CN102400099B - Technology for preparing nuclear fission reactor fuel clad surface CrAlSiN gradient coating - Google Patents

Abstract

The invention relates to a new CrAlSiN gradient coating process for deposition on the surface of a fuel cladding of a supercritical water-cooled reactor in a nuclear fission reactor, which has anti-high temperature oxidation corrosion performance and excellent mechanical properties. The CrAlSiN gradient coating is deposited on the surface of the substrate by multi-target reactive magnetron sputtering. The preparation process is divided into four consecutive stages: the first stage is to prepare the Cr gradient coating; the second stage is to prepare the CrAl gradient coating; the third stage is to prepare the CrAlSiN gradient coating. Preparing the CrAlN gradient coating; the fourth stage is preparing the CrAlSiN gradient coating, and then annealing. In the present invention, by rationally designing the microstructure with gradient changes in each element composition, the oxidation resistance temperature of the coating reaches 950°C, the hardness value reaches above 37GPa, and the adhesion to the substrate is higher than 34N, and the coating also has excellent thermal shock resistance, Wear resistance and other properties can greatly improve the service performance and service life of supercritical water-cooled reactor fuel cladding components.

Description

Preparation process of CrAlSiN gradient coating on nuclear fission reactor fuel cladding surface

technical field

The invention belongs to the technical field of surface modification of nuclear fission reactor components, and in particular relates to a chromium-aluminum-silicon-nitrogen (CrAlSiN) gradient deposited on the surface of a supercritical water-cooled reactor fuel cladding in a nuclear fission reactor with excellent high-temperature oxidation corrosion resistance and mechanical properties A new process for the preparation of coatings.

Background technique

As an efficient, economical and durable energy source, nuclear energy has significant comprehensive advantages in solving the energy crisis facing the world and protecting environmental quality. In 2002, the International Forum on Generation IV Reactors selected six types of reactors, and the supercritical water-cooled reactor (SCWR) was one of them. SCWR is a high-temperature and high-pressure water-cooled reactor that operates above the thermodynamic critical point of water, and is the most worthy of research and development in the future. SCWR has the advantages of simple system, high cycle efficiency, and good industrialization foundation, and is expected to become the main reactor type for low-cost power generation in the future. However, the fuel cladding is one of the most critical components of the SCWR. The highest steam temperature of SCWR, that is, the maximum thermal efficiency depends on the long-term creep strength and corrosion resistance of the fuel cladding material. Under supercritical conditions, the high temperature of the fuel cladding is as high as 650°C, the pressure of supercritical steam parameters is as high as 25MPa, the temperature exceeds 500°C, and the density of the moderator in the core changes greatly, all of which exceed those of the current pressurized water reactor and Extent of accumulated experience in BWR design. Therefore, the existing fuel cladding materials can no longer meet the requirements of corrosion resistance and mechanical properties in supercritical water-cooled reactors [Optimum design of low-activity F/M steel for supercritical water-cooled reactor fuel cladding tubes. Kang Renmu, Liu Guoquan, Hu Benfu et al. Atomic Energy Science and Technology. Vol. 43 No. 6. 2009]. At present, low-swelling austenitic stainless steels such as D9, 1.4970, 316Ti, etc. are the main candidates for SCWR fuel cladding. These materials have the advantages of high strength, low radiation swelling, good weldability, and good neutron economy. . However, the above-mentioned materials have poor high temperature oxidation corrosion resistance in supercritical water-cooled reactors. During the long-term service of SCWR fuel cladding, excessive corrosion rates will lead to fuel cladding rupture.

Depositing a functional coating resistant to high temperature oxidation and corrosion on the surface of SCWR fuel cladding can effectively solve the above problems, so this technology has become a research hotspot in the academic and engineering circles in recent years. Considering the relatively high content of Cr in steel and the influence of Cr element on steel passivation, people initially tend to deposit Cr alloy coating on the surface of fuel cladding. On the one hand, the interface between the Cr alloy coating and the substrate can form Fe-Cr compounds to achieve chemical metallurgical bonding and good adhesion; Elements can form an oxide film, hinder the penetration of corrosive media, and have good resistance to high temperature oxidation. However, the strength and hardness of Cr alloy coatings are relatively low, and strong thermal shock may lead to ductile deformation and premature cracking of the coating [Hardness and cavitation of Fe-Cr-based coatings by supersonic flame spraying. Wu Yuping, Lin Pinghua , Wang Zehua. Journal of Heat Treatment of Materials. Volume 30, Issue 1.2009]. Subsequently, people tended to Cr-based nitride coatings. Compared with Cr alloy coatings, Cr-based nitride coatings have more advantages in terms of oxidation and corrosion resistance. For example, the oxidation resistance temperature of CrN coating can reach 600°C; in addition, it also has a good hardness of about 18GPa [Hard and superhard coatings - structure, performance, preparation and characterization, Song Guihong, Du Hao, He Chunlin; Beijing: Chemical Industry Press.2007]. In recent years, with the rapid development of nanotechnology, Cr-based nanocomposite coatings have shown excellent advantages in high-temperature oxidation resistance, hardness, friction and wear resistance, and thermal shock resistance, which has attracted widespread attention from researchers. . For example, the CrAlSiN nanocomposite coating has a high temperature oxidation resistance of over 1000°C and has excellent mechanical properties. The coating hardness can reach 41GPa [Mechanical properties and oxidation behavior of (Al, Cr) N and (Al, Cr, Si) N coatings for cutting tools deposited by HPPMS. K. Bobzin, N. Bagcivan, P. Immich. Thin Solid Films.517.2008].

Although Cr-based nanocomposite coatings have excellent corrosion resistance and mechanical properties, when they are applied to steel substrates commonly used in fuel cladding, they need to face a huge problem, that is, the interface bonding force between the coating and steel . Due to the great disparity in properties between the coating and the substrate, the coating/substrate interface of the fuel cladding is prone to failure during service, resulting in peeling off of the coating. In view of this, many researchers have solved the above problems by modulating the element composition and structure of the coating. For example, some people have also improved the interfacial bonding force with the substrate by forming a coating with a gradient change in element composition. Due to the gradient change of the coating composition, the coating has no sub-layer interface, and at the same time, the coating and the substrate share elemental components, so that they can achieve chemical metallurgical bonding, which can greatly improve their interfacial bonding force. In addition, gradient structural coatings often exhibit superior toughness and thermal shock resistance. In view of the excellent performance of the gradient structure film, there is no research and application of CrAlSiN gradient coating so far. The task of the present invention is a new process for depositing a CrAlSiN gradient coating with high temperature oxidation corrosion resistance and excellent mechanical properties on the surface of supercritical water-cooled reactor fuel cladding in nuclear fission reactors.

Contents of the invention

The present invention aims at the technical shortcomings of poor high-temperature corrosion resistance of low-expansion austenitic stainless steel used in supercritical water-cooled reactor fuel cladding in current nuclear fission reactors, and combines high-temperature oxidation-resistant coating technology to provide an excellent resistance to high-temperature corrosion and oxidation. A new chromium-aluminum-silicon-nitride (CrAlSiN) gradient coating process for nuclear fission reactor fuel cladding surface coating with good performance and mechanical properties and low swelling austenitic stainless steel substrate.

The purpose of the present invention is achieved through the following technical solutions:

The preparation process for depositing a CrAlSiN gradient coating on the surface of nuclear fission supercritical water-cooled reactor fuel cladding provided by the present invention is characterized in that it includes the following process steps in sequence:

(1) Substrate surface polishing and cleaning

Austenitic stainless steel for supercritical water-cooled reactor fuel cladding was selected as the base material, and its surface was ground and polished with water sandpaper with different roughness in turn; then, it was cleaned with degreasing agent in an ultrasonic vessel; then it was pickled and degreased. Rinse with ionized water and dry with N ₂ gas; finally, put the dried substrate into a vacuum chamber and clean it by plasma bias backsputtering process, the process parameters are: background vacuum is 5×10 ^-4 Pa, backsputtering The splash bias voltage is -300V, the working gas is Ar gas, the backsplash pressure is 1.0Pa, and the backsplash time is 20min;

(2) Deposition of chrome-aluminum-silicon-nitride (CrAlSiN) gradient coating

An ultra-high vacuum multi-target magnetron sputtering coating machine was used to deposit a CrAlSiN gradient coating on the surface of the substrate. The background vacuum degree of the coating machine was 5×10 ^-4 Pa, and the deposition temperature was 200°C. The coating deposition process included the following 4 consecutive time periods:

(a) In the first period of time, after the vacuum chamber is evacuated to the background vacuum degree, Ar gas is introduced into the vacuum chamber with a flow rate of 200 sccm and a working pressure of 0.3 Pa, and then the Cr target is opened for sputtering Sputtering, the sputtering power is 200W, and the deposition time is 4min to 6min, thus depositing a pure Cr coating on the surface of the substrate with a deposition thickness of 80 to 120nm;

(b), in the second period of time, keep the Ar gas flow and the sputtering power of the Cr target in the step (a), simultaneously turn on the Al target for sputtering, and gradually increase the sputtering power of the Al target linearly from 50W to 100W, Realize co-sputtering of Cr target and Al target, so as to obtain CrAl coating with gradually increasing Al content, and adjust the deposition time so that the thickness of CrAl coating is 180-220nm;

(c), in the third period of time, keep the Ar gas flow of (b) step, and the sputtering power of the Cr target and the Al target, and feed _N gas into the vacuum chamber at the same time, and the _N gas flow is gradually changed from 0 sccm Increase linearly to 150sccm, and keep the working pressure at 0.5Pa to realize co-sputtering of Cr target and Al target in (Ar+N ₂ ) mixed atmosphere, so as to obtain CrAlN coating with gradually increasing N content. By adjusting the deposition time The thickness of the CrAlN coating is 250-300nm;

(d) In the fourth time period, turn on the Si target sputtering, the sputtering power is linearly increased from 50W to 100W, and at the same time, the sputtering power of the Cr target and the Al target is adjusted linearly from 200W and 100W to 300W and 200W respectively , the flow rate of N ₂ gas is gradually increased linearly from 150 sccm to 250 sccm to realize the co-sputtering of Cr target, Al target and Si target in (Ar+N ₂ ) mixed atmosphere, thereby obtaining nitrogen, silicon and aluminum content gradually increasing CrAlSiN coating, and the microstructure of (Cr, Al, Si) N nanocrystals embedded in the Si ₃ N ₄ amorphous phase is formed in the near surface area, and the thickness of the CrAlSiN coating is 2.5-3.0 μm by adjusting the deposition time ;

(3) Annealing the deposited gradient coating

The deposited CrAlSiN gradient coating is subjected to in-situ annealing treatment in an uninterrupted vacuum environment, and the sample is taken out for later use after the annealing treatment is completed.

In the above technical solution, the purpose of the annealing treatment is to release the residual stress in the coating, accelerate the diffusion and mutual dissolution of elements between the coating and the substrate and each sub-layer, and strengthen the interface structure. The process parameters of the in-situ annealing are: The vacuum degree is 5×10 ^-4 Pa, the annealing temperature is 400°C, the heating rate is 20°C/min, the holding time is 90min, and the cooling method is to cool down to room temperature with the furnace.

In the above technical solution, the purity of the Cr target, Al target and Si target used for depositing the CrAlSiN gradient coating is all 99.99%.

In the above technical solution, the roughness of the water sandpaper with different roughness is 300-1200 mesh.

In the above-mentioned technical scheme, the cleaning composition of the degreasing agent used is sodium carbonate 160g/L, sodium citrate 45g/L, active agent 5g/L, sodium phosphate 50g/L.

In the above technical solution, the austenitic stainless steel substrate is D9, or 1.4970, or 316Ti.

The CrAlSiN gradient coating prepared by the preparation process for depositing a CrAlSiN gradient coating on the surface of nuclear fission supercritical water-cooled reactor fuel cladding provided by the present invention has a coating thickness variation of 2.5-3.0 μm; temperature can be as high as 950°C; hardness is above 37GPa ; The interface binding force is over 34N.

Compared with the prior art, the present invention has the following advantages and beneficial technical effects:

(1) The CrAlSiN gradient coating prepared by the present invention has excellent high temperature oxidation and corrosion resistance, and its temperature can be as high as 950°C.

(2) The CrAlSiN gradient coating prepared by the present invention can effectively prevent O and other impurity elements such as Cl from corroding the substrate because Cr and Al can form a dense oxide film protective layer with O; Enrichment can also effectively hinder the diffusion of O, H and other elements; in addition, since the near-surface area of the coating is a nanocomposite structure of Si ₃ N ₄ amorphous phase coated nanocrystalline (Cr, Al, Si) N, it can significantly Enhance high temperature oxidation corrosion resistance.

(3) The CrAlSiN gradient coating prepared by the present invention has excellent mechanical properties, and its hardness is above 37 GPa. Because the CrAlSiN gradient coating has a nanocomposite structure near the surface, the coating has high surface hardness and excellent wear resistance; due to the structure with gradient changes in element composition, it helps to relieve the thermal stress of the coating , while making the coating have better toughness and thermal shock resistance.

(4) The CrAlSiN gradient coating prepared by the present invention has a good interfacial bonding force with the substrate, which is more than 34N. The bottom of the coating is rich in Cr elements, so it can undergo chemical metallurgical bonding with the substrate; at the same time, because the composition of the coating elements gradually changes in a gradient, the composition structure of each sub-layer interface does not have a significant mutation, which will strengthen the coating and substrate. Interfacial bonding force and interfacial fracture toughness.

(5) The present invention deposits a CrAlSiN gradient coating on the surface of the supercritical water-cooled reactor fuel cladding, which can greatly improve the service performance and service life of the fuel cladding.

Description of drawings

Figure 1 is a schematic diagram of the structure of the CrAlSiN gradient coating.

Detailed ways

The following specific examples will be used to further describe the present invention in detail, but this does not imply any limitation to the protection scope of the present invention.

The instrument used in the embodiment of the present invention:

Ultra-high vacuum multi-target magnetron sputtering coating machine, model QX-500;

The supercritical water-cooled reactor fuel cladding is made of 316Ti stainless steel; its geometric dimensions are: length 5cm×width 5cm×height 2cm.

Example 1

The preparation process of the CrAlSiN gradient coating of the present invention is carried out sequentially according to the aforementioned process steps and process conditions.

Depositing a CrAlSiN gradient coating on the surface of the 316Ti stainless steel substrate used for supercritical water-cooled reactor fuel cladding includes the following process steps:

(1) Surface polishing and cleaning of substrate samples

First, the surface of the substrate sample is ground and polished with 300-1200 mesh water sandpaper in sequence; then, the degreasing agent is cleaned in an ultrasonic vessel, and the degreasing agent is composed of sodium carbonate 160g/L, sodium citrate 45g/ L, active agent 5g/L, sodium phosphate 50g/L; Next, pickling and deionized water rinsing are carried out, and after pickling and rinsing are completed, the substrate sample is blown dry with _N2 gas; finally, the substrate sample is Placed in a vacuum chamber for plasma bias backsputter cleaning, the process parameters are: background vacuum 5× ^{10 -4} Pa, backsputter bias voltage 200V, sputtering Ar pressure 0.3Pa, backsplash time 20min;

(2) CrAlSiN gradient coating deposition

A QX-500 ultra-high vacuum multi-target magnetron sputtering coating machine was used to deposit CrAlSiN gradient coatings on the surface of 316Ti austenitic stainless steel substrate samples. The background vacuum used for deposition was 5×10 ^-4 Pa and the deposition temperature was 200 °C, the coating deposition process includes the following four consecutive time stages:

(a) In the first period of time, after the vacuum chamber is evacuated to the background vacuum degree used, Ar gas is first introduced into the vacuum chamber with a gas flow of 200 sccm and a working pressure of 0.3 Pa, and then the Cr target is turned on Carry out sputtering, its sputtering power is 200W, and deposition time is 4min, and at this moment, pure Cr coating is deposited on the surface of the substrate sample, and the thickness of deposited Cr coating is 80nm;

(b), in the second period of time, keep the Ar gas flow and the sputtering power of the Cr target in the step (a), simultaneously turn on the Al target for sputtering, and gradually increase the sputtering power of the Al target linearly from 50W to 100W, Realize the co-sputtering of Cr target and Al target, so as to obtain a CrAl coating with a gradual increase in Al content on the surface of the substrate sample, and adjust the deposition time so that the thickness of the deposited CrAl coating is 180nm;

(c), in the third period of time, keep the Ar gas flow of (b) step, and the sputtering power of the Cr target and the Al target, and start to feed _N gas into the vacuum chamber at the same time, and the _N gas flow is changed from 0sccm Gradually increase linearly to 150sccm, and keep the working pressure at 0.5Pa to realize co-sputtering of Cr target and Al target in (Ar+N ₂ ) mixed atmosphere, so as to obtain CrAlN with gradually increasing N content on the surface of the substrate sample coating, by adjusting the deposition time so that the thickness of the deposited CrAlN coating is 250nm;

(d) In the fourth period of time, keep the Ar gas flow in step (c), turn on the Si target sputtering, increase the sputtering power linearly from 50W to 100W, and linearly increase the sputtering power of the Cr target and the Al target respectively Increase to 300W and 200W, and linearly increase the flow rate of _N2 gas from 150sccm to 250sccm to realize the co-sputtering of Cr target, Al target and Si target in (Ar+ _N2 ) mixed atmosphere on the substrate sample surface , so as to obtain a CrAlSiN coating with a gradient increase in the content of each element, and the thickness of the deposited CrAlSiN coating is 2.5 μm;

(3) Coating annealing treatment

After the CrAlSiN gradient coating is deposited on the surface of the substrate sample, it is annealed in-situ in an uninterrupted vacuum environment. The process parameters are: vacuum degree 5×10 ^-4 Pa, annealing temperature 400°C, heating rate 20°C /min, the holding time is 90min, and the cooling method is to cool down to room temperature with the furnace; after the annealing treatment is completed, the sample is taken out for use.

The purpose of the annealing treatment is to release the residual stress in the coating, accelerate the diffusion and mutual dissolution of elements between the coating and the substrate and each sub-layer coating, and strengthen the interface structure.

The performance of the CrAlSiN gradient coating on the surface of the 316Ti austenitic stainless steel substrate in the above-mentioned embodiment 1 is detected, including the following performance indicators and testing process thereof:

(1) Use MH-5 microhardness tester to measure coating hardness

The test parameters are: loading load 70mN, holding time 10min, positive four-wheel cone diamond indenter. Test 8 points on different surface areas of the coating sample, and take the average value as the hardness value of the coating test. The results show that the hardness value of CrAlSiN gradient coating is 38GPa.

(2) Use the WS-2005 coating adhesion automatic scratch tester to test the interface bonding of the coating/substrate

The test parameters are: scratch rate 1.5mm/min, loading rate 5N/min to 150N/min, etc. The results show that the interfacial adhesion between CrAlSiN gradient coating and 316Ti steel substrate is 34N.

(3) Test the high-temperature oxidation resistance of the coating with a self-made box-type resistance furnace

The heat treatment process is: atmospheric heating atmosphere, holding temperature 950°C, holding time 90min, heating rate 50°C/min, cooling method furnace cooling. As a comparison, the 316Ti steel substrate sample without coating was put into the furnace together. After the annealing treatment, the weight test was carried out, and it was found that the weight gain of the coated sample was not obvious, while that of the uncoated sample was significant. The results show that the oxidation resistance temperature of CrAlSiN gradient coating is 950℃.

Example 2

The CrAlSiN gradient coating was prepared using the same process steps, process conditions and process parameters as in Example 1; because the coating performance is affected by the properties of the substrate, sublayer thickness, composition gradient, etc., the difference from Example 1 is Example 2 The substrate used is a 1.4970 austenitic stainless steel substrate. In this embodiment, a CrAlSiN gradient coating is deposited on the surface of the 1.4970 steel substrate.

The experimental results of Example 2 are: the thicknesses of the Cr, CrAl and CrAlN sub-layer coatings are 120 nm, 220 nm and 300 nm respectively; the thickness of the CrAlSiN gradient coating is 3.0 μm.

Except above-mentioned, other processing parameters are all identical with embodiment 1. Adopt the same coating performance testing method as in Example 1. The results show that the CrAlSiN gradient coating has a hardness of 39GPa, an interface adhesion with the substrate of 36N, and an anti-oxidation temperature of 950°C.

From the experimental results of Examples 1 and 2, it can be seen that the CrAlSiN gradient coating can significantly enhance the surface properties of supercritical water-cooled reactor fuel cladding. Compared with the stainless steel base material, it has more excellent high temperature oxidation resistance and surface mechanical properties, and has a higher interface bonding force with the base material, which can greatly improve the service performance and service life of the fuel cladding part.

Claims (7)

1. the preparation technology of a nuclear fission Supercritical-Pressure Light Water Cooled Reactor fuel sheath surface deposition CrAlSiN gradient cladding is characterized in that comprising successively following processing step:

(1) substrate surface polishing and cleaning

Select the Supercritical-Pressure Light Water Cooled Reactor fuel sheath to adopt austenitic stainless steel as base material, with the different waterproof abrasive paper of roughness, grinding and polishing is carried out on its surface successively; Subsequently, carrying out degreaser in ultrasonic container cleans; Carry out subsequently pickling and rinsed with deionized water, and use N ₂Air-blowing is done; At last, dry substrate is put into vacuum chamber, cleaned with bias plasma backwash technique, its processing parameter is: the base vacuum degree is 5 * 10 ^-4Pa, backwash bias voltage are that-300 V, working gas are Ar gas, and backwash air pressure is that 1.0 Pa, backwash time are 20 min;

(2) deposition chromium aluminium silicon nitrogen (CrAlSiN) gradient cladding

Adopt ultrahigh vacuum(HHV) multi-target magnetic control sputtering coating equipment at substrate surface deposition CrAlSiN gradient cladding, described coating equipment base vacuum degree is 5 * 10 ⁴200 ℃ of Pa, depositing temperatures, be coated with layer deposition process comprise following 4 continuous time section:

(a), within first time period, until vacuum chamber bleed reach the base vacuum degree after, pass into Ar gas in vacuum chamber, its airshed is 200 sccm, and operating air pressure is 0.3 Pa, opens subsequently the Cr target and carries out sputter, its sputtering power is 200 W, depositing time is 4min ~ 6min, and in the pure Cr coating of described substrate surface deposition, deposit thickness is 80 ~ 120 nm thus;

(b), within second time period, the Ar airshed and the Cr target sputtering power that keep (a) step, open simultaneously the Al target and carry out sputter, with Al target sputtering power by 50 W gradually linearity increase to 100 W, realize Cr target and Al target co-sputtering, thereby obtain the CrAl coating that Al content increases in gradient gradually, making the thickness of CrAl coating by the adjusting depositing time is 180 ~ 220 nm;

(c), within the 3rd time period, keep the Ar airshed of (b) step, and the sputtering power of Cr target and Al target, the while passes into N in vacuum chamber ₂Gas, N ₂Airshed by 0 sccm gradually linearity increase to 150 sccm, operating air pressure remains on 0.5 Pa, realizes that Cr target and Al target are at (Ar+N ₂) cosputtering in mixed atmosphere, thereby obtain the CrAlN coating that N content increases in gradient gradually, to make the thickness of CrAlN coating be 250 ~ 300 nm by regulating depositing time;

(d), within the 4th time period, open the sputter of Si target, its sputtering power increases to 100 W by 50 W linearities, the sputtering power with Cr target and Al target is adjusted to 300 W and 200 W by 200 W and 100 W linearities respectively simultaneously, with N ₂The flow of gas by 150 sccm gradually linearity increase to 250 sccm, realize that Cr target, Al target and Si target are at (Ar+N ₂) cosputtering in mixed atmosphere, thereby obtain the CrAlSiN gradient cladding that nitrogen, content of silicon and aluminum increase gradually, and surf zone forms (Cr, Al, Si) N Nanocrystals Embedded at Si near gradient cladding ₃N ₄Microstructure in amorphous phase, making the thickness of CrAlSiN gradient cladding by the adjusting depositing time is 2.5 ~ 3.0 μ m;

(3) gradient cladding with deposition carries out anneal

With the CrAlSiN gradient cladding of deposition, carry out in-situ annealing in uninterrupted vacuum environment and process, standby until the complete rear taking-up sample of anneal.

2. the preparation technology of nuclear fission Supercritical-Pressure Light Water Cooled Reactor fuel sheath surface deposition CrAlSiN gradient cladding according to claim 1, is characterized in that the processing parameter that carries out in-situ annealing is: vacuum tightness 5 * 10 ^-4Pa, 400 ℃ of annealing temperatures, 20 ℃/min of temperature rise rate, soaking time 90 min, the type of cooling are for cooling to room temperature with the furnace.

3. the preparation technology of nuclear fission Supercritical-Pressure Light Water Cooled Reactor fuel sheath surface deposition CrAlSiN gradient cladding according to claim 1, is characterized in that depositing CrAlSiN gradient cladding Cr target used, Al target and Si target, and their purity is 99.99%.

4. the preparation technology of according to claim 1 or 3 described nuclear fission Supercritical-Pressure Light Water Cooled Reactor fuel sheath surface deposition CrAlSiN gradient claddings, is characterized in that its roughness of the different waterproof abrasive paper of described roughness is followed successively by 300 ~ 1200 orders.

5. the preparation technology of nuclear fission Supercritical-Pressure Light Water Cooled Reactor fuel sheath surface deposition CrAlSiN gradient cladding according to claim 1 and 2, what it is characterized in that described degreaser consists of sodium carbonate 160 g/L, Trisodium Citrate 45 g/L, promoting agent 5 g/L, sodium phosphate 50 g/L.

6. the preparation technology of nuclear fission Supercritical-Pressure Light Water Cooled Reactor fuel sheath surface deposition CrAlSiN gradient cladding according to claim 1 is characterized in that described austenite stainless steel substrate is D9,1.4970 or 316Ti.

7. the CrAlSiN gradient cladding of according to claim 1-5 described techniques of any one preparations, the variation in thickness that it is characterized in that described CrAlSiN gradient cladding is 2.5 ~ 3.0 μ m, its resistance to high temperature oxidation temperature is up to 950 ℃; Hardness is more than 37 GPa; More than interface binding power reaches 34 N.