|Title of Invention||
|Abstract||The invention relates to a coating for temperable substrates, in particular of glass panes. This coating comprises for example directly on the substrate an StjN4 layer, thereon a CrN layer, thereon a Ti02 layer and lastly an StjN4 layer. To, The Controller of Patents The Patent Office Mumbai. -13-|
|Full Text|| FORM 2
THE PATENT ACT 1970 (39 of 1970)
The Patents Rules, 2003
(See Section 10, and rule 13)
TITLE OF INVENTION GLASS COATING
APPLIED MATERIALS GMBH & CO. KG
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed : -
The invention relates to a glass coating according to the preamble of patent claim.
Window glass is often provided with coatings which serve as a protection against the sun. These coatings comprise materials which reduce the transmission of visible light and largely reflect or absorb the heat-generating infrared rays. In countries with high insolation a very high proportion of the visible light is intentionally not allowed to pass. Panes are customarily offered for sale whose light transmission is approximately 8 to 50%.
Window glass, as a rule, is flat. However, there are also applications in which the window glass must be curved, for example in the case of round, semi-round or oval bay windows.
The process of coating bent glass uniformly is technically very difficult. For that reason attempts have been made to coat the glass first and to deform it subsequently. To deform a pane it must be heated to very high temperatures. During the heating, the coating is often damaged.
Brief heating to temperatures of approximately 700 0C with subsequent rapid cooling is also carried out with non-bent panes, if these are to acquire special properties, for example for reasons of safety, the property of shattering into small glass splinters in the event they are damaged. If these non-bent glasses are coated, the layers tend to peel off or form bubbles after they are heated. Due to the bubble formation, hazing of the window panes occurs, which, above approximately 0.5%, is perceived as disturbing.
The goal is therefore to provide coatings which upon heating of the glass do not peel off and do not form bubbles. Changes of the color values and changes of other optical properties are also undesirable.
A method for the production of bent and/or hardened coated glass is already known, in which the coating comprises at least one metal with an atomic number between 22 and 29, and a thin aluminum layer is applied over the coating (EP 0 301 755 B1).
A method for the production of heat-treated coated glass is furthermore known, in which first a solar control layer or an electrically conducting layer is applied onto a glass substrate. Upon it is applied a protective layer transparent in the range of visible light, which comprises a material from the group boron nitride, silicon
nitride, boronitride, siliconitride, carbon nitride, etc. (EP 0 546 302 B1 = DE 692 20 901 T2). The solar control layer here comprises a metal from the group including steel, titanium, chromium, zirconium, tantalum and hafnium and a nitride, boride or carbide of this metal. Onto the first protective layer a second protective layer can still be applied, which preferably comprises a metal oxide, for example titanium oxide or silicon oxide.
Furthermore, a coated glass is also known which can be exposed to heat treatments and which comprises a dielectric base layer, a metallic intermediate layer and an outer dielectric layer (EP 0 962429 Al). The base layer comprises here Si02, A1203, SiON, Si3N4 or AIN, while the intermediate layer comprises CrAl, CrSi and Si. The outer dielectric layer comprises Si3N4 or AIN or a mixture of the two.
Lastly, a heat-absorbing glass is also known, which includes a heat-absorbing film preferably comprised of a metal nitride or metal oxinitride (EP 0 530 676 BI = DE 69207 518 T2). Between the glass and the heat-absorbing film a transparent dielectric film, for example comprised of Si3N4, can additionally be provided.
The invention addresses the problem of providing a coating on a substrate which can withstand the temperature stresses during the bending of the substrate. This problem is solved through the characteristics of patent claim 1.
One advantage attained with the invention lies therein that the number of rejects in a mass production of coated substrates, which are subsequently bent through tempering, is very low. A further advantage of the invention is the realization of specific color values. In addition, the absorbing layer comprised of CrN, Cr, Ni, NiCr, NiCrN or NiCrOx itself is protected against impurities in the layer system during the tempering. Furthermore antireflection coating is attained resulting in low reflectance.
Embodiment examples of the invention are shown in the drawing and will be described in further detail in the following. In the drawing depict: Fig. 1 a glass coating comprised of four layers, Fig. 2 a glass coating comprised of five layers, Fig. 3 a glass coating comprised of five layers.
Figure 1 shows a coated substrate 1, which is comprised of the substrate 2 itself - for example glass - and a coating 7 including four layers 3 to 6. The four layers 3 to 6 are sequentially, starting with substrate 2, Si3N4, CrN, Ti02, Si3N4. Thus, disposed directly on the substrate 2 is first a layer 3 of Si3N4, on it a layer 4 of CrN, on it a layer 4 of CrN, on it a layer 5 of Ti02 and succeeding it a layer 6 of Si3N4.
The layers 3 and 6 have a thickness of 20 to 120 nm, while the layer 4 has a thickness of 5 to 40 nm. The layer 5 has a thickness of 4 to 120 nm.
In Fig. 2 is shown a further coated substrate 8 with a modified coating 9. The coating 9 differs from coating 7 in that between layers 3 and 4 a further layer 10 is inserted, which is comprised of Ti02 and has a layer thickness of 4 to 120 nm.
In the embodiment examples layer 5 can also be replaced by a suitable dielectric oxide layer other than Ti02, for example by Nb205. Instead of CrN as layer 4, NiCrN, NiCr or NiCrOx can also be employed. Of layers 3 and 6 at least one can be
comprised of SiNx, and can thus be a substoichiometric layer.
NiCrN or CrN are preferably sputtered in an argon atmosphere to which nitrogen has been added. In contrast, NiCrOx is preferably sputtered in an argon atmosphere with the addition of oxygen.
In Figure 3 is shown a further variant of a coating with five layers, in which a transparent SiNx layer 3 is succeeded by an Si02 layer 10.
It would also be possible to provide a semimetallic NiCoCr-N layer or a CoCrN layer or a substoichiometric NiCoCrNx or CoCrNx layer instead of an NiCrN layer 4.
The disposition of the two upper layers 5 and 6 is essential. The topmost layer 6 is comprised of Si3N4 and represents a chemically and mechanically highly stable layer. In addition; Si3N4 is temperature stable and can inhibit diffusing atoms and/or molecules, which can lead to concentrations of these molecules at the interface layer with layer 5. The Si3N4 layer acts virtually as a hard wall for diffusing foreign atoms. If these foreign atoms are for example Na+, this can lead to the liquefaction of the layer 5. The layer system would consequently no longer be thermally stable.
With an index of refraction n = 2.0 at a wavelength of X = 540 nm, Si3N4 can be considered to have low refractivity in comparison to Ti02.
Layer 5 comprised of Ti02 is also a chemically and mechanically stable layer, which, moreover, is temperature stable. Ti02 can absorb diffusing atoms/molecules, which leads to the concentration of these atoms/ molecules in the Ti02 layer. Ti02 acts practically like a sponge for diffusing foreign atoms, such as occur in particular in the temperature treatment of the layer system. With a refractive index of n = 2.4 - 2.6 at a wavelength X = 540 nm, Ti02 is among the high refractivity dielectric materials.
Since the Si3N4 layer and the Ti02 layer have different refractive indices, the sequence in which they occur is of great significance for the optical properties of the
combined layers 5 and 6. Exchanging the sequence of Ti02 and Si3N4 leads to entirely different optical properties. For example, antireflection depends strongly on the sequence of the dielectric layers. If the low refractivity dielectric layer is closer to the glass 2 than the high refractivity dielectric, reflection coating takes place. However, if the layers are reversed, antireflection coating is obtained.
By exchanging the two dielectric layers 5 and 6, a different color space also results. The combinations of color values, for example a*, B* and reflectivity, accessible with the particular layer sequences have only a small intersection. Therefore specific colors can only be attained with the combination according to the invention of the upper layers.
Layer 4 must be protected against Na+ ions which are emitted from the glass when a coated glass pane is heated. This task is assumed by layer 3, which is comprised for example of Si3N4. But, under thermal effects foreign atoms in layers 3 to 6,10 can also chemically change adjacent layers and even destroy them. It is known that Ti02 can bind foreign atoms very well without itself being destroyed. Hereby the absorbing layer 4 is protected.
It is especially important to keep oxygen away from layer 4. If oxygen enters this layer, the absorption of light changes drastically. If layer 4 is only embedded in Si3N4, this Si3N4 must not have any defects, for otherwise oxygen penetrates it. If, in contrast, an additional layer 5 is provided which can capture oxygen, the protective effect of the layers 3 and 5, embedding layer 4, is markedly increased. This is especially evident at the margin of a coated substrate 2, because here the oxygen also has the capacity of attacking layer 4 laterally. The Si3N4 layer can only act perpendicularly to its surface. Since the Ti02 layer 5 does not block oxygen but incorporates it, this layer 5 acts as a protection until it is saturated.
If the upper layers 5 and 6 are interchanged, into the Ti02 layer, which is now the topmost layer, oxygen and other foreign atoms, for example Na+, are incorporated
during the tempering. In this case at the barrier layer to the Si3N4 layer concentrations of oxygen and/or other foreign atoms can form, which, in the extreme case, can also destroy the Ti02 layer.
With the dispositions of layers 5 and 6 depicted in Fig. 1 and 2, in contrast, only a very small quantity of oxygen and/ or other foreign atoms passes through the barrier layer 6, such that only a small number of the atoms or molecules are incorporated into the Ti02 layer. Consequently, the Ti02 layer 5 has still some capacity available for absorbing internal impurities.
In the following the process parameters for the production of layers Si3N4, Ti02 and CrN will be described.
The Si3N4 layers were deposited from a polycrystalline Si target in an argon-nitrogen atmosphere. The layer thickness was varied through the transport rate. The dielectric titanium oxide layers were deposited from a metallic Ti target in an argon-oxygen atmosphere, while the semimetallic CrN or NiCrN layers were deposited from metallic Cr or NiCr targets in an argon- nitrogen atmosphere. The relevant process parameters are shown in the following Table:
Layer Ar [seem] N2 [seem] o2[seem] P[kW] U(V) I [A] Pressure [ u bar]
Si3N4 250 110 - 17.5 302 43.6 3.2
Ti02 280 - 90 24 305 48 2.7
CrN 150 25 - 5 392 12.7 2.6
Process parameters of the individual layers
P herein is the electric power, U the electric voltage and I the electric current of a sputter process. Ar, N2, 02 indicate the particular gas flow in seem: standard cubic centimeters per minute.
Samples of each layer system were produced and for 10 minutes exposed in a tempering furnace to a temperature of 700 °C for 10 minutes. All samples were
subjected to a Taber test. Before the stress tests the optical data and the scattered light component (haze) of the tempered and untempered samples were determined.
The changes of the optical values for the tested layer systems are summarized in the
Si3N4 Ti02 CrNx Ti02 Si3N4 Change through Tempering 'recess
Type SampleNo. Thick ness[A] Thick ness[A] Thick ness[A] Thick ness[A] Thickne ss[A] Ty AT b*T RyG a*R b*R
A 1 600 213 160 82 300 0,7 -1,3 -1,1 2,3 -1,2 -0,9
A 2 500 213 160 82 300 1,8 -1,6 -1,5 0,1 0,3 -2,8
A 3 600 213 160 82 300 1,7 -1,5 -1,2 0,6 0,0 -1,1
B 1 760 160 82 300 0,1 -1,4 0,0 2,7 -0,8 1,1
B 2 760 160 82 300 0,5 -1,6 1,1 2,2 -0,6 0,0
C 1 950 180 82 300 -4,7 0,1 -1,2 16,0 4,7 3,9
C 2 1000 180 82 300 -3,8 -0,8 -0,8 13,4 3,7 -0,5
C 3 640 160 82 300 -4,5 -1,0 -3,0 9,6 -0,2 7,5
Optical values and layer resistance before and after tempering(HT)
Ty is the light transmission of the colorimetric measure system Yxy (CIE 1931), RyG the glass- side light reflection Y of the colorimetric measure system Yx y (CIE 1931), thus the reflection of the uncoated substrate side. The values a* and b* are color coordinates corresponding to the L*a*b* system (CIELab Farbenraum, DESf 7174). Specifically, a*T or b*T are the respective a* or b* value of the transmission, while a*R or b*R indicate the a* respectively b* color value of the reflection. The CIELab system has three coordinate axes, which are at right angles to one another. L* is the brightness axis, a* the red-green axis and b* the yellow-blue axis.
Type A, type B and type C denote the tested samples with the following layer
Type A: glass / Si3N4 / T102 / CrN / Ti02 / Si3N4 (cf. Fig. 2)
Type B: glass / Si3N4 CrN / Ti02 / Si3N4 (cf. Fig. 1)
Type C: glass / Ti02 / CrN / Ti02 / Si3N4 (cf. Fig. 2 minus layer 3)
The tested layer systems of type A and B have only minor changes in the optical
data. This obviously does not apply to the counter-example C.
The Taber test provides information about the mechanical loading capacity of a
coating. The transmission is measured before and after the mechanical stress. An
increase of the transmission by more than 2% is not acceptable.
Si3N4 Ti02 CrNx TiO2 Si3N4
Type Sample No. Thicknesso[A] Thick ness[A] Thickn- ess[Al Thick nesso[A] Thick ness[A] AT before tempering AT after tempering
A 1 600 213 160 82 300 0.7 0.2
A 2 500 213 160 82 300 1.1 0.4
A 3 600 213 160 82 300 1.2 0.4
B 1 760 160 82 300 0.6 0.9
B 2 760 160 82 300 0.4 0.8
C 1 950 180 82 300 1.2 4
C 2 1000 180 82 300 1.8 2.6
C 3 640 160 82 300 1.7 3.1
Change of transmission through the Taber test before and after tempering
The coatings of type A and B pass the Taber test without problems. This applies especially to the tempered samples. The tempered samples of the layer system C do not pass the Taber test. AT indicates the difference of transmission of a sample after the Taber test minus the transmission of the sample before the Taber test. The Taber test is carried out on tempered and on untempered samples. Since the Taber test is a destructive test, the comparison "before tempering" and "after tempering" cannot be carried out on one and the same sample.
The third important parameter is the loss through scattering.
Si3N4 Ti02 CrNx Ti02 Si3N4
Type Sample No. Thickn ess [A] Thickne ssrA] Thickn ess [Al Thickn ess[A] Thickness [A] Hazebeforetempering Haze after tempering
A 1 600 213 160 82 300 0.33 0.49
A 2 500 213 160 82 300 0.27 0.44
A 3 600 213 160 82 300 0.40 0.43
B 1 760 160 82 300 0.31 0.4
B 2 760 160 82 300 0.48 0.44
C 2 1000 180 82 300 0.53 2.5
C 3 640 160 82 300 0.28 3.44
Scattered light component (haze) before and after tempering
These data also show: the layer system C is destroyed by the tempering process, while the layer systems of type A and B do not show an increased scattered light component after the tempering.
It was found in especially temperature-sensitive layer systems that graduated layers make possible a stepped adaptation of the physical parameters (especially of the coefficient of thermal expansion), which has an extremely advantageous effect on the thermal stability and, consequently, on the tempering process. This elasto-mechanical adaptation of the interfaces is known, for example from the field of production of glass fibers for optical telecommunication technology. In this case, the material dopings are also gradually adapted at interfaces in order to minimize mechanical tensions in glass forming processes (fiber drawing)
1. Substrate coating comprising a transparent Si3N4 or SiNx layer (3) directly on a substrate (2), a semimetallic layer (4) above the Si3N4 or SiNx layer (3) and with a further Si3N4 or SiNx layer (6) as well as with a dielectric oxide layer (5) from the group A1203, SnO, Ti02 and Si02, characterized in that the dielectric oxide layer (5) is disposed on the semimetallic layer (4) and the further Si3N4 layer (6) on the dielectric oxide layer (5).
2. Substrate coating as claimed in claim 1, characterized in that the semimetallic layer is a CrN layer.
3. Substrate coating as claimed in claim 1 , characterized in that between the transparent Si3N4 or SiNx layer (3) directly on the substrate (2) and the semimetallic layer (4) a dielectric oxide layer (10) is provided.
4. Substrate coating as claimed in claim 1 or claim 3, characterized in that for the substoichiometric SiNx layer, x is a number smaller than 4/3.
5. Substrate coating as claimed in claim 2, characterized in that, instead of the semimetallic CrN layer (4), a semimetallic NiCrN or NiCrOx layer is provided.
6. Substrate coating as claimed in one or several of the preceding claims, characterized in that the transparent Si3N4 or substoichiometric SiNx layers (3, 6) have each a layer thickness of 20 to 120 ran.
7. Substrate coating as claimed in one or several of the preceding claims, characterized in that the dielectric oxide layers (5, 10) have each a layer thickness of 4 to 120 run.
8. Substrate coating as claimed in one or several of the preceding claims, characterized in that the semimetallic NiCrN, CrN (4) or NiCrOx layers have a layer thickness of 5 to 40 ran.
9. Substrate coating as claimed in claim 1, characterized in that the substrate (2) is glass.
10. Substrate coating as claimed in claim 1, characterized in that the substrate (2) is a synthetic material.
11. Substrate coating as claimed in claim 1 , characterized in that additional layers comprised of Cr, Ni or NiCr are provided.
12. Substrate coating as claimed in claim 1, characterized in that the dielectric oxide layer s comprised Of Nb205.
Dated this 31st day of August, 2006
HIRAL CHANDRAKANT JOSHI
APPLIED MATERIALS GMBH & CO.KG
The invention relates to a coating for temperable substrates, in particular of glass panes. This coating comprises for example directly on the substrate an StjN4 layer, thereon a CrN layer, thereon a Ti02 layer and lastly an StjN4 layer.
The Controller of Patents
The Patent Office
|Indian Patent Application Number||1042/MUMNP/2006|
|PG Journal Number||35/2010|
|Date of Filing||31-Aug-2006|
|Name of Patentee||APPLIED MATERIALS GMBH & CO. KG|
|Applicant Address||SIEMENSTRASSE 100 D-63755 ALZENAU|
|PCT International Classification Number||C03C17/34|
|PCT International Application Number||PCT/EP04/003570|
|PCT International Filing date||2004-04-03|