CN104697210B - The solar spectrum selective absorbing film of a kind of in-situ self-grown and its preparation method - Google Patents

Abstract

The solar spectrum selective absorbing film of in-situ self-grown and an its preparation method, belong to solar spectrum selective absorbing film preparing technical field. By stainless steel metal base substrate and in stainless steel metal base substrate the spumescence nanostructure absorbing membrane of in-situ self-grown form, the thickness of absorbing membrane is 1～3 μm, in rete and film surface arrangement have relatively uniform by the Fe of spinel-like structural_3-x-yCr_xNi_yO₄The hole that (x=0.18～0.27, y=0.25～0.35) nanoparticle group piles up, the particle diameter of nanoparticle group is 20～60nm, and the size of hole is 20～80nm. The absorbing membrane of the present invention is keeping having structure simple under high solar absorption and low thermal emissivity prerequisite, and spumescence nanostructure growth in situ is in substrate, and in conjunction with close and firm, thermostability and weathering resistance are better. This film can be used in solar light-heat power-generation thermal-collecting tube field.

Description

The solar spectrum selective absorbing film of a kind of in-situ self-grown and its preparation method

Technical field

The invention belongs to solar spectrum selective absorbing film preparing technical field, it is specifically related to high-selenium corn Low emissivity solar spectrum selective absorbing film and its preparation method of the spumescence nanostructure of a kind of in-situ self-grown.

Background technology

Solar energy thermal transition is a kind of effciency of energy transfer and utilization ratio height and with low cost, the Solar use mode extensively can promoted in the whole society. Current solar thermal utilization enlivens, and has formed industry. No matter it is solar water heater or solar light-heat power-generation thermal-collecting tube, all to be had a core apparatus being used for absorbing solar radiation, i.e. coating for selective absorption of sunlight spectrum. This coating needs has higher absorption rate at Visible-to-Near InfaRed wave band (0.3～2.5 μm), has relatively low-launch-rate at infrared band (2.5 μm～20 μm). And for the heated body in a practical application, its thermal radiation concentration of energy is in the infrared range of spectrum that wavelength is 3.0～30.0 μm, in order to reduce thermosteresis, prevent the shortwave energy absorbed from falling with the radiation of long wave form again, heat emission ratio (usually representing with ε) low as far as possible will be kept in thermal radiation wave band. In a word, to be made absorbing surface exactly while absorbing solar radiation to greatest extent, reduce its radiation heat loss as far as possible. The material with this characteristic becomes current solar energy heat collection pipe and the focus of selective absorbing film field research.

The selective heat-absorbing film occurred in existing market has black chromium, AIN/Al, NiCrN_xO_y、TiN_xO_yDeng. Chromium plating film, because of electroplate liquid contaminate environment, eliminates at present gradually; Although AIN/Al light thermal property is better, but cannot work for a long time in high temperature air, so also reducing gradually; The NiCrN of current more use_xO_y、TiN_xO_yDeng absorption film, its manufacture craft is more complicated, it is necessary to the ratio of strict control two kinds of gases simultaneously, it is also desirable to use more accurate magnetic control sputtering device. NiCrN disclosed in China Patent Publication No. CNI584445A_xO_yAbsorption film is after having done gradual change to NiCr metal content, and best specific absorption just reaches 92%, and minimum radiant ratio is 0.1.TiN disclosed in China Patent Publication No. CN101240944A and CN201196495Y_xO_yFilm, its surface reloads one layer of SiO₂After antireflective film, specific absorption can reach 96%, and emittance is lower than 4%, and above rete also needs the content more accurately controlling nitrogen and oxygen in the process of preparation. For this reason, consider from extensive masking technique angle, it is necessary to introduce new Technology, thus obtain cheap high performance selective absorbing film.

Summary of the invention

It is an object of the invention to provide the high-selenium corn Low emissivity solar spectrum selective absorbing film of the spumescence nanostructure of a kind of in-situ self-grown and its preparation method.

The solar spectrum selective absorbing film of a kind of in-situ self-grown of the present invention, by stainless steel metal base substrate and in stainless steel metal base substrate the spumescence nanostructure absorbing membrane of in-situ self-grown form (as shown in Figure 1); The thickness of absorbing membrane is 1～3 μm, crosses and thick can increase thermal emissivity, too thin can affect specific absorption, and thicknesses of layers can by reaction times adjustment control. In the rete of absorbing membrane and film surface arrangement have relatively uniform from the Fe of spinel-like structural (as shown in the XRD figure of Fig. 2)_3-x-yCr_xNi_yO₄(x=0.18～0.27, y=0.25～0.35) nanoparticle group, particle diameter is 20～60nm, and the size of hole is 20～80nm (the SEM figure such as Fig. 3 is known). The molar composition ratio of film element can be able to be obtained by electronic spectrum data.

The preparation method of the solar spectrum selective absorbing film of a kind of in-situ self-grown of the present invention, its step is as follows:

1) alcohol swab wiping is used on stainless steel substrates surface, make surface darkening sliding and clean;

2) smooth surface and clean stainless steel substrates are put in the NaOH solution of 5M～20M, then join together in reactor, under 100～250 degrees Celsius, react 6～40h;

3) room temperature is naturally cooled to after being taken out by reactor, then by ultrasonic for reaction product 7～25h;

4) with deionized water wash after stainless steel substrates being taken out, finally dry under 20～90 degrees Celsius, thus the solar spectrum selective absorbing film of in-situ self-grown is obtained on stainless steel substrates surface.

The feature of absorbing membrane of the present invention is that structure is simple, and preparation technology is simple, and environmental friendliness, film and substrate are connected firmly, Heat stability is good. There is high-absorbility, low-launch-rate simultaneously, and the excellent properties such as weathering resistance is strong, long service life.

Described stainless steel metal base substrate is the one in the stainless steels such as SS201, SS202, SS302, SS408, SS410, SS416, SS409, SS440, SS316L, SS304. In this stainless steel, by mass percentage, ≤ 2.00%), phosphorus (P :≤0.045%), (S :≤0.030%) etc., thickness is 0.2～2mm to sulphur containing chromium (Cr:16.00～18.00%), nickel (Ni:10.00～14.0%), manganese (Mn:.

The specific refractory power of absorbing membrane can by regulating the hole size in micro-texture on film surface, rete and distribution, the hole size on film surface and distribution etc. to realize, and then control transition to the stainless steel-based end, from pottery property to metallicity from film surface.

Described spumescence nanostructure absorbing membrane, is connected firmly with substrate by hydrothermal method growth in situ on the stainless steel-based end. Wherein the form of sunlight high-selenium corn material is the nanostructure of the spumescence constructed by nanoparticle group, its size (20～60nm) is much smaller than infrared wavelength, and in this microstructure, it is distributed with more hole, sunlight can be caught better, reduce thermal emissivity, it is possible to realize the selective absorbing of infrared light and visible ray.

Described radiation absorption film is based on the membrane structure of spumescence nanostructure, and on its film, the light of incidence can be carried out repeatedly reflection, scattering and absorption by the hole of distribution. The local fields effect of combining nano particle greatly enhances the specific absorption of film simultaneously. This kind of film can pass through adjusting reaction time, NaOH concentration, temperature of reaction, product ultrasonic time, and then regulate number of apertures and size distribution etc. on the microstructure on film surface and film, make the energy of visible and near infrared solar spectrum section by selective absorbing, the thermal emissivity on surface can be suppressed simultaneously, thus has good high-selenium corn and Low emissivity effect.

The absorbing membrane of the present invention has following advantage:

Owing to have employed spumescence nano-structure film as absorption layer, surface pore size is much smaller than infrared light wavelength, the absorbing membrane of the present invention is made can significantly to improve solar spectrum specific absorption on the one hand, significantly reduce whole film emittance on the other hand, have the advantages that photo-thermal conversion efficiency is high, solar energy optical-thermal thermal-collecting tube can be widely used in. The advantages such as meanwhile, it is simple that this film has preparation method, and pre-treatment is convenient, environmental friendliness, energy one-step synthesis method.

The absorbing membrane of the present invention is keeping under high solar absorption and low thermal emissivity prerequisite, there is structure simple, spumescence nanostructure growth in situ is in substrate, in conjunction with close and firm, thermostability and weathering resistance are better, process 24 hours at 450 DEG C, also do not occur that rete is chapped situation, foam nanostructure substantially goes up and can keep, and is that pore dimension diminishes (15～45nm), nanoparticle granule footpath turns into about 45～80nm. This film can be used in solar light-heat power-generation thermal-collecting tube field.

The absorbing membrane of the present invention, the hydrothermal method being applicable to cheap and simple is prepared, it is not necessary to the pre-treatment of complexity and contaminate environment and post-processing step, have significance to the development in solar selectively photo-thermal film field.

Accompanying drawing explanation

Fig. 1: the spumescence nanostructure of fabricated in situ absorbs the section S EM figure of film, can find out that this film is foam-like porous nanostructure by figure, and growth in situ is in the substrate of stainless steel, and the size of membrane pores is about 20～80nm.

Fig. 2: the surperficial SEM that the spumescence nanostructure of fabricated in situ absorbs film schemes is that the nanoparticle group being about 20～60nm by particle diameter is formed by figure it can be seen that film surface.

Fig. 3: spumescence nanostructure absorbs the XRD figure of film. Spectrum line 2 shows, it is spinel structure that the spumescence nanostructure of fabricated in situ absorbs film, and peak is strong and crystallization is more weak; Spectrum line 3 shows, it is also spinel phase that the spumescence nanostructure that thermal treatment obtained after 24 hours in 450 DEG C of air absorbs film, and peak is strong and crystallization change is strong.

Fig. 4: synthesized spumescence nanostructure absorbs the electronic energy spectrum of film, according to the integral area ratio at the peak of element each in spectrogram, can obtain the molar content ratio of each element on film.

Fig. 5: spumescence nanostructure absorbs the reflection spectrum curve of film; Curve 1 represents the reflection spectrum curve in 0.3～20 micron spectral interval of the spumescence nanostructure absorption film of fabricated in situ. After curve 2 represents 450 DEG C of process, the spumescence nanostructure of fabricated in situ absorbs the reflection spectrum curve in 0.3～20 micron spectral interval of film.

Embodiment

Embodiment 1: stainless steel-based the end/preparation of spumescence nanostructure absorbing membrane

(1) first with alcohol swab wiping stainless steel substrates 12 times, make stainless steel substrates surface darkening sliding and clean, then stainless steel substrates is put in the NaOH solution of 16M, then pour into together in reactor;

(2) reactor is put into 200 degrees Celsius of baking ovens and react 22h, after then being taken out by reactor, naturally cool to room temperature, then supersound process 7 hours; With deionized water wash after finally stainless steel substrates being taken out, 90 DEG C of dryings, thus on stainless steel substrates, obtain the high-selenium corn Low emissivity solar spectrum selective absorbing film of the spumescence nanostructure of in-situ self-grown. Film thickness about 2.9 μm, in rete and film surface arrangement have the hole piled up relatively uniformly by the nanoparticle group of spinel-like structural, the particle diameter of nanoparticle group is 20～56nm, and the size of hole is 20～77nm. By the integral area ratio at the peak of element each in the electronic energy spectrum of Fig. 4 .1, the molar content ratio of each element on film can be obtained. The chemical formula that can obtain film is Fe_2.40Cr_0.27Ni_0.33O₄。

In addition, it is placed in High Temperature Furnaces Heating Apparatus by this film with 2 DEG C/min to heat up, in 450 DEG C of thermal treatments Temperature fall after 24 hours, to check the thermostability of this film.

$\mathrm{\α}=\frac{{\text{\∫}}_{0.3}^{2.5}[1-R\left(\mathrm{\λ}\right)P_{\mathrm{sun}}\left(\mathrm{\λ}\right)\mathrm{d\λ}}{{\∫}_{0.3}^{2.5}{P}_{\mathrm{sun}}\left(\mathrm{\λ}\right)\mathrm{d\λ}}---\left(1\right)$

$\mathrm{\ϵ}=\frac{{\∫}_{2.5}^{20}[1-R\left(\mathrm{\λ}\right){]P}_b\left(\mathrm{\λ}\right)\mathrm{d\λ}}{{\∫}_{2.5}^{20}{P}_b\left(\mathrm{\λ}\right)\mathrm{d\λ}}---\left(2\right)$

The specific absorption of film at 0.3～2.5 μm of spectrum range and the thermal emissivity at 2.5～20 μm of spectrum ranges, can calculate (as shown in Figure 5) according to above-mentioned formula (1), (2) and measured reflected spectrum data. In upper formula, α and ε represents specific absorption and thermal emissivity respectively; R (λ) represents the reflectivity at λ wavelength place, obtains at 0.3～2.5 μm of available spectrophotometer measurement, locates available Fourier infrared spectrograph measurement at 2.5～20 μm and obtains. P_sun(λ) represent the energy intensity of the solar radiation at λ wavelength place, adopt the normal data of ISO9845-1 (1992) and AM1.5; P_b(λ) represent the blackbody radiation intensity at λ wavelength place, adopt the radiation value of perfect black body during 300K.

The main energetic of sunlight concentrates on 0.3～2.5 μm of interval, and a kind of outstanding solar spectrum selective absorbing film has very high specific absorption in this interval; Have very low thermal emissivity (namely showing very high infrared reflectance at this spectrum range) simultaneously in 2.5～20 μm of intervals, suppress scattering and disappearing of the heat absorbed, thus realize the selective absorbing to sunlight. The film of the growth in situ that this experiment obtains has higher specific absorption that is 0.92 in 0.3～2.5 μm of interval, even if specific absorption also can reach 0.83 after 450 DEG C of thermal treatment. Interval at the mid and far infrareds of 2.5～20 μm, the blackbody radiation choosing 300K does reference, and in conjunction with the reflection spectrum of formula (2) and this interval, the thermal emissivity that can calculate this growth in situ film is be upgraded to 0.23 after 0.12,450 DEG C of thermal treatment. To sum up, it suffices to say that the rete that this experiment growth in situ obtains can absorb sunlight preferably in solar spectrum interval, simultaneously to the thermal radiation that emission is lower; Though performance has small size decline after 450 DEG C of thermal treatment. A kind of solar spectrum selective absorbing film preferably but this rete still be can yet be regarded as.

Embodiment 2: stainless steel-based the end/preparation of spumescence nanostructure absorbing membrane

(1) first make for 8 times surface darkening sliding and clean with alcohol swab wiping stainless steel substrates, then put in the NaOH solution of 5M, then pour into together in reactor.

(2) 100 degrees Celsius of baking oven 6h put into by reactor, after take out reactor and naturally cool to room temperature, reaction product carries out ultrasonic 7 hours, deionized water wash, 20 DEG C of dryings. Film thickness about 1 μm, in rete and film surface arrangement have the hole piled up relatively uniformly by the nanoparticle group of spinel-like structural, the particle diameter of nanoparticle group is 35～59nm, and the size of hole is 49～80nm.By the integral area ratio at the peak of element each in the electronic energy spectrum of Fig. 4 .2, the molar content ratio of each element on film can be obtained. The chemical formula that can obtain film is Fe_2.57Cr_0.18Ni_0.25O₄。

Embodiment 3: stainless steel-based the end/preparation of spumescence nanostructure absorbing membrane

(1) first make for 20 times surface darkening sliding and clean with alcohol swab wiping stainless steel substrates, then put in the NaOH solution of 20M, then pour into together in reactor.

(2) 250 degrees Celsius of baking oven 40h put into by reactor, after take out reactor and naturally cool to room temperature, reaction product carries out ultrasonic 25 hours, deionized water wash, 90 DEG C of dryings. Film thickness about 3 μm, in rete and film surface arrangement have the hole piled up relatively uniformly by the nanoparticle group of spinel-like structural, the particle diameter of nanoparticle group is 20～44nm, and the size of hole is 20～70nm. By the integral area ratio at the peak of element each in the electronic energy spectrum of Fig. 4 .3, the molar content ratio of each element on film can be obtained. The chemical formula that can obtain film is Fe_2.45Cr_0.20Ni_0.35O₄。

Claims (4)

1. the solar spectrum selective absorbing film of an in-situ self-grown, it is characterized in that: by stainless steel metal base substrate (1) and in stainless steel metal base substrate spumescence nanostructure absorbing membrane (2) of in-situ self-grown form, the thickness of absorbing membrane is 1～3 μm, in rete and film surface arrangement have relatively uniform by the Fe of spinel-like structural_3-x-yCr_xNi_yO₄The hole that nanoparticle group piles up, the particle diameter of nanoparticle group is 20～60nm, and the size of hole is 20～80nm; Wherein, x=0.18～0.27, y=0.25～0.35.

2. the solar spectrum selective absorbing film of a kind of in-situ self-grown as claimed in claim 1, it is characterized in that: described stainless steel metal base substrate (1) is by mass percentage, containing Mn :≤2.00%, S :≤0.030%, P :≤0.045%, Cr:16.00～18.00%, Ni:10.00～14.0%, thickness is 0.2～2mm.

3. the solar spectrum selective absorbing film of a kind of in-situ self-grown as claimed in claim 1 or 2, it is characterised in that: stainless steel metal base substrate (1) is the one in stainless steel SS201, SS202, SS302, SS408, SS410, SS416, SS409, SS440, SS316L or SS304.

4. the preparation method of the solar spectrum selective absorbing film of a kind of in-situ self-grown described in claim 1,2 or 3, its step is as follows:

1) alcohol swab wiping is used on stainless steel substrates surface, make surface darkening sliding and clean;

2) smooth surface and clean stainless steel substrates are put in the NaOH solution of 5M～20M, then join together in reactor, under 100～250 degrees Celsius, react 6～40h;

3) room temperature is naturally cooled to after being taken out by reactor, then by ultrasonic for reaction product 7～25h;

4) with deionized water wash after stainless steel substrates being taken out, finally dry under 20～90 degrees Celsius, thus the solar spectrum selective absorbing film of in-situ self-grown is obtained on stainless steel substrates surface.