METHOD OF PRODUCING A COMPONENT OF A COMPOSITE OF DIAMOND AND A BINDER

Abstract

A method of producing a component of a composite of diamond and a binder, wherein a Hot Isostatic gas Pressure process (HIP) is used, includes the step of enclosing a de-bound green body having compacted diamond particles in an infiltrant. The method includes the further steps of enclosing the de-bound green body and the infiltrant in a Zr-capsule that has Zirconium as a main constituent and sealing the Zr-capsule, and applying a predetermined pressure-temperature cycle on the unit formed by the de-bound green body, infiltrant and capsule in which the infiltrant infiltrates the de-bound green body and the de-bound green body is further densified in the sense that the volume thereof is decreased.

Claims

1. A method of producing a component of a composite of diamond having a diamond content of 25 vol % and a binder, wherein a Hot Isostatic gas Pressure process (HIP) is used, comprising the steps of: forming a de-bound green body having a diamond content of solids of at least 50 vol %; enclosing said de-bound green body and an infiltrant in a Zr-capsule that comprises zirconium as a main constituent and sealing the Zr-capsule; and applying a predetermined pressure-temperature cycle on a unit formed by said de-bound green body, infiltrant and capsule in which the infiltrant infiltrates the de-bound green body and the de-bound green body is further densified such that a volume thereof is decreased, wherein the predetermined pressure-temperature cycle includes a temperature and pressure increase, with or without holding times, until a predetermined maximum temperature being between 1450 to 1600 C. and a predetermined maximum pressure being between 50 to 3000 Bar is reached.

2. The method according to claim 1, wherein the predetermined pressure-temperature cycle includes a first step in which the temperature is increased to a temperature between 1100 to 1361 C.

3. The method according to claim 1, wherein, in a second step, a pressure of the unit is increased to a level of at least 40% of the predetermined maximum pressure to be applied during said pressure-temperature cycle, and not until after said pressure has been reached, the temperature is increased to the predetermined maximum temperature.

4. The method according to claim 1, wherein, when Si is the infiltrant, the time above 1541 C. in the predetermined pressure-temperature cycle should be less than 7 minutes.

5. The method according to claim 1, wherein the step forming of a de-bound green body includes partially removing a temporary binder from the green body by subjecting the green body to an elevated temperature.

6. The method according to claim 5, wherein the elevated temperature is >200 C. but <600 C.

7. The method according to claim 5, wherein 90 to 95 weight % of the temporary binder is removed.

8. The method according to claim 1, characterised in that wherein the diamond particles have a particle size in the range of 2-200 microns.

9. The method according to claim 1, characterised in that wherein the infiltrant enclosing the de-bound green body includes a densely packed powder and/or granules with bi-modual or multi-modual particle size distribution or as a dense replica of brown bodies and the capsule, where the density of the infiltrant in the capsule prior to sintering is >30% of a theoretical sintered density.

10. The method according to claim 1, wherein the infiltrant comprises Si as a main constituent.

11. The method according to claim 1, wherein the green body is subjected to a Cold Isostatic Pressing step prior to de-binding.

12. The method according to claim 1, wherein the predetermined pressure-temperature cycle includes increasing the pressure to a pressure being between 35 to 45 Bar, after which the temperature is increased to a temperature being between 1250 to 1350 C., keeping the temperature constant for a period of between 40 to 60 minutes during which the pressure is increased to 950 to 1050 Bar, after which both the temperature and pressure are further increased to 1550 to 1570 C. and 950 to 1150 Bar respectively.

13. A diamond composite having a diamond content of 25 vol % made according to the method of claim 1.

14. The diamond composite according to claim 13, wherein an area % of diamond in the diamond composite is above 40.

15. The diamond composite according to claim 13, wherein the Zr-content in the diamond composite is between 1.5 to 8.5 wt %.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG. 1 discloses a cross-section of a test set up consisting of a number of de-bound green bodies surrounded by a silicon-based infiltrant and a Zirconium-based capsule.

[0046] FIG. 2 discloses a side view of a sintered component obtained from the setup shown in FIG. 1, more precisely a light optical microscope image of a sintered insert, in which the geometry referred to in the examples and in the image the top of the insert is indicated and also where the outer diameter OD and height h, respectively, are measured.

[0047] FIG. 3. discloses particle size distribution given as the equivalent circle diameter of diamond particles in 2D-cross sections of sintered materials according to the invention and according to prior art. The number of particles is given on the y-axis and equivalent circle diameter in m is given on the x-axis. Sample 1 is the prior art material described in example 9 and sample 2, 3 and 4 are materials according to the invention as described in example 1, 8 and 7 respectively.

[0048] FIG. 4 shows schematic images illustrating which diamond particles that have been included/excluded within the area of analysis for each micrograph. Filled particles are included and non-filled particles are excluded from the analysis and all diamond particles are regarded as spherical.

[0049] FIG. 5 shows the cumulative probability of failure on the y-axis is plotted as a function of the measured B3B characteristic strength in MPa on the x-axis. Measured data from the prior art material as described in example 9 are shown as black diamonds and the measured data from the material according to the invention in example 1 are shown as light grey diamonds. The Weibull distribution function calculated from the experimental data for the material produced according to prior art is shown as a black solid line and the corresponding distribution curve for the material produced according to the invention is shown as a dashed black line.

EXAMPLES

Example 1HIP at 1125 Bar and 1570 C.

[0050] Diamond powders were dry blended together to form a uniform mixture. The diamond was a mixture of 80 wt % 20 to 30 micron and 20 wt % 4 to 8 micron diamond of grade MBM from Diamond Innovations Inc, this diamond blend is hereafter referred to as DPSD 1. Homogenous slurry was prepared using this mixture and then adding PEG1500 and PEG4000 as temporary organic binders, with de-ionized water as the fluid. The slurry was spray granulated to produce granules for pressing and the amount of organic binders in the powder was 9.26 wt % which corresponds to 23 vol %.

[0051] Granules were used in uni-axial pressing of green bodies in the shape of tool tips (buttons) typically used in mining operations (rock drilling) to a green density as high as possible with the used compaction technique. The force applied for the compaction of the green bodies was typically 40-50 kN. The relative diamond density in the green bodies was around 60%. The relative diamond density in percentage was calculated as the mass of diamonds in the green body (temporary organic binders and other additions excluded) divided by the volume of the green body obtained from the press tool drawing divided by the X-ray density of diamonds (3.52 g/cm.sup.3), multiplied by 100. Depending on the compaction technique and the shape of the body the density can vary slightly between different parts of the green body. The green bodies were slowly heated in the presence of air to partially remove the PEG to create a brown body 1 (de-bound green body) of enough strength for further handling. The weight of a representative green body was 7.651 g and 6.962 g after de-binding.

[0052] As shown in FIG. 1 four brown bodies 1 were placed in a Zr-capsule 3 with a sealed bottom and with a dense packed silicon powder blend 2 completely surrounding the brown bodies 1. The Zirconium capsule 3 was manufactured from a tube in the commercial Sandvik grade Zr 702 with a purity of 92.2 wt % and with Hf-content of 4.5 wt %. The dimensions of the capsule 3 were; outer diameter OD25.4 mm, inner diameter ID20.2 mm, wall thickness 2.6 mm, and height 130 mm, giving a capsule weight of 185 g. The capsule material had a melting point of 1852 C. The Si-powder blend 2 was a mixture of 86 wt % Silgrain coarse from Elkem with a purity of 99.5 wt % and with an oxygen content of 0.119 wt % analyzed by LECO and grain size of 0.2-0.8 mm and Silgrain HQ from Elkem with a purity of 98% and with an oxygen content of 0.059 wt % analyzed by LECO and a grain size between 20-300 microns. The tap density of this Si-blend 2 is about 1.36 g/cm.sup.3, measured by filling a calibrated volume (Ford cup) with the Si-powder blend during subsequent manual tapping of the Ford cup the same way as performed during the filling of the capsules and then measuring the weight, which corresponds to about 58% of the theoretical sintered density of silicon. After filling the capsule 3, it was sealed by welding. The total amount of Si added to the capsule 3 was 35 g and the total weight of the brown bodies 1 was 28 g.

[0053] The sealed capsules 3 were arranged in a HIP furnace. The temperature was increased to 400 C. under vacuum. After a 30 min hold time at 400 C., the argon gas pressure was rapidly raised to 40 Bar and then the temperature was increased with 16/min to 1300 C. At 1300 C. the pressure was increased to 1000 bar during roughly 55 minutes at constant temperature followed by a concurrent temperature and pressure increment until the maximum sintering temperature 1570 C. and the maximum pressure of 1125 Bar was reached after 20 min. The capsules 3 were then allowed to cool down freely during pressure release. After 15 min. the temperature was below 1000 C. and the pressure was about 800 Bar. After totally 1 hour of cooling, the temperature was about 200 degrees C. and the HIP furnace was opened. After HIP, the Zr-capsule was slightly distorted and had shrunk but was still sealed. The capsule 3 was put in an pickling bath containing 2% HF and 20% HNO.sub.3 in an aqueous solution for about 24 hours to remove the Zr-capsule and partly also the Si-residuals surrounding the inserts. After the acid treatment a final cleaning was performed using a grit blaster with SiC grit. The SiC grit removed Si and zirconium silicides from the sintered body but did not abrade the body itself, indicating that the body was well sintered and has a very high hardness and abrasion resistance. The cleaned sintered article is shown in FIG. 2, which shows a light optical microscope image of a sintered insert 4 having the geometry referred to in the examples. In the image, the top of the insert is indicated and also where the outer diameter OD and height h, respectively, are measured.

[0054] The densities of the HIP sintered bodies were measured using Archimedes' method and were between 3.50-3.52 g/cm.sup.3, se table 1.

TABLE-US-00001 TABLE 1 mass mass Sintered green brown mass mass Volume density Sample body body sintered increase sintered Archimedes No. (g) (g) (g) (%) (cm.sup.3) (g/cm.sup.3) 1a 7.651 6.962 11.177 60.54 3.180 3.510 1b 7.733 7.027 11.062 57.42 3.154 3.503 1c NA 6.963 11.144 60.05 3.180 3.505 1d NA 7.123 11.328 59.03 3.225 3.509

[0055] The dimensions outer diameter (OD) and height (h) of the sintered bodies was measured as shown in FIG. 2. The dimensions had decreased compared with the pressed green bodies, see table 2.

TABLE-US-00002 TABLE 2 Nominal OD OD Height Height Height Sample OD green sintered shrinkage green sintered shrinkage No. (mm) (mm) (%) (mm) (mm) (%) 1a 15.95 15.620 2.22 22.297 21.611 3.08 1b 15.95 15.684 2.00 21.958 21.426 2.42 1c 15.95 15.644 2.27 22.182 21.534 2.92 1d 15.95 15.692 2.00 22.276 21.923 1.58

[0056] Phase analysis performed using XRD (CuK-radiation). The diffractograms were collected with a PanAnalytical X'PertPro diffractometer from 20-90 degrees in 2 on a flat ground and polished area from the top of the samples as shown in FIG. 2. The High Score+ software was used for the evaluation (phase identification) and in all samples diamond, SiC (-Moissanite) and ZrSi.sub.2 were found. All diffraction peaks could be indexed. Some samples also showed the presence of other zirconium silicides, ZrC, residual Si and in some cases possible traces of zirconium oxides and in these cases only the first to third strongest line(s) could be detected.

[0057] The bodies were CT-scanned for defect detection but were found to not contain any pores or cracks larger than 3 times the voxel size. By CT it was also clearly seen that the Zr-distribution within the body is not homogenous.

[0058] The CT-system used for these scans were a v|tome|x s240 from GE Sensing and Inspection Technologies, using the following settings:

TABLE-US-00003 Magnification 9.1 Voxelsize (Resolution) 22 m X-ray voltage 80 kV X-ray current 270 A X-ray filter (Cu) 0.1 mm Detector timing 200 ms Detector averaging 3 Detector skip 1 Detector sensitivity 4 Number of projections 1200

[0059] After the CT scans were completed, the projections were reconstructed using datos|x 2.0 from GE Sensing and Inspection Technologies, and then analyzed with Volume Graphics StudioMax 2.1.

Example 2HIP at 1000 Bar and 1520 C.

[0060] Green bodies were prepared and de-bound (brown bodies) as in example 1. Also the capsule and the Si blend are the same as used in example 1. The total amount of Si added to the capsule was 36 g and the total weight of the brown bodies was 29 g. The temperature was increased to 400 C. under vacuum. After a 30 min hold time at 400 C., the argon gas pressure was raised to 40 Bar. Then the temperature was increased with 16/min to 1300 C. At 1300 C the pressure was increased from 40 Bar to 1000 bar during 55 minutes at a constant temperature followed by a temperature increase of 11 C./min to the maximum sintering temperature and pressure of 1520 C. and 1000 Bar. The capsules were then allowed to cool down freely with a constant pressure release. After 15 min the temperature was about 800 C. and the pressure was about 730 Bar. After 70 minutes cooling, the temperature was about 200 degrees C. and the HIP furnace was opened.

[0061] After HIP, the Zr-capsule was slightly distorted and had shrunk but was still sealed. The capsules was put in an acid bath containing HF(aq) for about 24 h to remove the Zr-capsule and partly also the Si-residuals surrounding the inserts. After the acid treatment a final cleaning was performed using a grit blaster with SiC grit. The SiC grit removed Si and zirconium silicides from the sintered body but did not abrade the body itself, indicating that the body was well sintered and has a very high hardness and abrasion resistance. The densities of the HIP sintered bodies were measured using Archimedes' method and were between 3.50-3.52 g/cm.sup.3 as shown in table 3. The dimensions were also measured and the OD and height of the sintered bodies had decreased compared with the pressed green bodies, see table 3.

TABLE-US-00004 TABLE 3 Sintered Mass mass mass mass Volume density Sample green brown sintered increase sintered Archimedes No. (g) (g) (g) (%) (cm.sup.3) (g/cm.sup.3) 2a 7.959 7.267 11.357 56.28 3.234 3.512 2b 7.938 7.246 11.369 56.90 3.253 3.495 2c 7.912 7.224 11.46 58.64 3.259 3.517 2d 7.87 7.194 11.458 59.27 3.256 3.519 Nominal OD OD Height Height Height Sample OD green sintered shrinkage green sintered shrinkage No. (mm) (mm) (%) (mm) (mm) (%) 2a 15.90 15.640 1.64 22.47 21.974 2.21 2b 15.90 15.654 1.55 22.46 21.984 2.12 2c 15.90 15.662 1.50 22.44 22.044 1.76 2d 15.90 15.663 1.49 22.43 22.064 1.63

Example 3HIP at 1130 Bar and 1570 C.

[0062] Diamond powders were weighed and dry blended together to form a uniform mixture according to DPSD 1. Slurry and greens were prepared as described in Example 1. Four brown bodies were placed in a Zr-capsule with a sealed bottom and with a dense packed silicon powder blend completely surrounding the brown bodies as shown in FIG. 1. The Zirconium capsule was manufactured as described in Example 1. The Si-powder blend was a mixture of 96 wt % Silgrain coarse from Elkem with a purity of 99.5 wt % and with an oxygen content of 0.119 wt % analyzed by LECO and 4 wt % of a graphite powder with a purity of 98% and a particle size<75 microns. The graphite was added to decrease and steer the amount of liquid Si but maintaining the amount of pressurizing media. After filling the capsule, it was sealed by welding. The total amount of SiC blend added to the capsule was 34 g. The sealed capsules were placed in the HIP furnace, and the furnace was run according to the cycle described in example 1. However, the measured maximum pressure was close to 1130 bar (compared to 1125 in example 1). The HIP was cooled for 80 minutes to about 100 C. before opening the furnace. After HIP, the Zr-capsule was slightly distorted and had shrunk but was still sealed. The capsule was removed by turning followed by a final cleaning using a grit blaster with SiC grit. The SiC grit removed silicon, silicon carbide and zirconium silicides from the sintered body but did not abrade the body itself, indicating that the body was well sintered and has a very high hardness and abrasion resistance. The densities of the HIP sintered bodies were measured using Archimedes' method and were between 3.49-3.50 g/cm.sup.3, se table 4.

TABLE-US-00005 TABLE 4 Sintered density Sample m brown m sintered m increase V sintered Archimedes No. (g) (g) (%) (cm.sup.3) (g/cm.sup.3) 3a 7.378 11.407 54.608 3.288 3.496 3b 7.561 11.492 51.99 3.287 3.496 3c 7.468 11.465 53.522 3.283 3.492 3d 7.56 11.472 51.746 3.285 3.492

[0063] The dimensions (outer diameter (OD) and height (h)) of one sintered body (No 3b) was measured as shown in table 5.

TABLE-US-00006 TABLE 5 Nominal OD OD h h h Sample OD green sintered shrinkage green sintered shrinkage No. (mm) (mm) (%) (mm) (mm) (%) 3b 15.90 15.771 0.81 22.43 22.057 1.66

Example 4HIP at 1135 Bar and 1570 C.

[0064] Diamond powders were dry blended together to form a uniform mixture. The diamond mixture was a multi-modal mixture of MBM-diamonds from Diamond Innovation with particle sizes in the range of 6 to 80 m, which gives a high density during compaction. This diamond blend will hereafter be referred to as DPSD 2. A homogenous slurry was prepared using this mixture and then adding 22.9 vol. % PEG1500 and PEG4000 as organic binders, with de-ionized water as the fluid. The slurry was spray granulated to produce granules for pressing and the amount of organic binders in the powder was 9.26 wt % which corresponds to 23 vol %. Granules were used in uni-axial pressing of green bodies in the shape of tool tips typically used in mining operations to a green density as high as possible with the used compaction technique. The pressing pressures were about 30 kN and the relative diamond density in the green bodies was around 66%. The green bodies were slowly heated in the presence of air to partially remove the PEG to create a brown body of enough strength for further handling. The weight of the green body was 8.432 g, and the weight of the brown body was 7.724 g.

[0065] The brown body was placed in a Zr-capsule with a sealed bottom together with two other brown bodies, one of which was as described in examples 1 and 2, and with a dense packed silicon powder blend according to example 1 completely surrounding the brown bodies. The Zirconium capsule were manufactured as described in example 1. After filling the capsule, it was sealed by welding. The total amount of Si added to the capsule was 38 g and the total weight of the brown bodies was 24 g. The temperature was increased to 400 C. under vacuum. After a 30 min hold time at 400 C., the argon gas pressure was raised to 40 Bar. The temperature was then increased with 16/min to 1300 C. At 1300 C. the pressure was increased from 40 Bar to 1000 bar during 45 minutes keeping the temperature constant followed by a temperature increase of 13.5 C./min to the maximum sintering temperature and pressure of 1567 C. and 1135 Bar. The capsule was then allowed to cool down freely with a constant pressure release. After 11 min the temperature was just below 1000 C. and the pressure was about 820 Bar. After about 40 minutes of cooling, the temperature was about 200 C. and the HIP furnace was opened.

[0066] After HIP, the Zr-capsule was slightly distorted and had shrunk but was still sealed. The capsule was removed by a turning operation followed by a grit blasting process with SiC grit. The SiC grit removed silicon and zirconium silicides from the sintered body but did not abrade the body itself, indicating that the body was well sintered and has a very high hardness and abrasion resistance. The density of the HIP sintered body was measured using Archimedes' method and was 3.504 g/cm.sup.3.

[0067] The dimensions were also measured and the outer diameter (OD) after sintering was 15.73 mm and the nominal ID (inner diameter) of the press tool was 15.95 mm which corresponds to 1.4% OD-shrinkage during sintering.

Example 5HIP at 1135 Bar and 1570 C.

[0068] Diamond powders were weighed and dry blended together to form a uniform mixture according to DPSD 2. A slurry and granulated powder was prepared as in Example 4. Granules were used in uni-axial pressing of green bodies in the shape of tool tips typically used in mining operations to a green density as high as possible with the used compaction technique. The relative diamond density in the green bodies was around 66%. The green bodies were slowly heated in the presence of air to remove the PEG partially to create brown bodies of enough strength for further handling. The weight of the green body was 8.553 g, and the weight of the brown body was 7.842 g. The brown body was placed in a Zr-capsule with a sealed bottom together with two other brown bodies, one of which was as described in examples 1 and 2, and with a dense packed silicon powder blend completely surrounding the brown bodies. The Zirconium capsule was manufactured as described in example 1. The Si-powder blend was a mixture of 96 wt % Silgrain coarse from Elkem with a purity of 99.5 wt % and with an oxygen content of 0.119 wt % analyzed by LECO and 4 wt % of a fine graphite powder with a purity of 98%. The graphite was added to decrease and steer the amount of liquid Si but maintaining the amount of pressurizing media. After filling the capsules it was sealed by welding. The total amount of SiC blend added to the capsule was 39.5 g and the weight of the brown bodies was 24 g.

[0069] The capsule was placed in a HIP furnace, which was run as described in example 4, maximum temperature and pressure were 1567 C. and 1135 bar.

[0070] After HIP, the Zr-capsule was slightly distorted and had shrunk but was still sealed. The capsule was removed by a turning operation followed by a grit blasting process with SiC grit. The SiC grit removed silicon and zirconium silicides from the sintered body but did not abrade the body itself, indicating that the body was well sintered and has a very high hardness and abrasion resistance. The density of the HIP sintered body was measured using Archimedes' method and was 3.498 g/cm.sup.3. The dimensions were also measured and the outer diameter (OD) after sintering was 15.75 mm and the nominal ID of the press tool was 15.95 mm which corresponds to 1.3% OD-shrinkage during sintering.

Example 6HIP at 1130 Bar and 1570 C., Ti.SUB.3.SiC.SUB.2 .Added

[0071] Diamond powders were dry blended together with a well de-agglomerated Ti.sub.3SiC.sub.2 powder to form a uniform mixture. The powder mixture contained 82 wt % of MBM-diamonds from Diamond Innovations with the DSPD 2 diamond particle size distribution, and 18 wt % of Ti.sub.3SiC.sub.2. Homogenous slurry was prepared using this mixture and then adding PEG1500 and PEG4000 as temporary organic binders and Dispex A40 as a dispersant agent for Ti.sub.3SiC.sub.2, with de-ionized water as the fluid. The slurry was spray granulated to produce granules for pressing and the amount of organic binders in the powder was 9.26 wt % corresponding to 23.6 vol %.

[0072] Granules were used in uniaxial pressing of green bodies in the shape of tool tips typically used in mining operations to a high green density with the used compaction technique (20 kN). The relative diamond density in the green bodies was 55%+/0.5%. The green bodies were slowly heated in the presence of air to partially remove the PEG to create a brown body of enough strength for further handling, see details in table 6.

[0073] Four brown bodies were placed in a Zr-capsule with a sealed bottom and with a densely packed silicon powder blend completely surrounding the brown bodies as shown in FIG. 1. The Zirconium capsule and Si blend were prepared as described in example 1. After filling the capsule, it was sealed by welding. The total amount of Si added inside the capsule was 31.5 g and the total weight of the brown bodies was 33 g.

[0074] The capsule was placed in the same HIP-charge as the capsule described in Example 3, and thus subjected to the same HIP-process.

[0075] After HIP, the Zr-capsule was slightly distorted and had shrunk but was still sealed. The capsule was removed by a turning operation followed by a grit blasting process with SiC grit. The SiC grit removed silicon, silicon carbide and zirconium silicides from the sintered body but did not abrade the body itself, indicating that the body was well sintered and has a very high hardness and abrasion resistance. The volume and densities of the HIP sintered bodies were measured using Archimedes' method and the densities were between 3.59-3.60 g/cm.sup.3, se table 6.

TABLE-US-00007 TABLE 6 m m Sintered green brown m Mass Sintered density Sample body body sintered increase volume Archimedes No. (g) (g) (g) (%) (cm.sup.3) (g/cm.sup.3) 6a 8.901 8.151 10.686 31.1 2.974 3.593 6b 8.913 8.162 10.831 32.7 3.014 3.593 6c 8.903 8.156 10.839 32.9 3.011 3.600 6d 8.891 8.144 10.783 32.4 2.995 3.600 Nominal OD OD Height Height Height Sample OD green sintered shrinkage green sintered shrinkage No. (mm) (mm) (%) (mm) (mm) (%) 6a 15.90 15.362 3.38 22.016 21.158 3.90 6b 15.90 15.390 3.21 22.027 21.263 3.47 6c 15.90 15.406 3.11 22.016 21.253 3.47 6d 15.90 15.352 3.45 22.029 na na

Example 7HIP at 150 Bar 1560 C.

[0076] Samples were prepared as in example 1 disclosed above. Capsule and Si blend are in accordance with description in example 1. The capsule, containing the de-bound green bodies (brown bodies) were positioned in a furnace and subjected to the following HIP-process:

[0077] The temperature was increased to 400 C. under vacuum. After a 30 min hold time at 400 C., the argon gas pressure was raised to 40 Bar. The temperature was then increased with 9.5/min to the maximum temperature of 1558 C. with the argon pressure was concurrently raised to 150 bar. The capsules were then allowed to cool down freely with a constant pressure release. After 18 min the temperature was below 1000 C. and the pressure was about 110 Bar. After 2.5 hours of cooling the temperature was below 100 degrees C. and the HIP furnace was opened.

[0078] After HIP, the Zr-capsule was slightly distorted and had shrunk but was still sealed. The capsules was put in an acid bath containing HF(aq) for about 24 h to remove the Zr-capsule and partly also the Si-residuals surrounding the inserts. After the acid treatment a final cleaning was performed using a grit blaster with SiC grit. The SiC grit removed silicon and zirconium silicides from the sintered body but did not abrade the body itself, indicating that the body was well sintered and has a very high hardness and abrasion resistance. The volume and density of the HIP sintered bodies was determined by Archimedes' method.

[0079] The dimensions were also measured and the outer diameter (OD) after sintering the nominal ID of the press tool was 15.95 mm (see table 7).

TABLE-US-00008 TABLE 7 Sintered m m m m V density Sample green brown sintered increase sintered Archimedes No. (g) (g) (g) (%) (cm.sup.3) (g/cm ) 7a 7.745 7.057 11.191 58.58 3.182 3.513 7b 7.849 7.142 11.263 57.70 3.206 3.509 7c 7.852 7.148 11.203 56.73 3.188 3.51 7d 7.856 7.148 11.198 56.66 3.187 3.51 OD OD OD h h h h Sample pressed sintered shrinkage pressed de-bound sintered shrinkage No. (mm) (mm) (%) (mm) (mm) (mm) (%) 7a nom 15.689 1.67 21.904 21.939 21.81 0.43 15.95 7b nom 15.82 1.03 21.960 21.96 21.803 0.71 15.95 7c nom 15.761 1.41 21.866 21.859 21.776 0.41 15.95 7d nom 15.796 1.23 21.850 21.818 21.649 0.92 15.95

Example 8HIP at 150 Bar and 1560 C.

[0080] The same pressure-temperature cycle as previously disclosed in Ex. 7 for HIP at 150 Bar and 1560 C. was applied to samples corresponding to those of Ex. 7 but the greens were pre-treated by cold isostatic pressing (CIP) before de-binding. The test showed that pretreatment by means of cold isostatic pressing before de-bounding did not prevent further shrink during the HIP process and full infiltration. The test resulted in approximately the same density as in example 7, but a slightly smaller volume after sintering.

TABLE-US-00009 TABLE 8 Sintered m m m V density Sample m de-bound sintered increase sintered Archimedes No. pressed (g) (g) (%) (cm.sup.3) (g/cm.sup.3) 8a 7.663 6.948 10.958 57.71 3.118 3.51 8b 7.808 7.11 11.124 56.46 3.166 3.51 8c 7.855 7.152 11.16 56.04 3.176 3.51 8d 7.877 7.172 11.195 56.09 3.193 3.502 OD OD OD h h h h Sample pressed sintered shrinkage pressed de-bound sintered shrinkage No. (mm) (mm) (%) (mm) (mm) (mm) (%) 8a nom 15.726 1.40 21.803 nm 21.53 1.25 15.95 8b nom 15.755 1.22 21.856 nm 21.702 0.70 15.95 8c nom 15.753 1.24 21.86 nm 21.658 0.92 15.95 8d nom 15.728 1.39 21.86 nm na na 15.95

Example 9, Prior ArtLow Pressure SinteringInfiltration in Vacuum at 1650 C.

[0081] Diamond brown bodies from the same batch as in Ex. 1 were placed in hBN-coated graphite crucibles with silicon lumps in a large access (200% in weight) placed in the bottom of the crucible. The silicon was Silicon 99 Refined-Si 30 015 from Elkem with a silicon content of 99.4 wt % and oxygen content of 0.004% analyzed by LECO and a with a particle size of 10-100 mm. The infiltration was performed under vacuum to the maximum temperature of 1650 C. as has been described in U.S. Pat. No. 7,008,672 B2. A fast temperature ramping, 50 C./min, was applied above 1000 C. to prevent extensive graphitization (>/=50 wt %) of the diamonds prior to Si-infiltration. The temperature was maintained for about 10 min and the samples were than cooled down freely. The access silicon was removed by SiC-grit blasting and the body inspected by Computer Tomography. No pores>3 the voxel size of 17 microns could be detected. The sintered density was 3.316 g/cm.sup.3. The sintered OD were 15.981 mm compared with the nominal dimensions of the press tool ID of 15.95 mm, which corresponds to an OD increase of 0.2%. Diffraction data were collected between 15-70 degrees in 2 theta on the top of an sintered and as-blasted insert using a Bruker D8 (Gadds) with CuK-radiation and a 0.5 mm collimator. The High Score+ software was used for the evaluation (phase identification) and diamond, SiC (-Moissanite) and Si were found.

TABLE-US-00010 TABLE 9 Sintered Sintered density m green body m brown body m sintered volume Archimedes (g) (g) (g) (cm.sup.3) (g/cm.sup.3) 7.726 7.150 11.068 3.336 3.316

Example 10, Prior ArtLow Pressure SinteringInfiltration in Vacuum at 1650 C.

[0082] Diamond brown bodies from the same batch as in Ex. 4 were placed in hBN-coated graphite crucibles with silicon lumps in a large access (200% in weight) placed in the bottom of the crucible. The silicon used was Silicon 99 Refined-Si 30 015 from Elkem with a silicon content of 99.4 wt % and oxygen content of 0.004% analyzed by LECO and a with a particle size of 10-100 mm. The infiltration was performed under vacuum to the maximum temperature of 1650 C. as has been described in U.S. Pat. No. 7,008,672 B2. A fast temperature ramping, 50 C./min, was applied above 1000 C. to prevent major graphitization (>/=50 wt %) of the diamonds prior to Si-infiltration. The temperature was maintained for about 10 minutes and the samples were than cooled down freely. The excess silicon was removed by SiC-grit blasting and the body inspected by Computer Tomography. No pores>3 the voxel size of 17 microns could be detected. The sintered density of the body was 3.334 g/cm.sup.3. The final OD were 15.956 mm compared with the nominal dimensions of the press tool ID of 15.95 mm, which corresponds to an OD increase of 0.04%.

[0083] Diffraction data were collected between 15-70 degrees in 2 theta on the top of an sintered and as-blasted insert using a Bruker D8 (Gadds) with CuK-radiation and a 0.5 mm collimator. The High Score+ software was used for the evaluation (phase identification) and diamond, SiC (-Moissanite) and Si were found.

TABLE-US-00011 TABLE 10 Sintered Sintered density m green body m brown body m sintered volume Archimedes (g) (g) (g) (cm.sup.3) (g/cm.sup.3) 8.530 7.803 11.207 3.358 3.334

Example 11, Prior Art

[0084] Diamond brown bodies from the same batch as in Ex. 1 and brown bodies manufactured as described in Ex. 4 were placed in open hBN-coated high density graphite crucibles with silicon lumps in a large access (200% in weight) are placed in the bottom of the crucible. The crucible was placed in a sinter-HIP furnace and heated with a fast temperature ramp rate, 50 C./min. At about 1420 C. the silicon melted and shortly thereafter it started to infiltrate the body. At 1500 C. argon pressure of 45 bars was applied in order to see if the body could be further densified and the temperature ramping then continued to maximum temperature of 1650 C. The temperature was maintained for about 10 min before the bodies were allowed to cool freely under argon. After sintering the bodies were removed from the crucibles but despite the large access of silicon they were not fully infiltrated and the top of the inserts had been converted into graphite and were completely removed during the SiC-grit blasting process.

Example 12, Abrasion Wear TestingDiamond Green Bodies with DPSD 1Invention Versus Prior Art

[0085] In the wear test the sample tips are worn against a rotating granite log counter surface in a turning operation. In the test the load applied to each insert was 200 N, the rotational speed was 270 rpm and the horizontal feed rate was 0.339 mm/rev. The sliding distance in each test was fixed to 230 m. Each sample was carefully weighed prior and after the test. Sample volume loss was calculated from measured mass loss and sample density and serves as a measurement of wear.

[0086] All samples in the test had exactly the same diamond grain size distribution DSPD 1, relative diamond density in the green body (60%) and geometry. Samples were sintered according to the invention (Ex. 1 and 7) and prior art (Ex. 9). The abrasion wear test clearly shows a significantly increased wear resistance for the near net bodies produced according to the invention compared to the near net bodies produced in accordance with prior art.

TABLE-US-00012 TABLE 11 Description Sintered Inserts from Ex. 1 Wear loss density Wear loss (1125 Bar), Sample No. (mg) (g/cm.sup.3) (mm.sup.3) Invention 1 0.1 3.5 0.03 2 0.2 3.509 0.06 3 0.3 3.501 0.09 Inserts from Ex. 7 (150 Bar), Sample No. Invention 1 0.4 3.513 0.11 2 0.3 3.510 0.09 Inserts from Ex 8 (150 Bar, pre-CIP) Sample No. Invention 1 0.4 3.510 0.11 2 0.2 5.502 0.06 Inserts from Ex. 9 Sample No. Prior art 1 1.0 3.299 0.30 2 0.9 3.303 0.27 3 1.1 3.305 0.33

Example 13Abrasion Wear TestDiamond PSD 2 and Ti.SUB.3.SiC.SUB.2 .Addition

[0087] All samples in the test had exactly the same diamond grain size distribution DSPD 2 and sample geometry, but different relative diamond density in the green body. The green bodies from Ex. 6, had only 55% relative diamond density compared with 66% for the Prior art green bodies in Ex. 10. The green bodies from Ex. 6 also contained 18 wt % Ti.sub.3SiC.sub.2.

[0088] The relative diamond density in percentage was calculated as the mass of diamonds in the green body (organic binders and other additions excluded) divided by the volume of the green body divided by the X-ray density of diamonds (3.52 g/cm.sup.3) multiplied by 100. Samples from Ex. 6 were sintered according to the invention and samples in Ex. 10 according to prior art.

TABLE-US-00013 TABLE 12 Description Sintered Inserts from Ex. 6 Wear loss density Wear loss Sample No. (mg) (g/cm.sup.3) (mm.sup.3) Invention 1 0.1 3.593 0.03 2 0.4 3.593 0.11 3 0.5 3.600 0.14 Inserts from Ex. 10 Sample No. Prior art 1 0.8 3.331 0.24 2 0.7 3.332 0.21 3 1.0 3.325 0.30

Example 14Toughness Testing

[0089] A toughness test was performed by a single point mechanical cutting in sandstone blocks by progressively applying more aggressive cutting conditions by increasing the depth of cut (DOC). The geometry of all inserts was the same and is shown in FIG. 2, but the diameters of the inserts according to the invention were slightly smaller than the diameters of the inserts manufactured according to prior art. Each insert was mounted for testing by shrink fitting into a steel tool body, giving a cutting pick. The mechanical properties of this sandstone block were: unconfined compressive strength (UCS) of about 120 MPa, unconfined tensile strength (UTS) of about 9.5 MPa, and Cerchar Abrasivity Index (CAI) of about 3.7. The point attack angle of the tool was 55 degrees and the line spacing was 2DOC (in mm). By increasing the depth of cut after a fixed number of cutting planes by 2 mm in DOC the passive and bending forces on the pick increased. The test was stopped when the insert failed. All inserts, except those marked with a > were tested until failure (insert breakage). The inserts marked with a > was stopped after finished all cuts at that DOC, but are still intact.

TABLE-US-00014 TABLE 13 Description Sintered inserts from Depth of cut at insert failure Sample Ex. 3, Sample No. (mm) Invention 1 14 2 >14 3 16 4 12 Sintered inserts from Ex 4, Sample No. Invention 1 >14 2 14 3 14 Sintered insert as described in Ex 1. Invention 1 14 2 14 3 14 4 14 Sintered insert from Ex. 9, Sample No. Prior art 1 12 Sintered inserts from Ex. 10, Sample No. Prior art 1 12 2 12

[0090] The results show a clear increase in toughness of for the inserts produced according to the invention compared with the inserts produced according to prior art.

Example 15Diamond Content in Sintered Inserts

[0091] The diamond content in the sample tips were determined using image analysis of SEM micrographs showing a representative cross section area of the insert tip. Sintered inserts were prepared by careful mechanical polishing of the insert tip to a depth of 2 mm below the top, final polishing step was done with 1 m diamond paste. High resolution SEM micrographs were taken in the backscatter electron mode, magnification 500, high voltage 10 kV and working distance8 mm. In the micrographs, diamonds appears as black grains which easily can be separated from the lighter matrix. Image analysis was done with software AxioVision SE64 Re1.4.9, to evaluate the area of all diamonds in the cross section. The grey scale thresholds defining which pixels shall be identified as diamond were set manually to give a good distinction between diamond and matrix. Results are presented as area % diamonds (total area of the micrograph identified as diamond phase in percentage of total micrograph area).

[0092] The results, see table 13A, clearly show that the diamond content after sintering according to the invention is significantly higher compared to the prior art infiltration method suitable for mass production of near net shape bodies.

TABLE-US-00015 TABLE 13A Average rel. Area % of Diamond diamond density diamond in PSD in in the green the sintered Description green body body (%) material Invention Sample from DPSD1 60 45.2 ex. 7 Invention Sample from DPSD1 60 47.3 ex. 8 Invention Sample from DPSD1 60 46.6 ex. 1 Prior art Sample from DPSD1 60 39.6 ex. 9 Invention Sample from DPSD2 66 52.2 ex. 4 Prior art Sample from DPSD2 66 40.5 ex. 10

Example 16, Prior ArtLow Pressure SinteringInfiltration of in Vacuum at 1650 C.

[0093] A brown bodies from the same batch as in Ex. 6 (82 wt % diamond and 18 wt % Ti.sub.3SiC.sub.2) were placed in hBN-coated graphite crucible with silicon lumps in a large access (200% in weight) placed in the bottom of the crucible. The silicon used was Silicon 99 Refined-Si 30 015 from Elkem with a silicon content of 99.4 wt % and oxygen content of 0.004% analyzed by LECO and a with a particle size of 10-100 mm. The infiltration was performed under vacuum to the maximum temperature of 1650 C. as has been described in U.S. Pat. No. 7,008,672 B2. A fast temperature ramping, 50 C./min, was applied above 1000 C. to prevent extensive graphitization (>/=50 wt %) of the diamonds prior to Si-infiltration. The temperature was maintained for about 10 minutes and the samples were than cooled down freely. The excess silicon was removed by SiC-grit blasting and a small part of the bottom was heavily reacted and craters had formed. The body inspected by Computer Tomography according to the description in example 1. The sintered body was essential free from porosity and looked fully infiltrated, but showed the presence of healed cracks with the length of several mm. The sintered density of the body was 3.390 g/cm.sup.3.

TABLE-US-00016 TABLE 14 Sintered Sintered density m brown body m sintered volume Archimedes (g) (g) (cm.sup.3) (g/cm ) 8.213 11.507 3.391 3.390

Example 17Diamond Particle Size Distribution in the Sintered Parts

[0094] The diamond particle size distribution (DPSD) in the sintered material was evaluated with image analysis of SEM micrographs. Sample preparation, SEM settings and used software are described in Example 15. Regions of the diamond phase were identified according to same grey scale threshold values as in Example 15. The area of each diamond particle cross section and equivalent circle diameters (ECD) (i.e. the diameter of a circle with the same area) are calculated and used to plot diamond particle size distribution for the invention versus prior art, see FIG. 3. To eliminate the effect of half particles cut by the micrograph frame, the DPSD analysis areas are slightly smaller than the micrograph and particles of two sides are included in the analysis, and particles on two opposite sides are totally excluded from the analysis, se schematic images in FIG. 4. It should be noted that reported particle diameters are valid for random two dimensional cross sections of the particles, and is not a true diameter of the three dimensional particle. All identified diamond particles with a minimum area of 2.5 m.sup.2 (ECD of 1.79 m) were included in the particle size analysis. Adjacent diamonds were sometimes first identified as the one particle and this was corrected manually by splitting it into correct number of particles.

[0095] The total number (summed) of diamonds in the finest size fractions (ECD of 2-4 m), see table 15, clearly differs between the material sintered according to the invention and the material sintered according to prior art (example 9).

TABLE-US-00017 TABLE 15 No. of Percentage of detected 2-4 m diamond diamond Diamond particles particles in PSD in with ECD relation to Description green body 2-4 m prior art (%) Invention Sample from DPSD1 1350 145 ex. 7 Invention Sample from DPSD1 1341 144 ex. 8 Invention Sample from DPSD1 1409 152 ex. 1 Prior art Sample from DPSD1 929 100 ex. 9

[0096] In the prior art material from Ex. 9 many of the small diamonds in the raw material have been consumed during the sintering process, but with the invented method significantly more of the small diamonds remained in the sintered structure thus yielding a higher sintered diamond density. In the presented examples of invention there are 44 to 52% more diamonds with equivalent circle diameter 2-4 m, compared to the prior art material from Ex. 9.

[0097] Depending on the DPSD in the raw material the finest diamond fraction will vary in both average size and distribution. In the sintered material the number of diamond particles measured by images analysis as above is plotted on the y-axis against their ECD-size on a logarithmic scale on the x-axis. The y-axis maximum in the plot (number of diamond particles) is identified and an ECD-size interval (x-axis) ranging from preferable +/30%, more preferable +/15%, most preferable +/10% around the maximum is selected and all particles within this interval is counted and called Number of Fines (NF). NF should be preferable >15%, more preferable >25% and most preferable >35% higher compared to the NF of the sintered prior art material when starting from the same DPSD in the raw material.

Example 18 Biaxial Strength Determination

[0098] In order to further show the benefits of the material according to the present invention, the biaxial strength using the Ball in three balls (B3B) method, of the material from Ex 1 (DPSD1) and the prior art material in Ex 9 (DPSD1) were determined using the B3B-method (ref below). The method is used to characterize a material property similar to transverse rupture strength (TRS), but under biaxial loadingthe so called B3B characteristic strength.

[0099] Thin discs (about 16 mm in diameter and 2.5 mm in thickness) were pressed and sintered according to the manufacturing route in Ex 1 and Ex. 9, respectively. After sintering the discs were etched (as described earlier) to remove the access Si, then ground to ensure flatness and polished on the prospective tensile side to obtain a mirror like surface. The dimensions of the discs after sintering and polishing were about 15.8 mm in OD and 2.1 mm in thickness for the samples manufactured according to Ex 1. (invention) and about 16.4 mm in OD with a thickness of about 2.2 mm for the samples manufactured according to Ex. 9 (prior art).

[0100] In the B3B test, 18 discs of material according to Ex. 1 and 17 discs of the material according to Ex. 9 were included and the measurement was performed using an Instron 5980 test frame equipped with a 50 kN load cell. The B3B-fixtures were provided by Montana Universitat Leoben, Austria. In the tests four steel balls, one loading ball and three supporting balls of 12.303 mm in diameter, were used and the set up and test procedure were performed exactly as described in Practical guide to Ball-on-tree-balls (B3B-) testing from 20141001 by T. Lube, W. Harrer and P. Supanicic. The testing was carried out in displacement control, with a crosshead displacement rate of 0.6 mm/min. The calculation of the stress values from the measured fracture loads was carried out by FEM, using the applet at http://www.isfk.at/de/960/ (see also A. Brger, P. Supancic, R. Danzer: The Ball on three Balls Test for Strength Testing of Brittle DiscsStress Distribution in the Disc. Journal of the European Ceramic Society 22 (2002) 1425-1436, doi:10.1016/50955-2219(01)00458-7). Weibull analysis of the test data was then conducted in order to evaluate the B3B characteristic strength as well as the Weibull modulus for both materials (see Table 16 below).

TABLE-US-00018 TABLE 16 Ex. 1 (Invention) Ex. 9 (Prior art) B3B characteristic strength* 747 MPa 656 MPa Weibull modulus 9 12 No of samples 18 17 *The given B3B strength values were obtained as the so called scale parameter of the Weibull distribution, i.e. the strength corresponding to 63.2% failure probability.

[0101] The results presented in table 16 show that the strength of the material obtained according to the invention is significantly higher than that of the prior art material.