阅读说明：本技术 一种高温空气中稳定的用于太阳能选择性涂层的金属陶瓷材料及其制备方法 (Cermet material stable in high-temperature air and used for solar selective coating and preparation method thereof ) 是由 康楚钒 于 2018-05-29 设计创作，主要内容包括：本发明涉及一种高温空气中稳定的用于太阳能选择性涂层的金属陶瓷材料及其制备方法。该用于太阳能选择性涂层的金属陶瓷材料,包括陶瓷电介质和位于所述陶瓷电介质中的金属合金颗粒；所述金属合金颗粒在暴露于高温下含氧环境中时,在金属合金颗粒周围形成有钝化作用的氧化层。制备该金属陶瓷材料时,使用至少两个阴极,通过反应PVD沉积陶瓷电介质和金属合金颗粒。利用本发明的金属陶瓷材料形成的太阳能选择性涂层,其膜层光学透明性提高,尤其在红外和近红外区域,因此膜层的发射率降低,吸收截止波长变小,从而有效地提高了太阳能选择性涂层的性能。(The invention relates to a cermet material stable in high-temperature air and used for a solar selective coating and a preparation method thereof. The metal ceramic material for the solar selective coating comprises a ceramic dielectric and metal alloy particles positioned in the ceramic dielectric; the metal alloy particles form a passivating oxide layer around the metal alloy particles when exposed to an oxygen-containing environment at elevated temperatures. The cermet material is prepared by depositing a ceramic dielectric and metal alloy particles by reactive PVD using at least two cathodes. The solar selective coating formed by the cermet material has the advantages that the optical transparency of the film layer is improved, particularly in the infrared and near-infrared regions, so that the emissivity of the film layer is reduced, the absorption cut-off wavelength is reduced, and the performance of the solar selective coating is effectively improved.)

1. A cermet material for solar selective coating, comprising a ceramic dielectric and metal alloy particles in the ceramic dielectric; the metal alloy particles form a passivating oxide layer around the metal alloy particles when exposed to an oxygen-containing environment at elevated temperatures.

2. The cermet material for solar selective coating according to claim 1, characterised in that the metal alloy particles are heat treated in an oxidising atmosphere at above 300 ℃ to passivate them.

3. The cermet material for a solar selective coating according to claim 1, wherein the metal alloy particles comprise at least one refractory metal and at least one element capable of forming a stable oxide on the refractory metal.

4. The cermet material for a solar selective coating according to claim 3, wherein the refractory metal comprises one or more of Nb, Ta, Ni, Mo, W; the elements capable of forming stable oxides on the refractory metal include one or more of Cr, Al, Ti, Si.

5. A method for preparing a cermet material for solar selective coating as defined in claim 1, characterized in that the ceramic dielectric and the metal alloy particles are deposited by reactive PVD using at least two cathodes; one of the at least two cathodes comprises aluminum or an aluminum alloy for depositing the ceramic dielectric and the other cathode comprises a refractory metal and an element capable of forming a stable oxide on the refractory metal for depositing the metal alloy particles.

6. The method of claim 5, wherein the cathode is a single target; or one of the cathodes is a dual target for depositing a more transparent film and the other cathode is a single target or dual target sputtered into the film using a medium frequency power supply.

7. The method of claim 5, wherein the deposition pressure is between 0.2Pa and 0.8 Pa; wherein, when the high metal volume fraction layer is plated, the power density of the target for providing aluminum and the target for providing metal alloy particles are both between 1.5 and 3.5W/cm 2; the low metal volume fraction layer is plated to provide a target power density for the aluminum of between 1.5 and 3.5W/cm2 and a target power density for the metal alloy particles of between 0.5 and 1.5W/cm 2.

8. A solar selective coating comprising an infrared reflective layer and the cermet material for a solar selective coating of claim 1 deposited on the infrared reflective layer.

9. The solar selective coating of claim 8, wherein an anti-diffusion barrier layer comprising silicon dioxide is deposited between the cermet material and the infrared reflective layer.

10. The solar selective coating of claim 8, wherein the cermet material has an anti-reflective coating deposited on top; the antireflective coating contains one or more of SiO2, SiN, or SiAlN.

Technical Field

The invention belongs to the technical field of solar energy and materials, and particularly relates to a metal ceramic material for a solar energy selective coating, which is stable in high-temperature air, and a preparation method thereof.

Background

Solar selective absorbing coatings are well known in the art and consist essentially of an infrared reflecting layer and an absorbing layer that is transparent in the infrared band. To increase efficiency, an anti-reflective layer may be added, which may improve the effects due to optical mismatch between the absorbing layer and the surrounding environment.

One way to make solar absorbing coatings highly transparent in the infrared band is to use ceramic layers, a material that incorporates metals into dielectric ceramics. The metal volume fraction varies from 10% to 50%. The effect of using two different metal volume fractions of ceramics on the solar heat collecting pipe is better. The best results are obtained when the first cermet has a volume fraction of metal of 40% and the second layer has a volume fraction of metal of 20%.

Luz Industries Israel has produced high temperature solar selective absorber coatings containing Al2O3 and Mo. However, these coatings do not exhibit oxidation resistance when the temperature exceeds 300 degrees celsius, and molybdenum slowly oxidizes and vaporizes. Platinum is also used for high temperature air stable coatings, but it is clear that the use of platinum adds significantly to the cost of such selective coatings. Another method to improve air stability is to deposit an excess of aluminum in the aluminum matrix, which can be achieved by reducing the oxygen flow during the reaction, while simultaneously depositing a refractory metal such as W, Ni, Nb, Mo or Ta. However, the deposited structure is naturally porous, so that oxygen will enter the film structure and oxidize the refractory metal.

Disclosure of Invention

The invention aims at the problems and provides a cermet material for a solar selective coating, which is stable in high-temperature air, and a preparation method thereof.

The technical scheme adopted by the invention is as follows:

A cermet material for solar selective coating comprising a ceramic dielectric and metal alloy particles located in the ceramic dielectric; the metal alloy particles form a passivating oxide layer around the metal alloy particles when exposed to an oxygen-containing environment at elevated temperatures.

Further, the metal alloy particles are heat-treated at 300 ℃ or higher in an oxidizing atmosphere to passivate them.

Further, the metal alloy particles comprise at least one refractory metal and at least one element capable of forming a stable oxide on the refractory metal.

Further, the refractory metal comprises one or more of Nb, Ta, Ni, Mo, W; the elements capable of forming stable oxides on the refractory metal include one or more of Cr, Al, Ti, Si.

A method for preparing the above-mentioned cermet material for solar selective coating, using at least two cathodes, depositing ceramic dielectrics and metal alloy particles by reactive PVD; one of the at least two cathodes comprises aluminum or an aluminum alloy for depositing the ceramic dielectric and the other cathode comprises a refractory metal and an element capable of forming a stable oxide on the refractory metal for depositing the metal alloy particles.

Further, the cathode is a single target; or one of the cathodes is a dual target for depositing a more transparent film and the other cathode is a single target or dual target sputtered into the film using a medium frequency power supply.

Further, the deposition pressure is between 0.2Pa and 0.8 Pa; wherein, when the high metal volume fraction layer is plated, the power density of the target for providing aluminum and the target for providing metal alloy particles are both between 1.5 and 3.5W/cm 2; the low metal volume fraction layer is plated to provide a target power density for the aluminum of between 1.5 and 3.5W/cm2 and a target power density for the metal alloy particles of between 0.5 and 1.5W/cm 2.

A solar selective coating comprising an infrared reflective layer and the cermet material for a solar selective coating described above deposited on the infrared reflective layer.

Further, an anti-diffusion barrier layer containing silicon dioxide is deposited between the cermet material and the infrared reflecting layer.

Further, an antireflection coating is deposited on the top of the cermet material; the antireflective coating contains one or more of SiO2, SiN, or SiAlN.

The invention has the following beneficial effects:

The invention deposits metal alloy particles in the ceramic dielectric medium to form the stable metal ceramic material used for the solar selective coating in high-temperature air, and the metal alloy particles are passivated in the high-temperature air to form an oxygen diffusion barrier layer to prevent the oxidation of the coating below. The optical transparency of the film layer of the solar selective coating formed by the metal ceramic material is improved, especially in the infrared and near-infrared regions, so that the emissivity of the film layer is reduced, the absorption cut-off wavelength is reduced, and the performance of the solar selective coating is effectively improved.

drawings

FIG. 1 is a schematic representation of a solar selective coating comprising an infrared reflecting layer and a cermet material.

FIG. 2 is a schematic representation of a solar selective coating comprising an infrared reflecting layer, an anti-diffusion barrier layer and a cermet material.

Fig. 3 is a schematic representation of a solar selective coating comprising an infrared reflecting layer, an anti-diffusion barrier layer, a cermet material and an anti-reflection coating.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, the present invention shall be described in further detail with reference to the following detailed description and accompanying drawings.