CN110629176A - A kind of Cr-Al alloy film and preparation method thereof based on Zr - Google Patents

Abstract

The invention discloses a Cr-Al alloy film with Zr as a base and a preparation method thereof, which uses a physical vapor deposition method to plate a multi-element alloy film on the surface of Zr, and belongs to the field of sputtering coating. The final film thickness of the plated alloy film is about 10 μm. The present invention is an example with the Cr-Al alloy film of 500nm, and the substrate used is Zr-4 alloy (Sn: 1.20-1.70, Fe: 0.18-0.24, Cr : 0.07‑0.13, Ni: 0.03‑0.08). The preparation method includes: grinding and polishing the zirconium alloy substrate; then cleaning and drying; and coating a Cr-Al alloy film on the surface of the zirconium alloy by using a DC magnetron sputtering technology. Through the method of sputtering Cr-Al alloy film on the Zr-4 alloy substrate of the present invention, the corrosion resistance and high-temperature oxidation resistance performance of the Zr alloy for nuclear fuel are further improved. The invention effectively improves the service life of the zirconium alloy pressure tube, reduces nuclear leakage accidents, and further improves the economic benefit and safety guarantee of the nuclear industry.

Description

A kind of Cr-Al alloy film and preparation method thereof based on Zr

technical field

The invention belongs to the field of sputtering coating, and in particular relates to a Cr-Al alloy film with Zr as a base and a preparation method thereof.

Background technique

At present, the world's demand for clean energy is increasing, and nuclear power has the advantages of environmental protection and huge production capacity. At the same time, as a high-radiation industry, its safety issues cannot be underestimated. The high-temperature water vapor driving the generator is discharged through the pressure tube made of zirconium alloy as the main material. The neutron absorption cross section of pure zirconium is very low, but because its strength and corrosion resistance performance cannot meet the requirements of manufacturing pressure pipes, people often add some alloying elements to zirconium to improve its mechanical properties and corrosion resistance, while not significantly Increased neutron absorption cross section. Zirconium alloys have good corrosion resistance, moderate mechanical properties, and low atomic thermal neutron absorption cross section (zirconium is 0.18 target) in high-temperature and high-pressure water vapor at 300-400 ° C, and have good compatibility with nuclear fuel. Therefore, it can be used as the core structure material (fuel cladding, pressure tube, bracket and tunnel tube) of water-cooled nuclear reactor. The dense oxide film that metal coating materials can form in high-temperature water vapor and water corrosion environments can effectively reduce the oxidation rate and protect the substrate; at the same time, the interface between the metal coating and the substrate is well bonded, which will become the focus of research on zirconium alloy film materials one of the directions.

The high-purity metal Cr has the advantages of high temperature resistance and oxidation resistance. It is widely used in engineering as a coating material. The elements Cr and Al are plated on the surface of zirconium alloys. Cr and Al will refine the grains and improve the oxidation resistance. Make the coating more dense.

In the prior art, the coatings prepared by multi-arc ion plating can not meet the requirements of nuclear reactor cladding coatings in terms of thickness, bonding ratio, and porosity, and the use of multi-arc ion plating technology will make the surface of the film layer There are large particles.

Contents of the invention

The invention provides a Zr-based Cr-Al alloy film and a preparation method thereof for pressure tubes in harsh environments such as high temperature and high pressure, strong neutron radiation, high temperature water impact, and boric acid corrosion.

The present invention adopts following technical scheme to realize:

A method for preparing a Cr-Al alloy film based on Zr, the preparation method adopts a metal target to form a Cr-Al alloy film on a zirconium alloy substrate, specifically comprising the following steps:

Step 1: Grinding and polishing the zirconium alloy substrate;

Step 2: Clean the zirconium alloy on the substrate after grinding and polishing, and then dry it;

Step 3: Coating a Cr-Al alloy film on the surface of the cleaned zirconium alloy by magnetron sputtering to finally obtain a Zr substrate with a Cr-Al alloy film grown on it.

The further improvement of the present invention is that in step 2, the ground and polished zirconium alloy substrate is ultrasonically cleaned with absolute ethanol and deionized water for 10 to 15 minutes, and then blown with high-purity nitrogen gas with a purity of 99.99%. Dry.

A further improvement of the present invention lies in that in step 3, the metal target is sputtered by a DC magnetron sputtering method, and the sputtering power is ~100W.

A further improvement of the present invention is that in step 3, the pressure of the chamber for DC magnetron sputtering is between 10 ^-3 Pa and 10 ^-2 Pa.

A further improvement of the present invention is that in step 3, pre-sputtering is used to remove the surface layer of the target.

The further improvement of the present invention is that in step 3, the Cr target and the Al target are placed on the rotating substrate holder, so that the target material is rotated evenly to prevent the target material from being damaged, wherein the rotation speed ω is in the range of 10r/min to 12r/min Inside, the coating thickness of the alloy film is controlled by adjusting the switching time of the target baffle; the specific steps are to open the baffle in front of the Cr target and the Al target at the same time, use plasma to bombard the Cr target and Al target for 20-30 minutes and deposit On the Zr substrate, a deposition layer of 40nm to 50nm is formed as a transition layer between the film and the substrate, and a Cr-Al alloy film is plated on the transition layer; finally, the baffles in front of the Cr target and the Al target are opened at the same time, and the plasma The target material is bombarded for 100 min to 110 min and deposited on the Zr substrate to form a deposition layer with a thickness of 450 nm to 500 nm.

A Zr-based Cr-Al alloy film is prepared by the above-mentioned method for preparing a Zr-based Cr-Al alloy film, and the thickness of the Cr-Al alloy film is 9 μm to 10 μm.

The present invention has following beneficial technical effect:

The invention provides a method for preparing a Cr-Al alloy film with Zr as the substrate, aiming at the conditions of pressure tubes in harsh environments such as high temperature and high pressure, strong neutron radiation, high temperature water impact, and boric acid corrosion. In the prior art, the coatings prepared by multi-arc ion plating can not meet the requirements of nuclear reactor cladding coatings in terms of thickness, bonding ratio, and porosity, and the use of multi-arc ion plating technology will make the surface of the film layer There are large particles. Therefore, the DC magnetron sputtering technology adopted in the present invention has great advantages.

The present invention provides a Cr-Al alloy film based on Zr, and the total thickness of the film is 500nm. Through the method provided by the present invention, sputtering a Cr-Al alloy film on the surface of the Zr alloy can further improve the high temperature corrosion resistance of the Zr alloy, and when it is applied to the protection of the inner side of the pressure tube, the service life of the pressure tube can be further improved, so that Increase the economics and safety of nuclear power.

Description of drawings

Fig. 1 is the scanning figure of plated Cr-Al alloy film;

Fig. 2 is the sectional view of plated Cr-Al alloy film;

Fig. 3 is a corrosion test diagram of the plated Cr-Al alloy.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

The present invention provides a kind of Cr-Al alloy film (the thermal neutron section of selected Cr, Al element is shown in Table 1) with Zr as the substrate, and this film is based on Zr-4 alloy (Sn: 1.20-1.70, Fe: 0.18-0.24, Cr: 0.07-0.13, Ni: 0.03-0.08) as the base. The final thickness of the plated Cr-Al alloy film is 9 μm to 10 μm, and the specific implementation of the present invention takes an alloy film with a thickness of 500 nm as an example.

Table 1

The present invention also provides the preparation method of this film material, it comprises the following steps:

1) Clean and dry the Zr-4 alloy substrate, and clean the equipment.

2) Sputtering a Cr-Al alloy film on the surface of the Zr-4 alloy by magnetron sputtering to finally obtain a Zr substrate with a Cr-Al alloy film grown on it.

Specifically, in step 1), the substrate was ultrasonically cleaned with absolute ethanol and deionized water for 10 minutes, and then dried with high-purity nitrogen with a purity of 99.99%. The JPG-450a double-chamber magnetron sputtering The equipment first uses the vacuum equipment to remove the dust in the cavity, and then uses absolute ethanol to scrub the inner wall of the cavity.

In step 2), the Cr-Al alloy film is sputtered by JPG-450a double-chamber magnetron sputtering equipment. Place the two targets on the rotating substrate holder, where the rotating speed ω=11r/min. The target material is a pure Cr target (99.95%), a pure aluminum target (99.99%), and argon gas with a purity of 99.99% is introduced; the sputtering power is 100W, the bias voltage is -70V, the argon flow rate is 30sccm, and the working pressure is 1.0× 10 ^-4 Pa; ; The pre-sputtering time is 15min to remove the surface material of the target.

A transition layer is first plated on the Zr substrate. The specific steps are:

Open the baffles in front of the Cr target and the Al target at the same time, bombard the Cr target and the Al target with plasma for 30 minutes and deposit them on the Zr substrate to form a deposition layer with a thickness of about 50 nm as a transition layer between the film and the substrate;

A Cr-Al alloy film is plated on the transition layer. The specific steps are:

At the same time, the baffles in front of the Cr target and the Al target were opened, and the target was bombarded with plasma for 100 min and deposited on the Zr substrate to form a deposition layer with a thickness of about 500 nm. A scanning image of the obtained Cr-Al alloy film is shown in FIG. 1 , and a cross-sectional view of the Cr-Al alloy film is shown in FIG. 2 . It can be seen from Figure 1 that the structure of the obtained Cr-Al alloy is uniform and dense, the particles are fine, and the performance is good; it can be seen from Figure 2 that the Cr-Al alloy layer grows in columnar crystals with a thickness close to 500 nanometers.

When the Cr-Al alloy coating technology based on Zr provided by the present invention is applied to the surface of the pressure pipe, excellent performance of high temperature water vapor corrosion resistance can be obtained. As can be seen from Figure 3, the alloy film is plated After that, the corrosion weight gain becomes smaller, indicating that the high temperature corrosion resistance is enhanced. The multi-element alloy film of the present invention can be applied to the zirconium alloy cladding, effectively solves the problem of thermal expansion mismatch between the coating and the substrate, reduces thermal stress, and further improves the hardness and wear resistance of conventional Cr coatings. The control of the coating strengthens the anti-oxidation performance and realizes the anti-oxidation protection effect of the coating in the high-temperature steam environment of 1200 °C.

Claims (7)

1. a kind of preparation method taking Zr as the Cr-Al alloy film of substrate, is characterized in that, this preparation method adopts metal target material to form Cr-Al alloy film on zirconium alloy substrate, specifically comprises the following steps: Step 1: Grinding and polishing the zirconium alloy substrate; Step 2: Clean the zirconium alloy on the substrate after grinding and polishing, and then dry it; Step 3: Coating a Cr-Al alloy film on the surface of the cleaned zirconium alloy by magnetron sputtering to finally obtain a Zr substrate with a Cr-Al alloy film grown on it. 2. a kind of preparation method taking Zr as the Cr-Al alloy film of substrate according to claim 1 is characterized in that, in step 2, zirconium alloy is used dehydrated alcohol and dehydrated alcohol to substrate after grinding and polishing treatment. The substrate was ultrasonically cleaned with ionized water for 10-15 minutes, and then dried with high-purity nitrogen gas with a purity of 99.99%. 3. a kind of preparation method taking Zr as the base Cr-Al alloy film according to claim 1, is characterized in that, in step 3, adopts dc magnetron sputtering method sputtering metal target material, sputtering power ~100W. 4. A method for preparing a Cr-Al alloy film based on Zr according to claim 1, characterized in that, in step 3, the cavity pressure for DC magnetron sputtering is between 10 ^-3 Pa～ Between 10 ^-2 Pa. 5. A method for preparing a Cr-Al alloy film based on Zr according to claim 1, characterized in that, in step 3, pre-sputtering is used to remove the surface layer of the target. 6. a kind of preparation method taking Zr as the base Cr-Al alloy film according to claim 1 is characterized in that, in step 3, Cr target and Al target are placed on the rotating substrate frame, make target The material is rotated evenly to prevent damage to the target. The rotation speed ω is in the range of 10r/min to 12r/min. The coating thickness of the alloy film is controlled by adjusting the switching time of the target baffle; the specific steps are to open the Cr target at the same time and the baffle in front of the Al target, use plasma to bombard the Cr target and the Al target for 20 minutes to 30 minutes and deposit on the Zr substrate to form a 40nm to 50nm deposition layer, which serves as a transition layer between the film and the substrate, and the transition layer is plated Cr-Al alloy film; finally open the baffles in front of the Cr target and the Al target at the same time, use plasma to bombard the target for 100min-110min and deposit it on the Zr substrate to form a deposition layer with a thickness of 450nm-500nm. 7. A kind of Cr-Al alloy film taking Zr as base, is characterized in that, adopts a kind of preparation method of the Cr-Al alloy film taking Zr as base according to any one of claims 1 to 6 to prepare, The Cr-Al alloy film has a thickness of 9 μm to 10 μm.