CN112391593A

CN112391593A - CrB with high Cr content and high elastic modulus2-Cr coating and preparation process thereof

Info

Publication number: CN112391593A
Application number: CN202011474390.8A
Authority: CN
Inventors: 王铁钢; 张雅倩; 刘艳梅; 阎兵; 范其香
Original assignee: Tianjin University of Technology and Education China Vocational Training Instructor Training Center
Current assignee: Tianjin University of Technology and Education China Vocational Training Instructor Training Center
Priority date: 2020-12-14
Filing date: 2020-12-14
Publication date: 2021-02-23
Anticipated expiration: 2040-12-14
Also published as: CN112391593B

Abstract

The invention discloses a CrB with high Cr content and high elastic modulus₂A Cr coating and a preparation process thereof, belonging to the technical field of coating preparation. Preparation of CrB on metal or hard alloy substrate by high-power pulse and pulse direct-current composite magnetron sputtering technology₂-Cr nanocomposite coating. In order to better control the content of Cr element in the coating, CrB is simultaneously selected as the target material₂Target and two metal Cr targets, respectively performing glow discharge cleaning and ion bombardment cleaning on the surface of the base material, depositing a metal Cr transition layer, and finally simultaneously starting the Cr targets and CrB₂Target, deposition of CrB₂-Cr coating, and the coating process is always carried out in an argon atmosphere. The invention has simple process and good repeatability; prepared CrB₂The content of Cr element in the Cr coating is obviously increased, and the coating hasHigher hardness and melting point, excellent high-temperature thermal stability and corrosion resistance, certain improvement on toughness, compact coating organization structure and strong binding force with a substrate.

Description

CrB with high Cr content and high elastic modulus2-Cr coating and preparation process thereof

Technical Field

The invention relates to the technical field of coating preparation, in particular to CrB with high Cr content and high elastic modulus₂-Cr coatings and processes for their preparation.

Background

With the rapid development of the industries such as aerospace, national defense and military industry and the like, the demand for difficult-to-cut materials/parts is gradually increased, such as titanium alloy, high-temperature alloy, composite material and the like, and when the titanium alloy, the high-temperature alloy, the composite material and the like are efficiently processed, the traditional cutter coating is difficult to meet the requirements of harsh working conditions due to the defects of poor heat resistance, low hardness and the like. Chromium diboride (CrB)₂) The coating has high melting point, high hardness, high wear resistance and corrosion resistance, and good chemical inertness, and is expected to meet the special processing requirements of the materials. But because of CrB₂The brittleness of the coating is high, and the coating used as a cutter coating is easy to crack in the cutting process, which limits CrB₂The popularization and application of the coating on the surface of the cutting tool urgently need to further improve the toughness. At present, CrB₂The preparation method of the coating mainly comprises a CVD method, a brushing method, a plasma spraying method and the like, wherein the CVD method has the problems of overhigh deposition temperature, environmental pollution and the like, and the plasma spraying method has the problem of CrB₂Because of high melting point and less tendency to form spreading, it is necessary to add SiC as an aid. The coating prepared by the brushing method has poor binding force with a substrate, so that the thermal shock performance is reduced, the sintering temperature is high, and SiC also needs to be introduced as a sintering aid. While SiC-incorporated coatings provide good ablation protection to the substrate material over a range of temperatures, the ablation resistance of the coating at higher temperatures is limited. Therefore, in order to obtain excellent coating performance, it is necessary to improve the coating composition and structure, and the coating preparation process, and to develop high-Cr content and high-elastic modulus CrB with good toughness₂-Cr coatings and processes for their preparation. In addition, Cr has good corrosion resistance, so CrB₂The Cr coating can be suitable for various complicated working conditions in extreme environments.

Disclosure of Invention

The invention aims to provide CrB with high Cr content and high elastic modulus₂The Cr element content of the prepared coating is increased, the toughening of the coating is improved, and the coating has good wear resistance and heat resistance.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

CrB with high Cr content and high elastic modulus₂-a Cr coating deposited on the surface of a substrate of metallic or ceramic material, with a Cr transition layer prepared between the substrate and the coating; the CrB₂The Cr coating is a nanocomposite structure.

The CrB₂The Cr coating consists essentially of differently oriented CrB₂、Cr₂B nanocrystalline and amorphous phase to form amorphous layer to wrap CrB₂And Cr₂Composite structure of B nanocrystals wherein CrB₂Crystal grain growth along (101) crystal plane, Cr₂The B crystal grains grow along the (022) crystal plane.

The CrB₂The hardness of the-Cr coating is adjustable between 15 and 35 GPa.

The CrB₂-Cr content in Cr coating 30-50 at.%.

The CrB with high Cr content and high elastic modulus₂The preparation process of the-Cr coating is to deposit CrB on a metal or ceramic material substrate by adopting a high-power pulse magnetron sputtering and pulse direct-current magnetron sputtering composite technology₂-a Cr nanocomposite coating; firstly, sputtering a Cr target I by utilizing a high-power pulse technology, carrying out ion bombardment cleaning on the surface of a substrate, and depositing a metal Cr transition layer; then adopting pulse direct current technology to sputter Cr target II and simultaneously using high power pulse technology to sputter CrB₂Target material, CrB is deposited in argon atmosphere₂-a Cr coating. The process comprises the following steps:

(1) fixing the matrix on a rotating frame in a vacuum chamber, connecting a Cr target I with a high-power pulse magnetron sputtering power supply, connecting a Cr target II with a pulse direct-current magnetron sputtering power supply, and connecting a CrB₂The target is connected with a high-power pulse magnetron sputtering power supply;

(2) firstly, carrying out glow discharge cleaning on a matrix to remove surface impurities; then, ion bombardment cleaning is carried out to improve the membrane/base binding force;

(3) depositing a Cr transition layer: after ion bombardment cleaning, keeping a high-power pulse power supply connected with a Cr target I switched on, reducing the bias voltage to-50 to-100V, depositing a metal Cr transition layer for 5 to 20min, keeping the target base distance at 80 to 120mm, and depositing at the temperature of 300 to 500 ℃; after the Cr transition layer is deposited, closing a high-power pulse magnetron sputtering power supply connected with a Cr target I;

(4) deposition of CrB₂-Cr coating: switching on a pulse direct current power supply connected with the Cr target II, wherein the output power is 0.05-0.3 kW, the target current is about 0.2-0.8A, the duty ratio is 60-80%, and the metal Cr target II is controlled to glow; simultaneous open connection CrB₂The high-power pulse power supply of the target has the average output power of 0.8-1.5 kW, and CrB is controlled₂Starting the target glow, the target current is 20-30A, and the CrB deposition is started₂A Cr coating, the target base distance is kept constant at 80-120 mm, and the working pressure is 3.0-6.0 multiplied by 10^-1Pa, the bias voltage of the substrate is-50 to-100V; the deposition time is determined according to the coating thickness requirement.

In the step (2), the glow discharge cleaning process includes: vacuumizing the background of the vacuum chamber to 1.0-3.0 x 10^-3Pa, introducing argon into the vacuum chamber to perform glow discharge cleaning on the surface of the substrate, increasing the pressure to 1.0-2.0 Pa, and adding-600-1000V direct current bias voltage for 5-20 min.

In the step (2), the ion bombardment cleaning process comprises: after glow discharge cleaning, a high-power pulse power supply connected with the Cr target I is switched on, the average output power is 0.8-1.5 kW, and the working pressure is 3.0-6.0 multiplied by 10^-1Pa, controlling the metal Cr target I to glow, and carrying out ion bombardment cleaning for 5-10 min at a target current of 20-30A.

The design mechanism of the invention is as follows:

the invention adopts the composite technology of high-power pulse magnetron sputtering and pulse direct current magnetron sputtering to deposit CrB on a metal or ceramic matrix₂The Cr nanometer composite coating is used for improving the bonding strength between the coating and a substrate, before the coating is deposited, the substrate is cleaned by ion bombardment by using a high-power pulse magnetron sputtering technology, and then a metal Cr transition layer with the thickness of about 100-300nm is deposited to play a role in buffering internal stress. Due to the metal or alloy matrix and CrB₂The thermal expansion coefficient difference of the coating is large, when the coating is cooled to room temperature, large thermal stress is often introduced, and the internal stress can be distributed in a gradient manner by the metal Cr transition layer, so that the combination between the coating and the substrate is improved, and the coating is prevented from being peeled off due to overlarge local stress. Finally, in argon atmosphere, using pulse DC magnetron sputtering techniqueRespectively sputtering Cr elementary substance target and CrB by high-power pulse magnetron sputtering technology₂Compound target, deposition of CrB₂-Cr nanocomposite coating, i.e. amorphous layer wrapped CrB₂And Cr₂B, the composite structure of the nanocrystalline improves the toughness of the coating, and realizes 'hard and tough'.

The invention adopts the composite technology of high-power pulse magnetron sputtering and pulse direct current magnetron sputtering to carry out film coating, the problems which often occur in a plurality of sputtering after a pulse direct current power supply is introduced into a magnetron sputtering film coating system are overcome, and the deposition rate of a boride film is close to the metal sputtering mode of a pure metal target. The periodic pulse voltage change realizes the periodic cleaning of the accumulated charges on the surface of the cathode target, and the compound coating and the insulating coating can be stably deposited for a long time. The high-power pulse discharge leads to the improvement of the ionization rate of the target material and the increase of the quantity of high-energy particles, the proportion of metal ions reaching the surface of the substrate is up to 92 percent, and after the surface of the substrate is bombarded by the high-energy ions, a clean activated interface is generated and the local epitaxial growth of the surface of the substrate is promoted, so that the bonding strength of the coating and the substrate is enhanced; the capability of adsorbing atoms on the surface of the substrate is also increased, and a coating with a more compact structure is formed. In addition, a nano composite structure is formed by controlling the content of Cr element in the coating, and the toughening and strengthening of the coating are realized.

The invention has the following advantages:

1. CrB developed by the invention₂The Cr coating has stable chemical property and is not easy to generate corrosion reaction with common chemical substances, and particularly, the content of Cr element in the coating is increased, so that the corrosion resistance of the coating is greatly improved; meanwhile, as the number of Cr atoms is increased, the formed amorphous phase can inhibit the expansion and propagation of microcracks, consume the energy at the tips of the microcracks and achieve the toughening effect.

2. CrB developed by the invention₂the-Cr nano composite coating has good heat resistance and wear resistance, and good mechanical properties, such as high hardness and large elastic modulus.

3. CrB developed by the invention₂the-Cr nano composite coating has the advantages of uniform thickness, compact structure, no defects of holes, large particles and the like, and good bonding strength with a matrix.

4. CrB developed by the invention₂The thermal stability and the thermal shock resistance of the-Cr nano composite coating are good.

5. CrB developed by the invention₂The preparation process of the-Cr nano composite coating is simple and has good repeatability.

Drawings

FIG. 1 shows CrB prepared by high power pulse and pulse DC composite magnetron sputtering technology₂Surface topography of the Cr coating.

FIG. 2 shows CrB prepared by high power pulse and pulse DC composite magnetron sputtering technology₂The profile of the Cr coating.

FIG. 3 shows CrB prepared by high power pulse and pulse DC composite magnetron sputtering technique₂The Cr content of the Cr coating varies with the sputtering power of the Cr target.

FIG. 4 shows CrB prepared by high power pulse and pulse DC composite magnetron sputtering technology₂-XRD pattern of Cr coating.

FIG. 5 shows CrB prepared by high power pulse and pulse DC composite magnetron sputtering technique₂-surface hardness test results of Cr coatings.

FIG. 6 shows CrB prepared by high power pulse and pulse DC composite magnetron sputtering technique₂Scratch morphology of Cr coating.

FIG. 7 shows CrB with different Cr contents prepared by high power pulse and pulse DC composite magnetron sputtering technology₂-XRD pattern of Cr coating.

Detailed Description

The technical solution of the present invention will be further described with reference to specific embodiments.

Example 1

This example is the deposition of CrB on a mirror polished single crystal Si wafer (100 orientation)₂-a Cr coating. Three targets in total, CrB₂One target and two Cr targets (Cr target I and Cr target II). Firstly, fixing a Si sheet on a rotating frame in a vacuum chamber, connecting a Cr target I with a high-power pulse magnetron sputtering power supply, connecting a Cr target II with a pulse direct-current power supply, and connecting a CrB₂Target connection high-power pulse magnetic controlA sputtering power supply.

Before being put into a vacuum chamber, the substrate is respectively ultrasonically cleaned in acetone and alcohol solution for 20 minutes, then is dried by high-purity nitrogen, and is fixed on a rotating frame in the vacuum chamber opposite to the target material. The coating process is carried out on a V-TECH AS610 type high-power pulse and pulse direct-current composite magnetron sputtering coating machine, and the cathode target material selects two metal Cr targets and one CrB target₂Target (purity 99.9% each); the Cr target I is connected with a high-power pulse magnetron sputtering power supply and is used for ion bombardment cleaning and Cr transition layer deposition on the surface of the substrate; cr target II connected pulse DC magnetron sputtering power supply for CrB₂Deposition of Cr coating, CrB₂Target for CrB only₂Deposition of Cr coating, the whole coating process being carried out in argon atmosphere.

The background of the vacuum chamber is firstly vacuumized to 2.5 multiplied by 10^-3Pa, introducing argon gas into a vacuum chamber to perform glow discharge cleaning on the surface of the sample, increasing the pressure to 1.1Pa, adding-780V direct current bias voltage, and performing discharge cleaning for 15 min; then, a high-power pulse magnetron sputtering power supply connected with the Cr target I is started, the average output power is 0.8kW, and the working pressure is 4.0 multiplied by 10^-1Pa, controlling the metal Cr target I to glow, controlling the target current to be about 22A, and then bombarding and cleaning for 6 min; then reducing the bias voltage to-50V, firstly depositing a metal Cr transition layer for 10min, keeping the target base distance at 100mm, and depositing at the temperature of 200 ℃; and after the deposition of the transition layer is finished, closing the high-power pulse magnetron sputtering power supply connected with the Cr target I.

Starting a pulse direct current magnetron sputtering power supply connected with the Cr target II, controlling the metal Cr target II to glow with the output power of 0.05kW, the target current of about 0.22A and the duty ratio of 60 percent, and simultaneously starting connection CrB₂The average output power of a high-power pulse magnetron sputtering power supply of the target is 1.0kW, and CrB is controlled₂The target glows with a target current of about 26A and deposition of CrB begins₂-Cr coating, target base distance is kept at 100mm, and working pressure is 4.0 x 10^-1Pa, substrate bias of-50V; the deposition time is 180 min.

FIG. 1 and FIG. 2 are CrB₂Surface and profile of the-Cr coating, as can be seen in FIG. 1, CrB prepared by the process of the present invention₂The surface of the-Cr coating is smooth and compact and is free ofParticle defects and no holes; as can be seen from FIG. 2, CrB prepared by the process of the present invention₂the-Cr coating has compact and uniform structure, a section of the-Cr coating is a tiny columnar crystal, and the coating, the transition layer and the substrate are well combined.

As can be seen from FIG. 3, CrB prepared in this example₂The Cr content in the Cr coating is about 32 at.%.

FIG. 4 is CrB prepared by the process of the present invention₂XRD diffraction pattern of the Cr coating, it being seen that the coatings produced with this process consist mainly of differently oriented CrB₂And Cr₂B crystal grains and a small amount of amorphous phase, wherein CrB₂Crystal grain growth along (101) crystal plane, Cr₂The B crystal grains grow along the (022) crystal plane.

Example 2

This example is a mirror polished AISI 304 stainless steel substrate (Cr-18.5, Ni-9.4, Mn-0.8, Si-0.4, P-0.1, balance Fe, all in weight percent) on which CrB was deposited₂-a Cr coating. The substrate is firstly ground and polished by metallographic abrasive paper, then is ultrasonically cleaned by acetone and alcohol respectively, and is fixed on a sample rack in a vacuum chamber opposite to the target after being dried. The coating deposition process and deposition parameters were the same as in example 1.

Testing CrB deposited on stainless steel substrate by using nano indenter and continuous rigidity method₂The nano-hardness of the Cr coating, the test results are shown in FIG. 5, the coating hardness ranges from 15.9 GPa to 19.9GPa, the average value of 18 point measurements is 17.6GPa, and the coating hardness is higher. The bonding strength of the coating and the substrate was tested by a scratch method, the radius of the tip of a diamond scribe was 200 μm, the normal load was gradually increased from 0.01 to 100N at a rate of 1N/s, the length of the scratch was 15mm, and the test speed was 0.2 mm/s. After 5 tests, CrB₂The average critical load between the Cr coating and the substrate was 46.9N. FIG. 6 CrB after scratch test₂Typical scratch morphology of Cr coatings, the arrows in the figure marking the position where the coating is completely peeled off from the substrate.

Example 3:

the difference from the embodiment 1 is that: the sputtering powers of the Cr targets II were adjusted to 0kW, 0.05kW, 0.1kW, 0.15kW, and 0.2kW, respectively, and the other processes were the same as in example 1.

The XRD diffraction pattern of each of the prepared coatings is shown in fig. 7, and the Cr content in the coating is 25.0 at.%, 31.8 at.%, 39.5 at.%, 42.5 at.% and 44.4 at.%, respectively (fig. 3). It can be seen that CrB increases with increasing Cr content in the coating when the sputtering power of the Cr target II is > 0.05kW₂Diffraction peaks gradually disappear, Cr₂The diffraction peak of B is gradually enhanced, and Cr is used in the coating₂Phase B is predominant with a small amount of amorphous phase.

Claims

1. CrB with high Cr content and high elastic modulus₂-a Cr coating characterized in that: the CrB₂-a Cr coating is prepared on a metal or ceramic material substrate, and a Cr transition layer is prepared between the substrate and the coating; the CrB₂The Cr coating is a nanocomposite structure.

2. The high Cr content, high elastic modulus CrB of claim 1₂-a Cr coating characterized in that: the CrB₂The Cr coating consists essentially of differently oriented CrB₂And Cr₂B nanocrystalline and amorphous phase to form amorphous layer to wrap CrB₂And Cr₂Composite structure of B nanocrystals wherein CrB₂Crystal grain growth along (101) crystal plane, Cr₂The B crystal grains grow along the (022) crystal plane.

3. The high Cr content, high elastic modulus CrB of claim 1₂-a Cr coating characterized in that: the CrB₂The hardness of the Cr coating is 15-35 GPa.

4. The high Cr content, high elastic modulus CrB of claim 1₂-a Cr coating characterized in that: the Cr content of the coating is 30-50 at.%.

5. High Cr content, high elastic modulus CrB as claimed in any of claims 1 to 4₂-a process for the preparation of a Cr coating, characterized in that: the process adopts a composite technology of high-power pulse magnetron sputtering and pulse direct-current magnetron sputtering on metal or ceramicCrB deposition on ceramic material substrate₂-a Cr coating; firstly, sputtering a Cr target I by utilizing a high-power pulse technology, carrying out ion bombardment cleaning on the surface of a substrate, and then depositing a Cr transition layer; then adopting pulse direct current technology to sputter Cr target II and simultaneously using high power pulse technology to sputter CrB₂Target material, CrB is deposited in argon atmosphere₂-a Cr coating.

6. The high Cr content, high elastic modulus CrB of claim 5₂-a process for the preparation of a Cr coating, characterized in that: the process comprises the following steps:

(2) firstly, carrying out glow discharge cleaning on a matrix to remove surface impurities; then, a high-power pulse power supply connected with the Cr target I is started to carry out ion bombardment cleaning so as to improve the film/substrate binding force;

7. High Cr content, high elastic modulus according to claim 5CrB of (2)₂-a process for the preparation of a Cr coating, characterized in that: in the step (2), the glow discharge cleaning process comprises the following steps: vacuumizing the background of the vacuum chamber to 1.0-3.0 x 10^-3Pa, introducing argon into the vacuum chamber to perform glow discharge cleaning on the surface of the substrate, increasing the pressure to 1.0-2.0 Pa, and adding-600-1000V direct current bias voltage for 5-20 min.

8. The high Cr content, high elastic modulus CrB of claim 7₂-a process for the preparation of a Cr coating, characterized in that: in the step (2), the ion bombardment cleaning process comprises the following steps: after glow discharge cleaning, a high-power pulse power supply connected with the Cr target I is switched on, the average output power is 0.8-1.5 kW, and the working pressure is 3.0-6.0 multiplied by 10^-1Pa, controlling the metal Cr target I to glow, and carrying out ion bombardment cleaning for 5-10 min at a target current of 20-30A.