CN110578123A - High hardness AlTiN/AlTiSiN multilayer nanocomposite coating and its preparation process - Google Patents

Abstract

The invention discloses a high-hardness AlTiN/AlTiSiN multi-layer nano composite coating and a preparation process thereof, belonging to the technical field of composite coating preparation. The AlTiN/AlTiSiN multi-layer nanocomposite coating is formed by alternately stacking AlTiN layers and AlTiSiN layers, the coating modulation period is 150-1000nm, and the number of periods is ≥2. The composite coating is prepared by arc ion plating technology. The process is: select metal Ti target, AlTi target, AlTiSi target, first deposit TiN transition layer after glow cleaning and bombardment cleaning, and finally pass nitrogen as the reaction gas. The modulation period of AlTi target and AlTiSi target is alternately turned on to deposit composite coatings. The coating prepared by the invention has dense structure, strong bonding force between the coating and the substrate, high hardness and strength, and good wear resistance.

Description

High hardness AlTiN/AlTiSiN multilayer nanocomposite coating and its preparation process

technical field

The invention relates to the technical field of composite coating preparation, in particular to a high-hardness AlTiN/AlTiSiN multi-layer nano composite coating and a preparation process thereof.

Background technique

In recent years, the use of wear-resistant hard coatings on mechanical, forged and formed components has become increasingly important to not only save costs, but also increase the service life of the material. AlTiN coating has been widely used in high-speed steel and cemented carbide tools due to its excellent high temperature hardness and oxidation resistance, which is largely due to the increase of aluminum elements. Compared with the binary coating TiN, the AlTiN coating acts as a protective layer for the tool, which can reduce the amount of wear and fracture caused by impact. Although the oxidation resistance of AlTiN coating has been significantly improved compared with other binary coatings, it still cannot meet the requirements of high hardness, high toughness and wear resistance in some high-speed cutting or dry cutting environments.

In order to develop a multi-layer nano-composite coating with dense structure, high hardness and wear resistance, this patent adopts the arc ion plating technology to deposit AlTiN/AlTiSiN multi-layer nano-composite coating on the metal or alloy substrate to further improve the performance of the single-layer coating. Mechanical properties and service life and excellent performance of multi-layer coatings are achieved.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a high-hardness AlTiN/AlTiSiN multilayer nanocomposite coating and a preparation process thereof. The prepared AlTiN/AlTiSiN multilayer nanocomposite coating has both high hardness, high wear resistance and high thermal stability.

For achieving the above object, the technical scheme adopted in the present invention is as follows:

A high-hardness AlTiN/AlTiSiN multi-layer nanocomposite coating is deposited on a metal or cemented carbide substrate. The AlTiN/AlTiSiN multi-layer nanocomposite coating is formed by alternately stacking AlTiN layers and AlTiSiN layers. The modulation period is 150-1000nm, and the number of periods is ≥2.

The modulation ratio of the AlTiN layer and the AlTiSiN layer is 1:1, and the total thickness of the deposited coating is 3 μm.

The AlTiN/AlTiSiN multi-layer nanocomposite coatings all have a face-centered cubic structure, no hexagonal phase with low hardness is formed, and the preferred orientation crystal plane of the coating is the diffraction peak of (Ti, Al)N (200).

The hardness of the AlTiN/AlTiSiN multi-layer nanocomposite coating is greater than 28GPa, and the bonding force with the substrate is greater than 100N.

The preparation process of the high-hardness AlTiN/AlTiSiN multi-layer nanocomposite coating is to deposit the AlTiN/AlTiSiN multi-layer nanocomposite coating on the substrate by using the arc ion plating technology, and the target materials are selected from pure metal Ti target, AlTi alloy target and AlTiSi Alloy target (the purity of the target material is 99.9wt.%); when depositing the AlTiN/AlTiSiN multi-layer nanocomposite coating, first open the Ti target, then alternately open the AlTi target and the AlTiSi target to deposit the corresponding AlTiN layer and AlTiSiN layer, The AlTiN/AlTiSiN multilayer nanocomposite coatings with AlTiN layers and AlTiSiN layers alternately superimposed on the substrate are prepared by controlling the deposition pressure, the flow rate of the gas and the arc flow parameters of each target when depositing the AlTiN layer and the AlTiSiN layer. .

When depositing the AlTiN/AlTiSiN multi-layer nanocomposite coating in the present invention, the arc current is set to 40-100A; when the AlTi target is turned on to deposit the AlTiN coating, the bias voltage is set to 60-150V (duty ratio 50%-90%), Pour in argon and nitrogen to adjust the deposition pressure to 0.5~2Pa; when the AlTiSi target is turned on to deposit AlTiSiN coating, set the bias voltage to 80~100V (duty ratio 50%~90%), and pass in argon and nitrogen to make the deposition pressure Adjust to 1-3Pa; set different modulation periods and deposition times of the coating according to the desired thickness of the coating.

When depositing the AlTiN coating, the flow rate of argon gas is 50sccm, the flow rate of nitrogen gas is 350sccm, and the total flow rate is 400sccm; when the AlTiSiN coating is deposited, the flow rate of argon gas is 50sccm, and the flow rate of nitrogen gas is 600sccm, The total flow is 650sccm.

The preparation process of the high-hardness AlTiN/AlTiSiN multilayer nanocomposite coating specifically includes the following steps:

(1) The targets are evenly distributed around the vacuum chamber of the arc ion plating equipment to ensure a high plasma concentration in the furnace chamber during the deposition process; the pretreated substrates are placed on the central turntable of the coating chamber; Mechanical pump and molecular pump are evacuated to make the vacuum chamber pressure below 3×10 ^-3 Pa;

(2) Glow bombardment cleaning: first use a high negative bias glow to clean the substrate for 10 to 30 minutes, then turn on the Ti target after glow cleaning, and adjust the bias voltage to -800V, -600V, -400V and -200V in turn for the surface of the substrate Carry out bombardment cleaning for 2 minutes respectively;

(3) Deposition of TiN transition layer: after glow bombardment cleaning, a TiN transition layer with a thickness of 10-350 nm is deposited on the surface of the substrate to improve the bonding force between the coating and the substrate;

(4) Deposition of multi-layer composite coating: The alloy AlTi target and AlTiSi target are turned on to deposit the multi-layer composite coating.

In the above step (2), the glow cleaning process is as follows: heating the furnace chamber to 200-500° C., feeding 200-400 sccm of argon gas, setting a pulse bias voltage of -600--1000V, and performing glow cleaning on the substrate ;

In the above step (2), the bombardment cleaning process is as follows: after glow cleaning, turn on the Ti target, adjust the argon flow rate to be 50-100sccm, and under negative bias conditions of -800V, -600V, -400V and -200V, respectively. Wash for 2 minutes.

In the above step (3), the process of depositing the TiN transition layer is as follows: after the glow bombardment cleaning, set the bias voltage to 50-100V (duty ratio of 60%-90%), turn on the Ti target, and pass in the argon gas flow rate of 50sccm , the nitrogen flow rate is 200sccm, the deposition pressure is adjusted to 0.5-1.2Pa, and the transition layer TiN is deposited for 10-30min.

The design mechanism of the present invention is as follows:

In the present invention, Si element is added to the AlTiN coating, and the solid solution strengthening effect of Al and Ti elements and amorphous Si ₃ N ₄ are used to refine crystal grains and improve hardness, and at the same time, AlTiN coating and AlTiSiN are alternately arranged to form multiple layers The nanocomposite coating can make the AlTiN/AlTiSiN multi-layer composite coating have excellent properties significantly better than the single-layer coating and meet people's extensive needs in the field of wear-resistant materials.

The nano-multilayer film prepared by the invention is a modulation structure, that is, a structure with a certain repetition period. By alternately depositing two different coatings with nanometer size, the obtained multi-layer nanocomposite structure will exhibit a superhard phenomenon with abnormally increased hardness, and concentrate the advantages of different materials to overcome the shortcomings of single-layer films. Better comprehensive mechanical properties, especially in high hardness, high toughness and excellent wear resistance.

The advantages of the present invention are as follows:

1. The AlTiN/AlTiSiN multi-layer nanocomposite coating developed by the present invention has high hardness and toughness, low friction coefficient and good wear resistance.

2. The AlTiN/AlTiSiN nanocomposite coating developed by the present invention has high high temperature thermal stability and corrosion resistance, and can be used in the field of high-speed dry cutting.

3. The AlTiN/AlTiSiN nanocomposite coating developed by the present invention has uniform thickness and compact structure, and has good bonding strength with the substrate.

4. The preparation process of the AlTiN/AlTiSiN nanocomposite coating developed by the present invention has good repeatability, wide application range and very strong practicability.

Description of drawings

Figure 1 shows the diffraction pattern of the AlTiN/AlTiSiN nanocomposite coating prepared by arc ion plating technology.

Figure 2 shows the surface topography of the AlTiN/AlTiSiN nanocomposite coating prepared by arc ion plating technology.

Figure 3 is a cross-sectional topography of the AlTiN/AlTiSiN nanocomposite coating prepared by arc ion plating technology.

FIG. 4 is a nanoindentation curve diagram of an AlTiN/AlTiSiN nanocomposite coating prepared by arc ion plating technology.

Figure 5 is the topography of the AlTiN/AlTiSiN nanocomposite coating prepared by arc ion plating technology after scratch test.

FIG. 6 is a graph showing the friction coefficient test curve of AlTiN/AlTiSiN coatings prepared by arc ion plating technology.

Detailed ways

The present invention will be described in further detail below through examples.

Example 1

In this example, an AlTiN/AlTiSiN multi-layer nanocomposite coating is deposited on a polished 304 stainless steel sheet, and the size of the sample is 25×30×1 mm.

The substrate was pretreated first: ultrasonically cleaned in acetone and alcohol for 15 minutes, then dried with high-purity nitrogen, and then placed on the sample holder in the vacuum chamber.

The coating process was carried out on an AIP-650 arc ion coating machine. Pure metal Ti targets, alloy AlTi targets, and alloy AlTiSi targets (all with a purity of 99.9 wt.%) with a diameter of 100 mm were used as targets. The working gas and reaction gas were respectively Use high-purity argon and nitrogen.

The targets are evenly distributed on the inner wall of the furnace of the arc ion plating equipment to ensure a high plasma concentration in the furnace cavity during the deposition process; the pretreated substrates are placed on the central turntable of the coating chamber;

Use mechanical pump and molecular pump to evacuate the vacuum chamber pressure below 3×10 ^-3 Pa, turn on the heating system and raise the temperature to 430℃, then pass argon gas for 400sccm into the vacuum chamber, set the bias voltage to -800V to illuminate the surface of the sample Photodischarge cleaning for 20min.

Then turn on the Ti target, adjust the argon flow rate to 50-100sccm, and adjust the negative bias voltage to -800V, -600V, -400V, -200V for 2 minutes of bombardment cleaning;

Then set the bias voltage to 100V (duty ratio 60%), turn on the Ti target, pass 50sccm of argon, 200sccm of nitrogen, adjust the deposition pressure to 0.8Pa, and deposit 20min of transition layer TiN;

Finally, the AlTi target and the AlTiSi target are turned on alternately, and the arc flow is set to 80A; when the AlTi target is turned on to deposit each layer of AlTiN layer: set the bias voltage to 80V (80% duty cycle), and flow 50sccm of argon and 350sccm of nitrogen , adjust the deposition pressure to 1Pa; when the AlTiSi target is turned on to deposit each layer of AlTiSiN layer, set a bias voltage of 100V (80% duty cycle), pass argon with a flow rate of 50sccm and nitrogen with a flow rate of 600sccm, adjust the deposition pressure to 2.8Pa, set The modulation period of the coating is 750 nm, 4 periods (8 layers in total) are deposited, the modulation ratio of the two coatings is 1:1, and the total thickness of the deposited coating is 3 μm.

Fig. 1 is the diffraction spectrum of the AlTiN/AlTiSiN nanocomposite coating prepared in this example. It can be seen that the coating is composed of a face-centered cubic structure, and no hexagonal phase with low hardness is generated. The preferred orientation crystal plane of the coating is is the diffraction peak of (Ti, Al)N (200).

Figure 2 shows the surface topography of the nanocomposite coating. The coating exhibits the characteristics of a typical arc ion plating coating, with a dense and uniform structure and a small amount of large particles on the surface.

Figure 3 is a cross-sectional topography of the nanocomposite coating, the thickness of the coating is about 3 μm, and the coating is well combined with the substrate.

FIG. 4 is a graph showing the change of hardness value of the nanocomposite coating tested by the nanoindentation technique. With the indentation of the nanoindentation probe, the hardness value of the tested coating increases rapidly at first, reaching a plateau value, and then gradually decreases due to the substrate effect. Generally, the plateau value is taken as the average hardness value of the coating. It can be seen from the figure that the hardness of the nanocomposite coating in this example is about 29GPa.

FIG. 5 is a graph showing the change of scratch morphology of the nanocomposite coating tested by a scratch tester. As can be seen from the figure, the coating adhesion is good, reaching 102N.

Figure 6 is a graph of the friction curve of the nanocomposite coating tested by a high temperature friction machine. The friction curve fluctuates due to the multi-layer structure or the uneven surface of the coating.

Example 2

In this example, the AlTiN/AlTiSiN multi-layer nanocomposite coating is deposited on the polished cemented carbide substrate, and the size of the sample is 25×30×3 mm.

The substrate was pretreated first: ultrasonically cleaned in acetone and alcohol for 15mim each, then dried with high-purity nitrogen, and then placed on a sample holder in a vacuum chamber.

The coating process was carried out on an AIP-650 arc ion coating machine. The target materials were pure metal Ti targets, alloy AlTi targets, and AlTiSi alloy targets (all with a purity of wt. 99.9%) with a diameter of 100 mm as targets. The gases used were high-purity argon and nitrogen.

Each target is evenly placed around the vacuum chamber of the arc ion plating equipment to ensure a high plasma concentration in the furnace chamber during the deposition process; the pretreated substrate is placed on the central turntable of the coating chamber;

First, the background vacuum of the vacuum chamber was evacuated to below 3×10 ^-3 Pa by mechanical pump and molecular pump, the heating system was turned on and the temperature was raised to 430°C, then argon gas was introduced into the vacuum chamber for 400sccm, and the bias voltage was set to -800V. The surface of the sample was cleaned by glow discharge for 20 min.

Then turn on the Ti target, adjust the argon flow rate to 50-100sccm, and adjust the negative bias voltage to -800V, -600V, -400V, -200V for 2 minutes of bombardment cleaning;

Then set the bias voltage to 100V (duty ratio 60%), turn on the Ti target, pass 50sccm of argon, 200sccm of nitrogen, adjust the deposition pressure to 0.8Pa, and deposit 20min of transition layer TiN;

Finally, the AlTi target and the AlTiSi target are turned on alternately, and the arc flow is set to 80A; when the AlTi target is turned on to deposit each layer of AlTiN layer: set the bias voltage to 80V (80% duty cycle), and flow 50sccm of argon and 350sccm of nitrogen , pass argon and nitrogen to adjust the deposition pressure to 1Pa; when the AlTiSi target is turned on to deposit each layer of AlTiSiN layer, set the bias voltage to 100V (duty ratio 80%), pass 50sccm of argon and 600sccm of nitrogen, pass Argon and nitrogen were used to adjust the deposition pressure to 2.8 Pa, the coating modulation period was set to 375 nm, the modulation ratio of the two coatings was 1:1, and the total thickness of the deposited coating was 3 μm.

The phase composition and microstructure of the nanocomposite coating prepared in this example are the same as those of the coating in Example 1, and consist of a coating with a face-centered cubic structure. The total thickness of the coating is about 3μm, and the hardness is as high as 32Gpa.

Claims (10)

1. The high-hardness AlTiN/AlTiSiN multilayer nano composite coating is characterized in that: the coating is deposited on a metal or hard alloy matrix, the AlTiN/AlTiSiN multilayer nano composite coating is formed by alternately overlapping AlTiN layers and AlTiSiN layers, the modulation period of the coating is 150-1000nm, and the periodicity is more than or equal to 2.

2. The high hardness AlTiN/AlTiSiN multilayer nanocomposite coating of claim 1, wherein: the modulation ratio of the AlTiN layer to the AlTiSiN layer is 1:1, the total thickness of the deposited coating is 3 μm.

3. The high hardness AlTiN/AlTiSiN multilayer nanocomposite coating of claim 1, wherein: the AlTiN/AlTiSiN multilayer nano composite coating is of a face-centered cubic structure, no low-hardness hexagonal phase is generated, and the preferred orientation crystal face of the coating is a diffraction peak of (Ti, Al) N (200).

4. The high hardness AlTiN/AlTiSiN multilayer nanocomposite coating of claim 1, wherein: the hardness of the AlTiN/AlTiSiN multilayer nano composite coating is more than 28GPa, and the bonding force with a base material is more than 100N.

5. The process for preparing high-hardness AlTiN/AlTiSiN multilayer nano composite coating according to any one of claims 1 to 4, wherein: the process is characterized in that an AlTiN/AlTiSiN multilayer nano composite coating is deposited on a substrate by adopting an arc ion coating technology, and a target material is selected from a pure metal Ti target, an AlTi alloy target and an AlTiSi alloy target (the target material purity is 99.9 wt%); when depositing the AlTiN/AlTiSiN multilayer nano composite coating, the Ti target is firstly started, then the AlTi target and the AlTiSi target are alternately started to deposit the corresponding AlTiN layer and AlTiSiN layer, and the deposition pressure, the gas flow and the arc flow parameters of each target when depositing the AlTiN layer and the AlTiSiN layer are controlled, so that the AlTiN/AlTiSiN multilayer nano composite coating with the AlTiN layer and the AlTiSiN layer alternately superposed with each other is prepared on the substrate.

6. The preparation process of the high-hardness AlTiN/AlTiSiN multilayer nano composite coating according to claim 5, characterized in that: when depositing the AlTiN/AlTiSiN multilayer nano composite coating, setting arc flow to be 40-100A; when an AlTi target is started to deposit an AlTiN coating, setting a bias voltage of 60-150V (duty ratio of 50% -90%), and introducing argon and nitrogen to adjust the deposition pressure to 0.5-2 Pa; when an AlTiSi target is started to deposit an AlTiSiN coating, setting a bias voltage of 80-100V (duty ratio of 50% -90%), and introducing argon and nitrogen to adjust the deposition pressure to 1-3 Pa; different modulation periods and deposition times of the coating are set according to the desired thickness of the coating.

7. The preparation process of the high-hardness AlTiN/AlTiSiN multilayer nano composite coating according to claim 6, characterized in that: when depositing the AlTiN coating, the flow of the introduced argon is 50sccm, the flow of the introduced nitrogen is 350sccm, and the total flow is 400 sccm; when the AlTiSiN coating is deposited, the flow rate of argon is 50sccm, the flow rate of nitrogen is 600sccm, and the total flow rate is 650 sccm.

8. The process for preparing high-hardness AlTiN/AlTiSiN multilayer nano composite coating according to claim 7, characterized in that: the process specifically comprises the following steps:

(1) Placing the pretreated substrate on a central rotating stand of a coating chamber, and controlling the air pressure of the vacuum chamber to be 3 x 10^-3pa below;

(2) Glow bombardment cleaning: firstly, glow washing the substrate for 10-30 min by adopting high negative bias glow, starting a Ti target after glow washing, and adjusting the bias to-800V, -600V, -400V and-200V in sequence to respectively carry out bombardment washing on the surface of the substrate for 2 min;

(3) And (3) depositing a TiN transition layer: depositing a TiN transition layer with the thickness of 10-350 nm on the surface of the substrate after glow bombardment cleaning so as to improve the binding force between the coating and the substrate;

(4) Depositing a multi-layer composite coating: and starting the alloy AlTi target and the AlTiSi target to deposit the multilayer composite coating.

9. The process for preparing high-hardness AlTiN/AlTiSiN multilayer nano composite coating according to claim 8, wherein: in the step (2), the glow cleaning process comprises the following steps: heating the furnace chamber to 200-500 ℃, introducing argon gas of 200-400 sccm, setting pulse bias voltage of-600-1000V, and performing glow cleaning on the substrate; the bombardment cleaning process comprises the following steps: after glow cleaning, starting the Ti target, adjusting the argon flow to be 50-100 sccm, and cleaning for 2min under negative bias conditions of-800V, -600V, -400V and-200V respectively.

10. The process for preparing high-hardness AlTiN/AlTiSiN multilayer nano composite coating according to claim 8, wherein: in the step (3), the process of depositing the TiN transition layer comprises the following steps: after glow bombardment cleaning, setting a bias voltage of 50-100V (duty ratio of 60% -90%), starting the Ti target, introducing argon gas flow of 50sccm and nitrogen gas flow of 200sccm, adjusting the deposition pressure to 0.5-1.2 Pa, and depositing a transition layer TiN for 10-30 min.