CN102277556A - Method for preparing nano composite ultra-hard thin film - Google Patents

Abstract

The invention belongs to the field of preparation of thin film materials and particularly relates to a method for preparing the nano composite ultra-hard thin film. The method comprises: firstly, depositing MeN on a substrate by means of magnetic filtered arc plasma deposition to form a 50-nanometer-thick MeN thin film serving as a transitional layer; secondly, continuing depositing MeN by means of magnetic filtered arc plasma deposition and co-depositing Si3N4 on the substrate by means of ion beam sputtering at the same time, wherein a direct current back bias voltage of -100V is applied onto the substrate in the process of co-deposition; and finally, obtaining the nanocrystalline MeN/amorphous Si3N4 nano composite ultra-hard thin film. In the invention, the magnetic filtered arc plasma deposition and the ion beam sputtering are combined and compensate each other for disadvantages on the basis of a characteristic that the working air pressure of the magnetic filtered arc plasma deposition is similar to that of the ion beam sputtering, and thus, the nanocrystalline MeN/amorphous Si3N4 nano composite ultra-hard thin film with high film and substrate bonding force is obtained.

Description

A kind of preparation method of nanocomposite superhard film

technical field

The invention belongs to the field of film material preparation, and in particular relates to a preparation method of a nanocomposite superhard film.

Background technique

Some harsh actual industrial and mining conditions such as high temperature, impact, heavy load, and strong corrosive media have made the research and development of surface technology develop rapidly in recent years, and have become an eye-catching emerging field in the scientific and technological circles. As an effective means to improve the surface properties of workpieces, hard thin film materials have attracted much attention from the material industry. Professor S. Veprek first proposed the design concept of nanocrystalline (nc)/amorphous (α) composite structure, the general formula is expressed as nc-MeN/α-Si ₃ N ₄

(Me=Ti, Cr, Zr, V). Its microstructure is generally nc-MeN nano-sized crystal phase uniformly embedded in the α-Si ₃ N ₄ amorphous framework matrix (skeleton thickness <1nm). The hardness of this nanocomposite film exceeds 40GPa, becoming a new type of superhard film material. This kind of superhard film overcomes the periodic structure error and process complexity of preparing superlattice superhard film, and this kind of film shows extremely superior mechanical properties (especially the synergistic enhancement of strength and toughness, and an elastic recovery of more than 90%) Rate), good chemical stability (such as oxidation resistance over 1000 °C and good corrosion resistance), etc., have great application advantages in the field of friction and wear.

Both CVD and PVD methods are used to prepare nc-MeN/α-Si ₃ N ₄ (Me=Ti, Cr, Zr, V) nanocomposite superhard films. The disadvantage of the CVD method is that the deposition temperature is too high (900~1200°C), which exceeds the conventional heat treatment temperature of steel tools and molds. At the same time, the silane gas used is explosive and has poor safety. The PVD film formation temperature is low (300~500°C), and silicon is sputtered from a solid target, which has high safety, but the ionization rate is low, and the reduction of deposition temperature reduces the film density and film-base bonding strength. Therefore, some new PVD technologies have emerged one after another, among which the magnetic filter cathodic arc plasma deposition technology is favored. It works in an arc discharge mode, has the characteristics of high ionization rate and high ion energy, and can synthesize a dense compound or alloy film with high film-base binding force at room temperature or near room temperature. The Si content in the preparation of nc-MeN/α-Si ₃ N ₄ nanocomposite superhard film is a crucial factor, and the silicon source can be provided by the cathode arc, because the cathode arc requires the target to have good conductivity and thermal expansion capacity , and the conductivity of silicon is poor, even if high conductivity silicon is used, the cost itself is high, and its poor thermal expansion ability will also lead to cracking of the target. If Me-Si alloy or composite target is used, the smelting and processing technology of such alloy or composite target is complicated, and the cost is high. At the same time, the Me/Si ratio of the target material is fixed, and the film composition is difficult to control flexibly. The silicon source must be introduced by other means.

Contents of the invention

The object of the present invention is to provide a method of co-deposition using magnetic filter cathodic arc and ion beam sputtering to prepare nanocrystalline MeN/amorphous Si ₃ N ₄ nanocomposite superhard film (Me=Ti, Cr, Zr, V) Methods.

The present invention adopts following technical scheme:

A preparation method for a nanocomposite superhard film, characterized in that, the nanocomposite superhard film is nanocrystalline MeN/amorphous _Si3N4 nanocomposite superhard film, wherein Me is Ti, Cr, _Zr , V, The preparation steps include: (1) placing the substrate in a vacuum chamber and pumping the vacuum to 5.0×10 ^-4 Pa; (2) depositing MeN on the substrate by means of magnetic filter arc ion plating to form a 50-100 nm thick MeN film as transition layer; (3) Continue to deposit MeN by magnetic filtered arc ion plating, and at the same time co-deposit Si ₃ N ₄ on the substrate by ion beam sputtering, and apply -100V DC negative bias to the substrate during the co-deposition process, Thus the nanocrystalline MeN/amorphous Si ₃ N ₄ nanocomposite superhard film is prepared.

When MeN is deposited by magnetic filter arc ion plating, the specific steps are as follows: N ₂ /Ar mixed gas is introduced into the source of the magnetic filter cathode, wherein the flow rate of Ar is 7.0 sccm, and the flow rate of N ₂ is 21.0 sccm. The arc discharge extracts the ion beam to deposit MeN on the substrate, and the working pressure is 0.1~0.3Pa.

The cathode current of the source of the magnetic filter cathode is 55-70A, the source coil current is 0.25-0.5A, the magnetic filter coil current is 1.0-4.0A, and the outlet coil current is 1.5A.

When using ion beam sputtering to deposit Si ₃ N ₄ , the Kaufman ion gun is used for ion beam sputtering. The Ar flow rate of the Kaufman ion gun is 8.0 sccm, the plate voltage is 1500~1700V, and the acceleration voltage is 120V, cathode discharge current 10A, beam current 50mA, Ar ion beam sputtering α-Si ₃ N ₄ target to deposit Si ₃ N ₄ , working pressure 0.1~0.3Pa.

The substrate is pretreated before being placed in the vacuum chamber. The pretreatment process is as follows: after the substrate is degreased and polished, it is placed in acetone and ethanol in sequence for ultrasonic cleaning, and after being taken out, it is blown dry with nitrogen.

The material of the substrate is titanium alloy (TC4), bearing steel (GCr15), and mold steel (5CrMnMo).

The present invention combines magnetic filter arc ion plating with ion beam _sputtering , utilizes the characteristics _of similar working pressures of the two, and makes up for each other's deficiencies. The MeN film with good adhesion to the substrate is deposited by filtered arc ion plating as a transition layer; then MeN is deposited by magnetic filtered arc ion plating, and Si ₃ N ₄ is deposited by ion beam sputtering at the same time to obtain a film with good adhesion to the substrate Nanocrystalline MeN/amorphous Si ₃ N ₄ nanocomposite film, the thickness of the film is 1 micron, in which MeN is embedded in the Si ₃ N ₄ matrix in a nanocrystalline phase, and its nanohardness is between 40GPa-60GPa.

The parameters of magnetic filtered arc ion plating and ion beam sputtering can be adjusted separately _and flexibly. Magnetic filtered arc ion plating can _flexibly control the density and energy of deposited ions. Arc plating is not suitable for the shortage of silicon targets. The two do not interfere with each other and play their respective advantages. They can prepare superhard nanocomposite films with good film-base bonding force, and improve the service life and production efficiency of workpieces. In the preparation process, it was found that the application of substrate negative bias plays a decisive role in the silicon content, the grain size of TiN, and the hardness of the film. The nanocomposite structure obtained under this process condition is an ideal structure for obtaining excellent mechanical properties.

Description of drawings

Fig. 1 is a cross-sectional transmission electron microscopic image of the nc-TiN/α-Si ₃ N ₄ nanocomposite superhard film material prepared in Example 1.

Detailed ways

Example 1:

Preparation of nanocrystalline TiN/ _{amorphous Si3N4} nanocomposite film:

(1) After the substrate is degreased and polished, put it into acetone and ethanol for ultrasonic cleaning in turn, after taking it out, dry it with nitrogen and place it in a vacuum chamber, and vacuum it to 5.0×10 ^-4 Pa;

(2) N ₂ /Ar mixed gas is introduced from the source of the magnetic filter cathode, in which the flow rate of Ar is 7.0 sccm, and the flow rate of N ₂ is 21.0 sccm, and arc discharge is generated on the cathode high-purity Ti target (purity 99.96%), and the cathode The current is 70A, the current of the source coil is 0.25A, the current of the magnetic filter coil is 3.0A, and the current of the outlet coil is 1.5A. The ion beam is drawn out, and a 50nm thick TiN film is deposited on the substrate, and the working pressure is 0.2Pa;

(3) Then the Ar ion beam is generated by the Kaufman ion gun, the Ar flow rate is 8.0sccm, the screen electrode voltage is 1600V, the acceleration voltage is 120V, the cathode discharge current is 10A, the beam current is 50mA, and the ion beam sputters the α-Si ₃ N ₄ target (purity 99.99%), working simultaneously with the magnetic filter cathodic arc described in 2), TiN and Si ₃ N ₄ are co-deposited on the substrate to prepare nanocrystalline TiN/amorphous Si ₃ N ₄ composite film, during the co-deposition process, the substrate Apply -100V DC negative bias, and the working air pressure is 0.1Pa.

Under the above process conditions, the nanocrystalline TiN/amorphous Si ₃ N ₄ nanocomposite thin film material was obtained. The transmission electron microscopic image of its cross-section is shown in Figure 1. After analysis and detection, the thickness of the film is 1 micron, and the TiN grains are Columnar nanocrystals with a diameter of 2 nanometers and a length of 10 nanometers, the nanocrystals are evenly embedded in the silicon nitride amorphous phase of about 1nm, the thickness of the amorphous phase between the grains is only about 1 nanometer, and the nanohardness of the film is 46GPa.

Example 2:

Preparation of nanocrystalline CrN/ _{amorphous Si3N4} nanocomposite films:

(1) After the substrate is degreased and polished, put it into acetone and ethanol for ultrasonic cleaning in turn, after taking it out, dry it with nitrogen and place it in a vacuum chamber, and vacuum it to 5.0×10 ^-4 Pa;

(2) N ₂ /Ar mixture gas is introduced from the source of the magnetic filter cathode, in which the flow rate of Ar is 7.0sccm, and the flow rate of N ₂ is 21.0sccm, and the high-purity Cr target (purity 99.96%) of the cathode is ignited to generate arc discharge, and the cathode The current is 65A, the current of the source coil is 0.5A, the current of the magnetic filter coil is 3.0A, and the current of the outlet coil is 1.5A. The ion beam is drawn out, and a CrN film with a thickness of 80 nanometers is deposited on the substrate, and the working pressure is 0.2Pa;

(3) Then the Ar ion beam is generated by the Kaufman ion gun, the Ar flow rate is 8.0sccm, the screen voltage is 1700V, the acceleration voltage is 120V, the cathode discharge current is 10A, the beam current is 50mA, and the ion beam sputters the α-Si ₃ N ₄ target (purity 99.99%), working simultaneously with the magnetic filter cathodic arc described in 2), CrN and Si ₃ N ₄ are co-deposited on the substrate to prepare nanocrystalline CrN/amorphous Si ₃ N ₄ composite film, during the co-deposition process, the substrate Apply -100V DC negative bias, and the working air pressure is 0.1Pa.

Under the above process conditions, a nanocrystalline CrN/amorphous Si ₃ N ₄ nanocomposite thin film material is obtained, and the nanohardness of the thin film is 41GPa.

Example 3:

Preparation of nanocrystalline ZrN/amorphous Si ₃ N ₄ nanocomposite films:

(1) After the substrate is degreased and polished, put it into acetone and ethanol for ultrasonic cleaning in turn, after taking it out, dry it with nitrogen and place it in a vacuum chamber, and vacuum it to 5.0×10 ^-4 Pa;

(2) N ₂ /Ar mixture gas is introduced from the source of the magnetic filter cathode, in which the flow rate of Ar is 7.0sccm, and the flow rate of N ₂ is 21.0sccm, and the arc is struck on the cathode high-purity Zr target (purity 99.96%) to generate arc discharge, and the cathode The current is 70A, the source coil current is 0.5A, the magnetic filter coil current is 3.0A, the exit coil current is 1.5A, the ion beam is drawn out, and a 100nm thick ZrN film is deposited on the substrate, and the working pressure is 0.2Pa;

(3) Then the Ar ion beam is generated by the Kaufman ion gun, the Ar flow rate is 8.0sccm, the screen electrode voltage is 1600V, the acceleration voltage is 120V, the cathode discharge current is 10A, the beam current is 50mA, and the ion beam sputters the α-Si ₃ N ₄ target (purity 99.99%), working simultaneously with the magnetic filter cathodic arc described in 2), ZrN and Si ₃ N ₄ are co-deposited on the substrate to prepare nanocrystalline ZrN/amorphous Si ₃ N ₄ composite film, during the co-deposition process, the substrate Apply -100V DC negative bias, and the working air pressure is 0.1Pa.

Under the above process conditions, a nanocrystalline ZrN/amorphous Si ₃ N ₄ nanocomposite thin film material is obtained, and the nanohardness of the thin film is 43GPa.

Claims (5)

1. a preparation method of nanocomposite superhard film, it is characterized in that, described nanocomposite _{superhard film is nanocrystalline MeN/amorphous Si N 4 nanocomposite} superhard film, wherein Me is Ti, Cr, Zr, V, the preparation steps include: (1) placing the substrate in a vacuum chamber and pumping the vacuum to 5.0×10 ^-4 Pa; (2) depositing MeN on the substrate by means of magnetic filtered arc ion plating to form MeN with a thickness of 50-100 nanometers The thin film is used as a transition layer; (3) Continue to deposit MeN by magnetic filter arc ion plating, and at the same time co-deposit Si ₃ N ₄ on the substrate by ion beam sputtering, and apply -100V DC negative bias to the substrate during the co-deposition process pressure, thereby preparing nanocrystalline MeN/amorphous Si ₃ N ₄ nanocomposite superhard films. 2. The preparation method of nanocomposite superhard film as claimed in claim 1, characterized in that, when depositing MeN by means of magnetic filter arc ion plating, specifically: the _N2 /Ar mixed gas is fed into the source of the magnetic filter cathode , where the flow rate of Ar is 7.0sccm, and the flow rate of _N2 is 21.0sccm. Arc discharge is generated on the cathode Me target, and the ion beam is drawn out to deposit MeN on the substrate. The working pressure is 0.1~0.3Pa. 3. the preparation method of nanocomposite superhard film as claimed in claim 2, is characterized in that, the cathodic current of described magnetic filter cathode source is 55～70A, and source coil current is 0.25-0.5A, and magnetic filter coil current is 1.0~4.0A, the output coil current is 1.5A. 4. the preparation method of nanocomposite superhard film as claimed in claim _{1, is characterized in that, adopts the mode deposition Si of ion beam sputtering N 4 ,} specifically adopt Kaufman ion gun to carry out ion beam sputtering, consider The Ar flow of the Furman ion gun is 8.0sccm, the plate voltage is 1500~1700V, the acceleration voltage is 120V, the cathode discharge current is 10A, the beam current is 50mA, and the Ar ion beam sputters the α-Si ₃ N ₄ target to deposit Si ₃ N ₄ , the working pressure is 0.1~0.3Pa. 5. The preparation method of the nanocomposite superhard film as claimed in any one of claims 1-4, wherein the base is pretreated before being placed in a vacuum chamber, and the pretreatment process is: the base is degreased, After polishing, put them in acetone and ethanol for ultrasonic cleaning in turn, and blow dry with nitrogen after taking them out.

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