A method for packing and synthesizing a thick layer of superhard material composite sheet

Abstract

The application discloses a kind of packing synthesis method of thick layer superhard material composite sheet, it is related to superhard material composite sheet synthesis technical field, comprising the following steps: (1) superhard powder and as catalyst and binder powder are mixed uniformly to obtain mixed powder;(2) mixed powder is laid flat and is loaded into metal cup, then hard alloy matrix is covered on the surface of mixed powder, cover is added on metal cup, to obtain preloading composite sheet;(3) preloading composite sheet is wrapped with metal foil, then it is placed in compaction mould after being wrapped with transmission pressure powder and is compacted;(4) preloading composite sheet is removed after demoulding, and is purified and shaped under high temperature in vacuum environment, to obtain purification and shaping composite sheet;(5) purification and shaping composite sheet is placed in heat preservation transmission pressure medium, and high temperature and high pressure synthesis is carried out, to obtain thick layer superhard material composite sheet.The application makes that metal cup shrinks uniformly when compaction powder, the synthesis of thick layer superhard material composite sheet can be realized, and the service life of compaction mould is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of synthesis of superhard material compacts, and particularly relates to a packing synthesis method of thick-layer superhard material compacts. BACKGROUND

[0002] Both the diamond or cubic boron nitride compacts belong to superhard material compacts, which are superhard materials synthesized by using diamond or cubic boron nitride particles as main materials on the surface of a hard alloy substrate. The superhard material compacts have the characteristics of high hardness and good wear resistance, and are widely used in the industries of petroleum drilling, geological exploration, coalfield drilling and machining tools, etc. The superhard material compacts are widely used in tool machining. In particular, the superhard material compacts are used for cutting machining in mechanical machining, and are applied to the tool industry. With the continuous development of the processing industry, the application range is wider and wider, which includes commonly used machine tool turning tools, machining drills, milling cutters for frame machining and profiling milling cutters. Influenced by the machining demand, the precision of the workpiece is required to be higher and higher, and the demand for the superhard material tools is also higher and higher. In general, the polycrystalline layer thickness of the superhard material compacts is only 0.5-1.2 mm, but the application advantage of the large-thickness superhard material compacts in milling cutters is more prominent, and the large-thickness superhard material compacts are more suitable for milling cutter manufacturing which needs rotating surface. Influenced by the high difficulty of synthesizing the large-thickness superhard material compacts, it is difficult to obtain consistent products, so many enterprises are unwilling to develop the synthesis of the large-thickness superhard material compacts, especially the synthesis of the large-thickness superhard material compacts with medium granularity of less than 10 microns. The heart of the polycrystalline layer is prone to unsintering, which is mainly affected by the uneven compaction of the powder in the early stage. The diamond or cubic boron nitride powder is packed into the rare metal thin cup with a thickness of only 0.5-0.22 mm. When a large amount of powder is packed into the rare metal thin cup, the compaction of the powder will make the metal thin cup expand and the diameter become larger, and the outer diameter cannot maintain the original shape, which makes the edge shrinkage and the heart shrinkage inconsistent in the synthesis process, resulting in difficult sintering or cracking of the heart. Meanwhile, the tantalum cup, niobium cup, zirconium cup or molybdenum cup used in the synthesis process of the compacts belongs to a relatively soft metal material, which is easy to be shaped. When the size of the mold made of die steel is controlled, the metal thin cup is easy to deform and enter the gap of the mold. When the mold is closed, the mold life is very short because the residual superhard material cubic boron nitride powder and diamond powder wear the mold wall. SUMMARY

[0003] The purpose of the present application is to provide a packing synthesis method of thick-layer superhard material compacts, so as to solve the problems existing in the prior art, make the metal cup shrinkage uniform when the powder is compacted, and realize the synthesis of the thick-layer superhard material compacts and improve the service life of the compaction mold.

[0004] In order to achieve the above-mentioned purpose, the present application provides the following solutions.

[0005] The application provides a packing synthesis method of thick-layer superhard material composite sheet, comprising the following steps:

[0006] (1) mixing superhard powder and powder serving as catalyst and binder to obtain mixed powder;

[0007] (2) laying the mixed powder in a metal cup, then covering a hard alloy base on the surface of the mixed powder, and covering the metal cup to obtain a pre-packed composite sheet;

[0008] (3) wrapping the pre-packed composite sheet with metal foil, then wrapping with pressure transmission powder, and then placing in a compaction mold for compaction;

[0009] (4) taking out the pre-packed composite sheet, and purifying and shaping the pre-packed composite sheet under high temperature in a vacuum environment to obtain a purified and shaped composite sheet;

[0010] (5) placing the purified and shaped composite sheet in a heat preservation and pressure transmission medium, and synthesizing under high temperature and high pressure to obtain the thick-layer superhard material composite sheet.

[0011] Preferably, the superhard powder is one or both of diamond and cubic boron nitride.

[0012] Preferably, the powder serving as catalyst and binder is one or both of cobalt powder and tantalum powder.

[0013] Preferably, the metal cup is a tantalum cup, a niobium cup, a zirconium cup or a molybdenum cup, and the cup cover of the metal cup is a tantalum cover, a niobium cover, a zirconium cover or a molybdenum cover.

[0014] Preferably, in step (3), the pressure for compaction in the compaction mold is 3-5 tons.

[0015] Preferably, in step (4), the high-temperature purification and shaping is performed under a vacuum environment of 10 -2 ~ 10 -5 Pa, at a temperature of 600-1100℃, and for a purification time of 1-3 hours.

[0016] Preferably, in step (5), the high-temperature and high-pressure synthesis is performed under the following conditions: a pressure of 5.5-7.5 GPa, a temperature of 1500-1800℃, and a heat preservation time of 10-20 min.

[0017] Preferably, in step (3), at least one pre-packed composite sheet wrapped with metal foil is placed in the compaction mold, and the metal foil outside each pre-packed composite sheet is wrapped with pressure transmission powder, and each pre-packed composite sheet is compacted.

[0018] The application has the following technical effects relative to the prior art:

[0019] This invention provides a method for filling and assembling a thick-layer superhard material composite sheet. The pre-assembled composite sheet is wrapped with a metal foil, then wrapped with a pressure-transmitting powder, and then placed in a compaction mold for compaction. This ensures that the metal cup shrinks evenly during the compaction of the powder, and the metal cup and the compaction mold are separated by the pressure-transmitting powder and the metal foil to prevent the superhard powder from abrading the wall of the compaction mold and to improve the service life of the compaction mold. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram illustrating the simultaneous compaction of four pre-assembled composite sheets in an embodiment of the present invention;

[0022] In the figure: 1-mixed powder, 2-metal cup, 3-hard alloy substrate, 4-metal foil, 5-pressure transmitting powder, 6-compacting mold, 61-mold sleeve, 62-mold pressure head. Detailed Implementation

[0023] like Figure 1 As shown, the present invention provides a method for filling and assembling a thick-layer superhard material composite sheet, comprising the following steps:

[0024] (1) Mix the superhard powder and the powder used as a catalyst and binder evenly to obtain mixed powder 1;

[0025] (2) Spread the mixed powder 1 into the metal cup 2, then cover the surface of the mixed powder 1 with the hard alloy substrate 3, and put a lid on the metal cup 2 to obtain a pre-assembled composite sheet.

[0026] (3) Wrap the pre-assembled composite sheet with metal foil 4, then wrap it with pressure-transmitting powder 5 and place it in the compaction mold 6 to compact it.

[0027] (4) Demold and remove the pre-assembled composite sheet, and purify and shape it at high temperature in a vacuum environment to obtain a purified and shaped composite sheet;

[0028] (5) The purified and shaped composite sheet is placed in a heat-insulating and pressure-transmitting medium and subjected to high-temperature and high-pressure synthesis to obtain a thick-layer superhard material composite sheet.

[0029] In one embodiment of the present invention, the superhard powder is one or both of diamond and cubic boron nitride. The particle size of the diamond is 2-120 μm, preferably 10 μm, and the particle size of the cubic boron nitride is 5-30 μm, preferably 10 μm. The particle size of diamond (2-120 μm) is the particle size range for diamond as the main material, and the particle size of cubic boron nitride (5-30 μm) is the particle size range for cubic boron nitride as the main material. When diamond is the main material, cubic boron nitride can be added as a component to achieve a toughening effect; when cubic boron nitride is used as a component, its particle size range is selected according to actual needs.

[0030] In one embodiment of the present invention, the powder used as both catalyst and binder is one or both of cobalt powder and tantalum powder. The cobalt powder has a particle size of 0.3-5 μm, preferably 2 μm, and the tantalum powder has a particle size of 0.3-5 μm, preferably 2 μm.

[0031] In one embodiment of the present invention, the superhard powder and the powder used as a catalyst and binder are ball-milled in a stainless steel container with an organic solvent for 1 to 5 hours, preferably 3 hours, then dried and sieved to obtain mixed powder 1. The drying temperature is 60-120°C, preferably 80°C, and the powder is sieved using an 80-150 mesh sieve, preferably 100 mesh.

[0032] As an embodiment of the present invention, the thickness of the cemented carbide substrate 3 covering the surface of the mixed powder 1 is 2.5-12 mm, preferably 8 mm. The cemented carbide substrate 3 is a tungsten carbide-cobalt alloy, such as cemented carbide of grades YG10 to YG18, preferably YG16.

[0033] As an embodiment of the present invention, the pressure-transmitting powder 5 can be wrapped with carbon powder, salt powder, or carbon or salt powder or tubes that are pre-made and can be used to fit a pre-loaded composite sheet into a graphite tube or salt tube, etc., which are suitable for uniform pressure transmission.

[0034] As an embodiment of the present invention, the metal cup 2 is a tantalum cup, a niobium cup, a zirconium cup or a molybdenum cup, preferably a niobium cup, and the lid of the metal cup 2 is a tantalum lid, a niobium lid, a zirconium lid or a molybdenum lid, preferably a molybdenum lid.

[0035] As an embodiment of the present invention, in step (3), the compaction pressure in the compaction mold 6 is 3 to 5 tons, preferably 4 tons.

[0036] As an embodiment of the present invention, in step (4), at 10 -2 ~10 -5 Under a vacuum environment of Pa, 10 is preferred. -4 High-temperature purification and shaping are carried out at 600℃~1100℃ for 1~3 hours.

[0037] As an embodiment of the present invention, in step (5), the conditions for high temperature and high pressure synthesis are: pressure 5.5-7.5 GPa, temperature 1500-1800℃, and holding time 10-20 min.

[0038] As an embodiment of the present invention, the heat-insulating and pressure-transmitting medium is pyrophyllite block. The purified and shaped composite sheet is matched with suitable pyrophyllite block and synthesized into a thick-layer superhard material composite sheet under high temperature and high pressure in a six-sided top press.

[0039] As an embodiment of the present invention, the thickness of the polycrystalline layer of the superhard material in the thick superhard material composite sheet can reach 6 mm.

[0040] As an embodiment of the present invention, in step (3), at least one pre-assembled composite sheet wrapped with a metal foil 4 is placed in the compaction mold 6, and pressure-transmitting powder 5 is wrapped around the metal foil 4 outside each pre-assembled composite sheet, and each pre-assembled composite sheet is compacted at the same time, so that 1 to 20 pre-assembled composite sheets can be compacted at the same time.

[0041] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0042] Example 1

[0043] (1) 88g of diamond micro powder with a particle size of 10μm, 6g of cubic boron nitride with a particle size of 2μm, 4g of cobalt powder with a particle size of 2μm, and 2g of tantalum powder with a particle size of 2μm were ball-milled in a stainless steel container with organic solvent for 3 hours, dried at 80℃, and sieved through a 100-mesh sieve to obtain diamond micro powder mixed with catalyst and binder; in this embodiment, diamond micro powder is the main material and cubic boron nitride is the auxiliary material.

[0044] (2) 15.5g of diamond micro powder mixed with catalyst and binder was spread into a 35mm diameter niobium cup and covered with an 8mm thick hard alloy (tungsten carbide-cobalt), and matched with a suitable molybdenum cap to obtain a pre-assembled composite sheet.

[0045] (3) Wrap the pre-assembled composite sheet with titanium foil, then wrap a layer of graphite powder and put it into the mold sleeve 61. The two ends of the mold sleeve 61 are blocked by the mold head 62. Apply 4 tons of pressure to the two ends and hold for 15 seconds before demolding.

[0046] (4) Place the compacted pre-assembled composite sheet in 10 -4 The purified and shaped composite sheet was obtained by holding the sheet at 700℃ for 2 hours in a vacuum furnace.

[0047] (5) The purified and shaped composite sheet is matched with a suitable pyrophyllite block and a thick layer of superhard material composite sheet is synthesized in the high temperature and high pressure of a six-sided press. The conditions for high temperature and high pressure synthesis are: pressure 6.5 GPa, temperature 1700℃, heat preservation for 15 minutes; the pressure is released to obtain a diamond composite sheet with a polycrystalline layer thickness of 4.5 mm.

[0048] Example 2

[0049] (1) 88g of diamond micro powder with a particle size of 10μm, 6g of cubic boron nitride with a particle size of 2μm, 4g of cobalt powder with a particle size of 2μm, and 2g of tantalum powder with a particle size of 2μm were ball-milled in a stainless steel container with organic solvent for 3 hours, dried at 80℃, and sieved through a 100-mesh sieve to obtain diamond micro powder mixed with catalyst and binder; in this embodiment, diamond micro powder is the main material and cubic boron nitride is the auxiliary material.

[0050] (2) 19g of diamond micro powder mixed with catalyst and binder was spread into a 35mm diameter niobium cup and covered with an 8mm thick hard alloy (tungsten carbide-cobalt), and matched with a suitable molybdenum cap to obtain a pre-assembled composite sheet.

[0051] (3) Wrap the pre-assembled composite sheet with tin foil, then wrap a layer of salt powder and put it into the mold sleeve 61. The two ends of the mold sleeve 61 are blocked with the mold head 62. Apply 4 tons of pressure to both ends and hold for 15 seconds before demolding.

[0052] (4) Place the compacted pre-assembled composite sheet in 10 -4 The purified and shaped composite sheet was obtained by holding the sheet at 700℃ for 2 hours in a vacuum furnace.

[0053] (5) The purified and shaped composite sheet is matched with a suitable pyrophyllite block and synthesized into a thick-layer superhard material composite sheet under high temperature and high pressure in a six-sided press. The conditions for high temperature and high pressure synthesis are: pressure 6.5 GPa, temperature 1700℃, heat preservation for 15 minutes; after depressurization, a diamond composite sheet with a polycrystalline layer thickness of 5.5 mm is obtained.

[0054] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for packing and assembling a thick-layer superhard material composite sheet, characterized in that, Includes the following steps: (1) The superhard powder and the powder used as a catalyst and binder are mixed evenly to obtain a mixed powder; (2) Spread the mixed powder evenly into a metal cup, then cover the surface of the mixed powder with a hard alloy substrate, and put a lid on the metal cup to obtain a pre-assembled composite sheet; (3) Wrap the pre-assembled composite sheet with metal foil, then wrap it with pressure-transmitting powder and place it in a compaction mold to compact it; put 4 to 20 pre-assembled composite sheets wrapped with metal foil into the compaction mold, and wrap each pre-assembled composite sheet with pressure-transmitting powder on the metal foil outside the pre-assembled composite sheet, and compact each pre-assembled composite sheet at the same time. (4) Demold and remove the pre-assembled composite sheet, at 10 -2 ~10 -5 Under a vacuum environment, the material is purified and shaped at a temperature of 600℃~1100℃ for 1~3 hours to obtain a purified and shaped composite sheet. (5) The purified and shaped composite sheet is placed in a heat-insulating and pressure-transmitting medium and subjected to high-temperature and high-pressure synthesis to obtain the thick-layer superhard material composite sheet.

2. The method for packing and assembling thick-layer superhard material composite sheets according to claim 1, characterized in that: The superhard powder is one or both of diamond and cubic boron nitride.

3. The method for packing and synthesizing thick-layer superhard material composite sheets according to claim 1, characterized in that: The powder used as a catalyst and binder is one or both of cobalt powder and tantalum powder.

4. The method for packing and synthesizing thick-layer superhard material composite sheets according to claim 1, characterized in that: The metal cup is a tantalum cup, a niobium cup, a zirconium cup, or a molybdenum cup, and the cup lid is a tantalum lid, a niobium lid, a zirconium lid, or a molybdenum lid.

5. The method for packing and synthesizing thick-layer superhard material composite sheets according to claim 1, characterized in that: In step (3), the compaction pressure in the compaction mold is 3 to 5 tons.

6. The method for packing and synthesizing thick-layer superhard material composite sheets according to claim 1, characterized in that: In step (5), the conditions for high-temperature and high-pressure synthesis are: pressure 5.5-7.5 GPa, temperature 1500-1800℃, and holding time 10-20 min.

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