阅读说明：本技术 一种DLC/CNx/MeN/CNx纳米多层膜及其制备方法 (DLC/CNx/MeN/CNx nano multilayer film and preparation method thereof ) 是由 杨芳儿 杨烁妍 郑晓华 常新新 于 2019-07-22 设计创作，主要内容包括：本发明涉及薄膜材料技术领域,为解决传统DLC薄膜与基体材料的结合强度较差、降低应力提高结合强度又会导致耐磨性能下降的问题,提供了一种DLC/CNx/MeN/CNx纳米多层膜,包括基体(1)、依次沉积于基体表面的金属过渡层(2)和纳米多层膜,所述纳米多层膜由若干纳米复合单元(3)组成,所述纳米复合单元由下至上依次为DLC层(4),第一梯度CNx层(5),金属氮化物层(6)和第二梯度CNx层(7)。本发明的纳米多层膜有效改善了传统沉积方法膜基结合力不高的问题,同时降低了内应力,并且有优良的耐磨性；制备方法步骤简单,工艺条件易于控制,制备过程安全无污染,成本低,易于实现产业化。(The invention relates to the technical field of film materials, and provides a DLC/CNx/Men/CNx nano multilayer film for solving the problems that the traditional DLC film has poor bonding strength with a substrate material and the wear resistance is reduced due to the fact that the bonding strength is improved by reducing stress, wherein the DLC/CNx/Men/CNx nano multilayer film comprises a substrate (1), a metal transition layer (2) and a nano multilayer film, wherein the metal transition layer and the nano multilayer film are sequentially deposited on the surface of the substrate, the nano multilayer film comprises a plurality of nano composite units (3), and the nano composite units sequentially comprise a DLC layer (4), a first gradient CNx layer (5), a metal nitride layer (6) and a second gradient CNx layer (7. The nano multilayer film effectively solves the problem of low film-substrate binding force of the traditional deposition method, reduces the internal stress and has excellent wear resistance; the preparation method has the advantages of simple steps, easily controlled process conditions, safe and pollution-free preparation process, low cost and easy realization of industrialization.)

1. A DLC/CNx/MeN/CNx nano multilayer film is characterized by comprising a substrate (1), a metal transition layer (2) and a nano multilayer film, wherein the metal transition layer and the nano multilayer film are sequentially deposited on the surface of the substrate, the nano multilayer film is composed of a plurality of nano composite units (3), and the nano composite units sequentially comprise a DLC layer (4), a first gradient CNx layer (5), a metal nitride layer (6) and a second gradient CNx layer (7) from bottom to top.

2. The DLC/CNx/MeN/CNx nano-multilayer film as claimed in claim 1, wherein the total thickness of the DLC/CNx/MeN/CNx nano-multilayer film is 0.6-10 μm.

3. The DLC/CNx/MeN/CNx nano-multilayer film according to claim 1, wherein the substrate is a high speed steel substrate.

4. The DLC/CNx/MeN/CNx nano-multilayer film as claimed in claim 1, wherein the metal transition layer is Ti or Cr; the metal nitride layer is a TiN layer or a CrN layer.

5. The DLC/CNx/MeN/CNx nano-multilayer film according to claim 1, characterized in that the nitrogen content of the first gradient CNx layer gradually increases from 0 at.% to 18 at.%.

6. The DLC/CNx/MeN/CNx nano-multilayer film according to claim 1, characterized in that the nitrogen content of the second gradient CNx layer gradually decreases from 18 at.% to 0 at.%.

7. The DLC/CNx/MeN/CNx nano-multilayer film as claimed in claim 1, wherein the DLC layer has a nano-indentation hardness of 20-32 GPa; the nano indentation hardness of the first gradient CNx layer and the second gradient CNx layer is 15-25 GPa; the nano indentation hardness of the metal nitride layer is 20-28 GPa.

8. The DLC/CNx/MeN/CNx nano-multilayer film as claimed in claim 1, wherein the nano-multilayer film has a thickness of 20-250 nm; the thickness of the nano composite unit is 5-100 nm.

9. A method for preparing DLC/CNx/MeN/CNx nano-multilayer film according to any of claims 1 to 8, characterized by comprising the following steps:

(1) pretreatment: ultrasonically cleaning a matrix in an acetone solution and absolute ethyl alcohol in sequence, drying the matrix, removing oily and dirty impurities on the surface of the matrix, and keeping the matrix clean and dry;

(2) preparation work: loading graphite target, metal target and pretreated substrate into vacuum chamber of vacuum coating machine, regulating target base distance, and pumping air pressure in vacuum chamber to 1.0 × 10 ^-3Introducing argon with the purity of 99.99% to keep the deposition pressure in the argon below Pa to be 0.6-1.2 Pa, and keeping the deposition temperature to be 150-350 ℃; the metal target is a Ti target or a Cr target;

(3) deposition of a metal transition layer: rotating the substrate above the metal target to form a metal transition layer on the surface of the substrate;

(4) deposition of nano-multilayer film:

a) transferring the substrate subjected to metal transition layer deposition to the position above the graphite target, adjusting the argon flow to be 30sccm, and plating a DLC layer;

b) introduction of N ₂Exposing the substrate treated in step a) to argon and N ₂Plating a first gradient CNx layer in the mixed atmosphere; controlling N ₂The flow is gradually increased from 0 to a set value;

c) transferring the substrate treated in step b) above a metal target under argon and N ₂Plating a metal nitride layer in the mixed atmosphere;

d) transferring the substrate treated in step c) above a graphite target under argon and N ₂Plating a second gradient CNx layer in the mixed atmosphere; and control N ₂Gradually transitioning the flow from the set value to 0;

and (d) repeating the steps a) to d), thus obtaining the DLC/CNx/MeN/CNx nano multilayer film.

10. The method for producing DLC/CNx/MeN/CNx nano-multilayer film according to claim 9, wherein,

in step b), the argon and N ₂In a mixed atmosphere of (2), N ₂The flow set point was 1/2 for argon flow;

step (ii) ofc) The method comprises the following steps: the argon and N ₂In a mixed atmosphere of (2), N ₂The mixing ratio of the argon to the argon is 1: 2;

in step d), said argon and N ₂In a mixed atmosphere of (2), N ₂The flow set point was 1/2 for the argon flow.

Technical Field

The invention relates to the technical field of thin film materials, in particular to a DLC/CNx/Men/CNx nano multilayer film and a preparation method thereof.

Background

Diamond-like Carbon (DLC) films have a wide application prospect in the fields of mechanical parts, electronic devices, biomedicine, and the like due to their advantages of higher hardness, good wear resistance, biocompatibility, and the like. At present, the preparation technology of the DLC film mainly comprises magnetron sputtering deposition, chemical vapor deposition, magnetic filtration cathode vacuum arc deposition and the like, but the DLC film has obvious residual stress, so that the DLC film is easy to fall off from a substrate during bearing.

The bonding strength between the DLC film and the base material is poor, and a large part of the reason is that the difference between the coefficients of thermal expansion of the DLC film and the base material is large, which results in large internal stress in the DLC film. At present, methods for reducing the internal stress of the DLC film mainly include a doping method and a nano multilayer film technology. The doping method reduces the internal stress of the film by doping a metal (Ti, Cr, Al) or a non-metal element in the DLC film, but some studies have shown that, after doping the element, the hardness and elastic modulus of the DLC film are reduced with a reduction in stress, resulting in a decrease in the wear resistance of the film.

The nano-multilayer film is a thin film formed by alternately depositing materials of two or more components. When the thickness of the single-layer film is larger, the internal stress of the single-layer film is higher, so that the film is easier to peel off from the substrate. However, the multilayer film structure can relieve internal stress to a great extent, because when the number of the interface layers of the multilayer film is large, the stress can be absorbed more effectively, and the expansion of cracks is prevented, so that the bonding force between the film and the substrate is effectively improved, and each thinner layer leads to a compact structure, and the wear resistance is further improved.

Chinese patent literature discloses a metal carbide/diamond-like carbon (MeC/DLC) nano multilayer film material and a preparation method thereof, and application publication number is CN101081557A, the microhardness of the film prepared by the invention is high and reaches HV 2000-4500, the friction coefficient is as low as 0.10-0.25, and the film-base binding force is more than or equal to 60N. Yanar et al (Chinese surface engineering 2018,31(2):66-74) discovered that when studying magnetron sputtering method for preparing DLC/CNx multilayer films, the hardness of the multilayer films is significantly improved compared with single-layer films, but the binding force is still low, and further improvement is needed.

Disclosure of Invention

The invention provides the DLC/CNx/Men/CNx nano multilayer film which has small internal stress, high bonding strength with a base material and excellent wear resistance, in order to overcome the problems that the traditional DLC film has poorer bonding strength with the base material, and the wear resistance is reduced by reducing the stress and improving the bonding strength.

The invention also provides a preparation method of the DLC/CNx/MeN/CNx nano multilayer film, which has the advantages of simple steps, easy control of process conditions, safe and pollution-free preparation process, low cost and easy realization of industrialization.

In order to achieve the purpose, the invention adopts the following technical scheme:

a DLC/CNx/MeN/CNx nano multilayer film comprises a substrate, a metal transition layer and a nano multilayer film, wherein the metal transition layer and the nano multilayer film are sequentially deposited on the surface of the substrate, the nano multilayer film is composed of a plurality of nano composite units, and the nano composite units sequentially comprise a DLC layer, a first gradient CNx layer, a metal nitride layer and a second gradient CNx layer from bottom to top.

According to the invention, the pure metal transition layer is deposited on the surface of the substrate, the DLC/CNx/MeN/CNx nano multilayer film is deposited, the appropriate metal transition layer is applied between the substrate and the nano multilayer film as an intermediate layer, the affinity of metal and carbon element is good, a chemical bonding interface can be formed between the metal transition layer and the diamond-like carbon film (DLC), the difference of the thermal expansion coefficient between the substrate and the diamond-like carbon film is relieved, the internal stress can be effectively reduced, the problem of low film-based bonding force in the traditional deposition method is improved, and the wear resistance is excellent. The crystal lattices of the metal nitride and the CNx coating are more easily matched, and the film-based bonding strength of the DLC/CNx nano coating on a common high-speed steel substrate can be effectively improved.

Preferably, the total thickness of the DLC/CNx/MeN/CNx nano multilayer film is 0.6-10 μm.

Preferably, the substrate is a high speed steel substrate.

Preferably, the metal transition layer is Ti or Cr. The Cr and Ti metals are preferably selected as the transition layer in the invention because the affinity of Cr, Ti and carbon elements is better, a chemical bonding interface can be formed between the transition layer and the diamond-like carbon film (DLC), and the difference of the thermal expansion coefficient between the substrate and the diamond-like carbon film is relieved, thereby reducing the internal stress of the film and improving the bonding strength of the film and the substrate.

Preferably, the metal nitride layer is a TiN layer or a CrN layer.

Preferably, the nitrogen content of the first gradient CNx layer increases gradually from 0 at.% to 18 at.%.

Preferably, the nitrogen content of the second gradient CNx layer gradually decreases from 18 at.% to 0 at.%.

The design of the gradient layer with gradually increased and decreased N content enables the gradient layer to have better mechanical compatibility with the DLC layer and the metal nitride layer, can better transit to the beginning of the next period, greatly reduces the tendency of interlayer stripping, and can obtain high hardness and interlayer bonding force. The nitrogen content is controlled to be 0-18 at.% because the nitrogen content of the CNx film layer obviously influences the hardness, elastic modulus, internal stress and other properties of the CNx film layer, too high nitrogen content causes too low hardness and elastic modulus of the CNx film layer, interlayer property matching is difficult, and the multilayer film cannot obtain excellent properties.

Preferably, the nano indentation hardness of the DLC layer is 20-32 GPa; the nano indentation hardness of the first gradient CNx layer and the second gradient CNx layer is 15-25 GPa; the nano indentation hardness of the metal nitride layer is 20-28 GPa.

Preferably, the thickness of the nano multilayer film is 20-250 nm; the thickness of the nano composite unit is 5-100 nm.

A preparation method of DLC/CNx/MeN/CNx nano multilayer film comprises the following steps:

(1) pretreatment: ultrasonically cleaning a matrix in acetone and absolute ethyl alcohol in sequence, drying the matrix, removing oily and dirty impurities on the surface of the matrix, and keeping clean and dry;

(2) preparation work: loading the graphite target, the metal target and the pretreated substrate into a vacuum chamber of a vacuum coating machine, and adjustingThe base distance of the target is adjusted, and the air pressure in the vacuum chamber is pumped to 1.0 multiplied by 10 ^-3Introducing argon with the purity of 99.99% to keep the deposition pressure in the argon below Pa to be 0.6-1.2 Pa, and keeping the deposition temperature to be 150-350 ℃; the metal target is a Ti target or a Cr target; the thickness of each layer can be controlled by the deposition time;

(3) deposition of a metal transition layer: rotating the substrate above the metal target to form a metal transition layer on the surface of the substrate;

(4) deposition of nano-multilayer film:

a) transferring the substrate subjected to metal transition layer deposition to the position above the graphite target, adjusting the argon flow to be 30sccm, and plating a DLC layer; b) introduction of N ₂Exposing the substrate treated in step a) to argon and N ₂Plating a first gradient CNx layer in the mixed atmosphere; controlling N ₂The flow is gradually increased from 0 to a set value;

c) transferring the substrate treated in step b) above a metal target under argon and N ₂Plating a metal nitride layer in the mixed atmosphere;

d) transferring the substrate treated in step c) above a graphite target under argon and N ₂Plating a second gradient CNx layer in the mixed atmosphere; and control N ₂Gradually transitioning the flow from the set value to 0;

repeating the steps a) to d), and alternating for a plurality of periods to obtain the DLC/CNx/MeN/CNx nano multilayer film.

The deposition principle of the direct-current magnetron sputtering method adopted by the invention is as follows: the argon gas bombards the surface of the cathode metal target or the graphite target under the action of an electric field by plasma generated by abnormal glow discharge, atoms on the surface of the target are sputtered out and are ejected to the surface of the substrate along a certain direction under the action of the electric field, and a coating is formed on the surface of the substrate.

Preferably, in step b), the argon and N are ₂In a mixed atmosphere of (2), N ₂The flow set point was 1/2 for the argon flow.

Preferably, in step c): the argon and N ₂In a mixed atmosphere of (2), N ₂The mixing ratio of argon to argon was 1: 2.

As a preferenceIn step d), argon and N are used ₂In a mixed atmosphere of (2), N ₂The flow set point was 1/2 for the argon flow.

Therefore, the invention has the following beneficial effects:

(1) the DLC/CNx/MeN/CNx nano multilayer film effectively solves the problem of low film-substrate binding force of the traditional deposition method, reduces the internal stress and has excellent wear resistance;

(2) the preparation method has the advantages of simple steps, easily controlled process conditions, safe and pollution-free preparation process, low cost and easy realization of industrialization.

Drawings

FIG. 1 is a schematic structural diagram of a DLC/CNx/MeN/CNx nano-multilayer film of the present invention.

FIG. 2 is a graph showing the bonding force test results of the DLC/CNx/MeN/CNx nano-multilayer film prepared in example 1.

FIG. 3 is a graph showing the frictional wear of the DLC/CNx/MeN/CNx nano-multilayer film obtained in example 1.

In fig. 1: the nano-composite material comprises a substrate 1, a metal transition layer 2, a nano-composite unit 3, a DLC layer 4, a first gradient CNx layer 5, a metal nitride layer 6 and a second gradient CNx layer 7.

Detailed Description

The technical solution of the present invention is further specifically described below by using specific embodiments and with reference to the accompanying drawings.

In the present invention, all the equipment and materials are commercially available or commonly used in the art, and the methods in the following examples are conventional in the art unless otherwise specified.

As shown in fig. 1, a DLC/CNx/MeN/CNx nano-multilayer film comprises a substrate 1, a metal transition layer 2 and a nano-multilayer film sequentially deposited on the surface of the substrate, wherein the nano-multilayer film is composed of a plurality of nano-composite units 3, and the nano-composite units sequentially comprise a DLC layer 4, a first gradient CNx layer 5, a metal nitride layer 6 and a second gradient CNx layer 7 from bottom to top.