CN104630706A - High-property optothermal transformation multiple-element alloy nitride film and preparation method thereof - Google Patents

Abstract

A high-performance photothermal conversion multi-element alloy nitride thin film and its preparation method, the multi-element alloy sputtering target was successfully prepared by powder metallurgy and vacuum arc melting, and the vacuum magnetron sputtering coating process was adopted Change the sputtering time and working pressure to prepare multi-element alloy nitride films with different thicknesses, providing new materials for solar spectrum selective absorption coatings. Typical structure of solar selective absorbing coating: infrared reflective layer, double absorbing layer, anti-reflection layer sandwich structure, the coating has higher absorption rate and thermal stability. In the present invention, a single-layer multi-element alloy nitride film is sputtered on a polished stainless steel substrate. After testing, the single-layer multi-element alloy nitride film has a higher absorption rate than other single-layer light-to-heat conversion films in the solar spectrum range. 79.82%, and the obtained multi-element alloy nitride thin film has uniform thickness, and has good bonding ability with the substrate and high temperature resistance. The invention is suitable for high-temperature vacuum heat collecting tubes, and has broad application prospects in the solar thermal field.

Description

A high-performance photothermal conversion multi-element alloy nitride thin film and its preparation method

technical field

The invention relates to the field of solar photothermal application, and mainly relates to a high-performance photothermal conversion multi-element alloy thin film and a preparation method thereof.

Background technique

With the growing problems of energy shortage and environmental pollution, it is imperative to expand the field of solar energy applications. Solar energy is a kind of clean renewable energy. Photothermal conversion is the most effective form of direct utilization of solar energy. The solar spectrum selective absorption coating is a medium that directly converts sunlight and light energy. Improving the conversion efficiency of solar energy has always been an important issue. The focus of solar thermal utilization. At present, solar spectrum selective absorption coatings for photothermal conversion are only used at medium and low temperatures. Among them, black chromium coatings and aluminum anodized coatings are the most mature and widely used. The main disadvantage is that the waste liquid is difficult to control and easy to control during the production process. cause problems such as environmental pollution. In recent years, ZHANG and MILLS of the University of Sydney in Australia have used DC co-sputtering to inject metal particles such as stainless steel and tungsten into the AlN dielectric substrate, which has increased the sputtering rate and greatly reduced the cost of the film. According to the Carnot cycle efficiency, the larger the temperature difference, the higher the conversion efficiency. In order to improve the light-to-heat conversion efficiency, the coating is required to be used at a higher temperature. The chemical reaction causes the bonding force to decrease or even peel off, and the optical performance drops sharply. High-temperature thermal stability and good optical properties have always been the key factors restricting the development of solar spectrum selective absorption coatings. Therefore, it is quite important to develop high-temperature stable high-performance solar selective absorption coatings.

Due to its unique composition ratio, structure and high mixing entropy, multi-element alloys and their nitrogen/oxygen cermet materials have organizational characteristics such as simplification of fiber structure, nano-precipitates, amorphous structure, and nano-grains. High strength, high hardness, high wear resistance, corrosion resistance, temper softening resistance, slow diffusion and other performance characteristics. Therefore, by designing the structure and film system of multi-element material coatings for selective absorption of solar energy, and developing suitable multi-element materials and vacuum magnetron sputtering processes, it has potential application value in the field of solar photothermal conversion.

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

(1) The preparation method is simple and easy to operate, the parameters are easy to adjust, and the cost is low;

(2) High deposition rate and uniform film;

(3) Provide a multi-element alloy nitride film with good optical performance and high temperature resistance, and solve the problems of element diffusion film peeling off at high temperature.

Contents of the invention

The technical problem to be solved by the present invention is to make full use of the excellent properties of multi-element alloys to provide a high-performance light-to-heat conversion multi-element alloy thin film and its preparation method, which can ensure good bonding force with the substrate and excellent Optical performance, but also to ensure good thermal stability.

In order to solve the problem of high temperature resistance and weather resistance of the solar spectrum selective absorption coating, the present invention first adopts the powder metallurgy method or the vacuum arc melting method to prepare the multi-element alloy target material; secondly, adopts the vacuum magnetron sputtering coating process to fill the working Gas argon Ar and reaction gas N ₂ , by changing the working pressure and sputtering time to obtain uniform multi-element alloy nitride films with different thicknesses; the composition of multi-element alloy targets is Al, Si and transition metal elements Nb , Ti, Ni, Zr, Mo, Hf, Ta, W, composed of at least four metal elements in an equimolar ratio. The high-performance photothermal conversion multi-element alloy nitride thin film has a thickness of 120-420nm.

Powder metallurgy method: According to the design composition, the atomic percentage is converted into a mass ratio and the powder of each element is weighed separately. The powders of each metal element (purity>99.9%) are ground and mixed evenly, pressed into Ar to protect the vacuum liposuction, and then sintered to obtain the required target size.

Vacuum arc melting method: according to the design composition, the atomic percentage is converted into mass ratio, and the blocks of each element (purity>99.9%) are weighed respectively, prepared and put into the copper mold of the vacuum electric arc furnace in turn, and repeatedly smelted at least five times to obtain a relatively high temperature. Uniform ingot casting, and then through cutting, turning, milling and other machining to obtain the required target size.

The main role of alloying elements: the addition of transition metal elements such as Nb, Ti, W, Zr can improve the high temperature resistance, corrosion resistance, diffusion barrier effect and spectral selective absorption of the film, and the addition of Al and Si can improve the oxidation resistance of the film performance.

The invention provides a high-performance light-to-heat conversion multi-element alloy nitride thin film and a preparation method thereof, specifically comprising the following steps:

Step 1: Put the quartz glass sheet (to facilitate the film thickness test) and the polished stainless steel substrate into alcohol and deionized water for ultrasonic cleaning respectively;

Step 2: Dry the cleaned substrate and place it on the sample stage corresponding to the vacuum chamber, place the prepared quaternary alloy target on the evaporation source of the vacuum chamber and connect it to a DC power supply;

Step 3: Close the magnetron sputtering vacuum chamber, and fill it with high-purity Ar and N2 when the vacuum degree is lower than 1.0×10-3Pa;

Step 4: Adjust the gate valve and fill the gas flow rate to adjust the working pressure to 0.2-1.0Pa, and pre-sputter for 5-15 minutes to remove the target surface pollutants;

Step 5: Rotate and sample stage, start coating sputtering, sputtering time is 10-45min, and finally obtain multi-element alloy nitride thin film.

In the step 1, the time of ultrasonic cleaning with alcohol and deionized water is 10-20 minutes respectively, and the cleaning is repeated 2-3 times, and the ultrasonic power is 80-100W.

In the second step, the working distance between the evaporation source and the sample stage is 60-80 mm.

The working method of the third step is: open the mechanical pump, pre-pump valve and mechanical pump angle valve, pump the vacuum chamber air pressure below 5.0Pa through the mechanical pump, close the mechanical pump angle valve and pre-pump valve, open the front valve And the molecular pump, when the rotational speed of the molecular pump exceeds 100L/s, open the gate valve of the molecular pump to start high vacuum, and use the molecular pump to pump the air pressure to less than 1.0×10-3Pa.

The invention uses the multi-element alloy as the sputtering target material, and sputters the multi-element alloy nitride thin film on the stainless steel and the quartz glass sheet by adopting the vacuum magnetron sputtering-direct current sputtering method. Provide a new type of high-entropy alloy nitride thin film and its preparation method, which can not only ensure good bonding force with the substrate and excellent optical properties, but also ensure good thermal stability, and provide a new method for solar spectrum selective absorption coatings. Material.

Description of drawings

Fig. 1 is the reflection spectrogram of the multi-element alloy nitride film sample prepared in embodiment 1

Fig. 2 is the reflection spectrogram of the multi-element alloy nitride film sample prepared in embodiment 2

Fig. 3 is the reflection spectrogram of the multi-element alloy nitride film sample prepared in embodiment 3

Fig. 4 is the SEM sectional view of the multi-element alloy nitride film sample prepared in embodiment 1

Fig. 5 is the SEM microstructure figure of the multi-element alloy nitride film sample prepared in embodiment 1

detailed description

Next, the quaternary alloy nitride thin film is prepared by using NbTiAlSi quaternary alloy target material in conjunction with the following three examples to further describe the present invention in detail, but it is not intended to limit the present invention.

Example 1

The composition is 1:1:1:1 equimolar ratio NbTiAlSi quaternary alloy target, using vacuum magnetron sputtering coating process, filled with working gas Ar and reactive gas N2, by changing the working pressure and sputtering time to obtain uniform multi-element alloy nitride films of different thicknesses. Specifically include the following steps:

Step 1: Put the quartz glass sheet (to facilitate the film thickness test) and the polished stainless steel substrate into alcohol and deionized water for 15 minutes, and repeat the above process twice;

Step 2: Dry the cleaned substrate and place it on the sample stage corresponding to the vacuum chamber, place the prepared quaternary alloy target on the evaporation source of the vacuum chamber and connect it to a DC power supply;

Step 3: Close the magnetron sputtering vacuum chamber, and when the vacuum degree is lower than 1.0×10-3Pa, fill with 16 sccm of Ar and 8 sccm of N2;

Step 4: The DC voltage is 400V, the current is 0.225A, and the power is fixed at 90W. Adjust the gate valve and fill the gas flow rate to adjust the working pressure to 0.2Pa, and pre-sputter for 15 minutes to remove the target surface pollutants;

Step 5: Rotate and sample stage, start coating sputtering, sputtering time is 15min, and finally obtain a multi-element alloy nitride film with a thickness of 177nm, see attached drawing 4; see attached drawing 5 for the surface structure of the film.

The measured reflectance spectrum of this multi-element alloy nitride thin film is shown in Figure 1, and the calculated absorption rate is 74.93%.

Example 2

The composition is 1:1:1:1 equimolar ratio NbTiAlSi quaternary alloy target, using vacuum magnetron sputtering coating process, filled with working gas Ar and reactive gas N2, by changing the working pressure and sputtering time Obtain uniform multi-element alloy nitride films of different thicknesses. Specifically include the following steps:

Step 1: Put the quartz glass sheet (to facilitate the film thickness test) and the polished stainless steel substrate into alcohol and deionized water for 15 minutes, and repeat the above process twice;

Step 2: Dry the cleaned substrate and place it on the sample stage corresponding to the vacuum chamber, place the prepared quaternary high-entropy alloy target on the evaporation source of the vacuum chamber and connect it to a DC power supply;

Step 3: Close the magnetron sputtering vacuum chamber, and when the vacuum degree is lower than 1.0×10-3Pa, fill with 20 sccm of Ar and 6 sccm of N2;

Step 4: The voltage is 400V, the current is 0.225A, and the power is fixed at 90W. Adjust the gate valve and fill the gas flow rate to adjust the working pressure to 0.6Pa, and pre-sputter for 15 minutes to remove the target surface pollutants;

Step 5: Rotate and sample stage, start coating sputtering, sputtering time is 30min, and finally obtain a multi-element alloy nitride film with a thickness of about 300nm.

The measured reflection spectrum of this multi-element alloy nitride film is shown in Figure 2, and the calculated absorption rate is 79.82%.

Example 3

The composition is 1:1:1:1 equimolar ratio NbTiAlSi quaternary high-entropy alloy target, using vacuum magnetron sputtering coating process, filled with working gas Ar and reactive gas N2, by changing the working pressure and sputtering Time to obtain uniform high-entropy alloy nitride films of different thicknesses. Specifically include the following steps:

Step 1: Put the quartz glass sheet (to facilitate the film thickness test) and the polished stainless steel substrate into alcohol and deionized water for 15 minutes, and repeat the above process twice;

Step 2: Dry the cleaned substrate and place it on the sample stage corresponding to the vacuum chamber, place the prepared quaternary alloy target on the evaporation source of the vacuum chamber and connect it to a DC power supply;

Step 3: Close the magnetron sputtering vacuum chamber, and when the vacuum degree is lower than 1.0×10-3Pa, fill with 16 sccm of Ar and 8 sccm of N2;

Step 4: The voltage is 400V, the current is 0.225A, and the power is fixed at 90W. Adjust the gate valve and fill the gas flow rate to adjust the working pressure to 0.2Pa, and pre-sputter for 15 minutes to remove the target surface pollutants;

Step 5: Rotate the sample stage and start coating sputtering, the sputtering time is 30min, and finally obtain a multi-element alloy nitride film with a thickness of about 290nm.

The measured reflection spectrum of this multi-element alloy nitride thin film is shown in Fig. 3, and the calculated absorption rate is 76.71%.

In summary, the multi-element alloy nitride film can not only ensure good bonding force with the substrate and excellent optical properties, but also ensure good thermal stability, and has potential applications in solar spectrum selective absorption coatings. Value.

Claims (7)

1. a preparation method for high-performance optical thermal transition many primitives alloy nitride film, is characterized in that: first, adopts powder metallurgic method to prepare many primitives alloy target material; Secondly, adopt vacuum magnetron sputtering coating film technique, be filled with argon working gas Ar and reactant gases N ₂, many primitives alloy nitride film of uniform different thickness is obtained by change operating air pressure and sputtering time; Many primitives alloy target material moiety is Al, Si and transition metal Nb, Ti, Ni, Zr, Mo, Hf, Ta, W, by equimolar ratio at least four kinds of metallic element compositions;

The method that powder metallurgic method prepares many primitives alloy target material is: according to design mix, atomic percent is converted into the powder that mass ratio takes each metallic element respectively; By the powder (purity >99.9%) of each metallic element by waiting atomic ratio ground and mixed even, hot isostatic pressing is shaped and sinters the sputtering target material needed for obtaining.

2. the preparation method of a kind of high-performance optical thermal transition many primitives alloy nitride film as claimed in claim 1, it is characterized in that: adopt vacuum arc melting method to substitute powder metallurgic method and prepare many primitives alloy target material, concrete steps are: atomic ratio is converted into according to design mix block (purity >99.9%) that mass ratio takes each metallic element respectively and prepares and ultrasonic cleaning is dried, vacuum arc fumace copper mold is put into successively to high-melting-point by low melting point, melt back obtains more uniform ingot casting at least five times, then through cutting, car, milling machining obtains required sputtering target material.

3. the preparation method of a kind of high-performance optical thermal transition many primitives alloy nitride film according to claim 1, it is characterized in that, described many primitives alloy nitride film thickness is 120 ~ 420nm.

4. the preparation method of a kind of high-performance optical thermal transition many primitives alloy nitride film as claimed in claim 1, is characterized in that, specifically comprise the following steps:

Step one: the stainless steel base of quartz glass plate and polishing is put into alcohol, deionized water ultrasonic cleaning respectively successively;

Step 2: dried by cleaned matrix and put in sample table corresponding to vacuum chamber, many primitives alloy target material of preparation is placed on vacuum chamber evaporation source and connects direct supply;

Step 3: close magnetron sputtered vacuum cavity, when vacuum tightness is lower than 1.0 × 10-3Pa, be filled with high-purity argon gas Ar reactant gases nitrogen N 2;

Step 4: regulator plate valve and insufflation gas flow rate regulation operating air pressure 0.2 ~ 1.0Pa, pre-sputtering 5 ~ 15min is to remove target material surface pollutent;

Step 5: rotate and sample table, start film coating sputtering, sputtering time is 10 ~ 45min, finally obtains many primitives alloy nitride film.

5. the preparation method of a kind of high-performance optical thermal transition many primitives alloy nitride film as claimed in claim 4, it is characterized in that: in described step one, be respectively 10 ~ 20min with alcohol, deionized water ultrasonic cleaning time, repeatedly clean 2 ~ 3 times, ultrasonic power is 80 ~ 100W.

6. the preparation method of a kind of high-performance optical thermal transition many primitives alloy nitride film as claimed in claim 4, is characterized in that: in described step 2, evaporation source and sample table operating distance are 60 ~ 80mm.

7. the preparation method of a kind of high-performance optical thermal transition many primitives alloy nitride film as claimed in claim 4, it is characterized in that: the mode of operation of described step 3 is: open mechanical pump, take out valve and mechanical pump angle valve in advance, by mechanical pump, gas pressure in vacuum is evacuated to below 5.0Pa, close mechanical pump angle valve and take out valve in advance, open front step valve and molecular pump, to molecular pump rotating speed more than 100L/s time, open molecular pump slide valve and start pumping high vacuum, utilize molecular pump to be evacuated to air pressure lower than 1.0 × 10-3Pa.