Low-silver composite reflective film and condensing mirror

Abstract

The application discloses a kind of low silver composite reflecting film and light collecting mirror, belongs to solar energy photothermal utilization technical field, including first antireflection layer, low silver composite reflecting layer, interface stability enhancement layer, gradient transition layer and second antireflection layer;Wherein, the low silver composite reflecting layer is based on Ag composite reflecting structure, including Ag and at least one alternative metal;The alternative metal is selected from one of Al, Cu;The low silver composite reflecting layer adopts layered structure, co-sputtering structure or gradient structure.The application constructs low silver composite reflecting structure, metal enhancement structure and gradient transition structure, reduces the amount of silver material while improving film layer reflection performance, interface stability and long-term weather resistance, and realizes the controllable deposition of film layer structure by combining PVD magnetron sputtering process, to meet the application requirements of concentrating system on solar reflectivity, long service life and green manufacturing.

Description

Technical Field

[0001] This invention relates to the field of solar thermal utilization technology, specifically to a low-silver composite reflective film and a concentrating reflector. Background Technology

[0002] Concentrating Solar Power (CSP) systems use concentrating mirrors to focus solar radiation onto an absorber, converting solar energy into heat, which then drives a power generation system to output electricity. Depending on the concentration method, existing CSP systems mainly include trough, tower, Fresnel, and dish types.

[0003] In the aforementioned concentrating system, the reflector, as a core optical component, directly affects the concentrating efficiency, operational stability, and service life of the system due to its solar reflectivity and long-term weather resistance. Furthermore, the reflector accounts for a significant portion of the total cost of the concentrating system, and its material composition and manufacturing process have a crucial impact on the system's economic viability.

[0004] Existing concentrators typically employ a reflective layer structure using the precious metal silver (Ag) as the primary reflective material to achieve high solar reflectivity. In current technology, concentrators often use a chemical silver plating process to form the silver reflective layer, which is then protected by a copper layer, a backing layer, or an organic protective layer. While this type of structure achieves high solar reflectivity, it still suffers from the following problems: 1) Existing reflective layers are highly dependent on the precious metal silver. With fluctuations in the price of silver and rising manufacturing costs, it is difficult to effectively control the manufacturing cost of reflective mirrors. 2) Traditional pure silver reflective layers are prone to silver migration, oxidation, sulfidation and interface failure under long-term high temperature, high humidity and ultraviolet radiation, which leads to a decrease in reflective performance and insufficient long-term weather resistance. 3) Existing low-silver solutions, after reducing the amount of silver material, usually lead to a decrease in solar reflectivity and a deterioration in the stability of the film structure, making it difficult to achieve low silver content, high reflectivity and long-term weather resistance. 4) Traditional chemical silver plating processes have certain limitations in terms of coating density, thickness uniformity, and interface stability, which can easily lead to insufficient product consistency and affect optical stability during long-term service. 5) Traditional chemical silver plating processes typically involve the use of silver salts, complexing agents, and other chemicals during production, which can easily generate silver-containing waste liquid and volatile pollutants, resulting in high environmental remediation costs.

[0005] Furthermore, as concentrating solar thermal systems develop towards higher temperatures, larger sizes, longer lifespans, and greener manufacturing, higher demands are placed on the reflective performance, structural stability, and long-term weather resistance of concentrating reflective films. Traditional pure silver reflective layer structures, due to their high silver content, insufficient weather resistance, and poor environmental adaptability, are gradually becoming unable to meet the development needs of next-generation concentrating systems.

[0006] Existing low-silver solutions typically reduce the Ag layer thickness or replace Ag with a low-cost metal. However, due to differences in reflectivity, coefficient of thermal expansion, and chemical stability among different metals, this can easily lead to a decrease in film continuity. Increased interfacial stress and deterioration of long-term stability make it difficult to simultaneously achieve low silver content, high reflectivity, and long-term weather resistance.

[0007] Therefore, there is an urgent need to provide a low-silver composite reflective film and its focusing mirror that combine low silver content, high reflectivity, film structure stability and long-term weather resistance, in order to solve the problem that existing low-silver reflective layers cannot achieve a balance between reflective performance, interface stability and long-term service reliability. Summary of the Invention

[0008] To address the issues of high dependence on precious silver in existing concentrating reflective films, decreased reflectivity and structural stability after silver reduction, and significant environmental impact from traditional chemical silver plating processes, this invention provides a low-silver composite reflective film and concentrating mirror suitable for trough, tower, Fresnel, and other concentrating solar collector systems. This invention forms a low-silver composite reflective film system with a continuous and dense interface by constructing an Ag-based composite reflective structure, an interface stabilization enhancement structure, and a gradient transition structure. Specifically: the Ag-based composite reflective structure reduces the amount of Ag material used while maintaining high reflectivity; the gradient transition structure reduces thermal stress at the film interface; and the interface stabilization enhancement structure reduces the risk of Ag migration and oxidation failure.

[0009] To achieve the above objectives, the present invention provides the following technical solution: A low-silver composite reflective film is disposed on the surface of a glass cover plate, and sequentially comprises the following layers from the side closest to the glass cover plate to the side furthest from the glass cover plate: a first anti-reflective layer, a low-silver composite reflective layer, an interface stabilization enhancement layer, a gradient transition layer, and a second anti-reflective layer. The low-silver composite reflective layer is an Ag-based composite reflective structure, comprising Ag and at least one alternative metal; the alternative metal is selected from Al and Cu. The low-silver composite reflective layer adopts a layered structure, a co-sputtering structure, or a gradient structure; When a layered structure is used, the thickness of the Ag layer is 20-90 nm; the thickness of the alternative metal layer is 10-70 nm. When a co-sputtering structure is used, Ag and the substitute metal can form a composite reflective structure, wherein the mass fraction of Ag is 40%-90% and the mass fraction of the substitute metal is 10%-60%. When a gradient structure is adopted, the composition of Ag and the substitute metal in the low-silver composite reflective layer varies along the thickness direction to form a gradient composite structure. The gradient transition layer is used to alleviate the thermal expansion mismatch stress between the low-silver composite reflective layer and the external functional layer, thereby improving the interfacial stability and long-term weather resistance of the film.

[0010] Furthermore, the gradient transition layer is a composite gradient structure composed of multiple layers of different metal components and dielectric components.

[0011] Furthermore, the gradient transition layer includes a high metal composition transition layer, a medium metal composition transition layer, and a low metal composition transition layer.

[0012] Furthermore, the metal content of the high metal component layer is 55%-65%, the metal content of the medium metal component layer is 45%-55%, and the metal content of the low metal component layer is 35%-45%.

[0013] Furthermore, the medium component includes one or more of AlSiOx, AlN, SiO2, ZnO, or combinations thereof.

[0014] Furthermore, the metal component includes stainless steel or aluminum.

[0015] Furthermore, the first antireflection layer and / or the second antireflection layer include one or more of SiO2, ZnO, Al2O3, TiO2, and SiNx.

[0016] Furthermore, the interface stabilization enhancement layer is a Cu layer, an Al layer, or an alloy layer thereof.

[0017] Furthermore, the low-silver composite reflective layer, interface stabilization enhancement layer, and gradient transition layer are formed using PVD magnetron sputtering technology.

[0018] To better achieve the objectives of the present invention, the present invention also provides a focusing reflector, including a glass cover plate and the low-silver composite reflective film disposed on the surface of the glass cover plate.

[0019] Compared with the prior art, the beneficial effects of this invention are: 1) By constructing a low-silver composite reflective structure, the amount of silver material used is reduced while maintaining high reflectivity, thereby reducing the manufacturing cost of the reflector; 2) By using PVD magnetron sputtering technology to form composite reflective films, the uniformity of film thickness, the density of structure, and the consistency of products can be improved. 3) By synergistically designing the metal reinforcement structure and the gradient transition structure, the interfacial compatibility, structural stability and long-term weather resistance of the film are improved, thereby reducing the risk of silver migration and oxidation failure. 4) This invention achieves a comprehensive balance between low silver content, high reflectivity, and long-term weather resistance through the synergistic effect of the low silver composite reflective structure, metal reinforcement structure, and gradient transition structure. 5) Compared with the traditional chemical silver plating process, the present invention uses PVD physical vapor deposition process to form a reflective film, which can improve the interfacial adhesion, thickness uniformity and long-term stability of the film, and reduce the waste liquid and volatile pollutants generated during the chemical silver plating process, thereby reducing the pressure of environmental protection. 6) This invention constructs a low-silver composite reflective film system that combines high reflectivity, long-term weather resistance, and environmental adaptability. It is suitable for concentrated solar energy systems operating in high-temperature, high-irradiance, and long-term outdoor environments, and has good engineering application prospects and industrialization value.

[0020] In summary, this invention achieves comprehensive optimization of high reflectivity, long service life, and environmentally friendly production requirements by synergistically designing a low-silver composite reflective structure, a metal reinforcement structure, and a gradient transition structure, while reducing the amount of silver material used. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a layer structure diagram of a low-silver composite reflective film according to the present invention.

[0023] Figure 2 This is a schematic diagram of a focusing mirror structure containing a low-silver composite reflective film.

[0024] Figure 3 The graph shows the reflectance spectrum of concentrating mirrors with different reflective layer systems.

[0025] Figure 4 This is a reflectance spectrum curve of a comparative mirror.

[0026] Figure 5 This is a reflectance spectrum curve of a concentrator mirror with a pure Al reflective layer structure.

[0027] The labels in the figure represent: 1-Hydrophobic functional layer; 2-Glass cover plate; 3-First antireflective layer; 4-Low silver composite reflective layer; 5-Interface stabilization enhancement layer; 6-Gradient transition layer; 6-1-High metal composition transition layer; 6-2-Medium metal composition transition layer; 6-3-Low metal composition transition layer; 7-Second antireflective layer; 8-Adhesive layer; 9-Supporting glass substrate; 10-Edge sealing structure. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] Example 1: Please refer to the appendix of the instruction manual. Figure 1 This embodiment provides a low-silver composite reflective film, which is disposed on the surface of a glass cover plate and includes, from the incident light side to the backlight side, the following layers in sequence: a hydrophobic functional layer 1, a first antireflective layer 3, a low-silver composite reflective layer 4, an interface stabilization enhancement layer 5, a gradient transition layer 6, and a second antireflective layer 7. The gradient transition layer 6 further includes, along the thickness direction, the following layers in sequence: a high metal composition transition layer 6-1, a medium metal composition transition layer 6-2, and a low metal composition transition layer 6-3.

[0030] The gradient structure in the low-silver composite reflective layer and the gradient transition layer are different functional structures; the gradient structure in the low-silver composite reflective layer is used to adjust the reflective performance and reduce the amount of silver used, while the gradient transition layer is used to improve the stress matching and long-term stability of the film interface.

[0031] The specific details of each floor are as follows: 1. Glass cover plate 2 In this embodiment, the glass cover 2 is made of low-iron ultra-clear glass, such as ultra-clear float glass, ultra-clear heat-strengthened glass or ultra-clear tempered glass, with a thickness of 1-2 mm.

[0032] Preferably, the glass cover 2 is made of low-iron ultra-clear glass with a transmittance greater than 90.8%.

[0033] By using low-iron ultra-white glass, the transmittance of sunlight can be increased, thereby improving the overall optical efficiency of the concentrating reflector.

[0034] Preferably, the glass cover plate 2 is low-iron ultra-white heat-strengthened glass or low-iron ultra-white tempered glass to improve structural stability and environmental adaptability.

[0035] II. Hydrophobic Functional Layer In this embodiment, the hydrophobic functional layer 1 is disposed on the outer surface of the glass cover plate 2, i.e. the incident light side.

[0036] Preferably, the hydrophobic functional layer 1 is a transparent hydrophobic functional layer, which can reduce the amount of water adhering to the glass surface and mitigate the impact of condensation and contaminant adhesion on the optical performance of the reflector.

[0037] Preferably, the hydrophobic functional layer 1 is formed of organosilicon material, fluorinated silicon material or nanocomposite material.

[0038] Preferably, the hydrophobic functional layer 1 is formed by spraying, spraying, roller coating or vapor deposition process.

[0039] III. First Anti-reflective Layer 3 and Second Anti-reflective Layer 7 In this embodiment, the first antireflective layer 3 is disposed on the inner surface of the glass cover plate 2. The second antireflective layer 7 is disposed on the side of the gradient transition layer 6 away from the low-silver composite reflective layer 4.

[0040] The first antireflection layer and the second antireflection layer include one or more of SiO2, ZnO, Al2O3, TiO2, and SiNx.

[0041] Preferably, the first and second antireflective layers are formed using a single-layer structure, a multi-layer composite structure, or a gradient refractive index structure to improve solar transmittance and reduce interface reflection loss.

[0042] Preferably, the thickness of the first antireflective layer 3 is 50-100 nm, and the thickness of the second antireflective layer 7 is 100-200 nm.

[0043] The first antireflection layer 3 and the second antireflection layer 7 are used to improve the optical matching performance of the film interface and enhance the overall solar reflectance efficiency.

[0044] IV. Low-silver composite reflective layer 4 In this embodiment, the low-silver composite reflective layer 4 is disposed on the side of the first antireflective layer 3 away from the glass cover plate 2, and is the core reflective functional layer of the film layer.

[0045] The low-silver composite reflective layer 4 is a composite reflective structure formed by Ag and a substitute metal. The substitute metal is selected from Al and Cu.

[0046] The low-silver composite reflective layer 4 is formed using a PVD magnetron sputtering process.

[0047] The low-silver composite reflective layer can be formed using one or more of the following structures: a) layered structure, b) co-sputtered structure, c) gradient structure with composition varying along the thickness direction.

[0048] When a layered structure is used, the thickness of the Ag layer is 20-90 nm; the thickness of the replacement metal layer is 10-70 nm.

[0049] When a co-sputtering structure is used, Ag and the substitute metal can form a composite reflective structure, wherein the mass fraction of Ag is 40%-90% and the mass fraction of the substitute metal is 10%-60%.

[0050] In one embodiment, the low-silver composite reflective layer 4 is a co-sputtered structure formed by Ag and Al, wherein the mass fraction of Al is preferably 20%, 30% or 60%.

[0051] When a gradient structure is used, the gradient structure is a composite structure in which the Ag component and the substitute metal component gradually change along the thickness direction of the film layer, wherein the content of the Ag component gradually decreases along the thickness direction, and the content of the substitute metal component gradually increases along the thickness direction, so as to form a gradient structure with changing composition.

[0052] For example, the total thickness of the gradient structure is 30-150 nm, and along the thickness direction: top 10-50 nm: Ag component content 80%, substitute metal component content 20%; middle 10-50 nm: Ag component content 60%, substitute metal component content 40%; bottom 10-50 nm: Ag component content 40%, substitute metal component content 60%.

[0053] The gradient structure can be achieved by adjusting the sputtering power, deposition rate, or gas parameters of the Ag target and the alternative metal target during magnetron sputtering.

[0054] Through the above-described composite structure design, compared to the traditional pure silver reflective layer structure, the amount of silver material used can be reduced while maintaining high reflectivity. The low-silver composite reflective layer forms a continuous and dense structure to improve the stability of the film interface and its service life.

[0055] The low-silver composite reflective layer maintains high solar reflectivity while reducing silver content and improves the long-term stability and weather resistance of the film through a composite metal synergistic reflection mechanism and an interface stabilization mechanism.

[0056] V. Interface Stability Enhancement Layer 5 In this embodiment, the interface stabilization enhancement layer 5 is disposed on the side of the low silver composite reflective layer 4 away from the first antireflection layer 3.

[0057] Preferably, the interface stabilization enhancement layer 5 is a Cu layer, an Al layer, or an alloy layer thereof.

[0058] Preferably, the thickness of the interface stabilization enhancement layer 5 is 100-150 nm.

[0059] Preferably, the interface stabilization enhancement layer is formed using a PVD magnetron sputtering process.

[0060] The interface stabilization enhancement layer 5 and the low-silver composite reflective layer 4 together form a composite reflective structure, which is used to improve the solar reflectivity and reduce the risks of silver migration, oxidation and environmental corrosion.

[0061] VI. Gradient Transition Layer 6 In this embodiment, the gradient transition layer 6 is a multilayer gradient structure in which the metal composition gradually changes along the thickness direction.

[0062] The total thickness of the gradient transition layer 6 is preferably 50-300 nm, wherein: a) The high metal composition transition layer 6-1 is disposed on the side of the interface stabilization enhancement layer 5 away from the low silver composite reflective layer 4; its thickness is preferably 20-100 nm.

[0063] b) The medium metal component transition layer 6-2 is disposed on the side of the high metal component transition layer 6-1 away from the interface stabilization enhancement layer 5; its thickness is preferably 20-100 nm.

[0064] c) The low metal component transition layer 6-3 is disposed on the side of the medium metal component transition layer 6-2 away from the high metal component transition layer 6-1; its thickness is preferably 10-100 nm.

[0065] Preferably, the gradient transition layer 6 comprises a composite structure formed by a metal component and a dielectric component. The metal component content of the high metal component layer is 55%-65%, the metal component content of the medium metal component layer is 45%-55%, and the metal component content of the low metal component layer is 35%-45%. Preferably, the dielectric component includes one or more of AlSiOx, AlN, SiO2, ZnO, or combinations thereof. The metal component includes stainless steel or aluminum.

[0066] Preferably, the gradient transition layer 6 is formed using a PVD magnetron sputtering process.

[0067] The gradient structure design described above can improve the interfacial compatibility between membrane layers, reduce interfacial stress, and enhance the stability and long-term weather resistance of the membrane structure.

[0068] Example 2: Based on Example 1, in this example, the low silver composite reflective film uses ultra-white tempered glass 2 with a thickness of 2 mm; the hydrophobic functional layer 1 is made of organosilicon material and formed by spraying process; the first antireflective layer is SiO2, and the second antireflective layer includes a SiO2 and ZnO composite layer, wherein the mass ratio of SiO2 to ZnO is preferably 2:1.

[0069] The thickness of the first antireflective layer 3 is 60 nm, and the thickness of the second antireflective layer 7 is 150 nm.

[0070] The low-silver composite reflective layer 4 is a co-sputtered structure formed by Ag and Al, with Ag having a mass fraction of 80% and Al having a mass fraction of 20%.

[0071] The interface stabilization enhancement layer 5 is a Cu layer with a thickness of 120 nm.

[0072] The total thickness of the gradient transition layer 6 is preferably 200 nm, wherein the thickness of the high metal composition transition layer 6-1 is 70 nm, the thickness of the medium metal composition transition layer 6-2 is 70 nm, and the thickness of the low metal composition transition layer 6-3 is 60 nm. The stainless steel content of the high metal composition layer is 60%, the stainless steel content of the medium metal composition layer is 50%, the stainless steel content of the low metal composition layer is 40%, and the dielectric component is SiO2.

[0073] Further process verification revealed that when the Ag mass fraction was below 40%, the continuity and reflective performance of the composite reflective layer risked decline. While an Ag mass fraction above 90% resulted in a slight increase in reflectivity, the amount of Ag material required increased significantly, and the improvement in long-term weather resistance was limited. Therefore, the Ag mass fraction is preferably controlled within the range of 40%-90%.

[0074] Example 3: A focusing reflector includes a glass cover plate 2, a low-silver composite reflective film disposed on the surface of the glass cover plate, an adhesive layer 8, and a supporting glass substrate 9; a second anti-reflective layer 7 is connected to the supporting glass substrate 9 through the adhesive layer 8 to form a sandwich composite structure. Preferably, the concentrating reflector is a trough-type concentrating reflector, a tower-type heliostat, a Fresnel-type concentrating reflector, or other solar concentrating reflectors.

[0075] Preferably, the adhesive layer 8 is selected from one or more of EVA, POE, PVB or SGP.

[0076] Preferably, the supporting glass substrate 9 is tempered glass. It can be formed into a planar structure or a curved structure according to the requirements of different concentrating systems. For example, when applied to a trough concentrating system, the supporting glass substrate 9 is preferably a parabolic curved structure to meet the requirements of the trough collector for concentrating accuracy and optical profile. When applied to a tower or Fresnel concentrating system, the supporting glass substrate 9 can adopt a planar structure or a slightly curved structure to meet the reflection control requirements of the heliostat system.

[0077] Preferably, the focusing mirror can adopt a sandwich encapsulation structure.

[0078] In this embodiment, the solar concentrator reflector can achieve a solar hemispherical reflectivity of over 95% in the 300-2500nm wavelength range, calculated based on the AM1.5 solar spectrum weighting.

[0079] In this embodiment, in the preferred Ag-20%Al composite reflective layer system, the solar spectral weighted hemispherical reflectivity can reach over 95%; under other low silver substitution ratios, the reflectivity can be adjusted within the range of over 90% depending on the substitution ratio.

[0080] In this embodiment, the edge of the focusing reflector may be provided with an edge sealing structure 10 to reduce the risk of external moisture and water vapor penetrating into the membrane layer area.

[0081] Preferably, the edge sealing structure 10 includes an edge sealing adhesive layer, an edge film-free area, an adhesive film edge wrapping structure, or a combination thereof.

[0082] By setting the edge sealing structure 10, the long-term environmental stability and service life of the membrane layer can be improved.

[0083] Example 4: A method for preparing a focusing reflector, comprising the following steps: S1: Functional membrane construction Using PVD vacuum magnetron sputtering, a first antireflective layer 3, a low-silver composite reflective layer 4, an interface stabilization and enhancement layer 5, a gradient transition layer 6, and a second antireflective layer 7 are sequentially formed on the inner surface of the glass cover plate 2.

[0084] Preferably, the low-silver composite reflective layer 4 is formed by layered sputtering, co-sputtering, gradient sputtering, or a combination thereof.

[0085] Preferably, each functional film layer is formed using a continuous online magnetron sputtering process to improve the uniformity of film thickness, the density of the structure, and the consistency of the product.

[0086] Compared to traditional chemical silver plating, this invention uses PVD physical vapor deposition to form a reflective film, which can improve the interfacial adhesion, thickness uniformity and long-term stability of the film, and reduce the waste liquid and volatile pollutants generated during chemical silver plating, thereby reducing the pressure on environmental protection.

[0087] S2: Concentrating Mirror Construction The glass cover plate 2, which forms a low-silver composite reflective film layer, is applied to the light-concentrating reflector structure, and the second anti-reflective layer 7 is connected to the supporting glass substrate 9 through the adhesive layer 8. Preferably, the focusing mirror adopts a sandwich encapsulation structure to improve the stability of the film structure and its service life.

[0088] In one embodiment, the edge of the focusing mirror may be provided with an edge sealing structure 10 to reduce the risk of external moisture and water vapor penetrating into the membrane layer area.

[0089] S3: Construction of hydrophobic functional layer A hydrophobic functional layer 1 is formed on the outer surface of the glass cover plate 2.

[0090] Preferably, the hydrophobic functional layer 1 is formed by spraying, spraying, roller coating or vapor deposition process.

[0091] More preferably, the hydrophobic functional layer 1 is a transparent hydrophobic functional layer, which can reduce the amount of water adhering to the glass surface and improve the anti-condensation, self-cleaning and outdoor adaptability of the reflector.

[0092] The principle of this invention is as follows: The hydrophobic functional layer 1 can reduce the amount of water and contaminants adhering to the surface, thereby improving the stability of the reflector. The first antireflection layer 3 and the second antireflection layer 7 are used to improve the optical matching performance of the film interface and improve the overall solar reflectance efficiency. The low-silver composite reflective layer 4 and the interface stabilization enhancement layer 5 together form a composite reflective structure to improve solar reflectance efficiency and reduce the amount of silver material used. The substitute metal in the low-silver composite reflective layer 4 can improve the stability of the film structure; the interface stabilization enhancement layer 5 can further reduce the risk of silver migration and oxidation failure, thereby improving the long-term weather resistance of the film. The gradient transition layer 6, through its gradually changing metal composition structure along the thickness direction, improves the interfacial matching between film layers, reduces interfacial stress, and improves the density and long-term weather resistance of the film structure.

[0093] Performance testing: (1) Reflectivity test: The solar spectral reflectivity of the concentrating mirror samples with different reflective layer systems was tested in the 300-2500nm band, and weighted calculation was performed based on the AM1.5 solar spectrum.

[0094] The test results are shown in Table 1: Table 1. Solar spectral reflectivity test results of concentrating mirror samples with different reflective layer systems.

[0095] The test results show that when the Al substitution content is 20%, the Ag-Al composite reflective layer can still maintain a solar spectral weighted reflectance of 95.1%, close to that of a pure Ag reflective layer. When the Al substitution content is increased to 30% and 60%, the reflectance decreases to 94.2% and 92.3%, respectively, indicating that as the Al substitution ratio increases, the amount of silver used further decreases, but the reflectance shows a downward trend. Therefore, the Al substitution content is preferably 20%-30%, and can be increased to 60% in scenarios where cost reduction is a high priority and a moderate decrease in reflectance is permissible.

[0096] Table 1 shows that in the Ag-Cu composite reflective layer, when the Cu substitution content is 20%, the solar spectral weighted reflectance is 94.4%; when the Cu substitution content increases to 60%, the reflectance decreases to 90.3%. This indicates that Cu can be used as a partial substitute for Ag, but an excessively high substitution ratio will significantly reduce reflective performance. Therefore, the Cu substitution content is preferably around 20%, and should not be too high.

[0097] Furthermore, a comparative example using a pure Al reflective layer ( Figure 5 Although it has a lower material cost, its solar reflectivity is significantly lower than that of the embodiments of the present invention, indicating that a single Al reflective system is difficult to achieve both high reflectivity and long-term stability requirements.

[0098] Test results show that this invention maintains high reflectivity while reducing the amount of silver material used. This invention improves the optical matching and reflection efficiency of the film layer through the synergistic effect of the low-silver composite reflection structure, the metal reinforcement structure, and the gradient transition structure.

[0099] (2) Weather resistance test: In accordance with the relevant accelerated aging test methods such as IEC 62108, ISO 9806 or ASTM G154, wet heat aging, ultraviolet aging and temperature cycling accelerated aging tests were conducted on Example 2 and the comparative example respectively.

[0100] Test results show that after 1000 hours of humid heat aging at 85℃ / 85%RH, the solar weighted hemispherical reflectance of Example 2 remained above 94.3%; after 1000 hours of UV aging, the reflectance decreased by less than 1.0%; and after 300 temperature cycles from -40℃ to 85℃, no obvious delamination, oxidation, or corrosion was observed in the film. Example 2 maintained high reflectance and good film stability even after long-term accelerated aging, without significant oxidation, corrosion, or interface failure. This indicates that the gradient transition structure and metal reinforcement structure improved the interfacial stability and long-term weather resistance of the film. In contrast, after long-term accelerated aging, the solar weighted hemispherical reflectance of the comparative example decreased to below 90%, and localized oxidation, corrosion, and interface failure occurred.

[0101] (3) Membrane structure stability test: The membrane stability of Example 2 and the comparative example were tested under high temperature and high humidity environment.

[0102] Test results show that after aging at 85℃ / 85%RH for 1000 hours, the solar weighted hemispherical reflectivity of Example 2 remained above 94.0%, indicating good film structure stability and reflectivity. No obvious oxidation, corrosion, delamination, or interface failure was observed. This demonstrates that the low-silver composite reflectivity structure and gradient transition structure improved the film's resistance to oxidation, corrosion, and interface failure.

[0103] In contrast, after aging in a high-temperature and high-humidity environment for 1000 hours, the solar-weighted hemispherical reflectance dropped to below 90%, and localized oxidation, interface corrosion, and film failure occurred.

[0104] This invention does not simply increase reflectivity by increasing Ag content, but achieves a comprehensive balance between low silver content and long-term stability through the synergistic effect of low silver composite reflective structure, interface stabilization enhancement structure and gradient transition structure.

[0105] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-silver composite reflective film, characterized in that: The following layers are disposed on the surface of the glass cover plate and, from the side closest to the glass cover plate to the side furthest from the glass cover plate, are sequentially: a first anti-reflection layer, a low-silver composite reflective layer, an interface stabilization enhancement layer, a gradient transition layer, and a second anti-reflection layer. The low-silver composite reflective layer is an Ag-based composite reflective structure, comprising Ag and at least one alternative metal; the alternative metal is selected from Al and Cu. The low-silver composite reflective layer adopts a layered structure, a co-sputtering structure, or a gradient structure; When a layered structure is used, the thickness of the Ag layer is 20-90 nm; the thickness of the alternative metal layer is 10-70 nm. When a co-sputtering structure is used, Ag and the substitute metal form a composite reflective structure, wherein the mass fraction of Ag is 40%-90% and the mass fraction of the substitute metal is 10%-60%. When a gradient structure is used, the composition of Ag and the substitute metal in the low-silver composite reflective layer varies along the thickness direction.

2. The low-silver composite reflective film according to claim 1, characterized in that, The gradient transition layer is a composite gradient structure composed of multiple layers of different metal components and dielectric components.

3. The low-silver composite reflective film according to claim 2, characterized in that, The gradient transition layer includes a high metal composition transition layer, a medium metal composition transition layer, and a low metal composition transition layer.

4. The low-silver composite reflective film according to claim 3, characterized in that, The high-metal-component layer has a metal content of 55%-65%, the medium-metal-component layer has a metal content of 45%-55%, and the low-metal-component layer has a metal content of 35%-45%.

5. The low-silver composite reflective film according to claim 3, characterized in that, The medium component includes one or more of AlSiOx, AlN, SiO2, ZnO, or combinations thereof.

6. The low-silver composite reflective film according to claim 3, characterized in that, The metal component includes stainless steel or aluminum.

7. The low-silver composite reflective film according to claim 1, characterized in that, The first antireflection layer and / or the second antireflection layer include one or more of SiO2, ZnO, Al2O3, TiO2, and SiNx.

8. The low-silver composite reflective film according to claim 1, characterized in that, The interface stabilization and enhancement layer is a Cu layer, an Al layer, or an alloy layer thereof.

9. The low-silver composite reflective film according to claim 1, characterized in that, The low-silver composite reflective layer, interface stabilization enhancement layer, and gradient transition layer are formed using PVD magnetron sputtering.

10. A concentrating reflector, comprising a glass cover plate and a low-silver composite reflective film as described in any one of claims 1-9 disposed on the surface of the glass cover plate.

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