)C particles in each of the reinforcing zones is between 0.2-2 m and an average grain size of WC particles in each of the reinforcing zones is between 20-30 m, wherein the average grain size of (W,Ti)C and WC grains is measured by Scanning Electron Microscopy (SEM) analysis, where several and different areas from samples were analysed and particle sizes were measured using Image J software from which an average particle size was calculated, and wherein a density in the reinforcing zones is between 83-96% of a theoretical density.

2. The composite material according to claim 1, wherein the composition of the manganese steel in the manganese steel zone has a chemical composition by weight of: carbon: 0.5 to 2.0%; manganese: 11 to 22%; silicon: 0.2 to 1.0%; chromium: 1 to 2%; Nickel: up to 0.6% Molybdenum: up to 0.5% and a balance of Fe.

3. The composite material according to claim 1, wherein a thickness of each interface layer is greater than 150 m, wherein the thickness is measured by Scanning Electron Microscopy (SEM) analysis where several and different areas from the samples were analysed and particle sizes were measured using Image J software from which the average particle size was calculated.

4. The composite material according to claim 1, wherein the interface layer is free of defects when examined using optical microscopy at 1000 magnification, and wherein the defects are pores or cracks.

5. The composite material according to claim 1, wherein bonding between the WC grains and the manganese steel and between the (W,Ti)C grains and the manganese steel in the reinforcing zones is >99%.

6. The composite material according to claim 1, wherein each of the reinforcing zones has a volume of between 30-75 cm.sup.3, wherein the volume is measured using X-ray diffraction.

7. The composite material according to claim 1, wherein at least 90% of the WC grains in the reinforcing zones have an irregular prismatic shapes.

8. A wear part comprising the composite material according to claim 1.

9. A method of producing the composite material according to claim 1, the method comprising the steps of: a) mixing together 65-98 wt % tungsten, 3-90 wt % titanium, 3-20 wt % carbon and 0-80% catalyst powders, wherein the catalyst powder is selected from Fe, Ni, Mo, Cr, W, Al, or a mixture thereof; b) compacting the mixed powders together to form at least one compacts; c) positioning and fixing at least one compact into an interior of a mold, wherein the distance between two neighbouring reinforcing zones is between 1-5 mm; d) pouring molten casting manganese steel into the mold to surround the at least one compact to initiate a self-propagating high temperature synthesis (SHS) reaction to produce a cast; e) heat treating the cast; and f) quenching the cast, wherein in step b) the powders are compacted with a pressure of between 400-700 mPa.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0024] FIG. 1: Shows a line drawing of the composition of the composite material.

[0025] FIG. 2: Shows an SEM image taken of the reinforced zone with low magnification on the left and high magnification on the right.

[0026] FIG. 3: Shows an SEM image taken of the interface layer with low magnification on the left and high magnification on the right.

[0027] FIG. 4: Shows an SEM image of the composite material

[0028] FIG. 5: Shows a perspective drawing of a wear part.

[0029] FIG. 6: Shows defects in sample E

DETAILED DESCRIPTION

[0030] FIG. 1 shows a composite material 2 comprising at least one reinforcing zone 4 comprising tungsten carbide (W,Ti)C and tungsten carbide (WC) and a manganese steel matrix; a manganese steel zone 6 that surrounds each of the reinforcing zones 4; and an interface layer 8 positioned between each of the reinforcing zones 4 and the manganese steel zone 6. In each of the reinforcing zones, the (W,Ti)C and WC acts to reinforce the manganese steel matrix.

[0031] The average grain size of the (W,Ti)C particles in each of the reinforcing zone(s) (4) is between 0.2-2 m, preferably between 1-2 m. The average grain size of the WC particles in each of the reinforcing zone(s) (4) is between 20-30 m, preferably between 20-25 m.

[0032] The average grain size of the (W,Ti)C and WC grains is measured by Scanning Electron Microscopy (SEM) analysis where several and different areas from the samples were analysed and particle sizes were measured using Image J software. Then, the average particle size was calculated.

[0033] In one embodiment the density of the reinforcing zones is between 4.5-7.5 g/cm.sup.3, preferably between 6-7 g/cm.sup.3.

[0034] In one embodiment the density of the reinforcing zones is between 83-96% of the theoretical density, preferably 85-94%.

[0035] Each interface layer 8 comprises (W,Ti)C, WC and manganese steel and can be distinguished from the reinforcing zones 4 as the shape and size of the (W,Ti)C and WC grains are different. The interface layer(s) 8 can be distinguished from the reinforcing zone(s) 4 can either: comparing the geometry and/or comparing the average grain size. If the geometry is being compared, the reinforcing zone(s) 4 comprise >90% WC grains having irregular prismatic geometry whereas the interface layer(s) 8 comprise <5% WC grains having rectangular prismatic geometry. A WC grain is considered to have rectangular prismatic geometry if the grains have 4 sharp edges. A (W,Ti)C is considered to have a core-rim structure with a round geometry if it has a dark colour core (rich in Ti) and light colour shell (rich in W). If the grain size is being compared the average WC grain size of in the interface layer(s) 8 is at least 5% less than the average WC grain size on the reinforcing zone(s) 4.

[0036] FIG. 2 shows a Scanning Electron microscope image using MIRA3 TESCAN equipment. A secondary electron detector (SE) with a high voltage of 15 KV and a working distance of 9 mm configuration were used. SEM image of the (W,Ti)C and WC grains in the reinforcing zone 4. FIG. 3 shows an SEM image of the (W,Ti)C and WC grains in the interface layer 8. The different (W,Ti)C and WC grain geometry and size can clearly be seen when comparing these two figures.

[0037] In one embodiment the wt % of (W,TiC) in each of the reinforcing zones 4 is between 80-98%, more preferably between 90-98%, even more preferably between 94-98% and the wt % of WC in each of the reinforcing zones 4 is between 0-30%, more preferably between 20-30%, even more preferably between 25-30%.

[0038] In one embodiment, the composition of the manganese steel in manganese steel zone 6 has the chemical composition by weight of: carbon: 0.5 to 2.0%; manganese: 11 to 22%; silicon: 0.2 to 1.0%; chromium: 1 to 2%; nickel: up to 0.6%, molybdenum: up to 0.5% and a balance of Fe.

[0039] In one embodiment, the chemical composition of the manganese steel in each of the reinforcing zones 4 has the chemical composition by weight of: 1-1.5% C, 11-14% Mn, 0.4-0.8% Si, 1.3-2.0% Cr, 0.6% Ni, 0.065% P.

[0040] In one embodiment, the hardness of the reinforcing zones 4 is between 900-1400 HV1, preferably between 1000-1400. The hardness of the manganese steel zone 6 is between 300-400 HV1.

[0041] Hardness is measured using Vickers hardness mapping on polished samples using a 1 kgf and a holding time of 15 seconds. A micro-hardness tester, Matsuzawa, model MXT was used. Hardness measurement profiles are performed starting from the non-reinforce zone, moving to the interface layer and then to the reinforced zone.

[0042] In one embodiment, the interface layer 6 is greater than 150 um wide, preferably greater than 100 m. FIG. 4 shows an SEM image taken at 15.0 kV, 219 magnification of the reinforced zone 4, the manganese steel zone 6 and the interface layer 8. The width of the interface layer 6 is measured from a start point 10, which is defined as being adjacent to the manganese steel zone 6 and the point at where the (W,Ti)C and WC grains are present. The end point 12 for measuring where the interface layer 8 ends, and therefore where the reinforcing zone 8 starts is considered to be where the average grain size of the WC grains has increased by 20% compared average WC grains measured at the start point 10 and/or where the percentage of WC grains having a triangular prismatic shape increases above 90%.

[0043] In one embodiment, the interface layer 8 is free of defects when measured using optical microscopy under 1000 magnification. Defects are considered to be cracks or pores.

[0044] In one embodiment, the bonding between the (W,Ti)C grains and the manganese steel and between the WC and the manganese steel in the reinforcing zones 4 is >99%, preferably >99.5%, more preferably >99.9%, most preferably 100%. The bonding % is measured by a Scanning Electron Microscope where the contact area and the bonding between the (W,Ti)C grains or WC grains and the manganese steel is evaluated. The presence of cracks and/or defects between the (W,Ti)C grains and the manganese steel and between the WC and the manganese steel in the reinforcing zones 4 would decrease the bonding %.

[0045] In one embodiment each of the reinforcing zones 4 has a volume of between 30-75 cm.sup.3. For example, but not limited to the reinforcing zone(s) 4 could have a length of between 100-200 mm, preferably between 100-150 mm, a width of between 20-30 mm, preferably between 20-25 mm and a thickness between 15-30 mm, preferably between 15-25 mm.

[0046] In one embodiment >95%, preferably >98%, more preferably >99% of the (W,Ti)C grains in the reinforcing zones 4 have a rounded shape. Preferably, the (W,Ti)C grains are uniformly distributed in the manganese steel in the reinforcing zone(s). In one embodiment >95%, preferably >98%, more preferably >99% of the WC grains in the reinforcing zones 4 have a triangular prismatic shape. Preferably, the TiC grains are uniformly distributed in the manganese steel in the reinforcing zone(s).

[0047] In one embodiment, there are a plurality of reinforcing zones 4 with its interface zone 8 and the distance between two neighbouring reinforcing zones 4 with its interface layer 8 is between 1-5 mm, preferably between 1-3 mm, more preferably between 1-2 mm.

[0048] FIG. 5 shows an example of a wear part 14 comprising the composite material 2 as described hereinabove or hereinafter. For example, the wear part 2 could be, but not limited to, a cone crusher or a stationary jaw crusher or a mobile jaw crusher that is configured to crush material or other material/rock processing unit. The reinforcing zone(s) 4 are positions on the wear parts 14 in the locations that are most subjected to high wear, for example on a crushing zone 18 of a cone crusher 16.

[0049] The method for producing the composite material 2 as described hereinbefore or hereinafter comprising the steps of: a) Mixing together 65-98 wt % tungsten, preferably 80-98 wt % tungsten; 3-90 wt %, preferably 10-90 wt % Ti; 3-20 wt %, preferably 3-20% carbon and 0-80%, preferably 10-20% catalyst powders; b) compacting the mixed powders together to form at least one compact using a compacting pressure of between 400-700 MPa, preferably 500-600 MPa more preferably 550-600 MPa; c) positioning and optionally fixing at least one compact into the interior of a mold; d) pouring molten casting manganese steel into the mold to surround the at least one compact to initiate a self-propagating high temperature synthesis (SHS) reaction to produce a cast; e) heat treating the cast; and then f) quenching the cast.

[0050] Preferably, the cast is treated at a temperature of between 1400-1500 C., the cast is quenched using water. Preferably, the catalyst is selected from Fe, Co, Ni, Mo, Cr, W, Al, or a mixture thereof. Carbon could be added in the form of graphite, amorphous graphite, a carbonaceous material or mixtures thereof. The compacts could for example be held in place using me a metallic fixation system to hold them in place during casting.

EXAMPLES

Example 1Samples

[0051] Sample A is a comparative sample of non-reinforced manganese steel having the composition 1-1.5% C, 11-14% Mn, 0.4-0.8% Si, 1.3-2.0% Cr, 0.6% Ni, 0.065% P.

[0052] Samples A-I are samples of composite materials produced by mixing together powders of tungsten, titanium, carbon and a catalyst powder. The compacting the mixed powders to form compacts which were then positioned in a mold and then molten manganese steel having a composition of 1-1.5% C, 11-14% Mn, 0.4-0.8% Si, 1.3-2.0% Cr, 0.6% Ni, 0.065% was poured into the mold to surround the compacts which initiated a SHS reaction, the cast was then heat treated at a temperature of 1450 C. and then quenching with water. Table 1 shows a summary of the reinforced samples:

TABLE-US-00001 TABLE 1 Summary of samples Bonding Average (%) (W, Ti)C (W, Ti)C Average WC WC Relative between Compacting grain size in content in grain size in content in Density in Manganese pressure reinforcing reinforced reinforcing reinforcing reinforcing steel and used zone zone zone zone Catalyst zone reinforcing Sample (mPA) (m) (wt %) (m) (wt %) (wt %) (%) zone A (inventive) 600 1.88 98 0 40 86 100 B (inventive) 600 1.04 90 20 10 45 85 100 C (inventive) 600 0.95 94 25 30 50 85 100 D (inventive) 600 0.82 98 0 45 86 100 E (comparative) 600 0.49 80 (pores) 0 50 82 80 F (inventive) 600 0.36 98 25 30 55 85 100 G (inventive) 600 0.74 98 25 20 60 94 100 H (inventive) 600 1.27 98 25 30 65 88 100 I (inventive) 600 1.04 98 25 25 70 85 100

[0053] It can be seen if the penetration of manganese steel is not good enough the bonding is reduced and results in the presence of cracks and/or pores.

Example 2Hardness

[0054] Vickers hardness was measured by a micro-hardness tester, Matsuzawa, model MXT using 1 kgf and a holding time of 15 seconds. Hardness measurement profiles are performed starting from the non-reinforce zone, moving to the interface layer and then to the reinforced zone.

[0055] The hardness measurement results are shown in Table 2 below:

TABLE-US-00002 TABLE 2 Hardness measurement Hardness in manganese steel Hardness in Hardness in Sample zone (HV1) Interface layer reinforced zone A (inventive) 582 36 956 90 1267 227 B (inventive) 460 62 937 85 1111 165 C (inventive) 469 37 970 82 1067 172 D (inventive) 487 32 920 67 1120 277 E (comparative) F (inventive) 552 53 950 81 1148 153 G (inventive) 450 50 886 19 1030 147 H (inventive) 472 119 876 86 1062 187 I(inventive) 621 37 926 30 1030 141

[0056] It can be seen that the inventive samples have an increased hardness in reinforced zones compared to the comparative samples. It was not possible to measure the hardness of E due to the large size of the pores.

Example 3Defects

TABLE-US-00003 TABLE 4 Defects Defects in the Defects in the Sample reinforced zone interface layer A (inventive) Small pores none B (inventive) Small pores none C (inventive) Small Pores none D (inventive) Small Pores none E (comparative) Big pores and cracks Big pores and cracks F (inventive) Small Pores none G (inventive) Small Pores none H (inventive) Small Pores none I (inventive) Small Pores none

[0057] Defects were assessed by using Scanning Electron microscopy analysis where cracks and pores are identified. The inventive samples only have small pores in the reinforced zone and no defects in the interface layer. Pores that can be seen at 100 magnification under an optical microscope are considered to be big and pores than can start to be seen at 1000 magnification under optical microscopy are considered to be small.