DE102010032892B3 - Coated product and use thereof - Google Patents

Abstract

Coated product (1) comprising at least one substrate (2), at least one barrier layer (3) and at least one functional layer (4), characterized in that the substrate (2) is a steel substrate, that the barrier layer (3) is an oxide layer , which is applied to the substrate by a single or combined HPPM sputtering process, so that the barrier layer (3) better reduces a change in the chemical composition of the functional layer (4) due to external temperature influences, so that the functional layer (4) comprises a silver Layer is, wherein the functional layer (4) is applied to the barrier layer (3), and that the change in the chemical composition of the functional layer by a temperature treatment of the coated product (1) for 85 hours at 600 ° C under an argon atmosphere, by means of measurement the reflection of electromagnetic radiation at a wavelength is, the reflection according to the temperature r treatment is at least 98% of the reflection before the temperature treatment.

Description

The invention relates to a coated product. The coated product comprises at least one substrate, at least one barrier layer and at least one functional layer.

Coated products comprising at least a substrate, a barrier layer and a functional layer have long been known. In this case, the barrier layer assumes an essential protective function within the product, in particular with respect to the functional layer, for example as an oxygen diffusion barrier, as corrosion protection against food, corrosion protection against aggressive environments, in particular at higher temperatures, corrosion protection against aggressive atmospheres (such as, for example, sulfur, selenium) Barrier against alkali diffusion, barrier against diffusion of components of the substrate into an adjacent functional layer. Barrier layers can expand the range of application of products that have a functional layer and open up new areas of application.

Typical coating processes for applying barrier layers are based on chemical vapor deposition (CVD) processes (eg, PECVD, PICVD) and physical vapor deposition (PVD) processes (eg, center frequency (MF). magnetron sputtering). Important for a good barrier effect is that the barrier layer is dense, d. H. especially non-porous, growing without pinholes. It is also important that the barrier layer grows smoothly in order to be able to apply further layers to the barrier layer.

As materials for barrier layers in particular oxides and nitrides and carbides of metals are known. The barrier effect depends not only on the composition of the material, but also on the density (porosity, pinholes) and the thickness of the barrier layer - usually the denser and the thicker the better.

Coated glass or glass ceramic products and processes for their production are known from the document DE 10 2007 033 338 A1 known. It is described that a silicon nitride layer is deposited on a surface of the substrate provided with a ceramic decoration by reactive sputtering, in particular by MF magnetron sputtering. The silicon nitride layer protects the decorative layer against external influences, so that the decorated glass or glass ceramic article shows a color change ΔE of less than 1.5, after an annealing between 600 and 700 ° C.

A coated glass product comprising a glass substrate having a transparent and conductive indium-tin-oxide (ITO) layer having a capping layer forming a redox barrier for the ITO layer, the ITO layer being pulsed, high-ionizing high-performance magentron sputtering (HPPMS) is obtained from the Scriptures DE 10 2008 028 141 A1 known.

HPPMS methods for applying transparent, conductive oxides are described by V. Sittinger et al. in Thin Solid Films 516, p. 5847-5859, (2008).

From the Scriptures US 2010/0092771 A1 For example, another coated product comprising a glass substrate, a layer A comprising at least one layer applied by means of an HPPMS process, a thin metal layer and a barrier layer B applied by means of an HPPMS process is known.

The object of the invention is to provide, starting from this prior art, an improved coated product which has at least one substrate, at least one barrier layer and at least one functional layer. The barrier layer is said to better reduce a change in the chemical composition of the functional layer due to external influences, in particular by other constituents of the product and / or the environment of the product, than a barrier layer of comparable thickness and composition known in the art.

In the following, further preferred embodiments of the coated product are described.

For the coated product ( 1 ) comprises the barrier layer ( 3 ), preferably oxides, in particular SiO ₂ , Al ₂ O ₃ .

• – das Substrat (2) ein Stahlsubstrat ist,
• – die Barriereschicht (3) eine Oxidschicht ist, die durch ein alleiniges oder kombiniertes HPPM-Sputterverfahrens auf das Substrat (2) aufgebracht ist, so dass die Barriereschicht (3) eine Veränderung der chemischen Zusammensetzung der funktionellen Schicht (4) durch äußere Temperatureinflüsse besser vermindert, die funktionelle Schicht (4) eine Silber umfassende Schicht ist, wobei die funktionelle Schicht (4) auf die Barriereschicht (3) aufgebracht ist, und die Veränderung der chemischen Zusammensetzung der funktionellen Schicht (4) durch eine Temperaturbehandlung des beschichteten Produkts (1) über 85 Stunden bei 600°C unter Argonatmosphäre, mittels Messung der Reflektion elektromagnetischer Strahlung bei einer Wellenlänge von 11 μm der funktionellen Schicht (4) ermittelbar ist, wobei die Reflektion nach der Temperaturbehandlung wenigstens 98% der Reflektion vor der Temperaturbehandlung beträgt.

The object is achieved by a coated product ( 1 ) comprising at least one substrate ( 2 ), at least one barrier layer ( 3 ) and at least one functional layer ( 4 ), in which

• - the substrate ( 2 ) is a steel substrate,
• The barrier layer ( 3 ) is an oxide layer deposited on the substrate by a sole or combined HPPM sputtering process ( 2 ) is applied, so that the barrier layer ( 3 ) a change in the chemical composition of the functional layer ( 4 ) is better reduced by external temperature influences, the functional layer ( 4 ) is a silver-comprising layer, wherein the functional layer ( 4 ) on the barrier layer ( 3 ) and the change in the chemical composition of the functional layer ( 4 ) by a temperature treatment of the coated product ( 1 ) at 600 ° C for over 85 hours Argon atmosphere, by measuring the reflection of electromagnetic radiation at a wavelength of 11 μm of the functional layer ( 4 ), wherein the reflection after the temperature treatment is at least 98% of the reflection before the temperature treatment.

Preferably, at least one further barrier layer, in particular a barrier layer, is applied by means of a sole or combined HPPM sputtering method and / or at least one further functional layer.

However, it is also possible to apply other layers, in particular intermediate layers or at least one covering layer.

In particular, the barrier layer ( 3 ) at a temperature of the substrate ( 2 ) of less than 100 ° C, in particular of less than 80 ° C applied and more preferably from 0 to 30 ° C.

Preferably, the HPPM sputtering method may be performed alone or in combination with other sputtering methods, especially HF, DC and MF sputtering methods. In particular, the combination can take place alternately or superimposed.

HPPM sputtering (HPPMS) or HiPIM sputtering; high power impulse magnetron sputtering (pulsed, high-performance, high-power magnetron sputtering); High Power Pulse Magnetron sputtering) as part of the process according to the invention is a sputtering process in which high-energy pulses are generated which lead to high power densities on the target material well above the 10 W / cm ² typical for conventional sputtering, depending on the target material and methods 100 bis 1000 W / cm ² or more. The usual frequencies in the HPPMS method are in the range 100 Hz to 10,000 Hz, typically at 500 Hz to a few kHz.

The high power densities result in the particles catapulted out of the target material having a higher energy than in the case of conventional sputtering. Not only neutral particles but also electrically charged particles (ions) can be generated. In particular, the ions can be specifically accelerated by a substrate bias on the substrate.

The higher energy of the particles leads to a higher mobility on the substrate surface and thereby promotes the growth of the barrier layer ( 3 ) in view of a higher density and lower porosity of the layer compared to layers applied by other methods.

By suitable process parameters, in particular pulse parameters, the surface topography of the applied, sputtered barrier layer ( 3 ) are modified. Various surface structures and roughness can be set. The growth of the barrier layer ( 3 ) can also be achieved by heating the substrate ( 2 ) influence.

The layer thicknesses of the barrier layers are preferably between 10 and 1000 nm, depending on the layer material and function that the barrier layer is to take over.

Also advantageous may be a combination of HPPM sputtering techniques with conventional medium frequency (MF), DC (DC) or radio frequency (RF) sputtering techniques. Compared to other sputtering methods, the HPPMS-reduced deposition rate can be compensated for, whereby positive aspects (in particular achieving a higher density of the barrier layer) of the higher-energy HPPMS particles are not lost. By superimposing HPPMS with a conventional sputtering method, the energy of the HPPM sputtering pulse can be coupled in better, since the plasma does not completely quench during the long pulse-off time due to the superimposition. The MF sputtering overlay also reduces electrical arcing in HPPM reactive sputtering processes. This reduces the number of defects of the applied layer (pinholes, local melts, droplets).

embodiments

100 nm thick barrier layers ( 3 ) from the barrier materials SiO ₂ , Al ₂ O ₃ by means of various HPPM sputtering parameters (variation of the pulse lengths from 20 to 150 μs, variation of the pulse pauses between 200 and 2000 μs, variation of the number of pulses in a pulse packet from 1 to 9, variation of the pauses between pulses in a pulse packet of 5 to 40 μs, HPPM sputtering in unipolar and bipolar modes, variation of HPPM sputtering power from 1 kW to 9 kW) with and without superposition with conventional sputtering techniques (DC and MF sputtering processes at different powers , MF sputtering at different pulse lengths and pulse pauses, MF sputtering in unipolar and bipolar modes).

The effect of the barrier layer on oxygen diffusion and diffusion of steel components into an adjacent functional layer (metal layer) was investigated.

In the steel diffusion barrier layer (barrier layer for minimizing the diffusion of constituents of the steel substrate into a functional layer) Layer of the coated product), it has been found that the barrier layers deposited by conventional sputtering processes have a poorer barrier effect than those barrier layers in which the HPPM sputtering process has been superimposed (combined). This was demonstrated on coated products of the structure: steel substrate / diffusion barrier layer (layer thickness 100 nm) / functional silver layer (layer thickness 50 nm) / Al ₂ O ₃ cover layer (layer thickness 100 nm), which were annealed under a protective gas atmosphere at 600 ° C. for 85 hours. The reflection of electromagnetic radiation at 11 μm wavelength was measured before and after annealing the coated product. Without a barrier layer, the reflection was reduced from 0.982 by about 11% to 0.868. Due to the standard MF barrier layer, the reduction is 3% to 0.951. The combination of unipolar and bipolar HPPM and MF sputtering leads to a reduction in the reflection of the functional silver layer of 2.1% and 1.3%, respectively (see 1 ).

Particularly positive results can be generated procedurally by choosing a suitable pulse pattern. In order to obtain a stable plasma with little electrical arcing, a long pulse-on-time (typically several 10 μs up to 200 μs) into a pulse packet of several short pulses (typically 30 microseconds or shorter, preferably 20 microseconds or shorter, preferably 10 μs or shorter), resulting in significantly fewer flashovers. The pulse packet can be designed only from unipolar or only bipolar or unipolar and bipolar pulse patterns.

The best result so far with regard to minimized diffusion of constituents of the steel substrate into the functional silver layer due to the intermediate barrier layer could be achieved with the combination of HPPMS pulse packages with bipolar MF superposition: the reflection at the silver layer was reduced from 0.982 to 0.974, ie only by less reduced by 1% (see 1 ). For stable process control of the reactive gas process, the HPPM sputtering process is operated via a suitable standard control mechanism (impedance control, plasma emission monitoring (PEM), partial pressure control), either directly or via the optionally operated superimposition of the DC, MF or HF sputtering method. As a result, an arbitrary operating point and a stoichiometry of the barrier layer to be applied can be set reproducibly. In the present case stoichiometric barrier layers should be deposited. However, non-stoichiometric barrier layers can also be deposited.

In principle, the invention can be used wherever a barrier layer is deposited by means of conventional sputtering methods. An extension of the existing sputtering system with HPPM sputtering pulser, optionally matched MF pulser, cable and control is necessary for this purpose. In addition, it may be advantageous to use a substrate bias in conjunction with HPPMS, since then the ions generated from the target material can be accelerated in a targeted manner toward the substrate.

In solar thermal receivers, barrier layers are used to prevent diffusion of constituents of the steel substrate into the adjacent, IR-reflecting (functional) layer. In particular, at high operating temperatures of the receiver (> 400 ° C) in Direktverdampfungskraftwerken or molten salt power plants, a barrier layer must be present, which prevents diffusion and thus does not significantly reduce the IR reflection of the functional layer.

An oxygen barrier layer on the basis of SiO ₂ could also serve as a protection against oxidation of the underlying layers (cermet, IR reflector) in case of vacuum breakage of the receiver and maintain the absorber property of the coating in air.

Preferably, the coated product is part of a solar thermal receiver.

The figures show:

1 Improvement of Diffusion Barrier to Diffusion of Steel Substrate Components in Different Process Combinations and Pulse Patterns.

2 : Comparison of Different Oxygen Diffusion Barrier Layers. An HPPMS-SiO ₂ barrier layer protects the silver functional layer best from degradation after 100 hours of aging the coated product at 500 ° C in air.

3 : A possible construction of a coated product ( 1 ) comprising a substrate ( 2 ), a barrier layer ( 3 ) and a functional layer ( 4 ), wherein the barrier layer ( 3 ) is applied by means of a sole or combined HPPM sputtering process, so that the barrier layer ( 3 ) a change in the chemical composition of the functional layer ( 4 ) is better degraded by external influences than a barrier layer which is applied by means other than HPPM sputtering processes and which has the same chemical composition and layer thickness as the barrier layer (US Pat. 3 ) having. In addition, the product includes 1 ) a cover layer ( 5 ).

LIST OF REFERENCE NUMBERS

1

Coated product

2

substratum

3

barrier layer

4

functional layer

5

topcoat

Claims (2)

Coated product ( 1 ) comprising at least one substrate ( 2 ), at least one barrier layer ( 3 ) and at least one functional layer ( 4 ), characterized in that the substrate ( 2 ) a steel substrate is that the barrier layer ( 3 ) is an oxide layer which is applied to the substrate by a sole or combined HPPM sputtering process, so that the barrier layer ( 3 ) a change in the chemical composition of the functional layer ( 4 ) is better reduced by external temperature influences, that the functional layer ( 4 ) is a silver-comprising layer, wherein the functional layer ( 4 ) on the barrier layer ( 3 ) and that the change in the chemical composition of the functional layer is achieved by a temperature treatment of the coated product ( 1 ) at 600 ° C under argon atmosphere over 85 hours, by measuring the reflection of electromagnetic radiation at a wavelength of 11 microns of the functional layer can be determined, wherein the reflection after the temperature treatment is at least 98% of the reflection before the temperature treatment. Use of the coated product ( 1 ) according to claim 1 as part of a solar thermal receiver.

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