CN116043162B

CN116043162B - Nano composite structural coating on surface of titanium alloy cutting tool and preparation method thereof

Info

Publication number: CN116043162B
Application number: CN202310218362.7A
Authority: CN
Inventors: 谢启; 付志强; 康嘉杰; 朱丽娜; 岳�文; 佘丁顺
Original assignee: Zhengzhou Research Institute China University Of Geosciences Beijing; China University of Geosciences Beijing
Current assignee: Zhengzhou Research Institute China University Of Geosciences Beijing; China University of Geosciences Beijing
Priority date: 2023-03-09
Filing date: 2023-03-09
Publication date: 2023-06-06
Anticipated expiration: 2043-03-09
Also published as: CN116043162A

Abstract

The invention discloses a nano composite structural coating on the surface of a titanium alloy cutting tool and a preparation method thereof, and particularly relates to the field of cutting tool protective coatings. The coating comprises a compact nanocrystalline structure metal connecting layer arranged on a cutter substrate; a dense nanocrystalline structure ceramic gradient transition layer arranged on the dense nanocrystalline structure metal connecting layer; a dense CrSiN nano composite structure reinforced supporting layer arranged on the dense nanocrystalline structure ceramic gradient transition layer; and a plurality of periodic functional layers are arranged on the reinforced supporting layer of the compact CrSiN nano composite structure. The nano composite structure coating provided by the invention has excellent film-base bonding strength and higher mechanical property, and obviously reduces cracking and peeling of the coating in the cutting process; the arrangement of the multi-layer periodic functional layer greatly reduces the adhesion and abrasion of the surface of the cutter, improves the cutting machining performance of the cutter, and prolongs the service life of the coated cutter by more than 10 times compared with the uncoated cutter substrate.

Description

Nano composite structural coating on surface of titanium alloy cutting tool and preparation method thereof

Technical Field

The invention relates to the field of cutter protective coatings for cutting, in particular to a titanium alloy cutting cutter surface nano composite structure coating and a preparation method thereof.

Background

The titanium alloy has the characteristics of high specific strength, high specific rigidity, excellent heat resistance, excellent corrosion resistance and the like, and is widely applied to the fields of modern national defense, aerospace, automobiles and ships, chemistry, biomedicine and the like. However, titanium alloy is also a typical difficult-to-machine material, and problems such as high temperature in a cutting area, poor quality of a machined surface, serious abrasion of a cutting tool and the like are easy to occur even under a lower cutting amount, so that the improvement of the production efficiency and the reduction of the production cost of titanium alloy parts are greatly limited. Achieving high quality and high efficiency cutting of titanium alloy materials is a hot spot of concern for modern machine manufacturing.

The main reasons for the inefficiency of cutting the titanium alloy material include the following four points. First, the titanium alloy has a small deformation coefficient, and is liable to cause a large cutting force, resulting in chipping of the cutting tool. Secondly, the elastic modulus of the titanium alloy is small, and larger deformation and elastic recovery are easy to occur during cutting machining, so that severe vibration of a machined part is caused, and the quality of the machined surface is poor and the abrasion of a cutter is aggravated. Thirdly, the titanium alloy has poor heat conduction performance, heat aggregation is easy to cause, and the temperature of a cutting area is increased, so that not only can the oxidative wear of the surface of a cutter be accelerated, but also the element interdiffusion between the cutter material and the titanium alloy material can be promoted, and serious adhesive wear and even cutter sticking phenomenon occur. Fourth, the high-temperature chemical activity of the titanium alloy is high, on one hand, the adhesion phenomenon between the titanium alloy and the cutter material can be further aggravated; on the other hand, the titanium alloy material is easy to react with elements such as hydrogen, oxygen, nitrogen and the like in the air at high temperature to form a hardening layer, so that a serious chill condition is caused. Therefore, the mechanical property and the frictional wear property of the surface of the titanium alloy cutting tool are enhanced, and the high-temperature oxidation resistance and the anti-adhesion property of the surface of the tool have obvious influence on improving the cutting processing efficiency of the titanium alloy material and prolonging the service life of the tool.

Currently, tools for titanium alloy cutting machining mainly include uncoated cemented carbide tools, coated cemented carbide tools, and superhard material tools typified by Polycrystalline Cubic Boron Nitride (PCBN) and polycrystalline diamond (PCD). Superhard material cutters have high thermal conductivity and hardness, but in view of their high cost, it is difficult to apply them to industrial production on a large scale. Compared with a non-coated hard alloy cutter, the coated hard alloy cutter can reduce the problem of Co binder diffusion to the surface caused by high cutting heat due to the existence of the surface protective coating, and can maintain the mechanical property of the hard alloy cutter substrate for a longer time. The protective coating of the cutter commonly used at present, such as TiN, crN, tiAlN, tiCN, has higher hardness and wear resistance, and can further improve the cutting machining performance and the service life of the cutter. However, due to the high chemical activity of the titanium element, the titanium alloy has strong affinity to common coating elements, and is easy to cause the phenomenon of 'sticking knife' and severe adhesive abrasion and even peeling of the coating on the surface of the cutter. In summary, developing a novel tool surface protective coating with high hardness, excellent friction and wear performance, high temperature resistance and anti-adhesion performance, comprehensively improving the cutting efficiency of the titanium alloy material and the service life of the tool is a technical problem to be solved by those skilled in the art.

Patent CN 108251797A discloses a TiAlN/CrN multilayer coating for a titanium alloy cutting tool and a preparation method thereof, wherein the coating adopts a magnetron sputtering process to form a nano multilayer structure by alternately depositing a plurality of TiAlN and CrN layers, but because of strong chemical affinity of titanium to aluminum element, adhesion is easy to occur, and further the coating is seriously adhered, worn and peeled off.

Patent CN 114318226A discloses an AlCrN/WN multilayer structure hard coating for titanium alloy cutting and a preparation method thereof, wherein the coating adopts an arc ion plating and direct current magnetron sputtering composite technology to deposit a multilayer AlCrN/WN coating, but a large number of columnar crystal boundaries exist in the coating, and a channel is provided for diffusion of elements such as oxygen, titanium and the like to the inside of the coating and a film-based interface at a higher service temperature, so that severe oxidative wear and peeling are initiated.

Disclosure of Invention

Therefore, the invention provides a nano composite structure coating on the surface of a titanium alloy cutting tool and a preparation method thereof, which aim to solve the problems of serious surface abrasion, easy peeling of the coating and the like of the conventional titanium alloy cutting tool.

The high-temperature resistant and wear-resistant layer of the compact CrSiCN nano composite structure obtained by improving the technological parameters such as substrate bias voltage, substrate bias current and the like in the preparation process of the plasma enhanced magnetron sputtering can obviously enhance the thermal stability, red hardness and wear resistance of the coating at high temperature due to the effects of fine crystal strengthening, solid solution strengthening and amorphous wrapping nano crystal strengthening; the nano microporous CrSiCN anti-adhesion antifriction layer is obtained by reducing the technological parameters such as substrate bias voltage, substrate bias current and the like in the preparation process of the plasma enhanced magnetron sputtering, so that the adhesion of titanium alloy on the surface of a cutter in the cutting process can be effectively reduced, and the friction coefficient is reduced. The nano composite structure coating also prevents dislocation and crack from sprouting and expanding in the coating and at the membrane-base interface through the arrangement of different functional layers and the design of a multi-layer composite structure, inhibits the diffusion of elements such as oxygen, hydrogen, titanium and the like to the inside of the coating and the membrane-base interface, further enhances the overall fracture toughness, mechanical property and friction and wear property of the coating and the membrane-base bonding strength of the coating between cutter substrates, and greatly improves the surface quality of processed parts and the service life of cutters.

In order to achieve the above object, the present invention provides the following technical solutions:

according to the nano composite structure coating on the surface of the titanium alloy cutting tool provided by the aspect of the invention, the coating comprises a dense nano crystal structure metal connecting layer arranged on a tool substrate; to improve the film-based bond strength between the subsequent coating and the tool substrate;

a dense nanocrystalline structure ceramic gradient transition layer arranged on the dense nanocrystalline structure metal connecting layer; so as to realize the gradient transition of interface performance between the soft metal connecting layer and the subsequent hard layer and further improve the film-base binding force;

a dense CrSiN nano composite structure reinforced supporting layer arranged on the dense nanocrystalline structure ceramic gradient transition layer; so as to improve the overall hardness and toughness of the coating;

a multi-layer periodic functional layer is arranged on the compact CrSiN nano composite structure reinforced supporting layer and consists of a plurality of alternately deposited compact CrSiCN nano composite structure high-temperature resistant wear-resistant layers and nano microporous structure CrSiCN anti-adhesion antifriction layers; so as to improve the long-acting wear-resistant antifriction performance of the surface of the coating.

Further, the metal connecting layer with the compact nanocrystalline structure is a Cr-based alloy material containing W, and the microstructure is a compact nanocrystalline columnar crystal or nanocrystalline equiaxed crystal structure; as an example, the elements contained are in atomic percent: cr:100-95 at%, W:0-5 at% and the microstructure is a compact nano columnar crystal or nano equiaxed crystal structure.

And/or the ceramic gradient transition layer with the compact nanocrystalline structure is CrN containing W and having gradient distribution of Cr and N _x The microstructure of the material is a compact nano columnar crystal or nano equiaxed crystal structure;

as an example, the elements contained are in atomic percent: cr:100-40 at.% gradient decreasing, N:0-55 at% gradient increment, W:0-5 at% and the microstructure is a compact nano columnar crystal or nano equiaxed crystal structure.

And/or the compact CrSiN nano composite structure reinforced supporting layer contains a CrSiN material of W, and the microstructure is a compact amorphous wrapped nano crystal nano composite structure;

as an example, the elements contained are in atomic percent: cr:25-45 at%, si:5-15 at%, N:45-55 at%, W:0-5 at% and the microstructure is a compact amorphous-coated nanocrystalline nanocomposite structure.

Further, the multilayer periodic functional layer is composed of a plurality of alternately deposited compact CrSiCN nano composite structure high-temperature resistant and wear-resistant layers and nano microporous structure CrSiCN anti-adhesion antifriction layers.

Further, the high-temperature-resistant and wear-resistant layer of the compact CrSiCN nano composite structure is made of a CrSiCN material containing W, and the microstructure is a compact amorphous wrapping nanocrystalline nano composite structure;

as an example, the elements contained are in atomic percent: cr:25-45 at%, si:5-15 at%, C:2-10 at, N:40-53 at%, W:0-5 at% and the microstructure is a compact amorphous-coated nanocrystalline nanocomposite structure.

Further, the nano microporous structure CrSiCN anti-adhesion antifriction layer is made of a CrSiCN material containing W, and the microstructure is a nano microporous structure;

as an example, the elements contained are in atomic percent: cr:25-48 at%, si:0.5-2 at%, C:15-25 at%, N:20-40 at%, W:0-5 at% and the microstructure is nano-microporous structure.

Further, the total thickness of the nano composite structure coating is 2-10 mu m;

and/or the thickness of the compact nanocrystalline structure metal connecting layer is 30-300 nm;

and/or the thickness of the ceramic gradient transition layer with the compact nanocrystalline structure is 50-500 nm;

and/or the thickness of the compact CrSiN nano composite structure reinforced supporting layer is 1-5 mu m;

and/or the thickness of the multi-layer periodic functional layer is 1-8 μm.

Further, in the multilayer periodic functional layer, the thickness of the high-temperature resistant and wear-resistant layer of the compact CrSiCN nano composite structure is 10-200 nm;

and/or the thickness of the single-layer nano microporous CrSiCN anti-adhesion antifriction layer is 10-300 nm.

According to the preparation method of the nano composite structure coating on the surface of the titanium alloy cutting tool provided by the invention, the method is a plasma enhanced unbalanced magnetron sputtering method;

comprising the following steps: firstly, carrying out surface pretreatment on a cutter substrate; for cleaning a tool substrate;

carrying out glow cleaning on the cutter substrate by using hot filament plasma; for deep cleaning and activating the substrate surface;

finally, carrying out surface nano composite structure coating deposition on the cutter substrate; for depositing the nanocomposite structured coating.

Further, the cutter substrate surface pretreatment method comprises the steps of immersing the cutter substrate into a metal cleaning agent aqueous solution for cleaning; rinsing the cutter substrate in deionized water; immersing the cutter substrate into absolute ethyl alcohol for ultrasonic cleaning; and finally, drying the cutter substrate by using compressed gas in a cold air manner, placing the cutter substrate in a drying box for drying, and then placing the cutter substrate in a film coating cavity.

As an example, the tool substrate surface pretreatment method includes: immersing the cutter substrate into a metal cleaning agent aqueous solution for ultrasonic cleaning for 1-3 times, wherein each time is 10-30 min; rinsing the cutter substrate in deionized water for 2-5 times; then immersing the cutter substrate into absolute ethyl alcohol for ultrasonic cleaning for 1-2 times, wherein each time is 5-15 min; and then drying the cutter substrate by using compressed gas, putting the cutter substrate into a drying box, drying the cutter substrate at 50-150 ℃ for 30-120 min, and then putting the cutter substrate into a coating cavity.

Further, the hot wire plasma glow cleaning method of the cutter substrate comprises the following steps:

1) Vacuumizing the film coating chamber and slowly heating;

2) Argon is introduced into the coating cavity, the air pressure in the coating cavity is controlled, and the glow wire plasma glow cleaning of the cutter substrate is carried out.

As an example, the hot wire plasma glow cleaning method of the tool substrate includes:

1) Vacuumizing and slowly heating the film coating chamber, wherein the heating temperature of the film coating chamber is set to be 200-500 ℃, and the background vacuum degree is better than 5 multiplied by 10 ^-3 Pa, the rotating speed of the workpiece frame is 5-80 rpm.

2) Argon with the flow of 40-90 sccm is introduced into the film coating cavity to control the air pressure in the film coating cavity to be 0.2-0.8 Pa, the pulse bias amplitude of the matrix is 300-1000V, the frequency is 20-80 kHz, the duty ratio is 10-90%, the hot wire discharge voltage is 40-200V, the hot wire heating current is 10-50A, the bias current of the matrix is 3-10A by adjusting the hot wire heating current, and the glow cleaning time of the cutter substrate is 10-120 min.

Further, the method for depositing the nano composite structure coating on the surface of the cutter substrate comprises the following steps: and (3) depositing a metal connecting layer with a compact nanocrystalline structure, depositing a ceramic gradient transition layer with a compact nanocrystalline structure, depositing a reinforced supporting layer with a compact CrSiN nano composite structure and depositing a multi-layer periodic functional layer.

As an example, the tool substrate surface nanocomposite structured coating deposition method includes:

1) Depositing a metal connecting layer with a compact nanocrystalline structure: the heating temperature of the film coating chamber is 200-500 ℃, the rotating speed of the workpiece frame is 5-80 rpm, the argon flow is 40-90 sccm, the air pressure in the film coating chamber is controlled to be 0.2-0.8 Pa, the matrix pulse bias amplitude is 50-200V, the frequency is 20-80 kHz, the duty ratio is 10-90%, and the hot wire discharge is carried outThe electric voltage is 40-200V, the heating current of the hot wire is 10-50A, the bias current of the substrate is 3-10A by adjusting the heating current of the hot wire, and the power density of the Cr target is 2-10W/cm ² The deposition time of the metal connecting layer with the compact nanocrystalline structure is 2-15 min.

2) Depositing a ceramic gradient transition layer with a compact nanocrystalline structure: the heating temperature of the film coating chamber is 200-500 ℃, the rotating speed of the workpiece frame is 5-80 rpm, the flow rate of argon is 40-90 sccm, nitrogen with the flow rate gradient increased to 60-120 sccm is introduced into the film coating chamber and can be divided into 2-5 gradients, so that the air pressure in the film coating chamber is controlled to be 0.2-1.2 Pa, the pulse bias amplitude of a substrate is 50-200V, the frequency is 20-80 kHz, the duty ratio is 10-90%, the discharge voltage of a hot wire is 40-200V, the heating current of the hot wire is 10-50A, the bias current of the substrate is 3-10A, and the power density of a Cr target is 2-10W/cm by adjusting the heating current of the hot wire ² The deposition time of each gradient transition layer is 2-15 min.

3) Deposition of a reinforced supporting layer of a compact CrSiN nano composite structure: the heating temperature of the film coating chamber is 200-500 ℃, the rotating speed of a workpiece frame is 5-80 rpm, the argon flow is 40-90 sccm, the nitrogen flow is 60-120 sccm, silane with the flow of 10-30 sccm is further introduced into the film coating chamber, the air pressure in the film coating chamber is controlled to be 0.2-1.5 Pa, the pulse bias amplitude of a substrate is 50-200V, the frequency is 20-80 kHz, the duty ratio is 10-90%, the discharge voltage of a hot wire is 40-200V, the heating current of the hot wire is 10-50A, the bias current of the substrate is 3-10A, and the power density of a Cr target is 2-10W/cm by adjusting the heating current of the hot wire ² The coating deposition time is 30-300 min.

4) Multilayer periodic functional layer: when a single layer of high-temperature resistant and wear-resistant layer with a compact CrSiCN nano composite structure is deposited, the heating temperature of a coating cavity is 200-500 ℃, the rotating speed of a workpiece frame is 5-80 rpm, the flow rate of argon is 40-90 sccm, the flow rate of nitrogen is 60-120 sccm, silane with the flow rate of 10-30 sccm and methane with the flow rate of 2-15 sccm are introduced into the coating cavity, the air pressure in the coating cavity is controlled to be 0.2-1.5 Pa, and the power density of Cr targets is 2-10W/cm ² The matrix pulse bias amplitude is 50-200V, the frequency is 20-80 kHz, the duty ratio is 10-90%, the hot wire discharge voltage is 40-200V, the hot wire heating current is 10-50A, and the pulse bias is controlled by adjustingHeating the current by the heat-saving wire to enable the bias current of the substrate to be 3-10A, and enabling the single-layer deposition time to be 2-20 min; when depositing the monolayer of the anti-adhesion antifriction layer of the CrSiCN with the nano micropore structure, the heating temperature of the film coating chamber is 200-500 ℃, the rotating speed of the workpiece frame is 5-80 rpm, the argon flow is 40-90 sccm, the nitrogen flow is 60-120 sccm, the silane flow is 1-5 sccm, the methane flow is 20-35 sccm, the air pressure in the film coating chamber is controlled to be 0.2-1.5 Pa, and the power density of the Cr target is 2-10W/cm ² The matrix pulse bias voltage amplitude is 0-50V, the frequency is 20-80 kHz, the duty ratio is 10-90%, the hot wire discharge voltage is 40-200V, the hot wire heating current is 0-15A, the matrix bias current is 0.1-2A by adjusting the hot wire heating current, and the monolayer deposition time is 4-80 min. The modulation period is 2-400.

And after the film coating is finished, turning off a sputtering power supply, a hot wire discharging power supply, a hot wire heating power supply and a matrix pulse bias power supply, turning off all the gas flow meters, turning off the heating of the vacuum chamber, and taking out the titanium alloy cutting tool with the nano composite structure coating after the temperature of the film coating chamber is reduced to 100 ℃.

The invention has the following advantages:

(1) The nano composite structure coating provided by the invention has excellent film-base bonding strength and higher mechanical property, can keep the red hardness of the cutter surface at more than 600 ℃ and high toughness and high-temperature oxidation resistance at more than 1000 ℃, and remarkably reduces cracking and peeling of the coating in the cutting process; meanwhile, the adhesion and abrasion of the surface of the cutter are greatly reduced by the arrangement of the multi-layer periodic functional layers, and the cutting machining performance of the cutter is improved, so that the service life of the coated cutter is prolonged by more than 10 times compared with that of a cutter substrate without a coating.

(2) Compared with the traditional magnetron sputtering technology, the plasma density is remarkably enhanced by utilizing the plasma enhanced unbalanced magnetron sputtering technology, the preparation method of the coating provided by the invention can not only obtain a compact nano composite structure high-hardness high-toughness coating, but also prepare a micro-texture anti-adhesion coating with a nano micropore structure by flexibly regulating and controlling the plasma density near a substrate in the deposition process of different film layers, and can comprehensively enhance the mechanical property, high temperature resistance and wear resistance and antifriction property of the coating by combining the design of a multilayer film.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It will be apparent to those of ordinary skill in the art that the drawings in the following description are exemplary only and that other implementations can be obtained from the extensions of the drawings provided without inventive effort.

The structures, proportions, sizes, etc. shown in the present specification are shown only for the purposes of illustration and description, and are not intended to limit the scope of the invention, which is defined by the claims, so that any structural modifications, changes in proportions, or adjustments of sizes, which do not affect the efficacy or the achievement of the present invention, should fall within the ambit of the technical disclosure.

FIG. 1 is a schematic structural diagram of a nanocomposite coating on a surface of a titanium alloy cutting tool according to example 1 of the present invention;

FIG. 2 is a flow chart of a process for preparing a nano composite structural coating on the surface of a titanium alloy cutting tool provided by the embodiment 1 of the invention;

in the figure, a 1-cemented carbide substrate; 2-a dense nanocrystalline structure metal connection layer; 3-a ceramic gradient transition layer with a compact nanocrystalline structure; 4-a reinforced supporting layer of a compact CrSiN nano composite structure; a 5-compact CrSiCN nano composite structure high-temperature resistant and wear-resistant layer; 6-a CrSiCN anti-adhesion antifriction layer with a nano micropore structure; 7-multiple periodic functional layers.

Detailed Description

Other advantages and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, by way of illustration, is to be read in connection with certain specific embodiments, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Example 1

The embodiment provides a tool with a carbide-cobalt hard alloy as a tool substrate.

The nano composite structure coating on the surface of the titanium alloy cutting tool has a structure shown in figure 1 and comprises a metal connecting layer with a compact nano crystal structure, a ceramic gradient transition layer with a compact nano crystal structure, a reinforced supporting layer with a compact CrSiN nano composite structure and a multi-layer periodic functional layer. Wherein, the multilayer periodic functional layer comprises a plurality of alternately deposited compact CrSiCN nano composite structure high-temperature resistant and wear-resistant layers and nano microporous structure CrSiCN anti-adhesion antifriction layers:

the total thickness of the nano composite structure coating is 4.3 mu m, the thickness of the compact nanocrystalline structure metal connecting layer is 78 nm, and the thickness of the compact nanocrystalline structure ceramic gradient transition layer is 170 nm; the thickness of the compact CrSiN nano composite structure reinforced supporting layer is 1.7 mu m; the thickness of the multilayer periodic functional layer is 2.4 mu m, wherein the thickness of the single-layer high-temperature resistant and wear-resistant layer of the compact CrSiCN nano composite structure is 35 nm; the thickness of the monolayer of the CrSiCN anti-adhesion antifriction layer with the nano micropore structure is 125 nm.

The dense nanocrystalline structure metal connection layer: the elements contained in the alloy are as follows in atom percent: cr:96.9 at.%, W:3.1 at.%, the microstructure is a compact nano columnar crystal structure;

the ceramic gradient transition layer with the compact nanocrystalline structure comprises three layers: the first transition layer comprises the following elements in atomic percent: cr:76.3 at.%, W:3.5 at.%, N:20.2 at%, thickness of 65 nm, and microstructure of compact nano columnar crystal structure; the second transition layer comprises the following elements in atom percent: cr:60.1 at.%, W:3.6 at.%, N:36.3 at.%, thickness is 55 nm, microstructure is compact nano columnar crystal structure; the third transition layer comprises the following elements in atomic percent: cr:46.4 at.%, W:3.6 at.%, N:50.0 at%, the thickness is 50 nm, and the microstructure is a compact nano columnar crystal structure;

the dense CrSiN nano composite structure reinforced supporting layer comprises: the elements contained in the alloy are as follows in atom percent: cr:39.2 at.%, W:3.9 at.%, si:9.0 at.%, N:47.9 at.%, the microstructure is a compact amorphous-coated nanocrystalline nanocomposite structure;

the multilayer periodic functional layer comprises a plurality of compact multi-element nano composite structure high-temperature resistant wear-resistant layers and nano microporous structure anti-adhesion antifriction layers which are alternately deposited, wherein the single-layer compact CrSiCN nano composite structure high-temperature resistant wear-resistant layers comprise the following elements in percentage by atom: cr:34.5 at.%, W:4.0 at.%, si:10.4 at.%, C: 5.9 at.%, N:45.2 at.%, the microstructure is a compact amorphous-coated nanocrystalline nanocomposite structure; anti-adhesion antifriction layer of monolayer nano-microporous structure: the elements contained in the alloy are as follows in atom percent: 43.8 at.%, W:3.1 at.%, si:1.1 at.%, C: 21.2 at.%, N:30.8 at.%, the microstructure is a nano microporous structure; the modulation period is 15.

The preparation method of the nano composite structure coating on the surface of the cutter comprises the following steps:

(1) Pretreatment of a hard alloy cutter substrate: soaking a hard alloy cutter substrate in a 5% metal cleaning agent aqueous solution, and ultrasonically cleaning for 2 times at 40 ℃ for 20 min each time; rinsing the substrate in deionized water for 3 times to remove the residual metal cleaning agent on the surface of the substrate, and then immersing the substrate in absolute ethyl alcohol for ultrasonic cleaning for 15 min; and then drying by using compressed nitrogen air, and finally putting the cutter substrate into a drying box, drying at 80 ℃ for 45 min and then loading into a coating cavity.

(2) The hot wire plasma glow cleaning of the hard alloy cutter substrate comprises the following three steps:

a. vacuumizing the film coating chamber and slowly heating to 300 deg.C and 2×10 background vacuum ^-3 Pa, turning on the workpiece frame to rotate at 15 rpm, turning on a hot wire discharge power supply, turning on a hot wire discharge voltage amplitude of 80V, turning on a hot wire heating power supply, slowly increasing hot wire heating current to 12A so as to further remove residual air in a coating cavity, wherein the air pressure in the coating cavity is lower than 2×10 again ^-3 After Pa, reducing the hot wire heating current to 3A;

b. argon with the flow of 60 sccm is introduced into the film coating cavity, so that the air pressure in the film coating cavity is 0.40 and Pa, a matrix pulse bias power supply is turned on, the matrix pulse bias amplitude is 600V, the frequency is 60 kHz, the duty ratio is 40%, the hot wire discharge voltage is 80V, the hot wire heating power is adjusted to 35A, the matrix bias current is 6.0 and A, and the glow cleaning time of the hard alloy cutter substrate is 45 min.

(3) The nano composite structure coating deposition on the surface of the cutter substrate comprises the following four steps:

a. depositing a metal connecting layer with a compact nanocrystalline structure: the heating temperature of the film coating chamber is 300 ℃, the rotating speed of the workpiece frame is 15 rpm, the argon flow is 60 sccm, the air pressure in the film coating chamber is kept to be 0.40 Pa, the pulse bias amplitude of the matrix is 100V, the frequency is 60 kHz, the duty ratio is 60%, the discharge voltage of the hot wire is 80V, the heating current of the hot wire is regulated to 28A, so that the bias current of the matrix is 4.5A, and the power density of the Cr target is 3.5W/cm ² And depositing a metal connecting layer with a compact nanocrystalline structure, wherein the deposition time of the coating is 5 min.

b. Depositing a ceramic gradient transition layer with a compact nanocrystalline structure: the heating temperature of the film coating chamber is 300 ℃, the rotating speed of the workpiece frame is 15 rpm, the argon flow is 60 sccm, the matrix pulse bias amplitude is 100V, the frequency is 60 kHz, the duty ratio is 60%, the hot wire discharge voltage is 80V, the hot wire heating current is regulated to 31A, so that the matrix bias current is 4.5A, and the Cr target power density is 3.5W/cm ² Introducing nitrogen into the coating cavity, firstly setting the flow rate of the nitrogen to 40 sccm to ensure that the air pressure in the coating cavity is 0.45 and Pa, and depositing a first layer of dense nanocrystalline structure ceramic gradient transition layer for 5 min; then regulating the flow of nitrogen to 60 sccm to ensure that the air pressure in the film plating chamber is 0.55 and Pa, and depositing a second layer of ceramic gradient transition layer with a compact nanocrystalline structure for 5 minutes; finally, regulating the flow of nitrogen to 80 sccm to ensure that the air pressure in the film plating chamber is 0.70 and Pa, and depositing a third layer of ceramic gradient transition layer with a compact nanocrystalline structure for 5 min.

c. Deposition of a reinforced supporting layer of a compact CrSiN nano composite structure: heating temperature of the coating chamber is 300 ℃, and the workpieceThe rotating speed of the frame is 15 rpm, the argon flow is 60 sccm, the nitrogen flow is 80 sccm, silane with the flow of 20 sccm is introduced into the film coating cavity, the air pressure in the film coating cavity is 0.90 Pa, the pulse bias amplitude of the matrix is 100V, the frequency is 60 kHz, the duty ratio is 60%, the discharge voltage of the hot wire is 100V, the heating current of the hot wire is regulated to 30A, the bias current of the matrix is 4.5A, and the power density of Cr target is 3.5W/cm ² The coating deposition time was 210 min.

d. Multilayer periodic functional layer: when a single layer of a compact multi-element nanocomposite structure high temperature resistant wear layer is deposited: the heating temperature of the film coating chamber is 300 ℃, the rotating speed of the workpiece frame is 15 rpm, the argon flow is 60 sccm, the nitrogen flow is 80 sccm, the silane flow is 20 sccm, and the methane flow is 10 sccm, so that the air pressure in the film coating chamber is 1.05 Pa, and the power density of the Cr target is 3.5W/cm ² The matrix pulse bias voltage amplitude is 100V, the frequency is 60 kHz, the duty ratio is 60%, the hot wire discharge voltage is set to be 100V, the hot wire heating current is regulated to be 30A, so that the matrix bias current is 4.5A, and the monolayer deposition time is 5 min; when depositing a monolayer of anti-stiction friction reducing layer of a nanopore structure: the heating temperature of the film coating chamber is 300 ℃, the rotating speed of a workpiece frame is 15 rpm, the argon flow is 60 sccm, the nitrogen flow is 80 sccm, the silane flow is 2 sccm, the methane flow is 25 sccm, the air pressure in the film coating chamber is 1.00 and Pa, the pulse bias amplitude of a substrate is 40V, the frequency is 60 kHz, the duty ratio is 60%, the discharge voltage of a hot wire is 80V, the heating current of the hot wire is 10A, the bias current of the substrate is 1.5 and A by adjusting the heating current of the hot wire, and the single-layer deposition time is 10 min; the modulation period was set to 15 and the total deposition time of the multi-layer periodic functional layer was 225 min.

And after the film coating is finished, turning off a sputtering power supply, a hot wire discharging power supply, a hot wire heating power supply and a matrix pulse bias power supply, turning off all the gas flow meters, turning off the heating of the vacuum chamber, and taking out the carbide-cobalt hard alloy cutter for cutting the titanium alloy coated with the nano composite structure coating after the temperature of the film coating chamber is reduced to 100 ℃.

Example 2

The present embodiment provides a tool substrate that is a PCBN tool.

A nano composite structure coating on the surface of a titanium alloy cutting tool comprises a compact nanocrystalline structure metal connecting layer, a compact nanocrystalline structure ceramic gradient transition layer, a compact CrSiN nano composite structure reinforced supporting layer and a multi-layer periodic functional layer. Wherein, the multilayer periodic functional layer comprises a plurality of alternately deposited compact CrSiCN nano composite structure high-temperature resistant and wear-resistant layers and nano microporous structure CrSiCN anti-adhesion antifriction layers:

the total thickness of the nano composite structure coating is 9.6 mu m, the thickness of the compact nanocrystalline structure metal connecting layer is 102 nm, and the thickness of the compact nanocrystalline structure ceramic gradient transition layer is 292 nm; the thickness of the compact CrSiN nano composite structure reinforced supporting layer is 3.9 mu m; the thickness of the multilayer periodic functional layer is 5.3 mu m, wherein the thickness of the single-layer high-temperature resistant and wear-resistant layer of the compact CrSiCN nano composite structure is 101 nm; the thickness of the monolayer of the CrSiCN anti-adhesion antifriction layer with the nano micropore structure is 162 and nm.

The dense nanocrystalline structure metal connection layer: the elements contained in the alloy are as follows in atom percent: cr:97.2 at.%, W:2.8 at.%, the microstructure is a compact nano columnar crystal structure;

the ceramic gradient transition layer with the compact nanocrystalline structure comprises four layers: the first transition layer comprises the following elements in atomic percent: cr:85.2 at.%, W:3.1 at.%, N:11.7 at%, the thickness is 95 nm, and the microstructure is a compact nano columnar crystal structure; the second transition layer comprises the following elements in atom percent: cr:75.2 at.%, W:3.3 at.%, N:21.5 at.%, the thickness is 87 nm, and the microstructure is a compact nano columnar crystal structure; the third transition layer comprises the following elements in atom percent: cr:58.6 at.%, W:3.3 at.%, N:38.1 at.%, thickness is 72 nm, microstructure is compact nano columnar crystal structure; the fourth transition layer contains the following elements in atom percent: cr:44.8 at.%, W:3.6 at.%, N:51.6 at%, thickness of 65 nm, and microstructure of compact nano columnar crystal structure;

the dense CrSiN nano composite structure reinforced supporting layer comprises: the elements contained in the alloy are as follows in atom percent: cr:37.3 at.%, W:3.8 at.%, si:11.2 at.%, N:47.7 at.%, the microstructure is a compact amorphous-coated nanocrystalline nanocomposite structure;

the total thickness of the multilayer periodic functional layer is 5.3 mu m, the multilayer periodic functional layer comprises a plurality of compact multi-element nano composite structure high-temperature-resistant wear-resistant layers and nano micropore structure anti-adhesion antifriction layers which are alternately deposited, wherein the single-layer compact CrSiCN nano composite structure high-temperature-resistant wear-resistant layers comprise the following elements in percentage by atom: cr:33.7 at.%, W:3.7 at.%, si:11.2 at.%, 3.9: 3.9 at.%, N:47.5 at.%, the microstructure is a compact amorphous-coated nanocrystalline nanocomposite structure; anti-adhesion antifriction layer of monolayer nano-microporous structure: the elements contained in the alloy are as follows in atom percent: 44.3 at.%, W:3.1 at.%, si:0.8 at.%, 20.6: 20.6 at.%, N:31.1 at.%, the microstructure is a nano microporous structure; the modulation period is 20.

A preparation method of a nano composite structural coating on the surface of a titanium alloy cutting tool comprises the following steps:

(1) PCBN cutter substrate pretreatment: immersing the PCBN cutter substrate in 5% metal cleaner aqueous solution, and ultrasonically cleaning for 3 times at 40 ℃ for 20 min each time; rinsing the substrate in deionized water for 3 times to remove residual metal cleaning agent on the surface of the substrate, and then immersing the substrate in absolute ethyl alcohol for ultrasonic cleaning for 2 times, wherein each time is 20 min; and then drying by compressed nitrogen, and finally putting the cutter substrate into a drying box, drying at 100 ℃ for 60 min, and then loading into a coating cavity.

(2) The hot filament plasma glow cleaning of the PCBN tool substrate comprises the following three steps:

a. vacuumizing the film coating chamber and slowly heating to 350 deg.C and 2×10 background vacuum ^-3 Pa, turning on the workpiece frame to rotate at 15 rpm, turning on a hot wire discharge power supply, turning on a hot wire discharge voltage amplitude of 80V, turning on a hot wire heating power supply, slowly increasing hot wire heating current to 11A so as to further remove residual air in a coating cavity, wherein the air pressure in the coating cavity is lower than 2×10 again ^-3 After Pa, reducing the hot wire heating current to 3A;

b. argon with the flow of 60 sccm is introduced into the film coating cavity, so that the air pressure in the film coating cavity is 0.42 and Pa, a matrix pulse bias power supply is turned on, the matrix pulse bias amplitude is 700V, the frequency is 60 kHz, the duty ratio is 40%, the hot wire discharge voltage is 80V, the hot wire heating power is adjusted to 35A, the matrix bias current is 6.0A, and the glow cleaning time of the PCBN tool substrate is 60 minutes.

a. depositing a metal connecting layer with a compact nanocrystalline structure: the heating temperature of the coating cavity is 350 ℃, the rotating speed of the workpiece frame is 15 rpm, the argon flow is 60 sccm, the air pressure in the coating cavity is kept to be 0.42 Pa, the pulse bias amplitude of the matrix is 100V, the frequency is 60 kHz, the duty ratio is 60%, the discharge voltage of the hot wire is 80V, the heating current of the hot wire is regulated to 29A, so that the bias current of the matrix is 4.5A, and the power density of the Cr target is 4.8W/cm ² And depositing a metal connecting layer with a compact nanocrystalline structure, wherein the deposition time of the coating is 5 min.

b. Depositing a ceramic gradient transition layer with a compact nanocrystalline structure: the heating temperature of the film coating chamber is 350 ℃, the rotating speed of the workpiece frame is 15 rpm, the argon flow is 60 sccm, the matrix pulse bias voltage amplitude is 100V, the frequency is 60 kHz, the duty ratio is 60%, the hot wire discharge voltage is 80V, the hot wire heating current is regulated to 30A, so that the matrix bias current is 4.5A, and the Cr target power density is 4.8W/cm ² Then introducing nitrogen into the coating cavity, firstly setting the flow rate of the nitrogen to be 35 sccm to ensure that the air pressure in the coating cavity is 0.47 and Pa, and depositing a first ceramic gradient transition layer for 5 min; then regulating the flow of nitrogen to 60 sccm to ensure that the air pressure in the film plating cavity is 0.56 and Pa, and depositing a second ceramic gradient transition layer for 5 minutes; then regulating the flow of nitrogen to be 85 sccm to ensure that the air pressure in the film coating cavity is 0.66 and Pa, and depositing a second ceramic gradient transition layer for 5 minutes; finally, regulating the flow of nitrogen to 110 sccm to ensure that the air pressure in the film plating cavity is 0.78 and Pa, and depositing a third ceramic gradient transition layer for 5 min.

c. Deposition of a reinforced supporting layer of a compact CrSiN nano composite structure: the heating temperature of the coating chamber is 350 ℃, the rotating speed of the workpiece frame is 15 rpm, the argon flow is 60 sccm, the nitrogen flow is 110 sccm, and then the coating chamber is filled with the coating solutionSilane with an inflow rate of 25 sccm makes the air pressure in the film plating cavity be 1.01 and Pa, sets the matrix pulse bias amplitude to be 100V, the frequency to be 60 kHz, the duty ratio to be 60%, sets the hot wire discharge voltage to be 100V, adjusts the hot wire heating current to 30A so that the matrix bias current is 4.5A, and the Cr target power density is 4.8W/cm ² The coating deposition time was 360 min.

d. Multilayer periodic functional layer: when a single layer of a compact multi-element nanocomposite structure high temperature resistant wear layer is deposited: the heating temperature of the coating cavity is 350 ℃, the rotating speed of the workpiece frame is 15 rpm, the argon flow is 60 sccm, the nitrogen flow is 110 sccm, silane with the flow of 27 sccm and methane with the flow of 12 sccm are introduced into the coating cavity, so that the air pressure in the coating cavity is 1.21 Pa, the power density of Cr target is 4.8W/cm < 2 >, the pulse bias amplitude of a substrate is 100V, the frequency is 60 kHz, the duty ratio is 60%, the discharge voltage of a hot wire is set to be 100V, the heating current of the hot wire is regulated to 22A, the bias current of the substrate is 4.5A, and the single-layer deposition time is 10 min; when depositing a monolayer of anti-stiction friction reducing layer of a nanopore structure: the heating temperature of the film coating chamber is 350 ℃, the rotating speed of the workpiece frame is 15 rpm, the argon flow is 60 sccm, the nitrogen flow is 110 sccm, the silane flow is 3 sccm, the methane flow is 35 sccm, the air pressure in the film coating chamber is 1.18 and Pa, the matrix pulse bias amplitude is 40V, the frequency is 60 kHz, the duty ratio is 60%, the hot wire discharge voltage is 80V, the hot wire heating current is 11A, the matrix bias current is 1.5A by adjusting the hot wire heating current, and the monolayer deposition time is 10 min; the modulation period was set to 20 and the total deposition time of the multi-layer periodic functional layer was 800 min.

(4) And after the film coating is finished, turning off a sputtering power supply, a hot wire discharging power supply, a hot wire heating power supply and a matrix pulse bias power supply, turning off all the gas flow meters, turning off the heating of the vacuum chamber, and taking out the PCBN tool for cutting the titanium alloy coated with the nano composite structure coating after the temperature of the film coating chamber is reduced to 100 ℃.

The tools obtained in example 1 and example 2 were examined for mechanical properties and wear resistance, and the results are shown in table 1.

TABLE 1 results of mechanical Properties and wear resistance test of nanocomposite coatings for cutting titanium alloys

Coating Properties	Example 1	Example 2
			Nanometer hardness, H (GPa)	58.6±0.23	66.1±0.67
Effective Young's modulus, E.times.GPa	532.7±2.86	508.5±2.31
			H/E*	0.11	0.10
H ³ /E* ² （GPa）	0.71	0.66
			Film-based bond Strength (N)	72	79
Wear rate (m) ³ /N∙m）	4.1×10 ^-17	3.6×10 ^-17

Therefore, the cutter prepared by the method has the advantages of good hardness, high toughness, low wear rate and prolonged service life.

While the invention has been described in detail in the foregoing general description and specific examples, it will be apparent to those skilled in the art that modifications and improvements can be made thereto. Accordingly, such modifications or improvements may be made without departing from the spirit of the invention and are intended to be within the scope of the invention as claimed.

Claims

1. A nano composite structural coating on the surface of a titanium alloy cutting tool is characterized in that,

the coating comprises a compact nanocrystalline structure metal connecting layer arranged on a cutter substrate;

a dense nanocrystalline structure ceramic gradient transition layer arranged on the dense nanocrystalline structure metal connecting layer;

a dense CrSiN nano composite structure reinforced supporting layer arranged on the dense nanocrystalline structure ceramic gradient transition layer;

a plurality of periodic functional layers are arranged on the compact CrSiN nano composite structure reinforced supporting layer;

the compact nanocrystalline structure metal connecting layer is a Cr-based alloy material containing W, and the microstructure is a compact nanocrystalline columnar crystal or nanocrystalline equiaxed crystal structure;

the ceramic gradient transition layer with the compact nanocrystalline structure is CrN containing W and having gradient distribution of Cr and N _x The microstructure of the material is a compact nano columnar crystal or nano equiaxed crystal structure;

the compact CrSiN nano composite structure reinforced supporting layer is made of a CrSiN material containing W, and the microstructure is a compact amorphous wrapped nano crystal nano composite structure;

the multilayer periodic functional layer consists of a plurality of alternately deposited compact CrSiCN nano composite structure high-temperature resistant and wear-resistant layers and nano microporous structure CrSiCN anti-adhesion antifriction layers.

2. The titanium alloy cutting tool surface nanocomposite coating according to claim 1, wherein the dense CrSiCN nanocomposite high temperature wear resistant layer is a CrSiCN material containing W;

the nano microporous CrSiCN anti-adhesion antifriction layer is a CrSiCN material containing W.

3. The titanium alloy cutting tool surface nanocomposite coating according to claim 1, wherein the total thickness of the nanocomposite coating is from 2 to 10 μιη;

and/or the thickness of the multi-layer periodic functional layer is 1-8 μm.

4. The titanium alloy cutting tool surface nanocomposite coating according to claim 2, wherein the thickness of the dense CrSiCN nanocomposite high temperature resistant wear resistant layer in the multilayer periodic functional layer is 10-200 nm;

the thickness of the single-layer nano microporous CrSiCN anti-adhesion antifriction layer is 10-300 nm.

5. A preparation method of a nano composite structure coating on the surface of a titanium alloy cutting tool is characterized in that the method is a plasma enhanced unbalanced magnetron sputtering method;

comprising the following steps: firstly, carrying out surface pretreatment on a cutter substrate; carrying out glow cleaning on the cutter substrate by using hot filament plasma; finally, carrying out surface nano composite structure coating deposition on the cutter substrate;

the surface pretreatment method of the cutter substrate comprises the steps of immersing the cutter substrate into a metal cleaning agent aqueous solution for cleaning; rinsing the cutter substrate in deionized water; immersing the cutter substrate into absolute ethyl alcohol for ultrasonic cleaning; finally, drying the cutter substrate by using compressed gas in a cold air manner, placing the cutter substrate in a drying box for drying, and then placing the cutter substrate in a film coating cavity;

the hot wire plasma glow cleaning method of the cutter substrate comprises the following steps:

1) Vacuumizing the film coating chamber and slowly heating;

2) Argon is introduced into the coating cavity, the air pressure in the coating cavity is controlled, and hot filament plasma glow cleaning of the cutter substrate is carried out;

the method for depositing the nano composite structural coating on the surface of the cutter substrate comprises the following steps: depositing a metal connecting layer with a compact nanocrystalline structure, depositing a ceramic gradient transition layer with a compact nanocrystalline structure, depositing a reinforced supporting layer with a compact CrSiN nano composite structure and depositing a multi-layer periodic functional layer;

the deposition method of the metal connecting layer with the compact nanocrystalline structure comprises the following steps: the heating temperature of the film coating chamber is 200-500 ℃, the rotating speed of the workpiece frame is 5-80 rpm, the argon flow is 40-90 sccm, the air pressure in the film coating chamber is controlled to be 0.2-0.8 Pa, the pulse bias amplitude of the substrate is 50-200V, the frequency is 20-80 kHz, the duty ratio is 10-90%, the hot wire discharge voltage is 40-200V, the hot wire heating current is 10-50A, the bias current of the substrate is 3-10A by adjusting the hot wire heating current, and the power density of Cr target is 2-10W/cm ² The deposition time of the metal connecting layer with the compact nanocrystalline structure is 2-15 min;

the method for depositing the ceramic gradient transition layer with the compact nanocrystalline structure comprises the following steps: the heating temperature of the film coating cavity is 200-500 ℃, the rotating speed of the workpiece frame is 5-80 rpm, the flow rate of argon is 40-90 sccm, nitrogen with the flow rate gradient increased to 60-120 sccm is introduced into the film coating cavity and divided into 2-5 gradients, so that the air pressure in the film coating cavity is controlled to be 0.2-1.2 Pa, the pulse bias amplitude of a substrate is 50-200V, the frequency is 20-80 kHz, the duty ratio is 10-90%, the discharge voltage of a hot wire is 40-200V, the heating current of the hot wire is 10-50A, the bias current of the substrate is 3-10A, and the power density of a Cr target is 2-10W/cm by adjusting the heating current of the hot wire ² The deposition time of each gradient transition layer is 2-15 min;

the compact CrSiN nano complexThe method for depositing the composite structure reinforced supporting layer comprises the following steps: the heating temperature of the film coating chamber is 200-500 ℃, the rotating speed of a workpiece frame is 5-80 rpm, the argon flow is 40-90 sccm, the nitrogen flow is 60-120 sccm, silane with the flow of 10-30 sccm is further introduced into the film coating chamber, the air pressure in the film coating chamber is controlled to be 0.2-1.5 Pa, the pulse bias amplitude of a substrate is 50-200V, the frequency is 20-80 kHz, the duty ratio is 10-90%, the discharge voltage of a hot wire is 40-200V, the heating current of the hot wire is 10-50A, the bias current of the substrate is 3-10A, and the power density of a Cr target is 2-10W/cm by adjusting the heating current of the hot wire ² The coating deposition time is 30-300 min;

the multilayer periodic functional layer deposition method comprises the following steps: when a single layer of high-temperature resistant and wear-resistant layer with a compact CrSiCN nano composite structure is deposited, the heating temperature of a coating cavity is 200-500 ℃, the rotating speed of a workpiece frame is 5-80 rpm, the flow rate of argon is 40-90 sccm, the flow rate of nitrogen is 60-120 sccm, silane with the flow rate of 10-30 sccm and methane with the flow rate of 2-15 sccm are introduced into the coating cavity, the air pressure in the coating cavity is controlled to be 0.2-1.5 Pa, and the power density of Cr targets is 2-10W/cm ² The matrix pulse bias voltage amplitude is 50-200V, the frequency is 20-80 kHz, the duty ratio is 10-90%, the hot wire discharge voltage is 40-200V, the hot wire heating current is 10-50A, the matrix bias current is 3-10A by adjusting the hot wire heating current, and the monolayer deposition time is 2-20 min; when depositing the monolayer of the anti-adhesion antifriction layer of the CrSiCN with the nano micropore structure, the heating temperature of the film coating chamber is 200-500 ℃, the rotating speed of the workpiece frame is 5-80 rpm, the argon flow is 40-90 sccm, the nitrogen flow is 60-120 sccm, the silane flow is 1-5 sccm, the methane flow is 20-35 sccm, the air pressure in the film coating chamber is controlled to be 0.2-1.5 Pa, and the power density of the Cr target is 2-10W/cm ² The matrix pulse bias voltage amplitude is 0-50V, the frequency is 20-80 kHz, the duty ratio is 10-90%, the hot wire discharge voltage is 40-200V, the hot wire heating current is 0-15A, the matrix bias current is 0.1-2A by adjusting the hot wire heating current, and the monolayer deposition time is 4-80 min; the modulation period is 2-400.