CN105859300A - Preparation method of diamond-cubic boron nitride-boron carbide composite material - Google Patents

Abstract

The invention relates to a method for preparing a diamond-cubic boron nitride-boron carbide composite material. The method adopts high-temperature and high-pressure sintering technology, and the specific steps are: under high temperature and high pressure conditions (HPHT, 5-6 GPa, 1350-1500°C) , using high-purity powders (Co, Ti, Al, Si, etc.) with a particle size of 20 nm‑20 μm as the sintering binder, and diamond, cubic boron nitride, and boron carbide (B ₄ C) powders with different content ratios as the Raw material preparation diamond-cubic boron nitride-boron carbide composite material. The method for preparing high-performance structural materials in the present invention is through the sintering composite technology of diamond, cBN, B ₄ C and binder, and sintered phases such as diamond, boron nitride, alloy solid solution, and cermet are formed in the composite material. The structure of the sintered body is uniform and dense, and has high heat resistance. The method has strong operability, and the synthesized product has high stability, can fill the gap between diamond and boron nitride composite materials, and is a new composite material suitable for cutting hard materials.

Description

A kind of preparation method of diamond-cubic boron nitride-boron carbide composite material

technical field

The invention belongs to the field of superhard material manufacturing for cutting tools, and specifically relates to a method for preparing a high-quality diamond-cubic boron nitride-boron carbide composite material with controllable content of diamond, cubic boron nitride and boron carbide and high thermal stability. .

Background technique

Modern machining technology is developing rapidly in the direction of high precision, high efficiency, flexibility and automation. New technical equipment, CNC machine tools, machining centers and new materials with excellent performance are increasingly widely used, especially the requirements for tool materials are increasing. higher. Superhard materials diamond, cubic boron nitride (cBN) and boron carbide (B ₄ C) and their composite materials (diamond, cubic boron nitride polycrystalline and composite sheets, boron carbide-based cermets, etc.) It has played an important role in modern manufacturing and is widely used in petroleum, geology, aviation, machining, metallurgy, electronics and other fields. The superhard material industry has become one of the country's seven strategic emerging industries and has received strong policy support.

It is generally believed that an ideal superhard material system should meet the following elements, namely high hardness, high fracture toughness, high thermal stability, and high chemical stability. Among the known superhard materials, diamond, cBN and B ₄ C are currently the most widely used, but they also have their own shortcomings and limitations. Diamond has ultra-high hardness (60-120 GPa), but its thermal stability and chemical inertness are poor, and it is easily oxidized at high temperature (680°C), and it has a chemical reaction with iron-containing alloys, making it suitable for processing iron-based materials. are greatly restricted. Cubic boron nitride has excellent heat resistance (1100°C) and chemical inertness, while its hardness (50-72 GPa) is only half that of diamond. B ₄ C with a rhombohedral structure, second only to diamond and cBN in hardness (Mohs hardness 9.36, microhardness 55-67 GPa), has nearly constant high-temperature hardness (>30 GPa), however, B ₄ C fracture toughness Low (2.5 MPa·m ^1/2 ), poor oxidation resistance (oxidation occurs at 600 °C in air, rapid oxidation at 900 °C), poor stability to metals (easy to react with metals to form metal borides), restricts its practical application. Diamond and cubic boron nitride alloys or solid solution composite materials in the prior art have certain advantages in hardness, and their heat resistance is generally higher than that of diamond (800°C), but this performance index is also low, and as the main application It is of great practical significance to prepare composite superhard materials with high heat resistance.

Therefore, the comprehensive performance can make up for the limitations of diamond, cBN and B ₄ C, and new superhard materials with high efficiency, high stability, high precision and long life can be achieved, which is an important development direction of the superhard material manufacturing industry.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a diamond-cubic boron nitride-boron carbide composite material with strong operability and high thermal stability, by effectively adjusting the relationship between diamond, boron nitride, boron carbide and binder The content ratio can improve the structure and compactness of the sintered body of the composite material, and at the same time can effectively improve the thermal stability of the material. The prepared composite material can be made into tools with different angles after laser cutting, welding and sharpening according to the tool requirements. .

The purpose of the present invention is achieved like this:

The preparation method of the diamond-cubic boron nitride-boron carbide composite material comprises the following steps:

①. Select diamond, cubic boron nitride and boron carbide powder as raw materials,

②. Mix the mixed powder selected in the above ① evenly and put it into a molybdenum cup for packaging.

③. The molybdenum cup assembled in ② is pre-pressed, vacuum pre-fired, pyrophyllite composite block cavity assembled, and high-pressure sintered to complete the preparation of the composite material;

The step ① of the composite material preparation method also includes a binder material.

The beneficial effects of the present invention are as follows:

1. The method adopted in the present invention can obtain a new type of composite material by adjusting the ratio of diamond, cBN, B ₄ C and binder, which has good synthesis repeatability and strong operability. The comprehensive performance can make up for the limitations of diamond, cBN and B ₄ C, and can achieve new superhard materials with high efficiency, high stability, high precision and long life.

2. The method for preparing the superhard composite material of the present invention has high stability of the synthesized product, and sintered phases such as diamond, boron nitride, alloy solid solution, and cermet are formed in the composite material, and the structure of the sintered body is uniform and compact, with High heat resistance (1400°C). It is suitable for cutting processing of chilled cast iron, heat-resistant alloy and hardened steel.

Description of drawings

Fig. 1 is a cross-sectional view of the cavity assembly of the pyrophyllite composite block in the present invention.

Numbers in Fig. 1: mixed powder 1, molybdenum cup 2, heating graphite tube 3, insulating sheet 4, thermal insulation graphite sheet 5, conductive metal sheet 6, conductive steel cap 7, pyrophyllite composite block 8.

detailed description

This application provides a method for preparing a diamond-cubic boron nitride-boron carbide composite material. The composite material can make up for the limitations of the properties of diamond, cBN and B ₄ C, and can achieve high efficiency, high stability, high Precision, long-life new superhard material.

The preparation method of composite material comprises the following steps:

①. Select diamond, cubic boron nitride, and boron carbide powder as raw materials; diamond, cubic boron nitride, and boron carbide powder are required to be purified to remove impurities, with an average particle size of 20 nm-20 μm, and the weight of diamond powder is 10-80 parts. The weight part of cubic boron nitride powder is 20-80 parts, and the weight part of boron carbide powder is 5-20 parts. It also includes a binder material, the binder powder is a compound or a simple substance according to the actual processing object needs, one or more of Co, Ti, Al, Si, SiC, the particle size is 20nm-20μm, the bonding The weight part of agent powder is 0-50 parts.

②. Evenly mix the mixed powder selected in the above ① and put it into a molybdenum cup for packaging;

③. The molybdenum cup assembled in ② is pre-pressed, vacuum pre-fired, pyrophyllite composite block cavity assembled, and high-pressure sintered to complete the preparation of the composite material. Pre-compression molding, vacuum pre-sintering treatment, pyrophyllite composite block cavity assembly, and high-pressure sintering process are to pre-press the assembled molybdenum cup at 5-20MPa, vacuum heat treatment at 500°C for 0.5-1h, and then put it into the graphite heating tube kit, and finally Put all the parts together into the pyrophyllite composite block for assembly, and carry out high-temperature and high-pressure synthesis on a six-sided top press. The synthesis conditions are 5-6GPa, 1350-1500 ℃, and the sintering holding time is 3-10min.

Example 1

As shown in Figure 1: diamond powder with a particle size of 0.5 μm, cBN powder with a particle size of 0.25 μm, B ₄ C with a diameter of 3 μm, and Si powder with a size of 1 μm are selected as raw and auxiliary materials, and the parts by weight are: 15 parts, 70 parts, and 10 parts, respectively. 5 servings. Mix the powder for 2 hours until it is uniform, put 1g of the mixed powder 1 into a molybdenum cup 2 with an inner diameter of 14.8mm after being pre-pressed at 5MPa, perform a vacuum heat treatment at 500°C for 0.5h, then put it into a heated graphite tube 3, and finally assemble Component insulation sheet 4, thermal insulation graphite sheet 5, conductive metal sheet 6, and conductive steel cap 7 are put into the pyrophyllite composite block 8. The size of the pyrophyllite composite block is 32.5mm×32.5mm×32.5mm, and the diameter of the synthetic cavity is 18mm. The graphite tube 7 has an inner diameter of 16mm and a height of 17mm. The six-sided top press (CS- , 6×14000 KN) for high-temperature and high-pressure synthesis, the synthesis conditions are 5 GPa, 1400 ℃, the sintering holding time is 3 minutes, and then the temperature is slowly lowered to room temperature. After the pressure is released, a superhard composite material of Φ14mm×3mm is obtained.

Example 2

As shown in Figure 1: Diamond powder with a particle size of 0.5 μm, cBN powder with a particle size of 0.25 μm, and B ₄ C micropowder with a particle size of 3 μm are selected as raw materials, and the parts by weight are: 60, 20, and 20, respectively. Mix the powder for 2 hours until uniform, put it into a molybdenum cup 2 with an inner diameter of 14.8 mm, pre-press 2 g of the mixed powder 1 at 5 MPa, heat treat at 500°C for 0.5 hours in a vacuum, and put it into a heated graphite tube 3, and finally insulate the assembled parts Sheet 4, thermal insulation graphite sheet 5, conductive metal sheet 6, and conductive steel cap 7 are put into the pyrophyllite composite block 8 together. 7 The inner diameter is 16mm and the height is 17mm. The six-sided top press (CS- , 6×14000 KN) for high-temperature and high-pressure synthesis, the synthesis conditions are 5 GPa, 1400 ℃, the sintering holding time is 5 minutes, and then the temperature is slowly lowered to room temperature, and the composite material of Φ14mm×5.5mm is obtained after pressure relief.

Claims (6)

1. the preparation method of diamond-cubic boron nitride-boron carbide composite material, it is characterised in that: this composite system Preparation Method comprises the following steps:

1. diamond, cubic boron nitride, boron carbide powder, are chosen as raw material；

2., by above-mentioned 1. in the mixed-powder chosen uniformly mix after put in molybdenum cup and be packaged；

3., the molybdenum cup that 2. assembles is assembled through pre-molding, vacuum preheating, pyrophyllite composite block cavity, high-pressure sinter Program completes the preparation of composite.

The preparation method of a kind of diamond-cubic boron nitride-boron carbide composite material the most according to claim 1, it is special Levy and be: this composite material and preparation method thereof step 1. in also include binder material.

The preparation method of a kind of diamond-cubic boron nitride-boron carbide composite material the most according to claim 1, it is special Levy and be: described diamond, cubic boron nitride, boron carbide powder require that purified treatment falls impurity, mean diameter 20 nm-20 μ M, diamond dust weight portion is 10-80 part, and cubic boron nitride powder weight portion is 20-80 part, and boron carbide powder weight portion is 5-20 part.

The preparation method of a kind of diamond-cubic boron nitride-boron carbide composite material the most according to claim 2, it is special Levy and be: described binding agent be Co, Ti, Al, Si, SiC therein one or more, particle diameter is 20 nm-20 μm, binding agent Powder weight part is 0-50 part.

5. according to the preparation side of a kind of diamond-cubic boron nitride-boron carbide composite material described in claim 1 or 3 or 4 Method, it is characterised in that: this composite material and preparation method thereof step 3. pre-molding, vacuum preheating, pyrophyllite composite block cavity Assemble, high pressure sintering processes be by the molybdenum cup that 2. assembles after 5-20MPa pre-molding, 500 DEG C of heat treatment 0.5-1h of vacuum Put into graphite heating pipe box part, finally all parts are put in the lump in pyrophyllite composite block and assemble, enterprising at cubic hinge press Row High Temperature High Pressure synthesizes, and synthesis condition is 5～6GPa, 1350～1500 DEG C, and the sintered heat insulating time is 3-10min.

The preparation method of a kind of diamond-cubic boron nitride-boron carbide composite material the most according to claim 5, it is special Levy and be: choose the diamond dust 15 parts of particle diameter 0.5 μm, 0.25 70 parts of μm cBN powder, the B of 3 μm₄C10 part, 1 μm 5 parts of Si powder is as raw and auxiliary material；By powder mixing 2h to uniformly, 1g mixed-powder (1) is put into the molybdenum cup of internal diameter 14.8mm (2) in, mixed-powder (1) is after 5MPa pre-molding, and 500 DEG C of vacuum purifies heat treatment 0.5h, is then placed in heating graphite In pipe (3), finally by assembling parts insulating trip (4), insulation graphite flake (5), conductive metal sheet (6), conductive steel cap (7), in the lump Putting in pyrophyllite composite block (8), pyrophyllite composite block a size of 32.5mm × 32.5mm × 32.5mm, synthetic cavity is a diameter of 18mm, graphite-pipe 7 internal diameter is 16mm, high 17mm；At cubic hinge press (CS-, 6 × 14000 KN) on carry out High Temperature High Pressure conjunction Become, synthesis condition is 5 GPa, 1400 DEG C, cools to room temperature slowly after sintered heat insulating time 3min, obtain after release Φ 14mm × The super-hard compound material of 3mm.