CN110616400B

CN110616400B - A laminated protective coating with high temperature water vapor oxidation resistance and strong toughness, preparation method and application

Info

Publication number: CN110616400B
Application number: CN201910905033.3A
Authority: CN
Inventors: 黄峰; 周靖媛; 李朋; 葛芳芳; 苏云婷; 祝涵
Original assignee: Ningbo Institute of Material Technology and Engineering of CAS
Current assignee: Ningbo Institute of Material Technology and Engineering of CAS
Priority date: 2019-09-24
Filing date: 2019-09-24
Publication date: 2021-08-24
Anticipated expiration: 2039-09-24
Also published as: CN110616400A

Abstract

The invention discloses a laminated protective coating with high temperature water vapor oxidation resistance and strong toughness, which comprises periodic alternating deposition of a Cr-N layer and a Cr-Al-Si-N layer, and the number of cycles of the alternate deposition is 4 ~40 times; the thickness of the Cr-Al-Si-N layer and the Cr-N layer in the unit cycle is 0.19-2.5 μm, and the thickness ratio thereof is 2.8-5.2. The invention discloses a method for preparing the above-mentioned laminated protective coating by a magnetron sputtering method and an application of the laminated protective coating in a zirconium alloy cladding material. The laminated protective coating prepared by the invention has a hardness of 15-22 GPa, a plastic index of 0.55-0.67, an anti-plastic deformation index of 0.07-0.09, and can resist 1200 ℃ water vapor corrosion for 4 hours, and has the ability to resist water vapor oxidation. Compared with the Cr-Al-Si-N coating with a single-layer structure, the improvement is 1.5-2 times.

Description

Laminated protective coating with high-temperature steam oxidation resistance and high toughness, and preparation method and application thereof

Technical Field

The invention belongs to the field of protective ceramic coatings, and particularly relates to a laminated protective coating with high-temperature steam oxidation resistance and high toughness, and a preparation method and application thereof.

Background

The zirconium alloy has the advantages of radiation resistance, low thermal neutron absorption cross section and the like, is a cladding material of the current mainstream light water reactor fuel, and has the key of ensuring the safety and the reliability of the nuclear reactor core in terms of stable performance and prolonged service life. However, in the case of coolant failure (LOCA), the zirconium alloy is liable to react with high-temperature water vapor to generate a large amount of hydrogen, thereby causing an explosion, which is a main cause of nuclear leakage due to the explosion of the nuclear power plant in fukushima, japan. Therefore, it is important in the nuclear safety field to prevent or relieve the reaction between the zirconium alloy and the high-temperature water vapor and improve the accident tolerance of the zirconium alloy.

The protective coating is plated on the surface of the zirconium alloy cladding material to prevent the zirconium alloy from reacting with high-temperature water vapor, and the method is one of effective methods for improving the fault tolerance of the zirconium alloy accident at present. Transition metal Cr-based multi-component coating materials, such as Al, Si and N-doped Cr-based ceramic materials, have a plurality of excellent properties of high-temperature oxidation resistance, high hardness, high modulus and the like, and are considered to be one of the materials most suitable for the nuclear cladding protective coating application (Illana-jac-2019).

Chinese patent application documents with publication numbers CN108486537A, CN109338303A and CN109234694A also successively disclose Cr-Al-Si-N protective coatings, which can effectively prevent zirconium alloy from reacting with water vapor under the high-temperature water vapor corrosion environment of 800-1200 ℃ and achieve the purpose of protecting the zirconium alloy. For example, the amorphous and nanocrystalline Cr-Al-Si-N protective coating disclosed in the patent application with the publication number of CN109338303A has the hardness of 18-23 GPa and can resist the steam oxidation at 800-1200 ℃ within a longer time (60 min).

However, although the Cr-Al-Si-N protective ceramic coating exhibits better high-temperature steam oxidation resistance and high hardness, the Cr-Al-Si-N protective ceramic coating has the essential defects of low toughness and large brittleness as a ceramic coating, and the Cr-Al-Si-N protective ceramic coating is easy to crack and peel off under stress in actual working conditions, so that the Cr-Al-Si-N protective ceramic coating cannot play a protective role.

Disclosure of Invention

Aiming at the technical problems, the invention aims to provide a laminated protective coating with high temperature steam oxidation resistance and high toughness, and overcomes the essential defects of high hardness, low toughness and high brittleness of the conventional high temperature steam oxidation resistant protective coating.

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

in a first aspect, the invention provides a laminated protective coating with high-temperature steam oxidation resistance and high toughness, which comprises Cr-N layers and Cr-Al-Si-N layers which are periodically and alternately deposited, wherein the number of the periods of the alternate deposition is 4-40; the total thickness of the Cr-Al-Si-N layer and the Cr-N layer in the unit period is 0.19-2.5 mu m, and the thickness ratio is 2.8-5.2;

the composition of the Cr-N layer and the Cr-Al-Si-N layer is expressed as Cr_xN_1-xAnd Cr_aAl_bSi_cN_100-a-b-cWherein x is more than or equal to 0.72 and less than or equal to 0.75, a is more than or equal to 50 and less than or equal to 53, b is more than or equal to 15 and less than or equal to 17, c is more than or equal to 7 and less than or equal to 10, and x, a, b and c are atomic ratios.

Preferably, the laminated protective coating grows perpendicular to the substrate, the Cr-N layer and the Cr-Al-Si-N layer are periodically and alternately deposited along the growth direction in sequence, and the surface layer of the laminated protective coating is the Cr-Al-Si-N layer.

Preferably, the Cr-N layer is Cr₂The ceramic two-phase composition of N and Cr has a density of 5.8-6.0 g/cm³。

The phase composition structure and density of the Cr-N layer are crucial to the enhancement of the toughness of the coating, experiments show that the chromium nitride has good mechanical property, the influence of the N content on the hardness and the toughness of the Cr-N monolayer is obvious, and according to a Cr-N phase diagram, when the N content ratio is too high (the N atom ratio is 33.5-50%), the monolayer can grow Cr₂The hardness of the Cr-N monolayer is high, but the plastic deformation performance is poor, the toughness is low and the brittleness is high; the proper N content (N atom ratio is 10-25%) can form Cr₂Ceramic two-phase composite structure of N and Cr, Cr₂The N ceramic phase has higher hardness, and the Cr metal phase has better plastic deformation capability, so that the Cr-N single layer meets the requirement of high hardness and simultaneously shows better toughness. Second, Cr is formed₂The N and Cr ceramic-gold two-phase composite structure overcomes the columnar crystal structure easily generated by the traditional single-phase CrN, eliminates the penetrating gap and obviously prolongs the time of resisting the high-temperature steam oxidation of the coating.

Preferably, the Cr-Al-Si-N layer is an amorphous coating, and the density of the Cr-Al-Si-N layer is 5.2-5.6 g/cm³. This is because compared with the crystalline structure, the amorphous compact structure can reduce the channel of rapid diffusion of corrosion, so that the high temperature water vapor corrosion resistance of the coating becomes better. Cr, Al, Si are due to their oxides (Cr)₂O₃、Al₂O₃、SiO₂) Is high in temperature resistance and is often selected as a high temperature oxidation resistant material.

Experiments show that the protective coating with the laminated structure is formed by alternately depositing the Cr-N ceramic layers and the Cr-Al-Si-N ceramic layers, so that the protective coating can resist high-temperature steam oxidation and simultaneously show better toughness, wherein the structure, the thickness, the density and the layer period number of each layer have important influence on the high-temperature steam corrosion resistance and the toughness enhancement. In addition, the laminated structure of the invention can break the penetrating defects (such as pores, impurities and the like) of the coating by the interface between layers on one hand, thereby effectively preventing the diffusion of water vapor and oxygen to the matrix along the penetrating gaps and leading the coating to have better or longer-time high-temperature oxidation resistance; on the other hand, the interface between layers can consume and absorb the energy of crack propagation, thereby preventing the crack propagation and improving the toughness of the coating.

In a second aspect, the invention provides a method for preparing the laminated protective coating with high temperature steam oxidation resistance and toughness, wherein the laminated structure of Cr-N and Cr-Al-Si-N is formed by alternate deposition through a physical vapor deposition method, preferably a magnetron sputtering method and a cathode arc method.

Preferably, the specific parameters for preparing the laminated protective coating by adopting a magnetron sputtering method are as follows: vacuum of back bottom lower than 8X 10^-5Pa, introducing N₂Using the mixed gas with the Ar gas ratio of 0.06-0.13 as a gas source, adjusting the gas pressure of the gas source to be 0.5-1 Pa, and sputtering Cr target and Cr in the gas source through alternative reaction_yAl_zSi_1-y-zAnd depositing the target to obtain the laminated protective coating, wherein y is more than or equal to 0.5 and less than or equal to 0.6, and z is more than or equal to 0.25 and less than or equal to 0.3.

Preferably, the Cr target and Cr_yAl_zSi_1-y-zSputtering targets by adopting a radio frequency auxiliary direct current power supply mode, wherein the power density of the Cr target is 4.2-4.6W/cm²，Cr_yAl_zSi_1-y-zThe power density of the target is 6.1-6.5W/cm²。

Preferably, the purity of the Cr target is 99.99%, and the Cr is_yAl_zSi_1-y-zThe purity of the target was 99.95%.

Preferably, the laminated protective coating is prepared by a magnetron sputtering method, and a bias voltage of-5 to-10V is applied to the laminated protective coating.

Preferably, the laminated protective coating is prepared by adopting a magnetron sputtering method, and N is introduced during the preparation of the Cr-N layer₂The ratio of Ar gas to Cr gas is 0.06-0.08, and the Cr target is nitrided before deposition.

More preferably, the nitriding treatment is performed by: by using N₂Reactively sputtering a Cr target as a source of sputtering gas, wherein N₂And the ratio of the Cr target to Ar gas is 0.06-0.08, observing the power supply voltage of the Cr target, and indicating that the nitridation is finished when the power supply voltage keeps unchanged along with the sputtering time.

In a third aspect, the invention provides the use of the laminated protective coating described above in zirconium alloy cladding materials. The concrete application is as follows:

a coating device comprises a substrate and a coating on the surface of the substrate, wherein the coating is the laminated protective coating with high-temperature steam oxidation resistance and obdurability, the substrate is made of Zr or Zr alloy, and the substrate is mirror-polished.

Compared with the prior art, the invention has the following advantages:

(1) according to the invention, a laminated protective coating with high-temperature steam oxidation resistance and toughness is developed by preparing a laminated structural coating with Cr-N layers and Cr-Al-Si-N layers which are alternately deposited, the essential defects of high hardness, low toughness and high brittleness of the existing high-temperature steam oxidation resistant protective coating are overcome, the hardness of the coating can reach 15-22 GPa, the toughness can reach 0.55-0.67 expressed by a plasticity index, and the plastic deformation resistance H is realized³/E^*20.07 to 0.09. The toughness-enhanced coating prepared by the invention is not easy to crack under stress and has good bonding force in actual service working conditions, so that the protective coating plays a protective role for a long time.

(2) According to the invention, by preparing the laminated structure of the Cr-N layer and the Cr-Al-Si-N alternate deposition, on one hand, the laminated structure effectively reduces the penetrability defect, and further effectively prevents the diffusion of water vapor and oxygen, so that the water vapor oxidation resistance is improved by 1.5-2 times compared with that of a Cr-Al-Si-N coating with a single-layer structure, and the corrosion resistance to water vapor at 1200 ℃ can be realized for 4 hours.

Drawings

FIG. 1 is a schematic structural view of a laminated protective coating of the present invention, wherein λ represents a periodic layer, N represents the number of periodic layers, 11 represents a substrate, 1A represents a Cr-Al-Si-N layer, and 1B represents a Cr-N layer.

FIG. 2 is a schematic diagram of an apparatus for preparing a multilayer protective coating according to the present invention, 1-chamber, 2-sample stage, 3A, 3B-target, 4-spacer, 5-gas outlet, and 6-gas inlet.

FIG. 3 is a cross-sectional microscopic topography of the laminated protective coating prepared in example 1, (a) an SEM topography, (b) a partially magnified TEM bright field image, (c) selective diffraction of Cr-N layer, and (d) selective diffraction of Cr-Al-Si-N layer.

FIG. 4(a) is a graphical representation of nanoindentation characterizing toughness, and FIG. 4(b) is a graphical representation of the nano-hardness and its toughness of the LbL protective coating prepared in example 1.

FIG. 5 is an SEM topography of a Vickers indentation generated after the laminated protective coating prepared by the invention is damaged by 2N pressure and a sectional SEM topography of the indentation after in-situ FIB cutting, wherein the SEM topography of the indentation in example 1 is (a-1), and the sectional topography of the indentation after in-situ cutting is (a-2); comparative example 1 the indentation SEM topography is (b-1) and the in-situ cut cross-sectional topography is (b-2).

FIG. 6 is a SEM cross-sectional morphology and EDX line scan analysis of the laminated protective coating prepared in example 1 of the present invention after high temperature water vapor etching.

Detailed Description

The structure of the laminated protective coating with high temperature steam oxidation resistance and toughness is shown in figure 1, and comprises a substrate 11 and the laminated protective coating deposited on the substrate 11 by a magnetron sputtering method, wherein the laminated protective coating comprises a Cr-N layer shown in 1B and a Cr-Al-Si-N layer shown in 1A to form a period lambda, the layer period number is N, the thickness ratio of the 1A layer to the 1B layer is sigma, the coating is prepared according to the following examples according to the difference of the thickness, the thickness ratio and the layer period number of the 1A layer and the 1B layer, and the structural characterization and the performance test of each coating are carried out or determined according to the following methods:

firstly, coating preparation

All examples were prepared as shown in FIG. 2 when the backing vacuum ≦ 8 × 10^-5When Pa is needed, the sample 7 is heated to 200 ℃ and is kept warm for 1h, and-15V to-10V is applied to the matrixThrough the gas inlet 6 of the chamber 1, Ar and N are respectively introduced₂The gas pressure of the chamber 1 is adjusted by controlling the opening and closing of the gas outlet 5 as a sputtering and reaction gas source in which a 3A target (Cr target) and a 3B target (Cr target) are alternately sputtered_yAl_zSi_1-y-zY is more than or equal to 0.5 and less than or equal to 0.6, and z is more than or equal to 0.25 and less than or equal to 0.3) to obtain the multilayer protective coating. The 3A target and the 3B target are separated by a partition plate 4 (the separation is to ensure that the 3A target and the 3B target work independently without interference and further do not interfere with each other when a Cr-N layer and a Cr-Al-Si-N layer are deposited), wherein, a radio frequency auxiliary direct current power supply applying mode is adopted in the process of sputtering the 3A target and the 3B target, and the sputtering power density, the deposition air pressure and the N of each target are controlled₂The flux gives the specific crystal structure and density of each layer. And in the deposition process, when a 3A target is sputtered, controlling the sample 7 in the sample table 2 to be over against the 3A target for reactive sputtering to obtain a Cr-N layer, and when a 3B target is sputtered, controlling the sample 7 in the sample table 2 to be over against the 3B target for reactive sputtering to obtain a Cr-Al-Si-N layer, so that the laminated protective coating shown in the figure 1 is obtained by alternately depositing and controlling the time and the period number N when the sample 7 is over against each target.

Second, coating structure characterization

1. Coating composition

The coating composition and its distribution were analyzed by X-ray energy spectrometer (EDX) using FEI Quanta (TM) 250 FEG. After the composition measurements, the Al/N ratio in the coating was corrected by standard ZAF methods using AlN as a standard. Selecting an area of not less than 30mm for each sample²And area, the average value of its composition is measured. And (3) performing SEM observation and EDX line scanning on the cross section of the coating corroded by the high-temperature steam, and determining the appearance characteristics and oxidation products of the coating oxidized by the steam.

2. Coating crystal structure

Using a German Bruker D8 Advance X-ray diffractometer (XRD) with Cu K_αIncident ray with wavelength of 0.154nm and theta/theta mode, controlling X-ray tube at 40kV and 40mA, measuring crystal structure of the coating, and filtering out K with nickel filter_βAnd (3) ray, setting the detection angle 2 theta to be 30-100 degrees, and setting the step length to be 0.01 degrees.

3. Morphology of the coating

And observing the surface and section morphology characteristics of the coating and the morphology characteristics of the coating after high-temperature water vapor oxidation by adopting a Hitachi S-4800 scanning electron microscope (SEM, emission gun voltage of 8KV), and carrying out component analysis on the morphology of the coating after oxidation by using an EDX (electronic data interchange) line scanning mode so as to qualitatively evaluate the protective capability of the coating. The cross-sectional topography of the coating was observed using FEI Tecnai Transmission Electron Microscopy (TEM) at a lower microscopic scale in bright field images and the selected diffraction function was chosen to determine the crystal structure of each layer in the stack.

Third, coating performance test

1. High temperature steam oxidation test of coatings

The high-temperature steam oxidation experiment is carried out in an alumina tube furnace with one end connected with a steam generator. The tube furnace temperature was set at 1200 ℃. And after the set temperature is reached, starting the steam generator, and introducing steam with uniform flow velocity into the furnace tube. And when the water vapor flow rate is stable, feeding the sample piece into the middle part of the furnace tube. Opening one end of the furnace mouth and plugging the furnace mouth by a corundum furnace pipe plug for heat preservation. After oxidizing at high temperature for 240min, taking out the sample and cooling to room temperature. And (3) packaging the oxidized sample by epoxy resin, and analyzing the appearance and the components of the cross section after grinding and polishing.

2. Hardness test of coating

Using MTS NANO G200 NANO indenter, Berkovich diamond indenter, to eliminate the effects of substrate effect and surface roughness, the maximum indentation depth was 1/10 of the coating thickness, and 10 test points were measured for each sample and averaged.

3. Toughness testing of coatings

As shown in FIG. 4(a), the plasticity index δ of the coating layer_HThe measurement was carried out according to the following formula (1):

the model produced by adopting American MTS isMeasuring the plastic and elastic deformation of the coating by using a NANO G200 NANO-indenter, configuring a tetrahedral Berkvich pressure head, setting the indentation depth to be 1/10 of the thickness of the coating, changing the load along with the indentation depth, measuring 10 matrix points of each sample and then averaging, wherein delta_HIs a toughness index, h_pPlastic deformation of the coating after nanoindentation_maxThe maximum deformation of the coating after the nanoindentation is pressed in.

The hardness H and indentation modulus E of each sample can be measured by the above method^*The plastic deformation resistance index ξ is measured in accordance with the above formula (2), specifically the ratio of the hardness to the indentation modulus.

Example 1

The embodiment is prepared by a magnetron sputtering method, and the parameters are as follows: vacuum of 8X 10^-5Pa, chamber pressure 0.7Pa, 3B target component Cr_0.6Al_0.3Si_0.1(ii) a The 3A target power density is 4.2W/cm²And the 3B target power density is 6.3W/cm²(ii) a Sputtering the 3A target (the 3B target is closed at this time), and introducing N₂The flow ratio of the sample to Ar gas is 0.06, the sample 7 is controlled to face a 3A target, and a Cr-N layer with the thickness of 105nm is obtained by sputtering; thereafter, the 3A target was turned off and N was adjusted₂And the flow ratio of the Cr-Al-Si-N protective coating to Ar gas is 0.13, starting the 3B target, starting sputtering the 3B target, controlling the sample 7 to face the 3B target, and sputtering to obtain Cr-Al-Si-N layers with the thickness of 420nm, wherein the Cr-N layers and the Cr-Al-Si-N layers are alternated for 20 times to obtain the Cr-N/Cr-Al-Si-N laminated protective coating with the period N of 20, wherein the thickness of the Cr-N layer in one period layer is 105nm, and the thickness of the Cr-Al-Si-N layer is 420 nm.

The prepared Cr-N/Cr-Al-Si-N (N ═ 20) laminated protective coating was structurally characterized, as shown in fig. 3(a), as a multi-layered laminated structure formed by alternating Cr-N layers and Cr-Al-Si-N layers. When TEM bright field image observation is carried out on one periodic layer, as can be seen from figure 3(b), the Cr-N layer and the Cr-Al-Si-N layer do not present a columnar crystal growth structure, have no obvious penetrating pore defects and have very dense coatings. The density of the Cr-N layer was determined to be 5.8g/cm³The component composition is Cr_0.73N_0.27And determining the crystal structure of the Cr-N layer by using TEM selected area diffraction, wherein Cr is shown as the attached figure 3(c)₂Two phases of N and Cr are compounded. For Cr-Al-Si-N thereofLayer was measured and the composition was Cr₅₃Al₁₇Si₇N₂₃The Cr-Al-Si-N layer was amorphous as measured by TEM selected area diffraction as shown in FIG. 3(d), and had a density of 5.5g/cm³。

The prepared Cr-N/Cr-Al-Si-N (N ═ 20) laminated protective coating is subjected to hardness and plasticity index delta_HAs a result, as shown in FIG. 4(b), the hardness of the coating was 18GPa, and the plasticity index delta_HIt was 0.67, and the plastic deformation resistance index ξ was 0.08.

FIG. 5(a-1) is an SEM (scanning electron microscope) topographic image of an indentation of the laminated protective coating, and it can be seen that the coating has a small number of cracks under the pressure failure, the length of the cracks is relatively short, the length of the cracks is 45-50 μm, and the cracks along the depth of the coating are observed after in-situ FIB cutting, as shown in FIG. 5(a-2), the number of the generated cracks is small, the width of the generated cracks is relatively narrow, the cracks are bent at a layer interface and limited at a transverse expansion position, so that the cracks penetrating through the whole coating are avoided, and the toughness of the coating is enhanced.

FIG. 6 is a cross-sectional view of the laminated protective coating after high temperature steam oxidation test for 4 hours at 1200 ℃ and EDX line scan showing no ZrO after corrosion₂And the generation shows that the coating plays a better protective role. ZrO formed on the polished zirconium without coating by high-temperature steam oxidation under the same conditions₂The thickness was 220. mu.m.

Example 2

The embodiment is prepared by a magnetron sputtering method, and the parameters are as follows: vacuum of back bottom 7X 10^-5Pa, chamber pressure 0.7Pa, 3B target component Cr_0.5Al_0.25Si_0.25(ii) a The 3A target power density is 4.4W/cm²And the 3B target power density is 6.1W/cm²(ii) a Sputtering the 3A target (the 3B target is closed at this time), and introducing N₂The flow ratio of the sample to Ar gas is 0.06, the sample 7 is controlled to face a 3A target, and a Cr-N layer with the thickness of 160nm is obtained by sputtering; thereafter, the 3A target was turned off and N was adjusted₂The flow ratio of Ar gas to the 3B target was 0.11, the 3B target was started, sputtering of the 3B target was started and the sample 7 was controlled to face the 3B target, and a 640nm thick Cr-Al-Si-N layer was obtained by sputtering, which was alternated 13 times, to obtain Cr-N/Cr-The Al-Si-N laminated protective coating is characterized in that the thickness of the Cr-N layer in one period layer is 160nm, and the thickness of the Cr-Al-Si-N layer in one period layer is 640 nm.

The prepared Cr-N/Cr-Al-Si-N (N ═ 13) laminated protective coating is structurally characterized to be a multilayer laminated structure, and Cr-N layers and Cr-Al-Si-N layers are formed alternately. And when TEM bright field image observation is carried out on one periodic layer, the Cr-N layer and the Cr-Al-Si-N layer do not present a columnar crystal growth structure, have no obvious penetrating pore defects and have very compact coatings. The density of the Cr-N layer was determined to be 6.0g/cm³The component composition is Cr_0.75N_0.25And determining the crystal structure of the Cr-N layer by using TEM selected area diffraction, Cr₂Two phases of N and Cr are compounded. The Cr-Al-Si-N layer is measured, and the component is Cr₅₀ Al₁₆Si₁₂N₂₂The crystal structure coating of the Cr-Al-Si-N layer is amorphous by using TEM selected area diffraction, and the density of the Cr-Al-Si-N layer is 5.6g/cm³。

The prepared Cr-N/Cr-Al-Si-N (N ═ 13) laminated protective coating is subjected to hardness and plasticity index delta_HThe coating hardness is measured to be 20GPa, and the plasticity index delta_H0.58 and an anti-plastic deformation index ξ of 0.07. The number of cracks of the coating under pressure failure is small, the length of the cracks is short, and the length of the cracks is 50-55 mu m. High-temperature steam oxidation test, after the steam corrosion test at 1200 ℃ for 4h, no ZrO exists after EDX line scanning shows corrosion₂And the generation shows that the coating plays a better protective role.

Example 3

The embodiment is prepared by a magnetron sputtering method, and the parameters are as follows: vacuum of back bottom 7X 10^-5Pa, chamber pressure 0.7Pa, 3B target component Cr_0.55Al_0.3Si_0.15(ii) a The 3A target power density is 4.6W/cm²And the 3B target power density is 6.5W/cm²(ii) a Sputtering the 3A target (the 3B target is closed at this time), and introducing N₂The flow ratio of the sample to Ar gas is 0.06, the sample 7 is controlled to face a 3A target, and a Cr-N layer with the thickness of 120nm is obtained by sputtering; thereafter, the 3A target was turned off and N was adjusted₂The flow ratio of Ar gas to the 3B target was 0.13, the 3B target was started, sputtering of the 3B target was started while controlling the sample 7 to face the 3B target, and a 480nm thick Cr-Al-Si-N layer was obtained by sputtering, alternately in this wayAnd (3) obtaining the Cr-N/Cr-Al-Si-N laminated protective coating with the period N of 30 times, wherein the thickness of the Cr-N layer in one period layer is 120nm, and the thickness of the Cr-Al-Si-N layer is 480 nm.

The prepared Cr-N/Cr-Al-Si-N (N ═ 30) multilayer protective coating was structurally characterized as a multilayer laminated structure formed by alternating Cr-N layers and Cr-Al-Si-N layers. And when TEM bright field image observation is carried out on one periodic layer, the Cr-N layer and the Cr-Al-Si-N layer do not present a columnar crystal growth structure, have no obvious penetrating pore defects and have very compact coatings. The density of the Cr-N layer was determined to be 6.0g/cm³The component composition is Cr_0.72N_0.28Determination of the crystal structure of the Cr-N layer by TEM selected area diffraction, Cr₂Two phases of N and Cr are compounded. The Cr-Al-Si-N layer is measured, and the component is Cr₅₁Al₁₇Si₈N₂₄The crystal structure coating of the Cr-Al-Si-N layer is amorphous by using TEM selected area diffraction, and the density of the Cr-Al-Si-N layer is 5.6g/cm³。

The prepared Cr-N/Cr-Al-Si-N (N-30) laminated protective coating is subjected to hardness and plasticity index delta_HThe coating hardness is measured to be 22GPa, and the plasticity index delta_H0.73 and a plastic deformation resistance index ξ of 0.09. The number of cracks of the coating under pressure failure is small, the length of the cracks is short, and the length of the cracks is 30-35 mu m. High-temperature steam oxidation test, after the steam corrosion test at 1200 ℃ for 4h, no ZrO exists after EDX line scanning shows corrosion₂And the generation shows that the coating plays a better protective role.

Example 4

The embodiment is prepared by a magnetron sputtering method, and the parameters are as follows: vacuum of back bottom 7X 10^-5Pa, chamber pressure 0.7Pa, 3B target component Cr_0.6Al_0.3Si_0.1(ii) a The 3A target power density is 4.5W/cm²And the 3B target power density is 6.4W/cm²(ii) a Sputtering the 3A target (the 3B target is closed at this time), and introducing N₂The flow ratio of the sample to Ar gas is 0.06, the sample 7 is controlled to face a 3A target, and a Cr-N layer with the thickness of 50nm is obtained by sputtering; thereafter, the 3A target was turned off and N was adjusted₂The flow ratio of Ar gas was 0.13, the 3B target was started, sputtering of the 3B target was started while controlling the sample 7 to face the 3B target, and sputtering was carried out to a thickness of 140nmThe Cr-Al-Si-N layers are alternated for 40 times to obtain the Cr-N/Cr-Al-Si-N laminated protective coating with the period N of 40, wherein the thickness of the Cr-N layer in one period layer is 50nm, and the thickness of the Cr-Al-Si-N layer is 140 nm.

The prepared Cr-N/Cr-Al-Si-N (N-40) laminated protective coating is characterized by a multilayer laminated structure, wherein Cr-N layers and Cr-Al-Si-N layers are alternately formed. And when TEM bright field image observation is carried out on one periodic layer, the Cr-N layer and the Cr-Al-Si-N layer do not present a columnar crystal growth structure, have no obvious penetrating pore defects and have very compact coatings. The density of the Cr-N layer was determined to be 6.0g/cm³The component composition is Cr_0.75N_0.25Determination of the crystal structure of the Cr-N layer by TEM selected area diffraction, Cr₂Two phases of N and Cr are compounded. The Cr-Al-Si-N layer is measured, and the component is Cr₅₃Al₁₇Si₇N₂₃The crystal structure coating of the Cr-Al-Si-N layer is amorphous by using TEM selected area diffraction, and the density of the Cr-Al-Si-N layer is 5.6g/cm³。

The prepared Cr-N/Cr-Al-Si-N (N is 40) multilayer protective coating is subjected to hardness and plasticity index delta_HThe coating hardness was measured to be 19GPa and the plasticity index delta_H0.75, and a plastic deformation resistance index ξ of 0.08. The number of cracks of the coating under pressure failure is small, the length of the cracks is short, and the length of the cracks is 22-32 mu m. High-temperature steam oxidation test, after the steam corrosion test at 1200 ℃ for 4h, no ZrO exists after EDX line scanning shows corrosion₂And the generation shows that the coating plays a better protective role.

Comparative example 1

The embodiment is prepared by a magnetron sputtering method, and the parameters are as follows: vacuum of back bottom 7X 10^-5Pa, chamber pressure 0.7Pa, 3B target component Cr_0.6Al_0.3Si_0.1(ii) a The 3A target power density is 4.3W/cm²And the 3B target power density is 6.2W/cm²(ii) a Sputtering the 3A target (the 3B target is closed at this time), and introducing N₂Controlling the flow ratio of the sample 7 to the Ar gas to be 0.06, and controlling the sample to be over against a 3A target to obtain a Cr-N layer with the thickness of 500nm by sputtering; thereafter, the 3A target was turned off and N was adjusted₂The flow ratio to Ar gas was 0.13, the 3B target was started, sputtering of the 3B target was started and sample 7 was controlled to be positiveAnd sputtering the 3B target to obtain Cr-Al-Si-N layers with the thickness of 2000nm, and alternating the layers for 4 times to obtain the Cr-N/Cr-Al-Si-N laminated protective coating with the period N of 4, wherein the thickness of the Cr-N layer in one period layer is 500nm, and the thickness of the Cr-Al-Si-N layer is 2000 nm.

The prepared Cr-N/Cr-Al-Si-N (N-4) laminated protective coating is characterized by a multilayer laminated structure, wherein Cr-N layers and Cr-Al-Si-N layers are alternately formed. SEM cross section appearance observation is carried out on a periodic layer, the Cr-N layer presents a columnar crystal growth structure, the Cr-Al-Si-N layer does not have obvious penetrating pore defects, and the coating is very compact. The density of the Cr-N layer was determined to be 5.4g/cm³The component composition is Cr_0.74N_0.26Determination of the crystal structure of the Cr-N layer by TEM selected area diffraction, Cr₂Two phases of N and Cr are compounded. The Cr-Al-Si-N layer is measured, and the component is Cr₅₃Al₁₇ Si₇N₂₃The crystal structure coating of the Cr-Al-Si-N layer is amorphous by using TEM selected area diffraction, and the density of the Cr-Al-Si-N layer is 5.2g/cm³。

The prepared Cr-N/Cr-Al-Si-N (N ═ 4) multilayer protective coating is subjected to hardness and plasticity index delta_HThe coating hardness is measured to be 13GPa, and the plasticity index delta_H0.58 and an index ξ for plastic deformation resistance of 0.06. The number of cracks of the coating under pressure failure is large, as shown in fig. 5(b-1), the length of the cracks is long, the length is 55-70 μm, the crack change along the depth of the coating is observed after in-situ FIB cutting, as shown in fig. 5(b-2), the number of the generated cracks is large, the width of the generated cracks is wide, the cracks are not turned at the interface of the layer, and the interface has no effect of inhibiting the crack from expanding, and the toughness of the coating is relatively poor. High-temperature steam oxidation test, after steam corrosion test at 1200 ℃ for 4h, the corrosion is found by EDX line scanning, and ZrO exists after the corrosion₂Generation of ZrO₂Has a thickness of 120 μm, is oxidized by high-temperature steam under the same conditions, and is not coated with ZrO formed after the zirconium is oxidized after polishing₂The thickness is 220 μm, which indicates that the coating only plays a certain protective role.

Furthermore, it should be understood that various changes and modifications can be made by those skilled in the art after reading the above description of the present invention, and such equivalent technical solutions also fall within the scope of the present invention as defined in the appended claims.

Claims

1. A laminated protective coating with high temperature water vapor oxidation resistance and strong toughness, characterized in that it comprises a Cr-N layer and a Cr-Al-Si-N layer deposited alternately periodically, and the period of the alternate deposition is The number of times is 4 to 40 times; the total thickness of the Cr-Al-Si-N layer and the Cr-N layer in the unit cycle is 0.19 to 2.5 μm, and the thickness ratio is 2.8 to 5.2;

The compositions of the Cr-N layer and the Cr-Al-Si-N layer are expressed as Cr _x N _1-x and _C _a Al _b SiC N _100-abc , wherein 0.72≤x≤0.75, 50≤a≤53 , 15≤b≤17, 7≤c≤10, x, a, b, c are atomic ratios.

2 . The laminated protective coating with high temperature water vapor oxidation resistance and strong toughness according to claim 1 , wherein the laminated protective coating grows perpendicular to the substrate, and is followed by a Cr-N layer along the growth direction. 3 . and Cr-Al-Si-N layers are periodically alternately deposited, and the surface layer of the laminated protective coating is a Cr-Al-Si-N layer.

3 . The laminated protective coating with high temperature water vapor oxidation resistance and strong toughness according to claim 1 , wherein the Cr-N layer is a ceramic two-phase composite of Cr ₂ N and Cr. 4 .

4 . The laminated protective coating with high temperature water vapor oxidation resistance and strong toughness according to claim 1 , wherein the density of the Cr-N layer is 5.8-6.0 g/cm ³ .

5 . The laminated protective coating with high temperature water vapor oxidation resistance and strong toughness according to claim 1 , wherein the Cr-Al-Si-N layer is an amorphous coating. 6 .

6 . The laminated protective coating with high temperature water vapor oxidation resistance and strong toughness according to claim 1 , wherein the density of the Cr-Al-Si-N layer is 5.2-5.6 g/cm ³ .

7. The method for preparing a laminated protective coating with high temperature water vapor oxidation resistance and strong toughness according to any one of claims 1 to 6, characterized in that a physical vapor method is used to alternately deposit a Cr-N layer and a Cr- Al-Si-N layer.

8 . The method for preparing a laminated protective coating with high temperature water vapor oxidation resistance and strong toughness according to claim 7 , wherein the physical gas phase method is a magnetron sputtering method. 9 .

9. The application of the laminated protective coating according to any one of claims 1 to 6 in a zirconium alloy cladding material.

10. A coating device, comprising a substrate and a coating on the surface of the substrate, wherein the coating is the laminated protective coating according to any one of claims 1 to 6, and the material of the substrate is Zr or Zr alloy.