CA2515379A1 - Process for producing a hard metal batch - Google Patents
Process for producing a hard metal batch Download PDFInfo
- Publication number
- CA2515379A1 CA2515379A1 CA002515379A CA2515379A CA2515379A1 CA 2515379 A1 CA2515379 A1 CA 2515379A1 CA 002515379 A CA002515379 A CA 002515379A CA 2515379 A CA2515379 A CA 2515379A CA 2515379 A1 CA2515379 A1 CA 2515379A1
- Authority
- CA
- Canada
- Prior art keywords
- hard metal
- wet slurry
- producing
- metal batch
- minutes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 229910052751 metal Inorganic materials 0.000 title claims abstract description 58
- 239000002184 metal Substances 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims description 15
- 238000001035 drying Methods 0.000 claims abstract description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000007791 liquid phase Substances 0.000 claims abstract description 5
- 239000007787 solid Substances 0.000 claims abstract description 4
- 238000001238 wet grinding Methods 0.000 claims abstract description 3
- 239000002002 slurry Substances 0.000 claims description 32
- 238000003825 pressing Methods 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 4
- 239000011230 binding agent Substances 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 10
- 239000002245 particle Substances 0.000 abstract description 2
- 239000010802 sludge Substances 0.000 abstract 4
- 239000000126 substance Substances 0.000 abstract 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 11
- 239000001301 oxygen Substances 0.000 description 11
- 229910052760 oxygen Inorganic materials 0.000 description 11
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 8
- 239000000843 powder Substances 0.000 description 6
- 239000008187 granular material Substances 0.000 description 5
- 238000009434 installation Methods 0.000 description 5
- 238000003801 milling Methods 0.000 description 5
- 239000007921 spray Substances 0.000 description 5
- 238000001125 extrusion Methods 0.000 description 3
- 229910001092 metal group alloy Inorganic materials 0.000 description 3
- 238000001694 spray drying Methods 0.000 description 3
- 239000000725 suspension Substances 0.000 description 3
- INZDTEICWPZYJM-UHFFFAOYSA-N 1-(chloromethyl)-4-[4-(chloromethyl)phenyl]benzene Chemical compound C1=CC(CCl)=CC=C1C1=CC=C(CCl)C=C1 INZDTEICWPZYJM-UHFFFAOYSA-N 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 230000002706 hydrostatic effect Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 239000004014 plasticizer Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- GHMLBKRAJCXXBS-UHFFFAOYSA-N resorcinol Chemical compound OC1=CC=CC(O)=C1 GHMLBKRAJCXXBS-UHFFFAOYSA-N 0.000 description 2
- 238000007493 shaping process Methods 0.000 description 2
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 2
- 239000003963 antioxidant agent Substances 0.000 description 1
- 230000003078 antioxidant effect Effects 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000010981 drying operation Methods 0.000 description 1
- 239000003995 emulsifying agent Substances 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 239000001993 wax Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/14—Treatment of metallic powder
- B22F1/148—Agglomerating
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/05—Mixtures of metal powder with non-metallic powder
- C22C1/051—Making hard metals based on borides, carbides, nitrides, oxides or silicides; Preparation of the powder mixture used as the starting material therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
- B22F2998/10—Processes characterised by the sequence of their steps
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Powder Metallurgy (AREA)
Abstract
The invention relates to a method for producing a hard metal stock by drying a wet sludge (3), which is obtained by the wet grinding of the hard substance and binding metal to the desired particle size, in the quantities required for the finished stock, using water as the liquid phase. According to the invention, the wet sludge (3) with a solid content of between 75 and 95 wt. %
and a layer thickness of between 0.2 and 2 mm is applied to a moving carrier belt (1). The wet sludge (3) is brought up to a maximum temperature in excess of 100 ~C - 150 ~C during a period of 1 - 7 minutes as it passes through a drying zone (4). The length of time in which the wet sludge (3) is heated to more than 100 ~C lies between 15 seconds and 2 minutes. The hard metal stock obtained in this manner is then cooled to an ambient temperature and crushed if required.
and a layer thickness of between 0.2 and 2 mm is applied to a moving carrier belt (1). The wet sludge (3) is brought up to a maximum temperature in excess of 100 ~C - 150 ~C during a period of 1 - 7 minutes as it passes through a drying zone (4). The length of time in which the wet sludge (3) is heated to more than 100 ~C lies between 15 seconds and 2 minutes. The hard metal stock obtained in this manner is then cooled to an ambient temperature and crushed if required.
Description
PROCESS FOR PRODUCING A HARD METAL BATCH
The invention relates to a process for producing a hard metal batch by drying a wet slurry produced by wet-milling the hard material and binder metal fractions to the desired grain size, using water as liquid phase, with or without fractions of a pressing aid.
Shaped parts formed from hard metal alloys are produced by pressing and sintering a hard metal batch. The hard metal batch contains the hard material and binder metal fractions desired in the finished hard metal alloy in finely distributed form, with or without the use of a pressing aid. In many cases to produce a hard metal batch of this type, the fine-particle starting powders with a mean grain size in the range of a few ~.un, and in some cases even smaller, are converted into granule form, i.e. into as ideal a spherical shape as possible, with a granule size of approximately 140 ~.m. This improves the flow properties of the hard metal batch, which in particular significantly simplifies the uniform filling of the press moulds for production of shaped parts of complex shape.
The granules are produced by spray-drying the desired hard metal batch in a spray-drying installation. A
process of this type using water as liquid phase is described, for example, in Austrian utility model AT U
4.929. A drawback of a process of this type is that it is relatively expensive. Good flow properties of the hard metal batch are not necessarily required for many shaping processes for further processing of a hard metal batch. These include, for example, the production of simple shaped parts by hydrostatic compacting or extrusion, but also the production of complex small shaped parts by powder injection molding.
The invention relates to a process for producing a hard metal batch by drying a wet slurry produced by wet-milling the hard material and binder metal fractions to the desired grain size, using water as liquid phase, with or without fractions of a pressing aid.
Shaped parts formed from hard metal alloys are produced by pressing and sintering a hard metal batch. The hard metal batch contains the hard material and binder metal fractions desired in the finished hard metal alloy in finely distributed form, with or without the use of a pressing aid. In many cases to produce a hard metal batch of this type, the fine-particle starting powders with a mean grain size in the range of a few ~.un, and in some cases even smaller, are converted into granule form, i.e. into as ideal a spherical shape as possible, with a granule size of approximately 140 ~.m. This improves the flow properties of the hard metal batch, which in particular significantly simplifies the uniform filling of the press moulds for production of shaped parts of complex shape.
The granules are produced by spray-drying the desired hard metal batch in a spray-drying installation. A
process of this type using water as liquid phase is described, for example, in Austrian utility model AT U
4.929. A drawback of a process of this type is that it is relatively expensive. Good flow properties of the hard metal batch are not necessarily required for many shaping processes for further processing of a hard metal batch. These include, for example, the production of simple shaped parts by hydrostatic compacting or extrusion, but also the production of complex small shaped parts by powder injection molding.
In all processes for producing a hard metal batch, it is important to achieve a maximum residual moisture content in the range of <0.25~ by weight and that the oxygen content in the batch does not exceed 1.2~ by weight.
Therefore, the object of the present invention is to provide a process for producing the hard metal batch for hard metal shaped parts whose production does not require good flow properties on the part of the hard metal batch which is significantly less expensive than previously known processes.
According to the invention, this is achieved by virtue of the fact that the wet slurry is applied to a moving carrier belt with a solids content of from 75~ by weight to 95~ by weight and a layer thickness of from 0.2 mm to 2 mm and as it passes through a drying zone is heated, over the course of in total 1 minute to 7 minutes, to a maximum temperature within a range from >100°C to 150°C, the time which it takes for the wet slurry to be heated to over 100°C being within a range from 15 seconds to 2 minutes, and that the hard metal batch which has been dried in this manner is cooled to room temperature and if necessary comminuted.
This allows particularly inexpensive production of a hard metal batch under air and at standard pressure conditions, and this batch can be successfully processed further by simple shaping processes, such as for example hydrostatic compacting or extrusion. For further processing of the hard metal batch, in particular by extrusion, it may be expedient for a pressing aid to be admixed to the wet slurry before it is dried. If this pressing aid is a water-insoluble pressing aid based on wax, such as for example paraffin, it is admixed to the wet slurry in the form of an emulsion which is produced with the aid of an emulsifier and the addition of water.
On account of the careful setting of solids content of the wet slurry, layer thickness, drying time and maximum temperature during the drying operation, the process according to the invention, despite the use of water as liquid phase and despite the drying in air at elevated temperatures, surprisingly allows the production of hard metal batches with an extremely low oxygen content. The oxygen content is under certain circumstances even lower than in hard metal batches which are produced in accordance with the prior art and in which the wet slurry is prepared using organic solvents, such as acetone, followed by drying in vacuo.
The maximum drying temperature and the drying time are matched to the layer thickness of the wet slurry applied. The greater the layer thickness, the higher the maximum drying temperature and the longer the drying time required.
To produce hard metal batches with very fine-grain hard material powders, which require significantly longer milling times, it is advantageous for an antioxidant, for example based on amino compounds, e.g.
aminoxethylate or resorcinol, to be added to the water prior to milling for producing the wet slurry, with the result that an excessive oxygen content in the dried batch is prevented even with these oxidation-sensitive hard metal batches.
The process according to the invention works particularly advantageously if the wet slurry is applied to the carrier belt in a layer thickness of from 0.5 mm to 1 mm, since the total time taken to pass through the drying zone can then be shortened to 1.5 minutes to 6 minutes, and the time taken for the wet slurry to be heated to over 100°C can be restricted to a range from 30 seconds to 60 seconds. This minimizes the oxygen uptake by the hard metal batch.
' CA 02515379 2005-08-08 It is particularly expedient for the wet slurry to be heated to the desired temperature first of all by hot air and then additionally by radiant heat, resulting in particularly rapid removal of the moisture from the wet slurry.
The radiant heat is in this case advantageously generated by infrared radiators.
The text which follows provides a more detailed explanation of the invention on the basis of production examples and with reference to a drawing, in which:
Figure 1 shows an outline diagram of a belt drying installation for carrying out the production process according to the invention.
Example 1 To produce a hard metal batch consisting of 6~ by weight of cobalt, 0.4~ by weight of vanadium carbide, remainder tungsten carbide, 36 kg of cobalt powder with a Fisher mean grain size of approximately 0.6 dun and an oxygen content of 0.56 by weight, 2.4 kg of vanadium carbide powder with a Fisher mean grain size of approximately 1.2 ~,un and an oxygen content of 0.25 by weight, and 563.5 kg of tungsten carbide powder with a BET surface area of 1.78 m2/g, which corresponds to a Fisher mean grain size of approximately 0.6 ~,un, and an oxygen content of 0.28 by weight were milled with 100 1 of water for 5 hours in an attritor.
The milling bodies used were 2000 kg of hard metal beads with a diameter of 9 mm. The rotational speed of the attritor was 78 rpm, and the wet slurry was circulated at a pumping rate of 1000 1/hour. The temperature of the wet slurry during milling was kept constant at approximately 40°C. The fully milled wet slurry had a viscosity of 4000 mPas at a shear rate of 5.18 [1/s].
A belt drying installation which operates in air and at standard pressure as shown in Figure 1 was used to dry the wet slurry produced in this manner. The belt drying installation shown in Figure 1 comprises a 3m long, revolving conveyor belt -1-. A feed device -2- for applying the wet slurry -3- to the conveyor belt -1- in different layer thicknesses is provided at the start of the conveyor belt -1-. This feed device is followed by a drying zone -4-. As it passes through this drying zone -4-, the wet slurry -3- which has been applied in layer form is heated in a first passage zone -5- by means of a hot air blower -6-.
In a subsequent second passage zone -7-, the pre-dried wet slurry is heated to the desired maximum temperature within a range from >100°C to 150°C by means of infrared radiators.
At the end-side turning point of the conveyor belt -1-, the dried hard metal batch drops into a collection vessel -8-.
In the present production example, the belt drying installation was operated at a belt velocity of 1 m/min, and the wet slurry -3- was applied to the conveyor belt -1- in a thickness of 0.8 mm. The total passage time through the drying zone -4- was 3 minutes, with the following temperature sequence:
after 20 seconds: 40°C
after 52 seconds: 50°C
after 84 seconds: 60°C
after 150 seconds: 95°C
after 165 seconds: 102°C
after 180 seconds: 110°C.
Even as it was passing through the first passage zone -5-, the applied wet slurry -3- was heated to a temperature of approximately 60°C by the hot air blower -6-, with the result that the majority of the water was evaporated. As a result, it was possible for the time of the second passage zone -7-, in which the wet slurry was at a temperature of more than 100°C, to be restricted to approximately 15 seconds in order to achieve the required maximum permissible residual moisture content in the dried hard metal batch.
Then, the dried hard metal batch was cooled to room temperature over the course of 20 seconds. The oxygen content of the hard metal batch dried in this manner was 0.53 by weight, and the residual moisture content was 0.13 by weight.
The dried hard metal batch was broken up in a hammer mill, to a particle size of approximately 0.4 mm, mixed with a plasticizer in the standard way and extruded to form a hard metal rod with a diameter of 16 mm.
This rod was then sintered for 80 minutes at 1410°C and then recompacted at 70 bar.
Metallurgical examination revealed an excellent quality of hard metal with the following properties:
Density: 14.83 g/cm3 Hardness HV30: 2.035 daN/mmz Magnetic saturation: 114 x 10'3T m3/kg Coercive force: 485 Oe.
For comparison purposes, two further hard metal batches of the same composition as in Example 1 were produced.
In Example 2, the hard metal batch was produced by spray drying, and in Example 3 the hard metal batch was produced by vacuum drying with organic solvent. The hard metal alloys produced from these hard metal batches were then compared with one another.
Example 2 To produce this hard metal batch, the same raw materials in the same ratio and the same quantities as in Example 1 were milled with 160 1 of water, under otherwise identical conditions, in an attritor.
A spray tower with a cylindrical section 6 m high with a diameter of 4 m was used to dry the wet slurry _ 7 _ produced in this manner. The spray tower was designed for countercurrent operation in accordance with the fountain principle.
The gas used to dry the wet slurry was air which was fed to the spray tower at 4000 m3/hour. The wet slurry was fed to the spray tower via a spray lance with a single-flurry nozzle having an outlet opening with a diameter of 1.12 mm, at a pressure of 15 bar. The air outlet temperature was set to a constant level of 88°C, which under the given conditions was achieved by an air entry temperature of 145°C.
The spray-dried hard metal granules produced in this way, with a mean grain size of 125 ~.un, had an oxygen content of 0.52 by weight and a moisture content of 0.15 by weight.
The hard metal granules produced in this way were mixed with a plasticizer in the standard way and extruded to form a hard metal rod with a diameter of 16 mm.
This rod was then sintered for 80 minutes at 1410°C and then recompacted at 70 bar.
The metallurgical assessment revealed a hard metal quality having the following properties:
Density: 14.85 g/cm3 Hardness HV30: 2030 daN/mm2 Magnetic saturation: 112 x 10-3T m3/kg Coercive force: 491 Oe.
Example 3 To produce this hard metal batch, the same raw materials in the same ratio and the same quantities as in Example 1 were milled for 8 hours in an attritor filled with 135 1 of acetone.
The temperature of the acetone/powder mixture during the milling was kept constant at approximately 35°C.
The fully milled suspension had a viscosity of <200 mPa at a shear rate of 5.18 [1/s].
A vacuum drier of conventional design was used to dry this hard metal suspension produced in this way.
In this case, the heat was supplied via hot water in a double jacket. Moreover, vacuum was applied to the suspension, so that the acetone evaporated. In addition, this vacuum drier was equipped with a slowly rotating stirring mechanism.
After a drying time of 10 hours, the hard metal batch produced in this way had an oxygen content of 0.48 by weight. The hard metal batch produced in this manner was pressed through a screen then mixed with a plasticizes in the standard way and extruded to form a hard metal rod with a diameter of 16 mm. This rod was then sintered for 80 minutes at 1400°C and then recompacted at 70 bar.
The metallurgical assessment revealed a hard metal quality with the following properties:
Density: 14.83 g/cm3 Hardness HV30: 2032 daN/mmZ
Magnetic saturation: 113 x 10-3T m3/kg Coercive force: 488 Oe.
Therefore, the object of the present invention is to provide a process for producing the hard metal batch for hard metal shaped parts whose production does not require good flow properties on the part of the hard metal batch which is significantly less expensive than previously known processes.
According to the invention, this is achieved by virtue of the fact that the wet slurry is applied to a moving carrier belt with a solids content of from 75~ by weight to 95~ by weight and a layer thickness of from 0.2 mm to 2 mm and as it passes through a drying zone is heated, over the course of in total 1 minute to 7 minutes, to a maximum temperature within a range from >100°C to 150°C, the time which it takes for the wet slurry to be heated to over 100°C being within a range from 15 seconds to 2 minutes, and that the hard metal batch which has been dried in this manner is cooled to room temperature and if necessary comminuted.
This allows particularly inexpensive production of a hard metal batch under air and at standard pressure conditions, and this batch can be successfully processed further by simple shaping processes, such as for example hydrostatic compacting or extrusion. For further processing of the hard metal batch, in particular by extrusion, it may be expedient for a pressing aid to be admixed to the wet slurry before it is dried. If this pressing aid is a water-insoluble pressing aid based on wax, such as for example paraffin, it is admixed to the wet slurry in the form of an emulsion which is produced with the aid of an emulsifier and the addition of water.
On account of the careful setting of solids content of the wet slurry, layer thickness, drying time and maximum temperature during the drying operation, the process according to the invention, despite the use of water as liquid phase and despite the drying in air at elevated temperatures, surprisingly allows the production of hard metal batches with an extremely low oxygen content. The oxygen content is under certain circumstances even lower than in hard metal batches which are produced in accordance with the prior art and in which the wet slurry is prepared using organic solvents, such as acetone, followed by drying in vacuo.
The maximum drying temperature and the drying time are matched to the layer thickness of the wet slurry applied. The greater the layer thickness, the higher the maximum drying temperature and the longer the drying time required.
To produce hard metal batches with very fine-grain hard material powders, which require significantly longer milling times, it is advantageous for an antioxidant, for example based on amino compounds, e.g.
aminoxethylate or resorcinol, to be added to the water prior to milling for producing the wet slurry, with the result that an excessive oxygen content in the dried batch is prevented even with these oxidation-sensitive hard metal batches.
The process according to the invention works particularly advantageously if the wet slurry is applied to the carrier belt in a layer thickness of from 0.5 mm to 1 mm, since the total time taken to pass through the drying zone can then be shortened to 1.5 minutes to 6 minutes, and the time taken for the wet slurry to be heated to over 100°C can be restricted to a range from 30 seconds to 60 seconds. This minimizes the oxygen uptake by the hard metal batch.
' CA 02515379 2005-08-08 It is particularly expedient for the wet slurry to be heated to the desired temperature first of all by hot air and then additionally by radiant heat, resulting in particularly rapid removal of the moisture from the wet slurry.
The radiant heat is in this case advantageously generated by infrared radiators.
The text which follows provides a more detailed explanation of the invention on the basis of production examples and with reference to a drawing, in which:
Figure 1 shows an outline diagram of a belt drying installation for carrying out the production process according to the invention.
Example 1 To produce a hard metal batch consisting of 6~ by weight of cobalt, 0.4~ by weight of vanadium carbide, remainder tungsten carbide, 36 kg of cobalt powder with a Fisher mean grain size of approximately 0.6 dun and an oxygen content of 0.56 by weight, 2.4 kg of vanadium carbide powder with a Fisher mean grain size of approximately 1.2 ~,un and an oxygen content of 0.25 by weight, and 563.5 kg of tungsten carbide powder with a BET surface area of 1.78 m2/g, which corresponds to a Fisher mean grain size of approximately 0.6 ~,un, and an oxygen content of 0.28 by weight were milled with 100 1 of water for 5 hours in an attritor.
The milling bodies used were 2000 kg of hard metal beads with a diameter of 9 mm. The rotational speed of the attritor was 78 rpm, and the wet slurry was circulated at a pumping rate of 1000 1/hour. The temperature of the wet slurry during milling was kept constant at approximately 40°C. The fully milled wet slurry had a viscosity of 4000 mPas at a shear rate of 5.18 [1/s].
A belt drying installation which operates in air and at standard pressure as shown in Figure 1 was used to dry the wet slurry produced in this manner. The belt drying installation shown in Figure 1 comprises a 3m long, revolving conveyor belt -1-. A feed device -2- for applying the wet slurry -3- to the conveyor belt -1- in different layer thicknesses is provided at the start of the conveyor belt -1-. This feed device is followed by a drying zone -4-. As it passes through this drying zone -4-, the wet slurry -3- which has been applied in layer form is heated in a first passage zone -5- by means of a hot air blower -6-.
In a subsequent second passage zone -7-, the pre-dried wet slurry is heated to the desired maximum temperature within a range from >100°C to 150°C by means of infrared radiators.
At the end-side turning point of the conveyor belt -1-, the dried hard metal batch drops into a collection vessel -8-.
In the present production example, the belt drying installation was operated at a belt velocity of 1 m/min, and the wet slurry -3- was applied to the conveyor belt -1- in a thickness of 0.8 mm. The total passage time through the drying zone -4- was 3 minutes, with the following temperature sequence:
after 20 seconds: 40°C
after 52 seconds: 50°C
after 84 seconds: 60°C
after 150 seconds: 95°C
after 165 seconds: 102°C
after 180 seconds: 110°C.
Even as it was passing through the first passage zone -5-, the applied wet slurry -3- was heated to a temperature of approximately 60°C by the hot air blower -6-, with the result that the majority of the water was evaporated. As a result, it was possible for the time of the second passage zone -7-, in which the wet slurry was at a temperature of more than 100°C, to be restricted to approximately 15 seconds in order to achieve the required maximum permissible residual moisture content in the dried hard metal batch.
Then, the dried hard metal batch was cooled to room temperature over the course of 20 seconds. The oxygen content of the hard metal batch dried in this manner was 0.53 by weight, and the residual moisture content was 0.13 by weight.
The dried hard metal batch was broken up in a hammer mill, to a particle size of approximately 0.4 mm, mixed with a plasticizer in the standard way and extruded to form a hard metal rod with a diameter of 16 mm.
This rod was then sintered for 80 minutes at 1410°C and then recompacted at 70 bar.
Metallurgical examination revealed an excellent quality of hard metal with the following properties:
Density: 14.83 g/cm3 Hardness HV30: 2.035 daN/mmz Magnetic saturation: 114 x 10'3T m3/kg Coercive force: 485 Oe.
For comparison purposes, two further hard metal batches of the same composition as in Example 1 were produced.
In Example 2, the hard metal batch was produced by spray drying, and in Example 3 the hard metal batch was produced by vacuum drying with organic solvent. The hard metal alloys produced from these hard metal batches were then compared with one another.
Example 2 To produce this hard metal batch, the same raw materials in the same ratio and the same quantities as in Example 1 were milled with 160 1 of water, under otherwise identical conditions, in an attritor.
A spray tower with a cylindrical section 6 m high with a diameter of 4 m was used to dry the wet slurry _ 7 _ produced in this manner. The spray tower was designed for countercurrent operation in accordance with the fountain principle.
The gas used to dry the wet slurry was air which was fed to the spray tower at 4000 m3/hour. The wet slurry was fed to the spray tower via a spray lance with a single-flurry nozzle having an outlet opening with a diameter of 1.12 mm, at a pressure of 15 bar. The air outlet temperature was set to a constant level of 88°C, which under the given conditions was achieved by an air entry temperature of 145°C.
The spray-dried hard metal granules produced in this way, with a mean grain size of 125 ~.un, had an oxygen content of 0.52 by weight and a moisture content of 0.15 by weight.
The hard metal granules produced in this way were mixed with a plasticizer in the standard way and extruded to form a hard metal rod with a diameter of 16 mm.
This rod was then sintered for 80 minutes at 1410°C and then recompacted at 70 bar.
The metallurgical assessment revealed a hard metal quality having the following properties:
Density: 14.85 g/cm3 Hardness HV30: 2030 daN/mm2 Magnetic saturation: 112 x 10-3T m3/kg Coercive force: 491 Oe.
Example 3 To produce this hard metal batch, the same raw materials in the same ratio and the same quantities as in Example 1 were milled for 8 hours in an attritor filled with 135 1 of acetone.
The temperature of the acetone/powder mixture during the milling was kept constant at approximately 35°C.
The fully milled suspension had a viscosity of <200 mPa at a shear rate of 5.18 [1/s].
A vacuum drier of conventional design was used to dry this hard metal suspension produced in this way.
In this case, the heat was supplied via hot water in a double jacket. Moreover, vacuum was applied to the suspension, so that the acetone evaporated. In addition, this vacuum drier was equipped with a slowly rotating stirring mechanism.
After a drying time of 10 hours, the hard metal batch produced in this way had an oxygen content of 0.48 by weight. The hard metal batch produced in this manner was pressed through a screen then mixed with a plasticizes in the standard way and extruded to form a hard metal rod with a diameter of 16 mm. This rod was then sintered for 80 minutes at 1400°C and then recompacted at 70 bar.
The metallurgical assessment revealed a hard metal quality with the following properties:
Density: 14.83 g/cm3 Hardness HV30: 2032 daN/mmZ
Magnetic saturation: 113 x 10-3T m3/kg Coercive force: 488 Oe.
Claims (5)
1. Process for producing a hard metal batch by drying a wet slurry produced by wet-milling the hard material and binder metal fractions to the desired grain size, using water as liquid phase, with or without fractions of a pressing aid, characterized in that the wet slurry (3) is applied to a moving carrier belt (1) with a solids content of from 75~ by weight to 95~ by weight and a layer thickness of from 0.2 mm to 2 mm and as it passes through a drying zone (4) is heated, over the course of in total 1 minute to 7 minutes, to a maximum temperature within a range from >100°C to 150°C, the time which it takes for the wet slurry to be heated to over 100°C being within a range from 15 seconds to 2 minutes, and in that the hard metal batch which has been dried in this manner is cooled to room temperature and if necessary comminuted.
2. Process for producing a hard metal batch according to claim 1, characterized in that the wet slurry is applied in a layer thickness of from 0.5 mm to 1.0 mm.
3. Process for producing a hard metal batch according to claim 2, characterized in that the drying zone (4) is passed through over the course of a total period of from 1.5 minutes to 6 minutes, and the maximum temperature is 120°C, the time which it takes for the wet slurry to be heated to over 100°C being within a range from 30 seconds to 60 seconds.
4. Process for producing a hard metal batch according to one of claims 1 to 3, characterized in that the wet slurry is heated to the desired temperature first of all by hot air and then by additional radiant heat.
5. Process for producing a hard metal batch according to claim 4, characterized in that the radiant heat is generated by infrared radiators.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ATGM64/2003 | 2003-02-10 | ||
| AT0006403U AT6486U1 (en) | 2003-02-10 | 2003-02-10 | METHOD FOR PRODUCING A HARD METAL APPROACH |
| PCT/AT2004/000041 WO2004070069A1 (en) | 2003-02-10 | 2004-02-09 | Method for producing a hard metal stock |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2515379A1 true CA2515379A1 (en) | 2004-08-19 |
Family
ID=28679284
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002515379A Abandoned CA2515379A1 (en) | 2003-02-10 | 2004-02-09 | Process for producing a hard metal batch |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US20060101945A1 (en) |
| EP (1) | EP1592817B1 (en) |
| KR (1) | KR20050111738A (en) |
| AT (2) | AT6486U1 (en) |
| CA (1) | CA2515379A1 (en) |
| DE (1) | DE502004000663D1 (en) |
| DK (1) | DK1592817T3 (en) |
| ES (1) | ES2263136T3 (en) |
| WO (1) | WO2004070069A1 (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080289495A1 (en) * | 2007-05-21 | 2008-11-27 | Peter Eisenberger | System and Method for Removing Carbon Dioxide From an Atmosphere and Global Thermostat Using the Same |
| US20140130670A1 (en) | 2012-11-14 | 2014-05-15 | Peter Eisenberger | System and method for removing carbon dioxide from an atmosphere and global thermostat using the same |
| US8500857B2 (en) | 2007-05-21 | 2013-08-06 | Peter Eisenberger | Carbon dioxide capture/regeneration method using gas mixture |
| US8163066B2 (en) | 2007-05-21 | 2012-04-24 | Peter Eisenberger | Carbon dioxide capture/regeneration structures and techniques |
| US9028592B2 (en) | 2010-04-30 | 2015-05-12 | Peter Eisenberger | System and method for carbon dioxide capture and sequestration from relatively high concentration CO2 mixtures |
| DK2563495T3 (en) | 2010-04-30 | 2020-01-06 | Peter Eisenberger | METHOD OF CARBON Dioxide Capture |
| US20130095999A1 (en) | 2011-10-13 | 2013-04-18 | Georgia Tech Research Corporation | Methods of making the supported polyamines and structures including supported polyamines |
| US11059024B2 (en) | 2012-10-25 | 2021-07-13 | Georgia Tech Research Corporation | Supported poly(allyl)amine and derivatives for CO2 capture from flue gas or ultra-dilute gas streams such as ambient air or admixtures thereof |
| EP3089809A4 (en) | 2013-12-31 | 2017-10-25 | Chichilnisky, Graciela | Rotating multi-monolith bed movement system for removing co2 from the atmosphere |
| CN108907092B (en) * | 2018-06-29 | 2020-08-28 | 安徽大卫模具有限公司 | Accurate drying device of disappearance mould |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2928725A (en) * | 1955-05-20 | 1960-03-15 | British Titan Products | Preparation of ferrous sulfate monohydrate suspensions |
| DE3063533D1 (en) * | 1979-11-12 | 1983-07-07 | Emi Plc Thorn | An electrically conducting cermet, its production and use |
| US4478888A (en) * | 1982-04-05 | 1984-10-23 | Gte Products Corporation | Process for producing refractory powder |
| US4397889A (en) * | 1982-04-05 | 1983-08-09 | Gte Products Corporation | Process for producing refractory powder |
| US5922978A (en) * | 1998-03-27 | 1999-07-13 | Omg Americas, Inc. | Method of preparing pressable powders of a transition metal carbide, iron group metal or mixtures thereof |
| AT4929U1 (en) * | 2001-03-29 | 2002-01-25 | Plansee Tizit Ag | METHOD FOR PRODUCING HARD METAL GRANULES |
| AT4928U1 (en) * | 2001-03-29 | 2002-01-25 | Plansee Tizit Ag | METHOD FOR PRODUCING A HARD METAL APPROACH |
-
2003
- 2003-02-10 AT AT0006403U patent/AT6486U1/en not_active IP Right Cessation
-
2004
- 2004-02-09 KR KR1020057014447A patent/KR20050111738A/en not_active Application Discontinuation
- 2004-02-09 CA CA002515379A patent/CA2515379A1/en not_active Abandoned
- 2004-02-09 EP EP04709165A patent/EP1592817B1/en not_active Expired - Lifetime
- 2004-02-09 AT AT04709165T patent/ATE328127T1/en not_active IP Right Cessation
- 2004-02-09 US US10/544,997 patent/US20060101945A1/en not_active Abandoned
- 2004-02-09 ES ES04709165T patent/ES2263136T3/en not_active Expired - Lifetime
- 2004-02-09 WO PCT/AT2004/000041 patent/WO2004070069A1/en active IP Right Grant
- 2004-02-09 DK DK04709165T patent/DK1592817T3/en active
- 2004-02-09 DE DE502004000663T patent/DE502004000663D1/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| DK1592817T3 (en) | 2006-09-25 |
| WO2004070069A1 (en) | 2004-08-19 |
| ATE328127T1 (en) | 2006-06-15 |
| KR20050111738A (en) | 2005-11-28 |
| EP1592817B1 (en) | 2006-05-31 |
| US20060101945A1 (en) | 2006-05-18 |
| DE502004000663D1 (en) | 2006-07-06 |
| EP1592817A1 (en) | 2005-11-09 |
| ES2263136T3 (en) | 2006-12-01 |
| AT6486U1 (en) | 2003-11-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP2596911B1 (en) | Method and apparatus for forming aggregate abrasive grains for use in the production of abrading or cutting tools | |
| EP1745117B1 (en) | Solid lubricant agglomerates and method for producing same for coating applications | |
| CA2515379A1 (en) | Process for producing a hard metal batch | |
| JPH08277159A (en) | Preparation of sintered alpha-al203 article and their use | |
| WO2001032383A1 (en) | Molded lump and production method therefor | |
| JP3697242B2 (en) | Method for producing hard metal granules | |
| CN104611600A (en) | Preparation method and system of super-thick cemented carbide | |
| US4886638A (en) | Method for producing metal carbide grade powders | |
| CN112266235A (en) | Method for preparing dolomite brick from calcium-magnesium phosphate ore tailings and composite magnesium raw materials | |
| EP2550340B1 (en) | Aggregate abrasives for abrading or cutting tools production | |
| US3077439A (en) | Processing of raw petroleum coke | |
| US5296177A (en) | Process for producing agglomerates from dusts | |
| US4478611A (en) | Method of making tungsten carbide grit | |
| CN107034407B (en) | A kind of production method of hard alloy | |
| US3980741A (en) | Method for the processing of black powder | |
| JP3640432B2 (en) | Method for producing fluid tungsten / copper composite powder | |
| US11268042B2 (en) | Abradable coating hBN filler material and method of manufacture | |
| CN117587311A (en) | Hard alloy material for anti-skid nails and preparation method thereof | |
| JP2818235B2 (en) | Spherical cement and its production method | |
| CN106636624A (en) | Method for preparing high-iron bauxite pellets | |
| JPS5957937A (en) | Manufacture of calcium carbonate hardened body | |
| JP2685893B2 (en) | Manufacturing method of iron powder with high packing density | |
| CN118754627A (en) | Ceramic particles for binder jet printing prepared based on thermal curing process, granulating method and application | |
| CN118744240A (en) | Preparation method of steel-bonded gold particles | |
| JPH0725593B2 (en) | Method for producing composition for producing silicon carbide sintered body |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |