CN115740456A - Polycrystalline diamond compact and preparation method thereof - Google Patents

Abstract

The invention provides a polycrystalline diamond composite sheet, comprising a cemented carbide substrate and a boron-containing polycrystalline diamond layer, a transition layer is laminated between the cemented carbide substrate and the boron-containing polycrystalline diamond layer, and the boron-containing _TiO2 and TiN are dispersed in the polycrystalline diamond layer. The present invention also provides a method for preparing the above-mentioned polycrystalline diamond composite sheet. The method is mainly to arrange the titanium layer, the boron-containing diamond micropowder layer, the transition layer powder layer and the cemented carbide substrate sequentially on the metal surface from bottom to top. cup, and then undergo high temperature and high pressure sintering to form an integrated structure. Therefore, the above-mentioned polycrystalline diamond composite sheet has improved heat resistance, wear resistance, compactness and interface bonding strength, which improves its wear resistance and sharpness as a tool, especially a tool, reduces internal stress, overcomes It solves the problem of poor heat resistance during welding, improves the processing efficiency and prolongs the service life of the tool.

Description

Polycrystalline diamond composite sheet and its preparation method

technical field

The invention belongs to the technical field of superhard composite materials, and in particular relates to a polycrystalline diamond composite sheet and a preparation method thereof.

Background technique

Polycrystalline diamond (Polycrystalline Diamond, PCD for short) composite sheet is a new type of superhard composite material that is sintered with diamond particles and cemented carbide matrix under high temperature and high pressure. It not only has the characteristics of high hardness, high wear resistance and good thermal conductivity of diamond, but also has the strength and toughness of cemented carbide. With the continuous development of industrial technology, the application field of polycrystalline diamond composite sheet has been continuously developed, especially in the application of cutting tools, such as aerospace, automobile, energy, geological petroleum exploration, military industry, precision important areas of manufacturing.

When the polycrystalline diamond composite sheet is used as a tool, it is easy to cause oxidation and graphitization of the polycrystalline diamond layer on the composite sheet under the influence of high temperature due to the insufficient heat resistance and impact toughness of the composite sheet when the tool is formed. The invention patent application CN 109128192 A owned by Shenzhen Institute of Advanced Technology discloses a polycrystalline diamond composite sheet and its preparation method; its polycrystalline diamond composite sheet includes a cemented carbide matrix layer, a polycrystalline diamond layer and a transition layer. The transition layer is stacked and bonded between the hard alloy base layer and the polycrystalline diamond layer, and the surface of the polycrystalline diamond layer away from the hard alloy base layer is combined with a CVD diamond layer, through each layer The synergistic effect of the polycrystalline diamond composite sheet gives it excellent wear resistance and high temperature resistance, and the bonding strength between the polycrystalline diamond layer and the cemented carbide substrate is improved.

However, the polycrystalline diamond composite sheet disclosed in the above-mentioned invention patent application still has uneven performance in various parts and regions. When used as a tool, the polycrystalline diamond layer is prone to oxidation and graphitization due to high temperature; Due to the existence of residual stress between the polycrystalline diamond layer and the cemented carbide substrate during the sheet synthesis process, it is easy to cause crack defects, especially when the composite sheet is welded on the substrate to make a tool, the heat resistance is poor, resulting in a decrease in the sharpness of the tool and a long service life. Low production cost increases, thereby limiting its wide application and development.

Contents of the invention

In view of this, the present invention clearly needs to provide a polycrystalline diamond composite sheet and a preparation method thereof, so that it has high heat resistance, wear resistance and compactness, and reduces production costs.

For this reason, technical scheme of the present invention is as follows:

A polycrystalline diamond composite sheet, comprising a cemented carbide substrate and a boron-containing polycrystalline diamond layer, wherein a transition layer is stacked between the cemented carbide substrate and the boron-containing polycrystalline diamond layer, and the boron-containing polycrystalline diamond layer _TiO2 and TiN are dispersed in the diamond layer.

Based on the above, the boron-containing polycrystalline diamond layer is sintered at high temperature and high pressure from a flat titanium layer and a boron-containing diamond micropowder layer. Among them, the function of the Ti layer is to absorb the gas in the boron-containing diamond micropowder layer in the process of high temperature and high pressure, and generate TiO ₂ and TiN to achieve the purpose of removing the gas, thereby improving the resistance of the polycrystalline diamond composite sheet. Abrasiveness and density.

Based on the above, the thickness of the titanium layer is 0.5-1 mm, the mass percentage of boron in the boron-containing diamond powder is 0.003%-1.2%, and the thickness of the boron-containing diamond powder layer is 0.8-2 mm.

Based on the above, the transition layer is formed by high-temperature and high-pressure sintering of transition layer powder, wherein, in terms of mass percentage, the transition layer includes uniformly mixed diamond particles accounting for 55% to 70%, and diamond particles accounting for 25%. %～30% of tungsten carbide particles and 5%～15% of binder, the particle size of the diamond particles is 3～40 μm, the particle size of the tungsten carbide particles is 2～10 μm, the binder The particle size is 5-10 μm.

Based on the above, the binder is one or more of metal binders Fe, Co or Ti.

Based on the above, the diameter of the transition layer is 0.5 to 0.8 times the diameter of the boron-containing polycrystalline diamond layer, and the thickness of the transition layer is lower than or equal to the thickness of the boron-containing polycrystalline diamond layer; Improve the heat resistance, wear resistance and compactness of the central area of the polycrystalline diamond composite sheet, reduce or avoid cracks in the central area of the composite sheet, and reduce costs.

Based on the above, the cemented carbide matrix is composed of WC-Co cemented carbide, and the particle size of the WC-Co cemented carbide is slightly smaller than or equal to the average particle size of the transition layer powder. In this way, the particle size of the WC-Co cemented carbide and the transition layer powder are close, mainly to reduce the interfacial stress inside the polycrystalline diamond compact, reduce the thermal expansion coefficient of the two, and improve the interfacial bonding force.

The invention provides a polycrystalline diamond composite sheet, which is composed of a titanium layer, a boron-containing diamond micropowder layer, a transition layer powder layer and a cemented carbide matrix laid in sequence from bottom to top, and the four are composited and formed by sintering at high temperature and high pressure. integrated structure.

The present invention also provides a method for preparing the above-mentioned polycrystalline diamond composite sheet, which is prepared by using a high-temperature and high-pressure method of a six-sided top press, comprising the steps of:

First spread the titanium powder on the bottom of the metal cup to form a titanium layer, and then spread the boron-containing diamond powder on the titanium layer to form a boron-containing diamond powder layer;

The transition layer powder is evenly spread on the boron-containing diamond micropowder layer to form a transition layer powder layer;

Lightly place the cemented carbide substrate on the powder layer of the transition layer, fasten the cup cover and press gently to make it flat to obtain an assembly block;

The assembly block is placed in the six-sided top press, and sintered under the conditions of a pressure of 5-8 GPa and a temperature of 1450-2000° C. to obtain the polycrystalline diamond composite sheet.

Wherein, after the polycrystalline diamond composite sheet is taken out from the six-sided constant pressure machine, a plurality of finished products are obtained through steps such as cutting and shaping, grinding, and polishing. Wherein, in the shaping treatment step, the above-mentioned polycrystalline diamond composite sheet can be made into various shapes such as sheet, triangle, and strip according to requirements.

Based on the above preparation method, the step of forming the transition layer powder layer includes: evenly spreading the transition layer powder on the center of the boron-containing diamond micropowder layer, and gently pressing it with a mold to make it flat to form a transition layer powder layer, and the diameter of the transition layer powder layer is 0.5 to 0.8 times the diameter of the boron-containing diamond micropowder layer.

Therefore, the above-mentioned polycrystalline diamond compact provided by the present invention includes a cemented carbide substrate, a boron-containing polycrystalline diamond layer, and a transition layer laminated and bonded between the cemented carbide substrate and the boron-containing polycrystalline diamond layer. The synergistic effect between them makes the polycrystalline diamond composite sheet have good heat resistance, wear resistance and compactness, and improves the bonding strength between the boron-containing polycrystalline diamond layer and the cemented carbide substrate.

The preparation method of the above-mentioned polycrystalline diamond composite sheet provided by the present invention is mainly that the method mainly first lays the titanium layer, the boron-containing diamond micropowder layer, the transition layer powder layer and the cemented carbide substrate in order from bottom to top in a metal cup. , and then the four are sintered at high temperature and high pressure to form an integrated structure. The boron element in the diamond powder layer is a heat-resistant and conductive material, which makes the above-mentioned polycrystalline diamond composite sheet have better heat resistance; at the same time, because it is located in the middle The thermal expansion coefficient of the transition layer powder layer is similar to that of the boron-containing diamond micropowder layer and the cemented carbide substrate, which improves the bonding performance at the interface of the polycrystalline diamond compact sheet and reduces the generation of internal stress, especially at the bottom. The Ti layer absorbs the gas in the boron-containing diamond micropowder layer in the process of high temperature and high pressure to generate TiO ₂ and TiN to achieve the purpose of degasification, thereby improving the wear resistance and density of the polycrystalline diamond composite sheet.

Therefore, the above-mentioned polycrystalline diamond composite sheet provided by the present invention has good heat resistance, wear resistance, compactness and interfacial bonding strength, which improves its wear resistance and sharpness as a tool, especially a cutting tool, and reduces the Internal stress; overcame the poor heat resistance during welding in the tool making process, improved the processing efficiency of the tool, and extended the service life of the tool.

Description of drawings

Fig. 1 is a photographic view of a polycrystalline diamond compact provided in Example 1 of the present invention.

Fig. 2 is a schematic diagram of the laying structure of raw materials during the preparation process of the polycrystalline diamond compact provided in Example 1 of the present invention.

Wherein, the element symbols in the above figures: 1. cemented carbide substrate, 2. transition layer powder layer, 3. boron-containing diamond micropowder layer, 4. titanium layer.

Detailed ways

The technical solutions of the present invention will be described in further detail below through specific implementation methods.

Embodiment one

Please refer to Fig. 1 and Fig. 2, the present embodiment provides a kind of polycrystalline diamond compact, is made up of cemented carbide substrate, transition layer and boron-containing polycrystalline diamond layer, and described transition layer is laminated and bonded on described cemented carbide Between the substrate and the boron-containing polycrystalline diamond layer, TiO ₂ and TiN are dispersed in the boron-containing polycrystalline diamond layer.

The above-mentioned polycrystalline diamond composite sheet is laminated in sequence from bottom to top with a flat titanium layer 4, a boron-containing diamond micropowder layer 3, a transition layer powder layer 2 and a cemented carbide substrate 1, and the four are composited and formed by sintering at high temperature and high pressure A superhard composite material. Wherein, the thickness of the titanium layer is 0.5 mm, the thickness of the boron-containing diamond micropowder layer is 0.8 mm, and the mass percentage of boron element is 0.05%. The powder layer of the transition layer is composed of 60% of 15 μm diamond particles, 25% of 10 μm tungsten carbide particles and 15% of 5 μm metal bond Ti which are uniformly mixed. The diameter of the transition layer powder layer is 0.8 times the diameter of the boron-containing diamond powder layer, and the thickness is 0.8 mm. The cemented carbide matrix is made of WC-Co cemented carbide, and the grain size of the alloy matrix is slightly smaller than that of the powder layer of the transition layer.

This embodiment also provides a specific preparation method of the above-mentioned polycrystalline diamond compact, comprising the following steps:

(1) First spread titanium powder on the bottom of the metal cup to form a 0.5 mm thick titanium layer 4, and then spread boron-containing diamond fine powder on the titanium layer 4 to form a 0.8 mm thick boron-containing diamond fine powder layer 3;

(2) Spread the transition layer powder evenly on the center of the boron-containing diamond micropowder layer 3, and gently press it with a mold to make it flat to form a transition layer powder layer 2 with a thickness of 0.8 mm, and the transition layer powder layer The diameter of 2 is 0.8 times of the diameter of the boron-containing diamond micropowder layer;

(3) Lightly place the cemented carbide substrate 1 on the transition layer powder layer 2, fasten the cup cover and press gently to make it flat to obtain an assembly block;

(4) Put the assembly block in the six-sided top press, and sinter it under the conditions of a pressure of 5 GPa and a temperature of 1480°C to synthesize a composite sheet blank;

(5) Grinding and polishing the above-mentioned synthesized composite sheet blanks to obtain a plurality of the above-mentioned finished polycrystalline diamond composite sheets. Among them, the wear resistance, compactness, heat resistance and processability of the finished polycrystalline diamond compacts are basically the same.

Embodiment two

This embodiment provides a polycrystalline diamond composite sheet, the structure of which is basically the same as that of the polycrystalline diamond composite sheet provided in Example 1, the main difference being that in this embodiment, the thickness of the titanium layer is 0.8 mm , the thickness of the boron-containing diamond micropowder layer is 1 mm, and the mass percentage of boron element therein is 0.003%; the transition layer powder layer is composed of uniformly mixed 10 μm diamond particles 55%, 8 μm tungsten carbide particles 30 % and 10 μm metal bond 15%, wherein the metal bond is Co and Ti with a mass ratio of 3:1.5; the diameter of the transition layer powder layer is 0.6 times the diameter of the boron-containing diamond powder layer, and the thickness is 0.5 mm; the particle size of the alloy matrix is slightly smaller than the particle size of the transition layer powder layer.

This embodiment provides a preparation method of the above-mentioned polycrystalline diamond composite sheet, which is basically the same as the preparation method of the composite sheet provided in Example 1, the main difference is that: in this embodiment, the composition of raw materials is different; each raw material The thickness of the layer is different; the diameter of the powder layer of the transition layer is different; the sintering pressure is 8 GPa, and the sintering temperature is 1800°C.

Embodiment three

This embodiment provides a polycrystalline diamond composite sheet, the structure of which is basically the same as that of the polycrystalline diamond composite sheet provided in Example 1, the main difference being that in this embodiment, the thickness of the titanium layer is 1 mm , the thickness of the boron-containing diamond micropowder layer is 1.2 mm, and the mass percentage of boron element therein is 1.2%; the transition layer powder layer is composed of uniformly mixed 20 μm diamond particles 65%, 5 μm tungsten carbide The metal bond 10% of particle 25% and 10 μm forms, and wherein, metal bond is Co and Ti that mass ratio is 3: 2; The diameter of described transition layer powder layer is 0.5 times of boron-containing diamond powder layer diameter, The thickness is 1.0 mm; the grain size of the alloy matrix is equal to the grain size of the transition layer powder layer.

This embodiment provides a preparation method of the above-mentioned polycrystalline diamond composite sheet, which is basically the same as the preparation method of the composite sheet provided in Example 1, the main difference is that: in this embodiment, the composition of raw materials is different; The diameters of the transition layer powder layers are different; the sintering pressure is 6 GPa, and the sintering temperature is 1500 °C.

performance verification

The wear resistance, thermal stability and processing life of the polycrystalline diamond compacts provided in Examples 1-3 and Comparative Examples 1 and 2 were tested.

Among them, Comparative Example 1 is a conventional polycrystalline diamond compact in the market.

Comparative Examples 2 to 4 are boron-containing polycrystalline diamond composite sheets, and their preparation methods are basically the same as those provided in Examples 1 to 3. The main difference is that: Comparative Examples 2 to 4 do not contain a titanium layer, and the The diameter of the transition layer powder layer is equal to the diameter of the corresponding boron-containing diamond powder layer. Wherein, Comparative Example 2 lacks a titanium layer compared with Example 1, Comparative Example 3 lacks a titanium layer compared with Example 2, and Comparative Example 4 lacks a titanium layer compared with Example 3.

Wear ratio detection refers to JB-T3235-1999.

The detection method of processing efficiency and processing life is: the polycrystalline diamond composite sheets provided in Examples 1-3 and Comparative Examples 1-4 are respectively made into cutting blades of the same specification and structure, and the cutting parameters (tool speed n=4000 r /min, tool feed f=400 mm/min) comparison of machining efficiency and machining life when machining aluminum alloy under the same conditions.

Thermal stability refers to the wear ratio and processing life of each polycrystalline diamond compact after being calcined at 750 °C for 2 min.

Among them, the test results of the polycrystalline diamond compact are shown in Table 1.

The performance test results of the polycrystalline diamond compacts obtained in each embodiment and comparative examples of table 1

Therefore, the above-mentioned polycrystalline diamond composite sheet provided by the embodiment of the present invention and the polycrystalline diamond composite sheet prepared by the above-mentioned method adopt boron-containing diamond micropowder to make the composite sheet, which improves the heat resistance of the composite sheet; A transition layer with a thermal expansion coefficient similar to that of diamond is set between the boron diamond micropowder layer and the cemented carbide layer, which improves the bonding performance at the interface of the polycrystalline diamond composite sheet, reduces the generation of internal stress, and improves its wear resistance, especially at the bottom The use of the titanium metal layer reduces the gas in the diamond layer, and the formation of titanium nitride improves the compactness of the center of the diamond layer, improves the processing efficiency, and prolongs the service life of the tool. The above-mentioned polycrystalline diamond composite sheet can be used to make milling and cutting tools, and can process metal materials, alloy materials, wood, etc.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: the present invention can still be Modifications to the specific implementation of the invention or equivalent replacement of some technical features; without departing from the spirit of the technical solution of the present invention, should be included in the scope of the technical solution claimed in the present invention.

Claims (10)

1. A polycrystalline diamond composite sheet, comprising a cemented carbide substrate and a boron-containing polycrystalline diamond layer, is characterized in that: a transition layer is stacked between the hard alloy substrate and the boron-containing polycrystalline diamond layer, and the _TiO2 and TiN are dispersed in the boron-containing polycrystalline diamond layer. 2. The polycrystalline diamond compact according to claim 1, characterized in that: the boron-containing polycrystalline diamond layer is formed by sintering at high temperature and high pressure a titanium layer and a boron-containing diamond micropowder layer laid flat. 3. The polycrystalline diamond composite sheet according to claim 2, characterized in that: the thickness of the titanium layer is 0.5-1 mm, and the mass percentage of boron in the boron-containing diamond powder is 0.003%-1.2%, The thickness of the boron-containing diamond micropowder layer is 0.8-2 mm. 4. The polycrystalline diamond compact according to claim 1 or 2 or 3, characterized in that: the transition layer is formed by sintering transition layer powder at high temperature and high pressure, wherein, by mass percentage, the transition layer The layers respectively include uniformly mixed diamond particles accounting for 55% to 70%, tungsten carbide particles accounting for 25% to 30%, and binders accounting for 5% to 15%. The particle size of the diamond particles is 3 to 40 μm, the particle size of the tungsten carbide particles is 2-10 μm, and the particle size of the binder is 5-10 μm. 5. The polycrystalline diamond compact according to claim 4, characterized in that: the binder is one or more of metal binders Fe, Co or Ti. 6. The polycrystalline diamond compact according to claim 4, characterized in that: the diameter of the transition layer is 0.5 to 0.8 times the diameter of the boron-containing polycrystalline diamond layer, and the thickness of the transition layer is less than Or equal to the thickness of the boron-containing polycrystalline diamond layer. 7. The polycrystalline diamond compact according to claim 4, characterized in that: the cemented carbide substrate is made of WC-Co cemented carbide, and the grain size of the WC-Co cemented carbide is slightly smaller than or equal to the The average particle size of the transition layer powder. 8. A polycrystalline diamond composite sheet, characterized in that: it consists of a titanium layer, a boron-containing diamond micropowder layer, a transition layer powder layer and a cemented carbide substrate that are laid sequentially from bottom to top, and the four are sintered at high temperature and high pressure and form an integral structure combined with each other. 9. A preparation method of polycrystalline diamond compact, comprising the steps of: First spread the titanium powder on the bottom of the metal cup to form a titanium layer, and then spread the boron-containing diamond powder on the titanium layer to form a boron-containing diamond powder layer; The transition layer powder is evenly spread on the boron-containing diamond micropowder layer to form a transition layer powder layer; Lightly place the cemented carbide substrate on the powder layer of the transition layer, fasten the cup cover and press gently to make it flat to obtain an assembly block; The assembly block is placed in the six-sided top press, and sintered under the conditions of a pressure of 5-8 GPa and a temperature of 1450-2000° C. to obtain the polycrystalline diamond composite sheet. 10. the preparation method of polycrystalline diamond compact according to claim 9 is characterized in that: the step of described forming transition layer powder layer comprises that described transition layer powder is evenly tiled in described boron-containing diamond micropowder layer on the central part, and gently press it with a mold to make it flat to form a transition layer powder layer, and the diameter of the transition layer powder layer is 0.5 to 0.8 times the diameter of the boron-containing diamond micropowder layer.

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