CN115677354A - A method for preparing nano-PCBN composite sheet with nano-CBN powder at high temperature and high pressure - Google Patents

Abstract

The invention discloses a method for preparing nano-PCBN composite sheet by using nano-CBN powder under high temperature and high pressure, which belongs to the field of superhard material manufacturing. The main process is to first treat the nano cubic boron nitride powder with acid and alkali, then mix nano alumina, nano titanium nitride and sintering aid with the nano cubic boron nitride powder according to a certain ratio, and put it into a high energy ball mill. The mixed raw materials are mixed by wet mixing method, and then vacuum high-temperature treatment is carried out in order to remove impurities and steam adsorbed on the surface of the powder; a layer of titanium film is coated on the hard alloy, and the hard alloy substrate covered with titanium is combined with the The mixed raw materials were assembled into a standard sample block, and after vacuum drying, they were placed in a six-sided top press for high temperature and high pressure to prepare PCBN composite sheets. The PCBN composite sheet prepared by the invention has high hardness, good toughness, good wear resistance, excellent high temperature performance, improved service life of the PCBN composite sheet, and the synthesis process is simple, controllable, easy to operate, high in production efficiency, and can meet industrial production.

Description

A method for preparing nano-PCBN composite sheet with nano-CBN powder at high temperature and high pressure

technical field

The patent of the invention belongs to the field of superhard material manufacturing, especially a method for preparing nano-PCBN composite sheet with nano-CBN powder under high temperature and high pressure.

Background technique

The main hard components of modern tool materials high-speed steel, cemented carbide, and ceramics are carbides, nitrides, and oxides. The hardness of these compounds is up to 3000HV, and the overall hardness of the bonding substance is below 2000HV. For the processing of modern engineering materials, in some cases, the hardness of the above tool materials is not enough, so superhard tool materials have emerged. Superhard tool materials mainly refer to cubic boron nitride (CBN) and diamond, which are several times harder than other tool materials. The hardness of diamond is the highest, up to 10000HV, and the hardness of CBN (8000-9000HV) is second only to diamond. Diamond tools are only suitable for processing non-ferrous metal materials and non-metal materials, and diamond tools have poor high temperature resistance; CBN tools are chemically inert to ferrous metals (metals containing iron group elements) and are resistant to high temperatures, especially suitable for cutting ferrous metals. In addition, it is also suitable for the processing of general hard and brittle materials.

However, cubic boron nitride single crystal is difficult to make large-sized tools, and has the anisotropy of single crystal, which is affected by the crystal cleavage mechanism. Some mechanical properties of CBN, such as hardness and wear resistance, are very strong. directionality, which limits its industrial application. In order to meet the needs of industrial processing, a cubic boron nitride composite sheet was developed. Generally, cubic boron nitride powder is used as raw material, with or without binder, and sintered under high temperature and high pressure conditions. The cubic boron nitride composite material sintered at high temperature and high pressure can make up for the shortcomings of single crystal in some aspects, and the size of the composite sheet is also larger, so there is a very broad development space in the industry.

The size of cubic boron nitride grains directly affects the sintering strength and fracture resistance of PCBN composite sheets. The fine cubic boron nitride particles can increase the interface area, improve the sintering strength and crack growth resistance of PCBN composite sheets, the smaller the cubic boron nitride grain size, the stronger the damage resistance of PCBN composite sheets, PCBN The cutting sharpness of the composite sheet is better. Small cubic boron nitride grains can provide a large reaction specific surface area, resulting in induced transformation and crystal epitaxial growth, and a fully dense PCBN composite sheet with a microstructure. The use of nano-scale CBN particles to prepare PCBN can significantly improve the density and hardness of the material, and broaden the application of PCBN composite sheets.

Contents of the invention

The purpose of the present invention is to provide a method for preparing nano-PCBN composite sheet with nano-CBN powder under high temperature and high pressure.

For realizing the purpose of the present invention, adopt following technical scheme to realize:

The invention provides a nano-PCBN (polycrystalline cubic boron nitride) composite sheet, which is prepared from the following mass fraction raw materials through high temperature and high pressure:

Cubic boron nitride powder 40-90%, nano-alumina 0-30%, nano-titanium nitride 0-10%, sintering aid 1-10%;

The sintering aid is one or more mixtures of Al powder, Ti powder, Co powder, and Ni powder, and the particle size range of the metal powder is < 1 μm.

Preferably, the CBN particle size range is < 1 μm.

Preferably, the particle size of the nano-alumina powder is less than 50 nm; the particle size of the nano-titanium nitride powder is less than 100 nm.

The preparation method of described PCBN cutter material, comprises the following steps:

① Cubic boron nitride powder treatment: Put the cubic boron nitride powder in a dilute hydrochloric acid solution with a mass fraction of 10% to 30%, boil it for 10 minutes to 50 minutes, wash it, and then wash the cubic boron nitride powder after acid treatment Put the body into a NaOH solution with a mass fraction of 10% to 30%, boil it for 10min to 50min and wash it, centrifuge the cubic boron nitride powder washed by acid and alkali, wash it with distilled water first and then with absolute ethanol, and then vacuum dry and set aside;

②Material mixing: put nano-alumina, nano-titanium nitride and sintering aids into the high-energy ball mill with nano-alumina, nano-titanium nitride and sintering aids and the cubic boron nitride powder treated in step ①, and mix them by wet mixing method, and then carry out vacuum drying after wet mixing;

③Vacuum high-temperature treatment: In order to remove impurities and steam adsorbed on the powder surface, the mixed material obtained in step ② is treated at 10 ^-1 -10 ^-3 vacuum and 800°C-1000°C for 1-3 hours;

④Treatment of the cemented carbide substrate: use a magnetron sputtering coater to coat a layer of titanium film on the cemented carbide of the surface # word trench, and obtain a cemented carbide substrate whose surface is covered with titanium;

⑤Standard block assembly: Assemble the mixed material obtained in step ③ and the cemented carbide substrate obtained in step ^④ into a standard sample block, and vacuum dry at ^10-1-10-3 vacuum and 200-400°C for 20-60min reserve;

⑥ High temperature and high pressure preparation: Put the standard sample block obtained in step ⑤ into a six-sided top press for high temperature and high pressure sintering to obtain a PCBN composite sheet.

Preferably, in steps ① and ②, ^the vacuum drying temperature is 40°C-80°C, the drying time is 12-24h, and the vacuum degree is ^10-1-10-3 ;

Preferably, in step ②, the wet mixing liquid medium is acetone or absolute ethanol, liquid medium: total weight of raw materials: total weight of grinding balls is 2:1:3, and the material of grinding balls is cemented carbide or agate;

Preferably, in step ②, the speed of the ball mill is 200-400r/min, and the ball milling time is 3-8h;

Preferably, in step ④, the thickness of the hard alloy substrate coated with titanium film is 0.5-2 μm;

Preferably, in step ⑥, the sintering process parameters are as follows: the sintering pressure is 5-8GPa, the sintering temperature is 1300-1800°C, and the holding time is 5-30min.

The beneficial effects of the present invention are:

1. The PCBN prepared by the present invention has high hardness, good toughness, good wear resistance, excellent high-temperature performance, and improves the service life of the PCBN composite sheet.

2. The performance of the prepared PCBN composite sheet can be adjusted by adjusting the particle size of the cubic boron nitride powder and adjusting the ratio of the cubic boron nitride powder and each binder component.

3. The synthesis process is simple, controllable, easy to operate, and the production efficiency is high, which can meet industrial production.

Detailed ways

This invention is further described below in conjunction with specific embodiment:

Example 1:

PCBN (polycrystalline cubic boron nitride) composite sheet is prepared from the following mass fractions of raw materials through high temperature and high pressure:

Cubic boron nitride powder 60%, nano-alumina 30%, Ti powder 10%; among them, the average particle size of cubic boron nitride powder is 300nm, the average particle size of Ti powder is 60nm, and the average particle size of nano-alumina is 20nm.

The preparation method of described PCBN composite sheet, comprises the following steps:

① Cubic boron nitride powder treatment: Put the cubic boron nitride powder in a dilute hydrochloric acid solution with a mass fraction of 30% for 30 minutes and wash it, then put the cubic boron nitride powder after acid treatment into the mass fraction Boil it in 30% NaOH solution for 20 minutes and wash it, centrifuge the cubic boron nitride powder washed by acid and alkali, wash it with distilled water first, then wash it with absolute ethanol alcohol, and then vacuum at 3.0×10 ^-3 at 60°C After vacuum drying at a certain temperature for 24 hours, it is ready for use;

② Mixing: Ball milling on a high-energy ball mill, liquid medium is absolute ethanol, liquid medium: total weight of raw materials: total weight of grinding balls is 2:1:3, the material of grinding balls is hard alloy, the speed is 300r/min, ball milling Time 6h; Vacuum drying at 3.0×10 ^-3 vacuum and temperature of 60°C for 24h;

③Vacuum high-temperature treatment: In order to remove impurities and steam adsorbed on the powder surface, the mixed material obtained in step ② was treated in a vacuum of 3.0×10 ^-3 at a temperature of 900°C for 1 hour;

④Treatment of the cemented carbide substrate: use a magnetron sputtering coater to plate a titanium film with a thickness of 1 μm on the cemented carbide of the surface # word trench, and obtain a cemented carbide substrate whose surface is covered with titanium;

⑤Standard block assembly: Assemble the mixed material obtained in step ③ and the cemented carbide substrate obtained in step ④ into a standard sample block, vacuum-dry at 3.0×10 ^-3 and 200°C for 30 minutes before use;

⑥ High temperature and high pressure preparation: Put the standard sample block obtained in step ⑤ into a six-sided top press to sinter the PCBN composite sheet under high temperature and high pressure. The sintering pressure is 6GPa, the sintering temperature is 1500°C, and the holding time is 10min.

Example 2:

PCBN (polycrystalline cubic boron nitride) composite sheet is prepared from the following mass fractions of raw materials through high temperature and high pressure:

Cubic boron nitride powder 60%, nano-alumina 30%, Al powder + Co powder 10%; among them, the mass ratio of Al powder: Co powder is 1:1, the average particle size of cubic boron nitride powder is 500nm, and the average particle size of Al powder The particle size is < 1μm, the average particle size of Co powder is 400nm, and the average particle size of nano-alumina is 50nm.

The preparation method of described PCBN composite sheet, comprises the following steps:

① Cubic boron nitride powder treatment: Put the cubic boron nitride powder in a dilute hydrochloric acid solution with a mass fraction of 30% for 20 minutes and wash it, then put the cubic boron nitride powder after acid treatment into the mass fraction Boil it in 30% NaOH solution for 30 minutes and wash it, centrifuge the cubic boron nitride powder washed by acid and alkali, wash it with distilled water first, then wash it with absolute ethanol alcohol, and then vacuum at 3.0×10 ^-3 at 70°C ② Mixing: Ball milling on a high-energy ball mill, the liquid medium is anhydrous ethanol, the liquid medium: the total weight of raw materials: the total weight of the balls is 2:1:3, and the material of the balls is hard quality alloy, rotating speed 300r/min, ball milling time 5h; vacuum drying at 3.0×10 ^-3 vacuum, 70°C temperature for 24h;

③Vacuum high-temperature treatment: In order to remove impurities and steam adsorbed on the powder surface, the mixed material obtained in step ② was treated in a vacuum of 3.0×10 ^-3 at a temperature of 800°C for 2 hours;

④Treatment of the cemented carbide substrate: use a magnetron sputtering coater to plate a titanium film with a thickness of 1.5 μm on the cemented carbide of the surface # word trench, and obtain a cemented carbide substrate whose surface is covered with titanium;

⑤Standard block assembly: Assemble the mixed material obtained in step ③ and the cemented carbide substrate obtained in step ④ into a standard sample block, and dry it in vacuum at 3.0×10 ^-3 for 30 minutes at a temperature of 300°C for later use;

⑥ High temperature and high pressure preparation: Put the standard sample block obtained in step ⑤ into a six-sided top press to sinter the PCBN composite sheet under high temperature and high pressure. The sintering pressure is 5.5GPa, the sintering temperature is 1600°C, and the holding time is 20min.

Example 3:

PCBN (polycrystalline cubic boron nitride) composite sheet is prepared from the following mass fractions of raw materials through high temperature and high pressure:

Cubic boron nitride powder 70%, nano-alumina 15%, nano-titanium nitride 5%, Al powder + Co powder 10%; among them, Al powder: Co powder mass ratio is 1:1, cubic boron nitride powder It consists of three particle sizes, the average particle size is 50nm, 300nm, and 800nm, and the mass ratio of the three is 3:5:2. The average particle size of Al powder is < 1μm, the average particle size of Co powder is 400nm, the average particle size of nano-alumina is 20nm, and the average particle size of nano-titanium nitride is 20nm.

The preparation method of described PCBN composite sheet, comprises the following steps:

① Cubic boron nitride powder treatment: Put the cubic boron nitride powder in a dilute hydrochloric acid solution with a mass fraction of 30% and boil it for 30 minutes, then wash it, then put the cubic boron nitride powder after acid treatment into the mass fraction Boil it in 30% NaOH solution for 30 minutes and wash it, centrifuge the cubic boron nitride powder washed by acid and alkali, wash it with distilled water first, then wash it with absolute ethanol alcohol, and then vacuum at 3.0×10 ^-3 at 80°C After vacuum drying for 15 hours at a certain temperature, it is ready for use;

② Mixing: Ball milling on a high-energy ball mill, liquid medium is absolute ethanol, liquid medium: total weight of raw materials: total weight of balls is 2:1:3, ball material is agate, speed is 200r/min, ball milling time is 8h ; Vacuum drying at 3.0×10 ^-3 vacuum and 80°C for 15 hours;

③Vacuum high-temperature treatment: In order to remove impurities and steam adsorbed on the powder surface, the mixed material obtained in step ② was treated in a vacuum of 3.0×10 ^-3 at a temperature of 900°C for 2 hours;

④Treatment of the cemented carbide substrate: use a magnetron sputtering coater to plate a titanium film with a thickness of 2 μm on the cemented carbide of the surface # word trench, and obtain a cemented carbide substrate whose surface is covered with titanium;

⑤Standard block assembly: Assemble the mixed material obtained in step ③ and the cemented carbide substrate obtained in step ④ into a standard sample block, and dry it in vacuum at 3.0×10 ^-3 and 400°C for 30 minutes before use;

⑥ High temperature and high pressure preparation: Put the standard sample block obtained in step ⑤ into a six-sided top press to sinter the PCBN composite sheet under high temperature and high pressure. The sintering pressure is 6GPa, the sintering temperature is 1700°C, and the holding time is 15min.

Claims (8)

1. A method for preparing nano-PCBN composite sheets at high temperature and high pressure with nano-CBN powder, is characterized in that it is realized by the following steps: A. Cubic boron nitride powder treatment: Put the cubic boron nitride powder in a dilute hydrochloric acid solution with a mass fraction of 10% to 30%, boil it for 10min to 50min, wash it, and then put the cubic boron nitride after acid treatment The powder is put into NaOH solution with a mass fraction of 10% to 30%, boiled for 10min to 50min and washed, and the cubic boron nitride powder washed by acid and alkali is centrifuged, washed with distilled water first, and then washed with absolute ethanol. Then vacuum-dry and set aside; B. Mixing: Put nano-alumina, nano-titanium nitride, sintering aid and the treated cubic boron nitride powder into a high-energy ball mill, mix by wet mixing, and vacuum dry after wet mixing; C. Vacuum high-temperature treatment: In order to remove impurities and steam adsorbed on the powder surface, the mixed material obtained in step ② is treated at 10 ^-1 -10 ^-3 vacuum and 800°C-1000°C for 1-3 hours; D, the treatment of cemented carbide substrate: use magnetron sputtering coater to plate a layer of titanium film on the cemented carbide of surface # word ditch, obtain the cemented carbide substrate that the surface is covered by titanium; E. Standard block assembly: Assemble the mixed material obtained in step ③ and the cemented carbide substrate obtained in step ^④ into a standard sample block, and ^vacuum dry it for 20- Standby after 60min; F. High temperature and high pressure preparation: put the standard sample block obtained in step ⑤ into a six-sided top press for high temperature and high pressure sintering to obtain a PCBN composite sheet. 2. The method according to claim 1, characterized in that: the CBN particle size range is < 1 μm. 3. The method according to any one of claims 1 to 2, characterized in that: cubic boron nitride powder 40-90%, nano-alumina 0-30%, nano-titanium nitride 0-10%, sintering Auxiliary agent 1-10%, sintering auxiliary agent is one or more mixtures of Al powder, Ti powder, Co powder, Ni powder, particle size is less than 1μm, nano-alumina powder particle size is less than 50nm, nano-titanium nitride powder The particle size is less than 100nm. 4. The method according to any one of claims 1 to 3, characterized in that: the cubic boron nitride powder can be a single path, or two to three mixed particle sizes. 5. The method according to any one of claims 1 to 4, characterized in that: the vacuum drying temperature is 40°C-80°C, the drying time is 12-24h, and the vacuum degree is 10 ^-1 -10 ^-3 . 6. The method according to any one of claims 1 to 5, characterized in that: the wet mixing liquid medium is acetone or absolute ethanol, the liquid medium: the total weight of raw materials: the total weight of grinding balls is 2:1:3, The material of the grinding ball is cemented carbide or agate; the speed of the ball mill is 200-400r/min, and the milling time is 3-8h. 7. The method according to any one of claims 1 to 6, characterized in that: the thickness of the titanium film coated on the cemented carbide substrate is 0.5-2 μm. 8. The method according to any one of claims 1 to 7, characterized in that: the sintering process parameters are: the sintering pressure is 5-8GPa, the sintering temperature is 1300-1800°C, and the holding time is 5-30min .