CN201539995U - Titanium Nitride Metal Ceramic Thin Films Doped with Tantalum Metal - Google Patents

Abstract

The utility model provides a titanium nitride cermet film doped with tantalum metal, which is sequentially composed of a titanium reflection layer sputtered on a substrate, a high temperature resistant tantalum metal doped titanium nitride absorption layer and a titanium nitride anti-reflection layer . Titanium nitride doped with high melting point metal tantalum has better high temperature resistance and oxidation resistance, among which titanium nitride (TaTiN) modified by tantalum doping has excellent spectral performance, and is a good solar selective absorbent material. According to the different refractive index and extinction coefficient of each film layer, not only the reflective layer, the absorbing layer and the anti-reflection layer are designed as gradient film layers, but also the absorbing layer (TaTiN) is designed as a multi-layer gradient film, so that the ultraviolet, Visible and infrared light (200~2500nm) after repeated reflection, refraction, interference and absorption, more than 96% of the radiation is absorbed by the coating and converted into heat, obtaining a high absorption rate, low reflectivity, good thermal stability solar selective absorbing coatings.

Description

Titanium Nitride Metal Ceramic Thin Films Doped with Tantalum Metal

technical field

The invention relates to a high-temperature solar spectrum selective absorption film, in particular to a titanium nitride cermet film doped with tantalum metal, which can be used for the development of high-temperature concentrating trough-type solar heat collecting tubes.

Background technique

High-temperature solar spectrum selective absorption film is one of the key technologies that determine the efficiency of high-temperature vacuum heat collector tubes and power generation efficiency. The excellent solar spectrum selective absorption film has high absorptivity (α) in the wavelength range of 0.3~2.5um and low emissivity (ε) in the wavelength range above 2.5um. The high-temperature solar spectrum selective absorption film not only has good spectral selectivity, but also needs to have good mechanical properties and high temperature resistance.

At present, the multilayer graded aluminum nitride aluminum (Al/N/Al) coating is widely used. This coating has good spectral selectivity, but when the temperature rises, the emissivity also rises sharply. Use below 250°C. A lot of research has been done abroad on the development of medium and high temperature solar selective absorption films. For example, Mo or W-doped Al ₂ O ₃ cermet composite films, Ni-modified Al ₂ O ₃ films, Ni-NiOX composite films, stainless steel-AlN double-layer ceramic films, etc. have been applied to commercialization. _Among them, Ni _, Al and Cu are mainly _used as _{the reflective} layer; the metal composite film is _used as the absorbing layer _; MgO, Si ₃ N ₄ , TiN, AlN, etc.

There are many methods for preparing solar selective absorption films, mainly including: electrodeposition, chemical vapor deposition, chemical conversion, evaporation and magnetron sputtering. Magnetron sputtering is a newly developed process in recent years. Metal-ceramic composite coatings prepared by magnetron sputtering are mainly used in medium and high temperature fields. Such as tungsten, chromium aluminum nitride selective coating, the substrate is made of metals with high reflectivity such as copper and aluminum, and metal particles such as tungsten and chromium are mixed into the aluminum nitride medium to obtain a metal-ceramic composite coating, and the heat collection temperature can be controlled. up to 350°C or more. Farooq MO etc. used Ni: SiO ₂ cermet as the absorbing layer, the volume ratio of Ni on the coating surface was 10%, and gradually changed to 90% at the bottom, the coating thickness was 100-170nm, the absorption rate was 0.96, and the emissivity was 0.03～0.14. ZhangQi-chu et al. used molybdenum-doped aluminum oxide (Mo-Al ₂ O ₃ ) cermet as the selective absorption coating material, Al ₂ O ₃ as anti-reflection layer, double-layer Mo-Al ₂ O ₃ cermet layer As the absorbing layer, Mo or Cu as the reflective layer, the coating is stable at 350°C, with an absorptivity of 0.96 and an emissivity of 0.11.

However, most of the film layers cannot maintain stable optical properties at a high temperature of 500 ° C, and the optical properties decrease. Nitride or oxide cermets have excellent optical properties, such as TiN, TiO ₂ , AlN, Al ₂ O ₃ and so on. Each has specific spectral properties. Among them, TiN and AlN films are completely transparent to the solar spectrum. However, the optical properties of cermet thin films can be changed by doping, ion implantation, and cluster embedding.

Utility model content

The utility model proposes a tantalum-doped titanium nitride cermet film for the problem of poor thermal stability of the selective absorption film at high temperature. According to the difference of the refractive index and extinction coefficient of each film layer, a gradient absorption film layer is designed to obtain high absorption. High efficiency, low reflectivity, good thermal stability solar selective absorbing coating.

In order to achieve the above-mentioned purpose, the utility model takes the following technical solutions:

A titanium nitride cermet film doped with tantalum metal is sequentially composed of a titanium reflection layer sputtered on a substrate, a high temperature resistant tantalum metal doped titanium nitride absorption layer and a titanium nitride anti-reflection layer.

The absorption layer is composed of multi-layer gradient absorption films with different metal contents, including a high metal content layer, a medium metal content layer and a low metal content layer, and the tantalum metal content gradually decreases among the three layers.

The total thickness of the absorbing film is 180-300nm.

The thickness of the titanium reflective layer is 300-500nm.

The thickness of the titanium nitride antireflection layer is 30-60nm.

The utility model has the advantage that titanium nitride doped with high-melting point metal tantalum has better high temperature resistance and oxidation resistance, wherein the titanium nitride (TaTiN) modified by tantalum doping has excellent spectral performance, and is a kind of Good solar selective absorber material. According to the different refractive index and extinction coefficient of each film layer, not only the reflective layer, the absorbing layer and the anti-reflection layer are designed as gradient film layers, but also the absorbing layer (TaTiN) is designed as a multi-layer gradient film, so that the ultraviolet, Visible and infrared light (200~2500nm) after repeated reflection, refraction, interference and absorption, more than 96% of the radiation is absorbed by the coating and converted into heat, obtaining a high absorption rate, low reflectivity, good thermal stability solar selective absorbing coatings.

Description of drawings

Fig. 1 is a schematic cross-sectional view of the cermet thin film of the present invention.

Fig. 2 is a schematic cross-sectional view of the four-target sputtering equipment used in the preparation of the present invention.

Detailed ways

The utility model will be further described below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 shows the utility model high-temperature metal tantalum-doped titanium nitride cermet film structural schematic diagram; Wherein this film comprises the titanium reflective layer 2 sputtered on the substrate successively, tantalum-doped titanium nitride multilayer The interface absorption layer 3 and the titanium nitride anti-reflection layer 4; wherein the absorption layer 3 includes a high metal content layer, a medium metal content layer and a low metal content layer, and the tantalum metal content gradually decreases between the three layers.

The composition, color and thickness of each coating are shown in Table 1

The structure of the four-target sputtering equipment used in the present invention is as shown in Figure 2, and the equipment can be used to prepare titanium (Ti) reflective layer, tantalum-doped titanium nitride (TaTiN) multilayer interface absorption layer and titanium nitride (TiN ) The cermet thin film that anti-reflection layer is formed, preparation method is as follows:

Four planar target electrodes are set in the sputtering furnace 7, two tantalum targets 8 and 10 and two titanium targets 9 and 11, the titanium target and the tantalum target are all installed on the side wall of the sputtering furnace; Material 1 (i.e. sample), the base material can realize its own rotation while rotating on the circular track of the rotating frame, which is beneficial to uniform coating. Different voltages are set between the targets 8, 9, 10, 11 and the substrate, argon gas is fed from the gas inlet pipe 5, and nitrogen gas is fed into the gas inlet pipe 6. The surface of the target is bombarded with argon ions, metal atoms and atomic groups are sputtered out, materials that cannot react with nitrogen are directly deposited on the substrate, and materials that react with nitrogen form nitrides and deposit on the substrate. Controlling the flow rate of nitrogen can control the amount of nitride formation. When excessive nitrogen is introduced, all the materials react to form nitrides and deposit on the substrate, thereby completing the preparation process of the composite coating.

The preparation process of each layer is described as follows:

First, a layer of metal reflective layer 2 is plated on the base material 1. The material of the reflective layer is titanium. Two titanium targets 9 and 11 are set up for the preparation of this layer. The substrate is placed on the rotating wheel frame, airtight, and vacuumized. When the vacuum reaches a certain requirement, an appropriate amount of argon gas is introduced from the intake pipe 5, and a bias voltage is applied to the substrate to clean the substrate. Turn on the titanium target and bombard the surface of the target with argon ions, so that atoms or atomic groups of titanium metal are sputtered out and deposited directly on the substrate. At this time, the nitrogen gas pipe 6 is closed, and the tantalum targets 8 and 10 do not work.

Then, a tantalum-doped titanium nitride cermet absorbing film is plated on the surface of the metal reflection layer 2 . All four targets are turned on when the absorber layer with high metal content is prepared, and one tantalum target and two titanium targets are turned on when the absorber layer with medium metal content and low metal content is plated. Argon gas is introduced from the inlet pipe 5, and the surface of the target is bombarded with argon ions, and nitrogen gas is introduced from the inlet pipe 6 at the same time to perform reactive sputtering in which the reactive gas is nitrogen. Among them, tantalum metal does not react with nitrogen, titanium reacts with nitrogen to form titanium nitride, and the two substances are deposited together on the substrate to form a tantalum-doped titanium nitride film. The content of tantalum in the tantalum metal-doped titanium nitride film is controlled by setting the target current, voltage, and nitrogen partial pressure, and the thickness of the film can be controlled by controlling the sputtering rate and time.

Finally, the anti-reflection layer is prepared, and a titanium target 9 or 11 is set in the sputtering chamber, and the remaining three targets do not work. A layer of titanium nitride anti-reflection film 4 is plated on the absorbing layer by the same method as above, which is a completely transparent cermet layer.

Example 1

The high-metal content TaTiN (HMCF) film system high-temperature solar vacuum heat collector selective absorption coating was plated in a four-target DC magnetron sputtering furnace. The target electrode is a tantalum target and a titanium target, and the process parameters are as follows:

Wherein, the first layer is a Ti reflection layer, the second layer is a TaTiN cermet absorption layer with low metal content, and the third layer is a TiN anti-reflection layer. It is determined that the spectral absorptivity of the obtained coating between 200nm and 2500nm is 93%, and the reflectivity is 0.9 (80°C).

Example 2

The low metal content TaTiN (LMCF) film system high-temperature solar vacuum heat collector selective absorption coating was plated in a four-target DC magnetron sputtering furnace. The target electrode is a tantalum target and a titanium target, and the process parameters are as follows:

Wherein, the first layer is a Ti reflection layer, the second layer is a TaTiN cermet absorption layer with a metal content between high content and low content, and the third layer is a TiN anti-reflection layer. It is determined that the spectral absorptivity of the obtained coating between 200nm and 2500nm is 95%, and the reflectivity is 0.7 (80° C.).

Example 3

TaTiN (MMCF) film-based selective absorption coating for high-temperature solar vacuum heat collectors was deposited in a four-target DC magnetron sputtering furnace. The target electrode is a tantalum target and a titanium target, and the process parameters are as follows:

Wherein, the first layer is a Ti reflection layer, the second layer is a TaTiN cermet absorption layer with a metal content between high content and low content, and the third layer is a TiN anti-reflection layer. It is determined that the spectral absorptivity of the obtained coating between 200nm and 2500nm is 95%, and the reflectivity is 0.8 (80° C.).

Embodiment four

TaTiN (HMCF---MMCF---LMCF) film system high-temperature solar vacuum heat collector selective absorption coating was plated in a four-target DC magnetron sputtering furnace. The target electrode is a tantalum target and a titanium target, and the process parameters are as follows:

Among them, the first layer is a Ti reflective layer, the second layer is a TaTiN cermet absorber layer with decreasing metal content, and the third layer is a TiN anti-reflection layer. It is determined that the obtained coating has a spectral absorptivity ≥ 96% and a reflectivity ≤ 0.6 (80° C.) between 200 nm and 2500 nm.

The above is only a preferred embodiment of the structure of the utility model, and does not limit the technical scope of the utility model, so any minor modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the utility model , all still belong to the scope of the technical solution of the utility model.

Claims (4)

1. titanium-nitride cermet film that tantalum is metal-doped is characterized in that: by the titanium reflecting layer of sputter on matrix, titanium nitride absorbed layer that resistant to elevated temperatures tantalum is metal-doped and titanium nitride antireflection layer constitute successively.

2. the titanium-nitride cermet film metal-doped according to the described tantalum of claim 1 is characterized in that: the gross thickness of this absorbing film is 180 ~ 300nm.

3. the titanium-nitride cermet film metal-doped according to the described tantalum of claim 1 is characterized in that: the thickness in described titanium reflecting layer is 300 ~ 500nm.

4. the titanium-nitride cermet film metal-doped according to the described tantalum of claim 1 is characterized in that: the thickness of described titanium nitride anti-reflection layer is 30 ~ 60nm.

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