A high-reflective mirror coating system that is resistant to high temperatures and corrosion

Abstract

A high-reflection mirror coating film system that is resistant to high temperatures and corrosion-resistant, relates to the field of thin film coating technology, and includes a metal substrate, the coating surface of which is sequentially coated with a first auxiliary film layer, a high-reflection silver film layer, a second auxiliary film layer, a low-refractive index coating layer, and a high-refractive index coating layer, wherein the first and second auxiliary film layers are both coated with metals: silicon nitride (Me:Si)N by a common sputtering process. X The compound is a multifunctional, integrated auxiliary layer that provides adhesion promotion, diffusion barrier, and oxidation protection, ensuring the high-reflectivity mirror coating system is durable and reliable even in high-temperature and corrosive environments. Preferably, the metal or metal alloy in the first and second auxiliary film layers is the same. Preferably, a metal interface layer is provided between the first auxiliary film layer and the highly reflective silver film layer to further inhibit the lateral migration of silver atoms.

Description

Technical Field

[0001] The present invention relates to the technical field of thin film coating, and more particularly to a high-reflection mirror coating film system that is resistant to high temperatures and corrosion. Background Art

[0002] Highly reflective mirror reflectors are widely used in lighting engineering and equipment applications, such as flash lamps, projectors, solar energy collection and decorative applications. The emerging market requirements are applications in the field of concentrated solar power (CSP) and as back reflectors for LEDs in MC-COB modules.

[0003] One existing technology is to create a surface reflector by coating a metal substrate with a highly reflective material, such as aluminum or silver. Durability and reflection-enhancing layers are often applied to the aluminum or silver coating. The most common method involves coating a metal substrate with a highly reflective coating, such as aluminum or silver, and then coating a single layer, such as silicon nitride (SiNx) or silicon oxynitride (SiOxNy), on top of the highly reflective coating.

[0004] More widely used are coating systems that incorporate at least two additional coatings over a high-reflectivity coating. To increase reflectivity, this coating system begins with a low-refractive-index coating, typically silicon oxide (SiOx), magnesium fluoride (MgF2), aluminum oxide (AlOx), or a mixture of silicon and aluminum oxide (SiAlxOy). This coating system also requires a high-refractive-index coating, which serves as the top layer, typically titanium oxide (TiOx), niobium oxide (NbOx), or zirconium oxide (ZrOx). For example, starting with the metal substrate and moving to the outermost coating, the order might be: metal substrate / aluminum (Al) / silicon dioxide (SiO2) / titanium dioxide (TiO2).

[0005] However, within the visible light wavelength range of 380 to 780 nanometers, silver's reflectivity can reach 98%, while aluminum's maximum reflectivity does not exceed 92%. Therefore, coatings based on silver as a reflective substrate are more suitable for manufacturing surface reflectors with the highest reflectivity. However, silver is a precious metal with a weak affinity. Its low chemical bonding makes it problematic when used in coatings, resulting in poor adhesion to many materials. Silver exhibits particularly poor adhesion to many types of oxides, further preventing it from forming a self-passivating film that acts as a natural barrier. This also makes silver more susceptible to corrosion. Existing known silver-based coating systems suffer from poor adhesion, stability, high-temperature resistance, and poor corrosion resistance. Therefore, coating aluminum sheet substrates with highly stable silver-based coating systems that are resistant to high temperatures and exhibit excellent corrosion resistance has become a key research topic in recent years. Summary of the Invention

[0006] The present invention provides a high-temperature resistant and corrosion-resistant high-reflective mirror coating film system, which aims to solve the above-mentioned problems existing in the prior art.

[0007] The technical solution adopted in the present invention is as follows:

[0008] A high-reflection mirror coating system that is resistant to high temperatures and corrosion, comprising a metal substrate having at least one coating surface, wherein the coating surface is coated with the following layers in sequence from the inside to the outside: a first auxiliary film layer, wherein the first metal is silicon nitride (Me1:Si)N X Compound; wherein Me1 represents a first metal or a first metal alloy, Si represents silicon or a silicon alloy, (Me1:Si) represents the ratio between Me1 and Si, and the index X represents the reaction coefficient of the nitrogen element N; the high reflective silver film layer is selected from a silver alloy or silver with a purity of at least 3N; the second auxiliary film layer is selected from a second metal: silicon nitride (Me2:Si)N X Compound; wherein Me2 represents a second metal or a second metal alloy, Si represents silicon or a silicon alloy, (Me2:Si) represents the ratio between Me2 and Si, and the index X represents the reaction coefficient of the nitrogen element N; low refractive index coating; high refractive index coating.

[0009] Furthermore, a metal interface layer is provided between the first auxiliary film layer and the high-reflection silver film layer. Preferably, the metal interface layer is a first metal or a first metal alloy layer.

[0010] Furthermore, the first metal and the second metal are the same metal or metal alloy.

[0011] Furthermore, the first auxiliary film layer and the second auxiliary film layer can each be titanium: silicon nitride (Ti:SiAl)N X Compound, Chromium:Silicon Nitride (Cr:SiAl)N X Compound, nickel-chromium alloy:silicon nitride (NiCr:SiAl)N X Compound or nickel vanadium alloy: silicon nitride (NiV:SiAl)N X Any one of the compounds.

[0012] Furthermore, the ratio (Me1:Si) and the ratio (Me2:Si) can be adjusted to have pure metal as the main component, pure silicon / silicon alloy as the main component, or any mixed ratio between the former two.

[0013] Furthermore, the ratio (Me1:Si) and the ratio (Me2:Si) should each be in any ratio between 10%:90% and 60%:40%, so that the structure of each compound is amorphous or at least in an amorphous state with microcrystals embedded therein.

[0014] Furthermore, the thickness of the first auxiliary film layer is between 2nm and 50nm, the thickness of the high-reflection silver film layer is between 30nm and 200nm, and the thickness of the second auxiliary film layer is between 0.5nm and 20nm.

[0015] Furthermore, the plated surface of the metal substrate has a substrate surface treatment layer for making its surface smooth and / or increasing the surface hardness.

[0016] Furthermore, the first auxiliary film layer is a nickel-chromium alloy: silicon nitride (NiCr:SiAl) N with a thickness between 10nm and 30nm and a ratio (NiCr:SiAl) of 50%:50%. X compound; the above-mentioned high-reflective silver film layer is silver with a thickness between 80nm and 120nm and a purity of at least 3N; the above-mentioned second auxiliary film layer is nickel-chromium alloy: silicon nitride (NiCr:SiAl) with a thickness of 3nm and a ratio (NiCr:SiAl) between 10%:90% and 60%:40%. X Compound, or chromium:silicon nitride (Cr:SiAl)N with a thickness between 2nm and 5nm and a ratio (Cr:SiAl) between 10%:90% and 60%:40% X compound.

[0017] Furthermore, a metal interface layer is provided between the first auxiliary film layer and the high-reflection silver film layer. The metal interface layer is a chromium layer or a nickel-chromium alloy layer with a thickness not exceeding 30 nm.

[0018] Furthermore, the metal substrate is aluminum or aluminum alloy with an aluminum oxide film layer on the coating surface; the low refractive index coating is silicon oxide SiO x or silicon:aluminum oxide (Si:Al)O x , the high refractive index coating is titanium oxide TiO x .

[0019] Furthermore, the above-mentioned first auxiliary film layer is a gradient structure in which the concentration of the first metal or the first metal alloy gradually decreases and then gradually increases from the metal substrate to the high-reflection silver film layer; the above-mentioned second auxiliary film layer is a gradient structure in which the concentration of the second metal or the second metal alloy gradually decreases from the high-reflection silver film layer to the low-refractive index coating layer.

[0020] Furthermore, the above-mentioned first auxiliary film layer and second auxiliary film layer can each be produced by a joint sputtering process from different sputtering targets or by using already mixed sputtering targets in a sputtering process, wherein the joint sputtering process used to prepare the first auxiliary film layer is composed of at least two groups of dual magnetrons, and the concentration gradient of the compound film layer obtained from the joint sputtering process of the first group of dual magnetrons is designed to have the highest metal concentration toward the metal substrate, and the concentration gradient of the compound film layer obtained from the joint sputtering process of the second group or the last group of dual magnetrons is designed to have the highest metal concentration toward the high-reflection silver film layer; the joint sputtering process used to prepare the second auxiliary film layer is composed of at least one group of dual magnetrons, and the concentration gradient of the compound film layer obtained from the joint sputtering process of each group of dual magnetrons is designed to have the highest metal concentration toward the high-reflection silver film layer.

[0021] Compared with the existing technology, the advantages of the present invention are:

[0022] First, the high-reflective mirror coating film system disclosed in the present invention sandwiches a high-reflective silver film layer between a first auxiliary film layer and a second auxiliary film layer, both composed of a metal:silicon nitride compound. This is a multifunctional comprehensive auxiliary layer that provides adhesion promotion, diffusion barrier, and anti-oxidation functions, ensuring that the high-reflective mirror coating film system has the advantages of high durability and high reliability under high temperature and corrosive environment conditions.

[0023] Secondly, in the present invention, a metal interface layer is provided between the first auxiliary film layer and the highly reflective silver film layer to further inhibit the lateral migration of silver atoms. Preferably, the metal or metal alloy composition of this metal interface layer is the same as that of the first auxiliary film layer, thereby significantly reducing the complexity of the entire film system and effectively controlling costs.

[0024] Third, in the present invention, the first auxiliary film layer is a nickel-chromium alloy: silicon nitride (NiCr:SiAl) with a thickness of 10nm to 30nm and a ratio of (NiCr:SiAl) of 50%:50%. X The second auxiliary film layer is a nickel-chromium alloy: silicon nitride (NiCr:SiAl) with a thickness of 3nm and a ratio (NiCr:SiAl) between 10%:90% and 60%:40%. X Compound, or chromium:silicon nitride (Cr:SiAl)N with a thickness between 2nm and 5nm and a ratio (Cr:SiAl) between 10%:90% and 60%:40% X The compound enables the second auxiliary film layer to have adhesion promotion, diffusion barrier and anti-oxidation effects, and its diffusion barrier and anti-oxidation functions are particularly outstanding. It also has good light transmittance.

[0025] Fourthly, in the present invention, the first auxiliary film layer and the second auxiliary film layer are both produced by a common sputtering process, so that the ratio between the metal component and the silicon component can be designed as needed to meet the preparation requirements of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the coating film structure of the present invention when no metal interface layer is present.

[0027] Figure 2 Schematic diagram of the coating film structure of the present invention containing a metal interface layer.

[0028] Figure 3 A comparison chart of the spectral reflectance of silver and aluminum.

[0029] Figure 4 Schematic diagram of the co-sputtering method.

[0030] Figure 5 This is a distribution diagram of the concentration gradient of the first auxiliary film layer deposited using the co-sputtering process.

[0031] Figure 6 This is a distribution diagram of the concentration gradient of the second auxiliary film layer deposited using the co-sputtering process. DETAILED DESCRIPTION

[0032] The specific embodiments of the present invention are described below with reference to the accompanying drawings. In order to fully understand the present invention, many details are described below, but for those skilled in the art, the present invention can be implemented without these details.

[0033] refer to Figures 1 to 6 A high-reflectivity, high-temperature-resistant, and corrosion-resistant mirror coating system includes a metal substrate (SO) having at least one coated surface. The metal substrate (SO) includes, but is not limited to, a metal coil or sheet with a thickness between 0.1 mm and 1.5 mm and a width between 500 mm and 1500 mm. For example, a sheet can have a minimum length of 10 cm, while a coiled metal strip can have a maximum length of several kilometers. Preferably, the metal substrate (SO) is composed of aluminum or an aluminum alloy.

[0034] Furthermore, the coating surface of the metal substrate SO is provided with a surface treatment coating SF, which has the function of smoothing the surface and / or increasing the surface hardness.

[0035] Specifically, the metal substrate SO is composed of aluminum, and an aluminum oxide film is formed on the coated surface of the aluminum through an anodizing process. This aluminum oxide film serves as the surface treatment coating SF. Of course, the surface treatment coating SF is not limited to an aluminum oxide film and can be made of a coated varnish or simply a highly polished metal surface.

[0036] The coating surface of the metal substrate SO is coated with a first auxiliary film layer L10, a high-reflection silver film layer L20, a second auxiliary film layer L30, a low-refractive index coating layer L40 and a high-refractive index coating layer L50 in sequence from the inside out.

[0037] Preferably, a metal interface layer L12 is added between the first auxiliary film layer L10 and the high-reflection silver film layer L20, that is, the coating surface of the metal substrate SO is coated with the first auxiliary film layer L10, the metal interface layer L12, the high-reflection silver film layer L20, the second auxiliary film layer L30, the low-refractive index coating L40 and the high-refractive index coating L50 in sequence from the inside to the outside.

[0038] For ease of understanding, the material selection and preparation process of each coating are explained in detail below. However, this does not mean that the layers in the coating film system can be completely independent of each other and have no effect on each other.

[0039] The highly reflective silver film layer L20 is made of a silver alloy or silver with a purity of at least 3N. This high-reflectivity coating is produced by magnetron sputtering, arc evaporation, or electron beam evaporation to ensure high reflectivity within the visible light wavelength range of 380 to 2500 nanometers. To ensure opacity, the thickness of the highly reflective silver film layer L20 is preferably between 30 and 200 nm. Specifically, silver with a thickness of 80 to 120 nm and a purity of at least 3N is used.

[0040] When electron beam evaporation is used to deposit the highly reflective silver film layer L20, an additional pure silver or silver alloy film layer must first be deposited on the coating surface of the metal substrate SO below the electron beam evaporated layer by magnetron sputtering to provide a seed crystal for the electron beam evaporated layer.

[0041] The first auxiliary film layer L10 is made of the first metal: silicon nitride (Me1:Si)N X Compound. It should be noted that: (Me1:Si)N X It is not a chemical formula, but an expression designed for the convenience of textual expression. Among them, Me1 represents a first metal or a first metal alloy; Si represents silicon or a silicon alloy; (Me1:Si) represents the ratio between Me1 and Si, and this ratio (Me1:Si) can preferably be adjusted to 100%:0%, or adjusted to 0%:100%, or a mixture of any proportion between the first two. The index X here represents the reaction coefficient of the nitrogen element N. The reaction coefficient X can vary between X=0 and X=1, where X=0 represents 0% reaction and X=1 represents 100% reaction. In addition, preferably, the first auxiliary film layer is a gradient structure in which the concentration of the first metal or the first metal alloy gradually decreases and then gradually increases from the metal substrate SO to the high-reflection silver film layer L20.

[0042] The second auxiliary film layer L30 is made of the second metal: silicon nitride (Me2:Si)N X Compound. It should be noted that: Me2:Si)N X It is not a chemical formula, but an expression designed for the convenience of textual expression. Wherein, Me2 represents a second metal or a second metal alloy, Si represents silicon or a silicon alloy, (Me2:Si) represents the ratio between Me2 and Si, and this ratio (Me2:Si) can preferably be adjusted to 100%:0%, or adjusted to 0%:100%, or a mixture of any proportion between the first two. The index X here represents the reaction coefficient of the nitrogen element N. The reaction coefficient X can vary between X=0 and X=1, where X=0 represents 0% reaction and X=1 represents 100% reaction. In addition, preferably, the above-mentioned second auxiliary film layer is a gradient structure in which the concentration of the second metal or the second metal alloy gradually decreases from the high-reflective silver film layer L20 to the low-refractive index coating L40.

[0043] The specific reasons for selecting the first auxiliary film layer L10 and the second auxiliary film layer are as follows:

[0044] The first auxiliary film L10 needs to provide good adhesion and diffusion barrier properties, and preferably also be an effective film layer that prevents silver oxidation at high temperatures. Oxidation of the silver film layer should be prevented, especially under high temperature conditions, by: a) occupying the interface atoms of the silver film layer and b) blocking gaseous substances, such as those released from the surface of the metal substrate SO, especially from the anodic oxide layer; or from the external gas atmosphere containing reactive gases.

[0045] One guideline for selecting materials with effective diffusion barrier properties is based on Fick's first law:

[0046]

[0047] Where J(mol*m -2 *s -1 ) describes the flux of the diffusive component, ∂C / ∂x(mol*m -4 ) describes the diffusion path or diffusion distance x and the diffusion coefficient D(m 2 *s -1 ). The diffusion coefficient, D, is a measure of the speed of the diffusion process and is temperature-dependent. To effectively inhibit intermetallic diffusion between silver and aluminum, the diffusion coefficient of the selected diffusion barrier material should be sufficiently low, even at elevated temperatures.

[0048] In their 2012 doctoral dissertation at Manchester Metropolitan University, "Diffusion studies in toughened low-e coatings", the authors Kulczyk-Malecka and Justyna provide some measured diffusion coefficients for silver atoms diffusing through certain diffusion barriers. These data will give a representative impression of the materials considered here:

[0049] Thin film material <![CDATA[ D Ag (m 2 *s -1 ) Diffusion coefficient of silver]]> <![CDATA[Titanium Dioxide (TiO2)]]> <![CDATA[7.5E -19 (200°C)…1.6E -18 (600°C)]]> <![CDATA[Silicon nitride (SiN x ).]]> <![CDATA[1.0E -20 …5.5E -20 (All at 650°C)]]>

[0050] From the above data, it can be seen that within the applicable temperature range, the diffusion coefficient of silicon nitride to silver is one order of magnitude lower than the diffusion coefficient of titanium dioxide to silver.

[0051] Numerous other publications have shown that silicon nitride is also an effective barrier material for moisture and oxygen diffusion. The advantage of silicon nitride is its amorphous structure, which remains amorphous even at elevated temperatures. Therefore, silicon nitride-based barrier and adhesion layers are often used to achieve these barrier properties.

[0052] A drawback of silicon nitride is its poor adhesion to silver. Therefore, adhesion-promoting components are required to form silicon nitride-based compound layers. Promising materials are metals, particularly those that partially react with nitrogen and readily mix with it. Such metals or metal alloys can further form a stable bond with silver, thereby a) ensuring adhesion and b) preventing oxidation of the silver surface atoms.

[0053] To ensure that the first auxiliary film layer L10 and the second auxiliary film layer L30 are amorphous or at least amorphous with embedded microcrystals, the silicon content in the ratio (Me1:Si) and the ratio (Me2:Si) should both be at least 40%. To ensure adhesion promotion, the metal content in the ratio (Me1:Si) and the ratio (Me2:Si) should both be at least 10%. Therefore, the ratios (Me1:Si) and (Me2:Si) are each between 10%:90% and 60%:40%.

[0054] The first auxiliary film layer L10 and the second auxiliary film layer L30 can each be titanium:silicon nitride (Ti:SiAl)N X Compound, Chromium:Silicon Nitride (Cr:SiAl)N X Compound, nickel-chromium alloy:silicon nitride (NiCr:SiAl)N X Compound or nickel vanadium alloy: silicon nitride (NiV:SiAl)N X Any one of the compounds.

[0055] The first auxiliary film layer L10, located beneath the highly reflective silver film layer L20, must promote adhesion, block diffusion, and prevent oxidation. Adhesion promotion is particularly important, so the first auxiliary film layer L10 needs to be thick and its metal content must be adequate. The second auxiliary film layer L30, located above the highly reflective silver film layer L20, must promote adhesion, block diffusion, and prevent oxidation. Diffusion and oxidation are particularly important. Furthermore, it must ensure light transmittance. Therefore, the second auxiliary film layer L30 needs to be thin and its silicon content must be adequate. Our testing has found that using (NiCr:SiAl)Nx offers the best performance in long-term high-temperature stability. Using (Cr:SiAl)Nx not only achieves excellent long-term high-temperature stability but also offers superior optical performance.

[0056] Therefore, the first auxiliary film L10 is made of nickel-chromium alloy: silicon nitride (NiCr:SiAl) with a thickness of 10nm to 30nm and a ratio of (NiCr:SiAl) of 50%:50%. X The second auxiliary film L30 is made of chromium: silicon nitride (Cr:SiAl)N with a thickness between 2nm and 5nm and a ratio (Cr:SiAl) between 10%:90% and 60%:40%. X Compound, or nickel chromium alloy: silicon nitride (NiCr:SiAl)N with a thickness of 3nm and a ratio (Cr:SiAl) between 10%:90% and 60%:40% X compound.

[0057] The first auxiliary film layer L10 and the second auxiliary film layer L30 are each produced in a sputtering process from different sputtering targets or by using pre-mixed sputtering targets. The following takes the production from different sputtering targets in a sputtering process as an example for detailed description.

[0058] Each co-sputtering process consists of a dual-magnetron configuration with a sputtering target A and a sputtering target B. Sputtering target A contains material A (MatA), while sputtering target B contains material B (MatB). If MatA contains a metal or metal alloy, MatB should be silicon or a silicon alloy. If MatB contains a metal or metal alloy, MatA should be silicon or a silicon alloy.

[0059] Regarding the arrangement of materials, whether MatA contains a metal or metal alloy, or whether MatB contains a metal or metal alloy, depends on the deposition order within the coating structure. Depending on the deposition order, the metal or metal alloy should face the surface treatment coating SF or the highly reflective silver film L20, which has been treated on the surface of the metal substrate SO. Therefore, in a compound film layer having a gradient concentration ratio, the side of the compound film layer with the highest metal-nitride gradient forms an interface with the surface treatment coating SF or the highly reflective silver film L20.

[0060] Each sputtering target can be driven and operated with process power independent of the co-target. Therefore, the vapor flow from target MatA (VA) is different from the vapor flow from target MatB (VB). On the substrate, the two vapor flows mix together to form a new film layer. By adding a reactive gas, such as nitrogen, the deposited film reacts to form a mixed compound film. This co-sputtered film is typically not a homogeneous mixture, but rather has a gradient profile. This gradient profile depends on the inclination angle of the sputtering material flow, the distance between the sputtering targets, and the power distribution across the sputtering targets. In magnetron systems using rotatable targets, the inclination angle of the sputtering flow can be easily adjusted by tilting the magnet system positioned below the sputtering target material portion.

[0061] Figure 4 (RA+B) in Figure 1 shows an example of the overall deposition rate distribution on the substrate surface. In this example, the vapor flow rate (VA) contributes 60%, while the (VB) contributes 40%. Clearly, the vapor flow rate (VA) contributes more to (RA+B). (RA) shows the deposition rate distribution for the vapor flow rate (VA) only, while (RB) shows the deposition rate distribution for the vapor flow rate (VB) only. A corresponding gradient can be obtained in the mixture between MatA and MatB. This gradient structure of co-sputtered films is not a problem and is even desirable in compound film design.

[0062] In the present invention, the first auxiliary film layer L10 has a gradient structure, and the co-sputtering process used to prepare it is composed of at least two groups of dual magnetrons. The concentration gradient of the compound film layer obtained from the co-sputtering process of the first group of dual magnetrons is designed so that the highest metal concentration is toward the metal substrate SO, and the concentration gradient of the compound film layer obtained from the co-sputtering process of the second or last group of dual magnetrons is designed so that the highest metal concentration is toward the high-reflective silver film layer L20.

[0063] Specifically, the sputtering target used for the first metal component used to prepare the first auxiliary film L10 can be a titanium target, a chromium target, a nickel-chromium target, a nickel-vanadium target, or other alloys containing titanium, chromium, or nickel. The sputtering target used for the silicon component can be a pure silicon target, a silicon-aluminum alloy target, a silicon-chromium alloy target, a silicon-titanium alloy target, or other silicon-dominated alloys.

[0064] More specifically, when the first auxiliary film L10 is nickel-chromium alloy: silicon nitride (NiCr:SiAl)N X When a compound is used, the sputtering target used for the first metal component is a nickel-chromium target, preferably an alloy of 80% nickel and 20% chromium; the sputtering target used for the silicon component is a silicon-aluminum alloy target, preferably with a silicon content higher than 80%; and the ratio (NiCr:SiAl) is preferably 50%:50%. Figure 5 The concentration gradient distribution of the first auxiliary film L10 deposited by the co-sputtering process is shown in Figure 2. We achieved satisfactory results by obtaining the sputtering material flow rate under the standard tilt angle of MatA 0° and MatB 0°, but other tilt angles can also be used as an attempt for further optimization.

[0065] In the present invention, the second auxiliary film layer L30 has a gradient structure, and the co-sputtering process used to prepare the second auxiliary film layer L30 is composed of at least one group of dual magnetrons. The concentration gradient of the compound film layer obtained from the co-sputtering process of each group of dual magnetrons is designed to have the highest metal concentration toward the high-reflection silver film layer L20.

[0066] Specifically, the sputtering target used to prepare the second metal component of the second auxiliary film layer L30 can be a titanium target, a chromium target, a nickel-chromium target, a nickel-vanadium target or other alloys containing titanium, chromium or nickel, preferably a nickel-chromium target or a chromium target; the sputtering target used to prepare the silicon component of the second auxiliary film layer L30 is a pure silicon target, a silicon-aluminum alloy target, a silicon-chromium alloy target, a silicon-titanium alloy target or other silicon-dominated alloys.

[0067] More specifically, when the second auxiliary film L30 is chromium:silicon nitride (Cr:SiAl)N X When the compound is formed, the sputtering target used for the second metal component is a chromium target, and the sputtering target used for the silicon component is a silicon-aluminum alloy target, preferably with a silicon content higher than 80%; and the ratio (Cr:SiAl) is preferably between 10%:90% and 60%:40%.

[0068] Figure 6 The figure shows the concentration gradient distribution of the second auxiliary film L30 deposited by the co-sputtering process. The optimal tilt angle of the sputtering material flow for MatA depends on the metal / metal alloy used. For example, for (Cr:SiAl)Nx compounds, we found that the optimal tilt angle is -20°, while for (NiCr:SiAl)NX The optimal tilt angle for the sputtered material of MatB, i.e., the portion that contributes silicon / silicon alloy nitride to the second auxiliary film L30, is 20°.

[0069] A key issue with PVD (Physical Vapor Deposition) coatings is the potential presence of so-called pinholes within the coating. These pinholes can still act as moisture conduction pathways. Depending on their size and density, these pinhole-sized defects can cause degradation with long-term exposure to extreme humidity. This effect is widely explained by the lateral migration of silver atoms.

[0070] Therefore, a metal interface layer L12, facing the highly reflective silver film layer L20, is applied between the first auxiliary film layer L10 and the highly reflective silver film layer L20 to inhibit the lateral migration of silver atoms. The metal constituting the metal interface layer L12 should have a higher solubility than silver, higher cohesive energy or binding energy, lower lattice mismatch, and a good metal bond. While metals with higher solubility relative to silver, such as aluminum or copper, may have some advantages in inhibiting the lateral migration of silver, they may also have disadvantages, such as reducing the initial reflectivity of silver if dissolved in silver. Adding a pure metal film between the first auxiliary film layer L10 and the highly reflective silver film layer L20 will increase costs. However, if this pure metal is the same as the metal component used in the first auxiliary film layer L10, the complexity of the entire coating system will not increase significantly, effectively controlling costs. This is also a factor in the selection of the metal components for the first auxiliary film layer L10 and the second auxiliary film layer L30. Therefore, compromise metals can be pure chromium or a chromium alloy, pure nickel or a nickel alloy, or pure titanium or a titanium alloy.

[0071] For example, if a (Ti:Si)Nx compound layer is used for the first auxiliary film layer L10, the metal interface layer L12 should be composed of titanium. If a (Cr:Si)Nx compound layer is used for the first auxiliary film layer L10, the metal interface layer L12 should be composed of chromium. If a (NiCr:Si)Nx or (NiV:Si)Nx compound is used for the first auxiliary film layer L10, the metal interface layer L12 should be composed of nickel, a nickel-chromium alloy, or a nickel-vanadium alloy.

[0072] The thickness of the metal interface layer L12 shall not be greater than 30 nm, and is preferably less than 10 nm.

[0073] The low-refractive-index coating L40 is formed by magnetron sputtering or electron beam evaporation using silicon oxide SiOx or silicon:aluminum oxide (Si:Al)Ox. The thickness of the low-refractive-index coating L40 is preferably between 10 nm and 200 nm, more preferably between 40 nm and 100 nm.

[0074] The high refractive index coating L50 is made of titanium oxide TiOx and deposited by magnetron sputtering or electron beam evaporation. The thickness of the high refractive index coating L50 is preferably between 10 nm and 200 nm, more preferably between 40 nm and 100 nm.

[0075] Two specific coating film structures of the present invention are listed below:

[0076] Example 1:

[0077]

[0078] The coating system in Example 1 was tested under various conditions, and changes in total reflectance (YD65 / 2°) and coating adhesion were observed. YD65 / 2° was measured in accordance with ISO 6719:2010 and the combined ISO / CIE standard, ISO 10526:1999 / CIES 005 / E-1998 (CIE standard illuminants for quantitative colorimetric analysis). Coating adhesion was measured using the 100-grid cross-hatch adhesion test described in ISO 2409:2013 and GB / T 9286-1998. The test results for the specific coating system in Example 1 are as follows:

[0079]

[0080] Example 2:

[0081]

[0082] The coating system in Example 2 was tested under various conditions, and changes in total reflectance (YD65 / 2°) and coating adhesion were observed. YD65 / 2° was measured according to ISO 6719:2010 and the combined ISO / CIE standard, ISO 10526:1999 / CIES 005 / E-1998 (CIE standard illuminants for quantitative colorimetric analysis). Coating adhesion was measured using the 100-grid cross-hatch adhesion test described in ISO 2409:2013 and GB / T 9286-1998. The test results for the specific coating system in Example 2 are as follows:

[0083]

[0084] In summary, the high-reflection mirror coating film disclosed in the present invention has very high reflectivity in the wavelength range of 400 nanometers to 2500 nanometers, and has the advantages of high durability and high reliability under high temperature and corrosive environment conditions.

[0085] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A high-reflection mirror coating system that is resistant to high temperatures and corrosion, comprising a metal substrate having at least one coating surface, characterized in that The coating surface is coated with the following layers from the inside to the outside: The first auxiliary film layer is made of nickel chromium silicon aluminum nitride (NiCr:SiAl) X Compound, (NiCr:SiAl) represents the ratio between NiCr and SiAl, and the index X represents the reaction coefficient of nitrogen N; Highly reflective silver film layer, made of silver alloy or silver with a purity of at least 3N; The second auxiliary film layer is made of nickel chromium silicon aluminum nitride (NiCr:SiAl)N X Compound, (NiCr:SiAl) represents the ratio between NiCr and SiAl, index X represents the reaction coefficient of nitrogen element N, or, chromium nitride silicon aluminum (Cr:SiAl)N X Compound, (Cr:SiAl) represents the ratio between Cr and SiAl, and the index X represents the reaction coefficient of nitrogen element N; Low refractive index coating; High refractive index coating; The thickness of the first auxiliary film layer is between 2nm and 50nm, the thickness of the high-reflection silver film layer is between 30nm and 200nm, and the thickness of the second auxiliary film layer is between 0.5nm and 20nm.

2. A high-reflection mirror coating film system that is resistant to high temperatures and corrosion-resistant according to claim 1, characterized in that : A metal interface layer is also provided between the first auxiliary film layer and the high-reflection silver film layer.

3. A high-reflection mirror coating film system that is resistant to high temperatures and corrosion-resistant according to claim 2, characterized in that :The metal interface layer is a first metal or a first metal alloy layer.

4. The high-temperature resistant and corrosion-resistant high-reflective mirror coating film system according to claim 1, characterized in that The ratio (Cr:SiAl) in the second auxiliary film layer can be adjusted to be dominated by pure metal, dominated by silicon alloy or any mixed ratio between the former two.

5. The high-temperature resistant and corrosion-resistant high-reflective mirror coating film system according to claim 4, characterized in that : The ratio (Cr:SiAl) in the second auxiliary film layer is any ratio between 10%:90% and 60%:40%, so that the structure of the compound is an amorphous state or at least an amorphous state with microcrystals embedded.

6. The high-temperature resistant and corrosion-resistant high-reflective mirror coating film system according to claim 1, characterized in that The coated surface of the metal substrate has a substrate surface treatment layer that makes its surface smooth and / or increases the surface hardness.

7. The high-temperature resistant and corrosion-resistant high-reflective mirror coating film system according to claim 1, characterized in that The first auxiliary film layer is a nickel chromium silicon aluminum (NiCr:SiAl) nitride with a thickness of 10nm to 30nm and a ratio of (NiCr:SiAl) of 50%:50%. X compound; the high reflective silver film layer is silver with a thickness between 80nm and 120nm and a purity of at least 3N; the second auxiliary film layer is nickel chromium silicon aluminum nitride (NiCr:SiAl) N with a thickness of 3nm and a ratio (NiCr:SiAl) between 10%:90% and 60%:40%. X Compound, or chromium silicon aluminum (Cr:SiAl)N with a thickness between 2nm and 5nm and a ratio (Cr:SiAl) between 10%:90% and 60%:40% X compound.

8. The high-temperature-resistant and corrosion-resistant high-reflective mirror coating film system according to claim 7, characterized in that A metal interface layer is provided between the first auxiliary film layer and the high-reflection silver film layer. The metal interface layer is a chromium layer or a nickel-chromium alloy layer with a thickness not exceeding 30 nm.

9. A high-temperature resistant and corrosion-resistant high-reflective mirror coating film system according to claim 1, 7 or 8, characterized in that The metal substrate is aluminum or aluminum alloy with an aluminum oxide film layer generated by an anodic oxidation process on the coating surface; the low refractive index coating is silicon oxide SiO x Or silicon aluminum oxide (Si:Al)O x , the high refractive index coating is titanium oxide TiO x .

10. A high-temperature resistant and corrosion-resistant high-reflective mirror coating film system according to claim 1 or 7, characterized in that : The first auxiliary film layer has a gradient structure in which the concentration of NiCr gradually decreases from the metal substrate to the high-reflection silver film layer and then gradually increases; the second auxiliary film layer has a gradient structure in which the concentration of NiCr or Cr gradually decreases from the high-reflection silver film layer to the low-refractive index coating layer.

11. The high-temperature resistant and corrosion-resistant high-reflective mirror coating film system according to claim 10, characterized in that : The first auxiliary film layer and the second auxiliary film layer can each be produced in a sputtering process from different sputtering targets or by using already mixed sputtering targets through a joint sputtering process, wherein the joint sputtering process used to prepare the first auxiliary film layer is composed of at least two groups of dual magnetrons, and the concentration gradient of the compound film layer obtained from the joint sputtering process of the first group of dual magnetrons is designed to have the highest metal concentration toward the metal substrate, and the concentration gradient of the compound film layer obtained from the joint sputtering process of the second group or the last group of dual magnetrons is designed to have the highest metal concentration toward the high-reflection silver film layer; the joint sputtering process used to prepare the second auxiliary film layer is composed of at least one group of dual magnetrons, and the concentration gradient of the compound film layer obtained from the joint sputtering process of each group of dual magnetrons is designed to have the highest metal concentration toward the high-reflection silver film layer.

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