CN103966589A - Method for forming high-performance selective absorption processing film - Google Patents

Abstract

The invention relates to a method for forming a selective absorption surface of a heat collector using solar energy and a selective absorption processing film formed based on the method, and the selective absorption surface has good heat collection characteristics and is capable of being formed on a metal substrate. The method for forming the selective absorption surface is characterized in that the selective absorption surface is formed on the surface of the abovementioned metal substrate by impregnating the metal substrate in a chemical conversion treating fluid containing sulfuric acid and sodium dichromate or sulfuric acid and chromic anhydride, and the chemical conversion treating fluid contains a metal salt of oxyacid or a metal salt of haloid acid.

Description

High performance selective absorbs the formation method of processing film

Technical field

The present invention relates to solar heat-collection plate, selective absorbing film and utilize the heat collector of sun power, be particularly formed at the improving technology of the selectivity absorption surface of the substrate surface of solar heat-collection plate.

Background technology

Use the heat collector that utilizes sun power of collecting plate universal gradually as effectively utilizing one of method of sun power, but also requiring this heat collector that utilizes sun power to have can be in efficient absorption solar heat, and the heat energy absorbing is difficult for d/d characteristic.

Therefore, as the heat collector that utilizes sun power, be preferably its substrate surface and can form and have high to the wavelength 0.3 μ m in sunlight～lower than the specific absorption of the light of 2.5 μ m and be the selective absorbing film of the characteristic that the specific absorption of light of 2.5～25 μ m is low to wavelength.

In the past, utilized the heat collector of sun power to have a kind of stainless steel surface at excellent corrosion resistance to form the product of selectivity absorption surface.As this method that forms selectivity absorption surface at stainless steel surface, there are the methods such as chemical conversion processing, plating, sputter, thermooxidizing and coating blackwash.

In these methods, chemical conversion processing is industrial best practice.As chemical conversion processing method, can enumerate acidic oxidation method, alkaline oxygenated method, sulfidation-oxidation method, molten salt bath method etc.As existing chemical conversion processing method, the known invention that has record in patent documentation 1～7.

In patent documentation 1～6, acidic oxidation method and alkaline oxygenated method are enumerated.Wherein, acidic oxidation method is by the acidic solution that contains potassium bichromate, sodium dichromate 99 or chromic anhydride and sulfuric acid, at the temperature of 50～150 DEG C, flood and within several minutes, carry out chemical conversion processing, form selectivity absorption surface on the surface of ferrite class and austenitic stainless steel thus.

In patent documentation 7, recorded a kind of by the aqueous sulfuric acid that contains sulfuric acid, add sodium metavanadate make chemical conversion process solution, under the bath temperature of 85.5～124 DEG C, flood stainless steel, thereby can process by the short period of time formation method of the selectivity absorption surface of the heat collector that utilizes sun power of the selectivity absorption surface good in stainless steel surface forming property.

But, in the case of for example only being undertaken chemical conversion processing by the mixture of sulfuric acid and sodium dichromate 99 or sulfuric acid and chromic anhydride, (α-ε) of sunlight specific absorption α-infrared emission rate ε of sign selective absorbing film performance is lower, does not reach the level of the thermal-arrest characteristic that can fully meet selectivity absorption processing film.

Formerly technical literature

Patent documentation 1: Japanese kokai publication sho 52-89837 communique

Patent documentation 2: Japanese kokai publication sho 55-77667 communique

Patent documentation 3: Japanese kokai publication sho 56-53346 communique

Patent documentation 4: Japanese kokai publication sho 58-136949 communique

Patent documentation 5: Japanese kokai publication sho 61-174382 communique

Patent documentation 6: Japanese kokai publication sho 62-155471 communique

Patent documentation 7: Japanese kokai publication sho 2009-185327 communique

Summary of the invention

The problem that invention will solve

Therefore, the object of the invention is to, provide a kind of formation method of the selectivity absorption surface that can form on the surface of metal substrate the heat collector that utilizes sun power of the good selectivity absorption surface of thermal-arrest characteristic and the selectivity forming based on the method to absorb processing film.

Particularly can provide the selectivity that a kind of low this conduct of emissivity with the region of ultra-red high, relevant to thermal radiation for the specific absorption of UV, visible ray, near infrared region light utilizes the high thermal-arrest characteristic that the selectivity absorption surface of the heat collector of sun power is excellent specific property to absorb the formation method of processing film.

For solving the means of problem

The inventor etc. process condition to the chemical conversion of the metal substrate that utilizes the selectivity absorption surface that the selectivity absorption surface of the heat collector of sun power is excellent specific property in order to the low this conduct of emissivity that obtains having the region of ultra-red high, relevant to thermal radiation to the specific absorption of UV, visible ray, near infrared region light, particularly stainless chemical conversion processing condition conducts in-depth research, and found that and can reach object of the present invention.

, the present invention is as described below.

(1) a kind of formation method of selectivity absorption surface, it is by being immersed in metal substrate in the chemical conversion treatment solution that contains sulfuric acid and sodium dichromate 99 or sulfuric acid and chromic anhydride, form selectivity absorption surface on said metal substrates surface, it is characterized in that the metal-salt that this chemical conversion treatment solution contains oxygen acid or the metal-salt of haloid acid.

(2) the formation method of the selectivity absorption surface as described in above-mentioned (1), is characterized in that, the metal in above-mentioned metal-salt is selected from least a kind in transition metal, Na, K.

(3) the formation method of the selectivity absorption surface as described in above-mentioned (1) or (2), is characterized in that, in above-mentioned transition metal chosen from Fe, chromium, nickel, zinc, cobalt at least a kind.

(4) the formation method of the selectivity absorption surface as described in above-mentioned (1) or (2), is characterized in that, the concentration of the above-mentioned metal-salt in above-mentioned chemical conversion treatment solution is 250～2500mg/L.

(5) the formation method of the selectivity absorption surface as described in above-mentioned (1) or (2), is characterized in that, the negatively charged ion in above-mentioned metal-salt is SO ₄ ^2-, NO ₃ ^-, Cl ^-or PO ₄ ^3-.

(6) the formation method of the selectivity absorption surface as described in above-mentioned (1) or (2), is characterized in that, above-mentioned metal-salt is ferric sulfate [Fe ₂(SO ₄) ₃] and chromium sulphate [Cr ₂(SO ₄) ₃] wherein at least one.

(7) a kind of selectivity absorbs and processes film, it is to utilize the selectivity of the heat collector of sun power to absorb processing film, it obtains by metal substrate being immersed in the chemical conversion treatment solution that contains sulfuric acid and sodium dichromate 99 or sulfuric acid and chromic anhydride, it is characterized in that the metal-salt that this chemical conversion treatment solution contains oxygen acid or the metal-salt of haloid acid.

The effect of invention

The formation method of selectivity absorption surface of the present invention, by add the metal-salt of oxygen acid or the metal-salt of haloid acid in the chemical conversion treatment solution that contains sodium dichromate 99 or chromic anhydride, can make metal-salt control the oxygenizement of sulfuric acid-sodium dichromate 99 system, and can regulate the speed of growth of selectivity absorption surface, improve the film density of selectivity absorption surface.Can improve thus the sunlight specific absorption α of formed selectivity absorption surface, and can suppress infrared emission rate ε, improve selectivity absorptive character (α-ε), thereby improve the thermo-efficiency of the heat collector that utilizes sun power.

Brief description of the drawings

Fig. 1 is the schematic diagram that is related to of vitriol addition and selectivity absorptive character (α-ε).

Embodiment

The formation method of the selectivity absorption surface of the heat collector that utilizes sun power of embodiment of the present invention is described below.According to the embodiment of the present invention, can on the metal substrate of the heat collector for utilizing sun power, particularly stainless steel plate, form the selectivity absorption surface that thermal absorptivity is high and heat reflectivity is low.

As the thermal equilibrium performance of the selectivity absorption surface of the heat collector for utilizing sun power, preferably there is absorbing properties and the infrared emission rate ε infrared radiation rejection 0.15 below of sunlight specific absorption α more than 0.90, more preferably sunlight specific absorption α more than 0.92, infrared emission rate ε is below 0.12.

The inventor is in order to obtain having to UV, visible ray, the specific absorption of near infrared region light is high, for example, after the emissivity of the region of ultra-red relevant to thermal radiation utilizes the chemical conversion processing condition of the metal substrate (stainless steel) of the selectivity absorption surface that the selectivity absorption surface of the heat collector of sun power is excellent specific property to further investigate compared with low this conduct, found that: by further add the metal-salt of oxygen acid and/or haloid acid in the chemical conversion treatment solution that contains oxidative compound, and metal substrate be impregnated in wherein, just can obtain applicable selectivity absorption surface.

Oxidative compound is not particularly limited, as long as can use with the form of the aqueous solution.As oxidative compound, for example, can enumerate sulfuric acid (H ₂sO ₄) etc. sulfuric acid based compound, potassium permanganate (KMnO ₄) etc. permanganate, sodium dichromate 99 (Na ₂cr ₂and chromic acid (VI) (CrO O7) ₃) etc. chromic salt, nitric acid (HNO ₃) and saltpetre (KNO ₃) etc. nitric acid based compound, hydrogen peroxide (H ₂o ₂) and sodium peroxide (Na ₂o ₂) etc. superoxide etc.In the present invention, preferably by sulfuric acid and sodium dichromate 99 use.

As oxygen acid, for example, can enumerate sulfuric acid, nitric acid and phosphoric acid etc.As haloid acid, for example, can enumerate hydrochloric acid, Hydrogen bromide and hydroiodic acid HI etc.

As the metal in metal-salt, for example, can enumerate transition metal and basic metal etc.Wherein, be preferably Fe, Cr, Ni, Zn, Co, V, Mn, Na, K.In this case, preferably will be with SO ₄ ^2-, NO ₃ ^-, Cl-or PO ₄ ^3-for the metal-salt of negatively charged ion is as additive.

As metal-salt, for example, can enumerate ferric sulfate, iron(ic) chloride, iron nitrate, single nickel salt, nickelous chloride, nickelous nitrate, chromium sulphate, chromium nitrate, zinc sulfate, zinc phosphate, zinc chloride, zinc nitrate, rose vitriol, cobalt chloride, manganous sulfate, Manganous chloride tetrahydrate and manganous nitrate etc.

Wherein, be preferably ferric sulfate [Fe ₂(SO ₄) ₃] and chromium sulphate [Cr ₂(SO ₄) ₃], more preferably ferric sulfate [Fe ₂(SO ₄) ₃] and chromium sulphate [Cr ₂(SO ₄) ₃] at least one of them is added in chemical conversion treatment solution and uses, more preferably and with ferric sulfate [Fe ₂(SO ₄) ₃] and chromium sulphate [Cr ₂(SO ₄) ₃].

In the present invention, although the reaction control agent by metal-salt as the oxygenizement of control sulfuric acid-sodium dichromate 99 system, but because it has the function that regulates selectivity to absorb the speed of growth of processing film, therefore, by the concentration range of the metal-salt in chemical conversion treatment solution is set as to proper range, can form the high-density selectivity absorption processing film with highly selective assimilated efficiency.

, the concentration of the metal-salt in chemical conversion treatment solution is preferably 100～2500mg/L, more preferably 250～2500mg/L.By the concentration of the metal-salt in chemical conversion treatment solution is controlled to 100～2500mg/L, can improve selectivity absorption characteristic [α (specific absorption)-ε (emissivity)].

More than the concentration of the metal-salt in chemical conversion treatment solution is set as to 100mg/L, can fully improve performance; And by this concentration is controlled at below 3000mg/L, can suppress separating out of metal-salt, prevent the rough sledding that dirt settling appears in metallic substrate surfaces.

The sulfuric acid concentration (bath concentration) that solution entirety is processed in chemical conversion is preferably 400～800g/L, 450～650g/L more preferably.By sulfuric acid concentration is controlled at 450g/L with on boost productivity.And by the concentration of sulfuric acid is controlled at below 650g/L, be easy to realize the control in order to obtain the selectivity absorption surface with highly selective assimilated efficiency.

In addition, the sodium dichromate 99 in chemical conversion processing solution entirety and the concentration (bath concentration) of chromic anhydride are preferably respectively 60～400g/L and 45～300g/L, are more preferably respectively 80～200g/L and 60～150g/L.Be that 80g/L is above or to make the concentration of chromic anhydride be more than 60g/L by making the concentration of sodium dichromate 99, by forming the enough films of thickness, can realize highly selective assimilated efficiency.In addition, be respectively below 200g/L and below 150g/L by making the concentration of sodium dichromate 99 and chromic anhydride, will be easy to realize the control in order to obtain the selectivity absorption surface with highly selective assimilated efficiency.

As the metal substrate that carries out chemical conversion processing, typical preferred product are stainless steel plate; Consider more preferably ferrite class stainless steel from the angle of erosion resistance.The formation method of selectivity absorption surface of the present invention is not limited to ferrite class stainless steel, also can be applicable to austenitic stainless steel and Martensite Stainless Steel.

In above-mentioned stainless steel plate, the carbon content of the Martensite Stainless Steel that ferrite class stainless steel and carbon number are many is less, be generally the chromium steel of iron (Fe)-chromium (Cr) alloy, austenitic stainless steel is the chromium-nickel steel of iron (Fe)-chromium (Cr)-nickel (Ni) alloy.

As the Steel Pattern Number of stainless steel plate, particularly, for example, can enumerate SUS304, SUS430, SUS444 or SUS316 etc., but be not limited to this.

In addition,, in the time carrying out above-mentioned stainless chemical conversion processing, in order to obtain stable and uniform oxide compound tunicle, be preferably metallic surface state even.Because the distribution of tissue, composition, working method, thermal treatment and the internal stress of metal is generally inhomogeneous, so that condition of surface is conventionally inhomogeneous.Therefore be preferably by mechanical mill, belt-sanding, the various lapped face processing such as abrasive particle grinding or chemical grinding of flowing, make the center line average roughness (Ra) of stainless steel surface below 0.07 μ m, for chemical conversion processing.

Consider the thermal equilibrium performance of formed selectivity absorption surface, dipping temperature is preferably 50～150 DEG C, more preferably 80～120 DEG C.When being 120 DEG C while processing below at dipping temperature, have advantages of that the weather resistance of the dense film of being used to form is good; On the other hand, when being 80 DEG C while processing above at dipping temperature, have advantages of and can complete at short notice chemical conversion processing.

Above-mentioned thermal equilibrium performance refers to high and low to the emissivity of the infrared region radiation from relevant to the thermal radiation of the selectivity absorption surface characteristic of specific absorption of the absorption of UV to the major portion as sunlight heat, visible ray, near infrared region, be the heat of efficient absorption sunlight and the heat that keeps because radiation is by the few characteristic of the amount of dissipation, use in the present invention selectivity absorptive character (α-ε) to represent.

The thickness of the selectivity absorption surface forming by above-mentioned chemical conversion processing condition in addition, is preferably 50～250nm, 50～150nm more preferably.By making thickness more than 50nm, can be easy to form the selective absorbing film with superperformance, by making thickness below 150nm, can suppress peeling off of selective absorbing film.The thickness of selective absorbing film can be measured by the ordinary method such as X-ray fluorescence method or Auger electron spectroscopy.

(embodiment)

Below, enumerate concrete example and further describe the present invention, but scope of the present invention is not limited to this.

(embodiment 1～12, comparative example 1～13)

In following treatment solution, make stainless steel plate (SUS444) during the processing of 116 DEG C is bathed, react with the dipping time shown in table 1～table 3, sulfate concentration.It should be noted that Fe ₂(SO ₄) ₃and Cr ₂(SO ₄) ₃all equivalent is added.The raw material for the treatment of solution used all uses the reagent of Japanese Northeast chemistry.

[treatment solution composition]

The evaluation of carrying out selectivity absorption characteristic as described below.

Specific absorption α is by using the V-570 processed of Japan Spectroscopy Corporation to measure the reflectivity R of UV, visible ray, near infrared region (300～2100nm), and utilizes the formula I of following formula 1 and formula II to calculate and obtain.

Emissivity ε is the FT/IR-400 by using Japan Spectroscopy Corporation's system, is the reflectivity R that measures region of ultra-red (2500～25000nm) equally, and utilizes the formula III of following formula 1 and formula IV to calculate and obtain.

[formula 1] α (λ)=1-R (λ) ... I

$\mathrm{\α}=\frac{{\∫}_{300}^{2100}\mathrm{\α}\left(\mathrm{\λ}\right)S\left(\mathrm{\λ}\right)\mathrm{d\λ}}{{\∫}_{300}^{2100}S\left(\mathrm{\λ}\right)\mathrm{d\λ}}\·\·\·\mathrm{II}$

(S: sunlight projectile energy)

ε(λ)＝１-R(λ) ...Ⅲ

$\mathrm{\ϵ}=\frac{{\∫}_{2500}^{25000}\mathrm{\ϵ}\left(\mathrm{\λ}\right)T\left(\mathrm{\λ}\right)\mathrm{d\λ}}{{\∫}_{2500}^{25000}T\left(\mathrm{\λ}\right)\mathrm{d\λ}}\·\·\·\mathrm{IV}$

(T: blackbody radiation energy)

The test-results of processing film is shown in table 1～table 3 and Fig. 1.

(table 1)

The evaluation result of table 1 selective absorbing film

(table 2)

The evaluation result of table 2 selective absorbing film

(table 3)

The evaluation result of table 3 selective absorbing film

Shown in table 1～table 3 and Fig. 1, interpolation vitriol just can be reduced to infrared emission rate ε the numerical value of regulation.Known in addition, by sulfate concentration being controlled to the scope of 250～2500g/L, just the sunlight specific absorption α of selectivity absorption surface can being maintained to high value, and can reduce infrared emission rate ε.Particularly, in the time of scope that sulfate concentration is 250～2500g/L, the sunlight specific absorption α in embodiment 8,10～12 is more than 92%.

Industrial applicability

According to the formation method of selectivity absorption surface of the present invention, can manufacture and there is selectivity absorption surface higher to the specific absorption of UV, visible ray, near infrared region, to the lower excellent specific property of the infrared emission rate ε of the region of ultra-red relevant to thermal radiation, use the universal desirable of the heat collector that utilizes sun power with higher thermal efficiency of this selectivity absorption surface.

Claims (7)

1. a formation method for selectivity absorption surface, is characterized in that, by metal substrate being immersed in the chemical conversion treatment solution that contains sulfuric acid and sodium dichromate 99 or sulfuric acid and chromic anhydride, forms selectivity absorption surface in described metallic substrate surfaces,

The metal-salt that described chemical conversion treatment solution contains oxygen acid or the metal-salt of haloid acid.

2. the formation method of selectivity absorption surface as claimed in claim 1, is characterized in that,

Metal in described metal-salt is selected from least a kind in transition metal, Na, K.

3. the formation method of selectivity absorption surface as claimed in claim 1 or 2, is characterized in that, in described transition metal chosen from Fe, chromium, nickel, zinc, cobalt at least a kind.

4. the formation method of selectivity absorption surface as claimed in claim 1 or 2, is characterized in that, the concentration of the described metal-salt in described chemical conversion treatment solution is 250～2500mg/L.

5. the formation method of selectivity absorption surface as claimed in claim 1 or 2, is characterized in that, the negatively charged ion of described metal-salt is SO ₄ ^2-, NO ₃ ^-, Cl ^-or PO ₄ ^3-.

6. the formation method of selectivity absorption surface as claimed in claim 1 or 2, is characterized in that, described metal-salt is ferric sulfate [Fe ₂(SO ₄) ₃] and chromium sulphate [Cr ₂(SO ₄) ₃] at least one of them.

7. selectivity absorbs and processes a film, and it is to utilize the selectivity absorption of the heat collector of sun power to process film that described selectivity absorbs processing film, it is characterized in that,

Described selectivity absorbs processing film and obtains by metal substrate being immersed in the chemical conversion treatment solution that contains sulfuric acid and sodium dichromate 99 or sulfuric acid and chromic anhydride,

The metal-salt that described chemical conversion treatment solution contains oxygen acid or the metal-salt of haloid acid.