CN201344667Y - Selective solar photo-thermal absorbing coat - Google Patents

Abstract

The utility model belongs to the field of solar energy equipment, in particular to a selective absorbing coating used on the surface of a flat-plate solar heat collector for absorbing and utilizing solar energy. A selective solar light and heat absorbing coating, which is composed of multiple layers of metal and non-metal, the above-mentioned selective solar energy is attached to the metal plate, and it is characterized in that: the coating is attached to the metal plate The order is bottom layer-aluminum nitride composite layer-aluminum nitride composite layer-aluminum trioxide (whether a new aluminum nitride composite substance is generated after the second layer of aluminum and N ₂ and other reactive gases). The utility model can provide a selective absorption film layer with excellent solar energy selective absorption characteristics and strong film layer. The film layer has high bonding strength and good weather resistance, and at the same time has high of production efficiency.

Description

A Selective Solar Photothermal Absorbing Coating

【Technical field】

The utility model belongs to the field of solar energy equipment, in particular to a selective absorbing coating used on the surface of a flat-plate solar heat collector for absorbing and utilizing solar energy.

【Background technique】

Solar water heaters absorb the sun's radiant heat. It is the most mature and advanced product in my country's solar thermal utilization. Provide the people with new water heater products that are environmentally friendly, safe, energy-saving and hygienic. There are three most common types of solar water heaters: sun-dried solar water heaters, flat-plate solar water heaters and vacuum tube solar water heaters. The heat collector and the water tank of the sun-dried solar water heater are integrated into one. The structure is simple and the price is low. However, the insulation is poor, so it cannot be used overnight, let alone in winter. The flat-plate solar water heater is composed of a flat-plate solar collector, a water storage tank, a circulation pipe, and a support. The heat absorber has structural types such as copper-aluminum composite tube-sheet type, all-copper tube-sheet type, and flat box type formed by stainless steel stamping and welding. The solar collector, the key component of which is the core of the solar collector, is now mostly made of copper-aluminum composite plate material. The solar spectrum selective absorption coating is applied to the heat-collecting surface of the solar collector, and is mainly composed of an infrared high-reflection layer, an absorption layer and an anti-reflection layer. The surface absorbs light to increase the absorption efficiency; the infrared high-reflection layer reduces the external radiation inside the heat collector and reduces heat loss; the absorption layer is used to absorb sunlight and provide heat source for the heat collector. In the photothermal conversion of solar energy, the refractive index of the medium in the absorbing layer of the selective absorbing coating should be as low as possible, and the refractive index of the antireflection layer should be as low as possible, so as to obtain solar energy with high photothermal conversion efficiency. Selective absorption coating, but at the same time, it is also necessary to pay attention to the deposition rate of the medium so as not to be too low, so as not to affect the production efficiency. In the preparation process of the coating, magnetron reactive sputtering or radio frequency response and intermediate frequency reactive sputtering methods are used, and metal or non-metallic targets are used. Due to target poisoning, the deposition rate of the anti-reflection layer is very low, which reduces the production efficiency. Greatly reduced. Due to the low production efficiency of the anti-reflection layer, most of the solar collectors currently on the market do not use the sunlight selective absorption coating provided with the anti-reflection layer. For the solar selective absorption coating used in the low temperature range of the vacuum environment, the selective absorption coating has been studied and widely used. The advantages of this film system and process method are that A1 single-target DC magnetron sputtering coating work, equipment The operation is simple, and the film layer has a high absorption rate. It is more suitable for the use of all-glass vacuum tubes in the low temperature range. However, for medium and high temperature applications, the infrared emissivity increases significantly with the increase of temperature, resulting in increased heat loss of the collector and thermal efficiency. Significantly decreased. In order to improve the thermal stability of the selective absorbing coating in the high-temperature range and reduce the infrared emissivity, a high-temperature stable metal double-target co-sputtering deposition technology has been researched and developed. This coating has a multi-layer structure. The thermal performance is stable in the high temperature range, and the absorption/emission ratio is small. However, the key to this coating and process method is that high-temperature stable metals such as W, MO, and SS must be used, and double-electrode target co-sputtering must be used; resulting in low deposition rate, long production cycle, complex process, and rare and expensive targets. ,high cost. Therefore, there is a need for a selective absorbing coating with high absorption rate, low emissivity, and good thermal stability and its preparation technology. But there is no technical solution that can overcome the above shortcomings in the industry so far.

【Content of utility model】

The purpose of this utility model is to provide a selective absorption film layer with excellent solar energy selective absorption characteristics, and the film layer is firm, the film layer has high bonding strength and good weather resistance, and has relatively High production efficiency.

In order to achieve the above-mentioned technical purpose, the technical solution adopted by the utility model includes the following technical content: a selective solar light and heat absorbing coating, which is composed of multi-layer metal and non-metal composite, the above-mentioned selective solar Attached to the metal plate, it is characterized in that: the order of the coating on the metal plate is followed by bottom layer-aluminum nitride composite layer-aluminum nitride composite layer-aluminum trioxide (the second layer of aluminum in this After reacting with _N2 and other reactive gases, whether to generate new aluminum nitride composite substances)

The bottom layer is one of stainless steel, molybdenum or nickel.

The thickness of the bottom layer-aluminum nitride composite layer-aluminum nitride composite layer-aluminum oxide is 80nm-120nm.

The thickness of each layer of the bottom layer-aluminum nitride composite layer-aluminum nitride composite layer-aluminum trioxide is: the bottom layer is 15nm-25nm; the aluminum nitride composite layer is 25nm-35nm; the aluminum nitride composite layer is 25nm-35nm; Aluminum oxide 15nm-25nm.

The optimal thickness of each layer of the bottom layer-aluminum nitride composite layer-aluminum nitride composite layer-aluminum oxide is: bottom layer 20nm; aluminum nitride composite layer 30nm; aluminum nitride composite layer 30nm; aluminum oxide 20nm.

The aluminum nitride composite layer coating needs to add nitrogen in the vacuum chamber when performing reactive sputtering, and the amount of nitrogen added is 20 sccm-40 sccm Pa.

Described stainless steel is to use SUS304 stainless steel.

By adopting the above-mentioned technical solution, the utility model has obtained the following technical advantages and effects: the utility model adopts the composite film layer of stainless steel-aluminum nitride composite layer-aluminum nitride composite layer-aluminum trioxide as a flat plate Selective absorbing coating for solar collectors. This composite film layer has very good solar energy selective performance. The metal bottom layer is made of stainless steel, molybdenum or nickel as the metal bottom layer. The above metals will be coated on copper or aluminum plates. It has very strong bonding fastness, thereby enhancing the fixing fastness of the entire absorbing film layer; in addition, the above-mentioned stainless steel, molybdenum or nickel all have very good infrared reflection properties, which can very effectively reduce the thermal emissivity of the film layer, and nitrogen Aluminum oxide is used as the absorbing layer, and reacts with nitrogen and oxygen filled in the vacuum chamber during magnetron sputtering to form a reactive sputtering film, and reactive sputtering produces gradient absorbing film layers with different metal volume ratios. Adjust the thickness of the film layer and the metal volume ratio to form a light interference absorption film layer, which greatly enhances the absorption of visible light by the film layer, thereby greatly enhancing the absorptivity of the above film layer; The aluminum film layer or silicon dioxide film layer can use the stable performance of aluminum oxide or silicon dioxide to play the role of anti-reflection and sealing for the film layer below it, and protect the absorbing layer from water in the atmosphere. Corrosion by components, salt, etc., greatly improves the weather resistance of the film layer, and significantly prolongs the service life of the above film layer. At the same time, because the film layer has microscopic surface porosity, it can prevent the reflection of visible light, so it also has anti-reflection properties. Function.

【Description of drawings】

Fig. 1 is a schematic diagram of the film layer structure of the present invention.

【Detailed ways】

The utility model is described in detail below:

The utility model is an improvement made for the coating process of the heat collecting chip material used in the existing flat-plate solar heat collector. Now the commonly used heat collecting chips are generally thin copper plates or aluminum plates, so the utility model in The solar selective absorbing coating is a technical improvement made with the above two commonly used material substrates. The coating is composed of multiple layers of metal and non-metal, and the above-mentioned selective solar coating is attached to a metal plate, which is a thin copper plate or an aluminum plate. As shown in Figure 1, the order in which the coating is attached on the metal plate 5 is metal bottom layer 4-aluminum nitride composite layer 3-aluminum nitride composite layer 2-aluminum trioxide 1, according to different metal characteristics , the metal bottom layer 4 in the present utility model is one of stainless steel, molybdenum or nickel. The composite film layer made of these materials, that is, the solar selective absorption coating, is mainly that the above-mentioned metals, aluminum and copper can be stably and firmly attached to the aluminum or copper substrate after reactive sputtering In this way, a firm adhesion base is established for the entire composite film layer. In addition, these metal materials also have strong infrared reflection properties, which can reduce the thermal emissivity of the composite film layer and improve the thermal performance of the solar panel core, that is, the high absorption rate of visible light and the high reflection of infrared radiation. The energy of visible light stays as far as possible. Metal bottom layer 4 described in the utility model, the material of metal bottom layer (comprising any one of stainless steel, molybdenum, nickel)-aluminum nitride composite layer 3-aluminum nitride composite layer 2-aluminum trioxide 1 has a thickness of 80nm- 120nm. The thickness mentioned above is a relatively reasonable film thickness for screening. The thickness of each film layer produced by the above-mentioned film layer during reactive sputtering is that the metal bottom layer 4 is 15nm-25nm; the aluminum nitride composite layer 3 absorption layer is 25nm-35nm; the aluminum nitride composite layer 2 is 25nm -35nm; aluminum oxide 1 is 15nm-25nm. The above-mentioned thickness range can be adjusted according to specific usage requirements and technical indicators such as the usage of solar equipment. But in general, the best film layer structure metal bottom layer is 20nm; aluminum-nitrogen-aluminum is 60nm in total; aluminum oxide is 20nm.

The processing process of the above-mentioned film layer is as follows: firstly, the metal substrate 5, that is, the thin copper plate or aluminum plate is subjected to surface pretreatment, and then it is put into the pretreatment chamber and passed through a mass flow meter under a vacuum condition of 10 ⁻² Pa. Introduce 60sccm of Ar gas, adjust the vacuum degree at 0.6pa, turn on the target power supply, the target power supply is 480v, and the current is 4.5A. Perform ion etching before plating, and the processing time is 10-25 minutes. Bombard the surface of the substrate 5 with an Ar ion source, and the current density is 0.8A/cm ² so that the solid impurities on the surface of the above-mentioned thin copper plate or aluminum plate are well cleaned up. Generally, only one surface is needed for ion etching, because the solar energy is plated Selective absorbing coating is also performed on at least one surface. Performing ion etching can thoroughly clean the surface of the base material 5, that is, the thin copper plate or the aluminum plate, improve the adhesion when the film is plated, and increase the service life of the film.

After the surface pretreatment of the substrate 5 is performed, the plating process of the film layer can be started, and this process is realized by vacuum magnetron reactive sputtering. Put the above-mentioned processed thin copper plate or aluminum plate into the vacuum sputtering chamber, and plate the metal bottom layer 4 by magnetron sputtering under the vacuum condition of 0.5Pa, adopt stainless steel target or nickel target or molybdenum target to carry out, pass into nitrogen 42sccm , keep the working air pressure at 0.5pa, the current at 5A, and the magnetron sputtering time at 5 minutes. When the thickness reaches 20nm, it can enter the plating of the next film layer.

Put the substrate that has been plated with the bottom layer of the metal into a vacuum chamber equally, plate the absorber layer by reactive sputtering, and use an aluminum target to carry out magnetron sputtering. During sputtering, 30 sccm of oxygen gas and 20 sccm of nitrogen gas are introduced, and the working pressure is maintained at 20 sccm. 0.5pa, current 5A, magnetron sputtering time is 7 minutes. When the thickness reaches 30nm, it can enter the plating of the next film layer. Other gases that can be introduced can also be introduced during the sputtering of the absorbing layer. When different film systems are plated, different gases are introduced according to the sequence in the film systems.

Put the substrate that has been plated with the metal bottom layer into a vacuum chamber equally, plate an absorber layer by reactive sputtering, and use an aluminum target to carry out magnetron sputtering. During sputtering, 25 sccm of oxygen gas and 15 sccm of nitrogen gas are introduced, and the working pressure is maintained at 0.5pa, current 5A, magnetron sputtering time is 10 minutes. When the thickness reaches 30nm, it can enter the plating of the next film layer.

Finally, put the Al2O3 1 coated with the metal bottom layer into a vacuum chamber, and plate the ceramic layer on the surface by reactive sputtering, and use an aluminum target for magnetron sputtering. Oxygen is 45 sccm, the working pressure is maintained at 0.5 Pa, the current is 5 A, and the magnetron sputtering time is 5 minutes. When the thickness reaches 20nm, it can enter the plating of the next film layer.

The above description is to be considered as the preferred embodiment only. Various other variations of the invention will be appreciated by those skilled in the art and those who make or use the invention. Therefore, it should be understood that the above-mentioned illustrated embodiments are only exemplary, and it does not limit the scope of the present utility model. The scope of the present utility model is interpreted according to the principle of patent law, including the principle of equivalents defined by the claims.

Claims (7)

1. A selective solar light and heat absorbing coating, which is composed of multiple layers of metal and non-metal, and the above-mentioned selective solar energy is attached to the metal flat plate, characterized in that: the coating is on the metal flat plate The sequence of attachment on top is bottom layer-aluminum nitride composite layer-aluminum nitride composite layer-aluminum trioxide. 2. A selective solar heat absorption coating according to claim 1, characterized in that: the bottom layer is one of stainless steel, molybdenum or nickel. 3. A selective solar photothermal absorption coating according to claim 1, characterized in that: the thickness of the bottom layer-aluminum nitride composite layer-aluminum nitride composite layer-aluminum oxide is 80nm- 120nm. 4. A selective solar light and heat absorbing coating according to claim 1, characterized in that: the thickness of each layer of the bottom layer-aluminum nitride composite layer-aluminum nitride composite layer-aluminum oxide is , bottom layer 15nm-25nm; aluminum 25nm-35nm; aluminum 25nm-35nm; aluminum oxide 15nm-25nm. 5. A selective solar light and heat absorbing coating according to claim 3, characterized in that: the optimal composition of the bottom layer-aluminum nitride composite layer-aluminum nitride composite layer-aluminum oxide The thickness is: bottom layer 20nm; aluminum nitride composite layer 30nm; aluminum nitride composite layer 30nm; aluminum oxide 20nm. 6. A selective solar photothermal absorption coating according to claim 1, characterized in that: the aluminum nitride composite layer-aluminum nitride composite layer, the coating needs to be Nitrogen is added into the vacuum chamber, and the amount of nitrogen added is 20 sccm-40 sccm Pa. 7. A selective solar heat absorption coating according to claim 1, characterized in that: said stainless steel is SUS304 stainless steel.

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