U.S. patent application number 09/847663 was filed with the patent office on 2003-02-13 for heat treatable coated articles with metal nitride layer and methods of making same.
Invention is credited to Neuman, George, Stachowiak, Grzegorz, Wang, Hong.
Application Number | 20030031879 09/847663 |
Document ID | / |
Family ID | 25301185 |
Filed Date | 2003-02-13 |
United States Patent
Application |
20030031879 |
Kind Code |
A1 |
Neuman, George ; et
al. |
February 13, 2003 |
Heat treatable coated articles with metal nitride layer and methods
of making same
Abstract
A heat treatable coated article including a solar management
layer for reflecting infrared (IR) or the like, is provided between
a substrate and an overlying dielectric layer. An underlying
dielectric layer between the substrate and solar management layer
is optional. In certain embodiments, the solar management layer may
include NiCrN.sub.x while the dielectric layer(s) may include a
nitride such as silicon nitride. By nitriding the solar management
layer, it has been found that the resulting coated article is more
color stable upon heat treatment (HT). For example, the coated
article may have a .DELTA.E* value (transmissive and/or glass side
reflective) of no greater than 5.0, more preferably no greater than
4.0, and most preferably no greater than 3.0. Coated articles
herein may be used in the context of insulating glass (IG) window
units, vehicle windows, or the like.
Inventors: |
Neuman, George; (Ann Arbor,
MI) ; Stachowiak, Grzegorz; (Ann Arbor, MI) ;
Wang, Hong; (Belleville, MI) |
Correspondence
Address: |
NIXON & VANDERHYE P.C.
8th Floor
1100 North Glebe Road
Arlington
VA
22201-4714
US
|
Family ID: |
25301185 |
Appl. No.: |
09/847663 |
Filed: |
May 3, 2001 |
Current U.S.
Class: |
428/428 ;
428/698 |
Current CPC
Class: |
Y10T 428/12847 20150115;
Y10T 428/12944 20150115; C03C 17/3435 20130101 |
Class at
Publication: |
428/428 ;
428/698; 428/1 |
International
Class: |
B32B 017/06 |
Claims
What is claimed is:
1. A coated article comprising: a layer system supported by a glass
substrate, said layer system comprising a metal nitride inclusive
layer located between first and second dielectric layers, wherein
the second dielectric layer is at least partially nitrided and
positioned so that the metal nitride inclusive layer is between the
second dielectric layer and the glass substrate; and wherein said
coated article has a transmissive .DELTA.E*.sub.T value no greater
than 5.0 after at least about 5 minutes of heat treatment at a
temperature(s) of at least about 600 degrees C.
2. The coated article of claim 1, wherein said coated article has a
transmissive .DELTA.E*.sub.T value no greater than 4.0 after said
heat treatment.
3. The coated article of claim 1, wherein said coated article has a
transmissive .DELTA.E*.sub.T value no greater than 3.0 after said
heat treatment, and wherein the coated article has a transmissive
a* color value that is negative both before and after said heat
treatment.
4. The coated article of claim 1, wherein said coated article has a
transmissive .DELTA.a* value no greater than 1.3 following said
heat treatment.
5. The coated article of claim 4, wherein said coated article has a
transmissive .DELTA.a* value no greater than 1.1 following said
heat treatment.
6. The coated article of claim 5, wherein said coated article has a
transmissive .DELTA.a* value no greater than 0.8 following said
heat treatment.
7. The coated article of claim 1, wherein the coated article has a
transmissive a* color value that is negative both before and after
said heat treatment.
8. The coated article of claim 1, wherein said metal nitride
inclusive layer comprises NiCrN.sub.x.
9. The coated article of claim 8, wherein said second dielectric
layer comprises silicon nitride.
10. The coated article of claim 1, wherein said first dielectric
layer comprises silicon nitride and is from 30-250 {acute over
(.ANG.)} thick, said metal nitride inclusive layer comprises
NiCrN.sub.x and is from 20-600 {acute over (.ANG.)} thick, and said
second dielectric layer comprises silicon nitride and is from
100-500 {acute over (.ANG.)} thick.
11. The coated article of claim 10, wherein said first dielectric
layer is from 50-120 {acute over (.ANG.)} thick, said metal nitride
inclusive layer is from 50-350 {acute over (.ANG.)} thick, and said
second dielectric layer is from 210-310 {acute over (.ANG.)}
thick.
12. The coated article of claim 1, wherein the article is
characterized by the following transmissive color characteristics
before said heat treatment: a* 0.0 to -5.0 b* -2.0 to -15.0 L* 10.0
to 70.0.
13. The coated article of claim 12, wherein the article is
characterized by the following transmissive color characteristics
before said heat treatment: a* 0.0 to -2.0 b* -3.0 to -9.0 L* 20.0
to 50.0.
14. The coated article of claim 1, wherein the coated article has a
sheet resistance (R.sub.s) of no greater than 250 ohms/sq. after
said heat treatment, and wherein said heat treatment causes sheet
resistance of said coated article to decrease.
15. A coated article comprising: a layer system supported by a
glass substrate, said layer system comprising a metal nitride
inclusive layer located between said glass substrate and an at
least partially nitrided dielectric layer, wherein the metal
nitride comprises at least one of NiN.sub.x and CrN.sub.x and
contacts said dielectric layer; and wherein said coated article has
a glass side reflective .DELTA.E*.sub.G value no greater than 5.0
in view of thermal tempering including heat treating for at least
about 5 minutes.
16. The coated article of claim 15, wherein said coated article has
a .DELTA.E*.sub.G value no greater than 4.0 after said thermal
tempering.
17. The coated article of claim 16, wherein said coated article has
a .DELTA.E*.sub.G value no greater than 3.0 after heat treatment
comprising heat treatment for at least about 5 minutes at
temperature of at least about 600 degrees C., and wherein the
coated article has a glass side reflective a* color value that is
negative both before and after said heat treatment.
18. The coated article of claim 15, wherein said coated article has
a glass side reflective .DELTA.a* value no greater than 1.0
following said thermal tempering.
19. The coated article of claim 18, wherein said coated article has
a glass side reflective .DELTA.a* value no greater than 0.6
following said thermal tempering.
20. The coated article of claim 18, wherein said coated article has
a glass side reflective .DELTA.a* value no greater than 0.3
following said thermal tempering.
21. The coated article of claim 15, wherein the coated article has
a glass side reflective a* color value that is negative both before
and after said thermal tempering.
22. The coated article of claim 15, wherein said metal nitride
inclusive layer comprises NiCrN.sub.x.
23. The coated article of claim 15, wherein said dielectric layer
is in contact with said metal nitride inclusive layer and comprises
silicon nitride.
24. The coated article of claim 15, wherein the coated article has
a sheet resistance (R.sub.s) of no greater than 500 ohms/sq. after
said thermal tempering, and an wherein said thermal tempering
causes sheet resistance of said coated article to decrease.
25. A coated article comprising: a layer system supported by a
glass substrate, said layer system comprising a NiCrN.sub.x
inclusive layer wherein at least 50% of the Cr is nitrided, said
NiCrN.sub.x inclusive layer being located between and contacting
first and second dielectric layers, wherein the second dielectric
layer is at least partially nitrided and positioned so that the
NiCrN.sub.x inclusive layer is between the second dielectric layer
and the glass substrate; and wherein said coated article has a
transmissive .DELTA.E*.sub.T value no greater than 5.0 following or
due to heat treatment.
26. The coated article of claim 25, wherein said NiCrN.sub.x
inclusive layer is sufficiently nitrided so that the coated article
has a .DELTA.E* <=4.0 following heat treatment for at least
about 5 minutes at temperature of at least 600 degrees C.
27. A method of making a coated article, the method comprising:
providing a glass substrate; depositing a metal on the substrate in
an atmosphere including a significant amount of nitrogen in order
to form a metal nitride inclusive layer on the glass substrate;
depositing a dielectric nitride inclusive layer on the substrate
over the metal nitride inclusive layer; and heat treating the
article which includes at least the metal nitride inclusive layer
and the dielectric nitride inclusive layer for at least 5 minutes,
the metal nitride inclusive layer being nitrided to an extent so
that after said heat treating the article has a .DELTA.E value of
no greater than 5.0.
28. The method of claim 27, wherein the article has a .DELTA.E
value of no greater than 4.0.
29. The method of claim 28, wherein the article has a .DELTA.E
value of no greater than 3.0.
30. The method of claim 27, further comprising depositing another
dielectric layer onto the substrate, so that the metal nitride
inclusive layer is deposited onto the substrate over the another
dielectric layer.
31. The method of claim 27, where the metal nitride inclusive layer
comprises NiCrN.sub.x, and wherein the dielectric nitride comprises
silicon nitride.
32. The method of claim 27, wherein the .DELTA.E value is
transmissive or glass side reflective.
33. The method of claim 27, wherein the metal nitride comprises
CrN.sub.x.
34. A coated article comprising: a layer system supported by a
glass substrate, said layer system comprising a metal nitride
inclusive layer located between first and second dielectric layers,
wherein the second dielectric layer is at least partially nitrided
and positioned so that the metal nitride inclusive layer is between
the second dielectric layer and the glass substrate; and wherein
said coated article has a transmissive .DELTA.a* value no greater
than 1.1 after at least about 5 minutes of heat treatment at
temperature of at least about 600 degrees C.
35. The coated article of claim 34, wherein said coated article has
a transmissive .DELTA.a* value no greater than 0.8 after at least
about 5 minutes of heat treatment at temperature of at least about
600 degrees C.
36. A method of making a coated article, the method comprising:
providing a glass substrate; depositing a metal on the substrate in
an atmosphere including a significant amount of nitrogen in order
to form a metal nitride inclusive layer on the glass substrate;
depositing a dielectric nitride inclusive layer on the substrate
over the metal nitride inclusive layer; and heat treating the
article which includes at least the metal nitride inclusive layer
and the dielectric nitride inclusive layer for at least 5 minutes,
the metal nitride inclusive layer being nitrided to an extent so
that after said heat treating the article has a transmissive
.DELTA.a* value of no greater than 1.1.
37. The coated article of claim 1, wherein said coated article has
a glass side reflective .DELTA.b*.sub.G value no greater than 1.1
following said heat treatment.
38. The coated article of claim 1, wherein said coated article has
a glass side reflective .DELTA.b*.sub.G value no greater than 0.7
following said heat treatment.
39. The coated article of claim 15, wherein said coated article has
a glass side reflective .DELTA.b*.sub.G value no greater than 1.1
following said thermal tempering.
40. The coated article of claim 25, wherein said coated article has
a glass side reflective .DELTA.b*.sub.G value no greater than 1.1
following said heat treatment.
41. A coated article comprising: a layer system supported by a
glass substrate, said layer system comprising a metal nitride
inclusive layer located between first and second dielectric layers,
wherein the second dielectric layer is at least partially nitrided
and positioned so that the metal nitride inclusive layer is between
the second dielectric layer and the glass substrate; and wherein
said coated article has a glass side reflective .DELTA.b*.sub.G
value no greater than 1.1 after at least about 5 minutes of heat
treatment at temperature of at least about 600 degrees C.
42. The coated article of claim 41, wherein said coated article has
a glass side reflective .DELTA.b*.sub.G value no greater than 0.7
following said heat treatment.
Description
[0001] This invention relates to coated articles that have
approximately the same color characteristics as viewed by the naked
eye before and after heat treatment (e.g., thermal tempering), and
corresponding methods. Such coated articles may be used in
insulating glass (IG) units, vehicle windows, and/or other suitable
applications.
BACKGROUND OF THE INVENTION
[0002] The need for color matchability of coated articles (before
heat treatment vs. after heat treatment) is known. Glass substrates
are often produced in large quantities and cut to size in order to
fulfill the needs of a particular situation such as a new
multi-window and door office building, vehicle window needs, etc.
It is often desirable in such applications that some of the windows
and/or doors be heat treated (i.e., tempered, heat strengthened or
bent), while others need not be. Office buildings often employ IG
units and/or laminates for safety and/or thermal control. It is
often desirable that the units and/or laminates which are heat
treated (HT) substantially match their non-heat treated
counterparts (e.g., with regard to color, reflectance, and/or the
like) for architectural and/or aesthetic purposes.
[0003] U.S. Pat. No. 5,376,455 discloses a coated article
including: glass/Si.sub.3N.sub.4/NiCr/Ag/NiCr/Si.sub.3N.sub.4.
Unfortunately, the coating system of the '455 patent is not
sufficiently color matchable after heat treatment with its
non-heat-treated counterpart. In other words, the coating system of
the '455 patent has a rather high .DELTA.E value. This means that,
unfortunately, two different coated articles with different
coatings (one to be heat treated, the other not to be) must be made
for customers who want their heat-treated and non-heat-treated
coated articles to approximately match colorwise as viewed by the
naked eye.
[0004] As with the '455 patent, it has mostly been possible to
achieve matchability only by providing two different layer systems,
one of which is heat treated (HT) and the other is not. The
necessity of developing and using two different layer systems to
achieve matchability creates additional manufacturing expense and
inventory needs which are undesirable.
[0005] However, commonly owned U.S. Pat. No. 5,688,585 discloses a
solar control coated article including
glass/Si.sub.3N.sub.4/NiCr/Si.sub.3N.sub- .4, wherein matchability
is achieved with a single layer system. As explained at column 9 of
the '585 patent, it is a "requirement" of the '585 invention that
the NiCr layer be substantially free of any nitride. An object of
the '585 patent is to provide a sputter coated layer system that
after heat treatment is matchable colorwise with its
non-heat-treated counterpart. However, the '585 patent uses a heat
treatment (HT) of only three (3) minutes (col. 10, line 55). Longer
heat treatments are often desired in order to attain better
tempering or HT characteristics. Unfortunately, as explained below,
it has been found that with longer HT times the coatings of the
'585 patent cannot maintain low .DELTA.E values and thus lose color
matchability. In particular, it has surprisingly been found by the
instant inventor that in coatings such as that of the '585 patent,
.DELTA.E values jump significantly upward after HT for 4-5 minutes
at a temperature of from about 600 to 800 degrees C.
[0006] Consider the following layer stack (see Example 7 below):
glass/Si.sub.3N.sub.4/NiCr/ Si.sub.3N.sub.4, where the underlayer
of Si.sub.3N.sub.4 is about 50-70 {acute over (.ANG.)} (angstroms)
thick, the NiCr layer is about 325 {acute over (.ANG.)} thick (the
NiCr layer is not nitrided as deposited as can be seen in FIG. 15),
and the overcoat of Si.sub.3N.sub.4 is about 210-310 {acute over
(.ANG.)} thick. As explained in Example 7 below, this coated
article has a rather high transmissive .DELTA.E* value of about 5.9
after a heat treatment (HT) at 625 degrees C. for ten (10) minutes.
This high transmissive .DELTA.E value means that a HT version of
the '585 coated article does not approximately match colorwise
non-heat-treated counterpart versions with regard to transmissive
color after 10 minutes of HT. This is not desirable.
[0007] The instant inventor believes that the high .DELTA.E* value
associated with the coating of Example 7 herein is caused for at
least the following reasons. FIG. 15 is an XPS plot illustrating
the Example 7 coating before heat treatment (HT), while FIG. 16
illustrates the Example 7 coating after HT. As shown in FIG. 15,
before heat treatment the three different layers are fairly
separate and distinct. For example, prior to HT it can be seen that
the Ni slopes 3 on either side of the NiCr layer are very steep, as
are the Si and N slopes 5 and 7, respectively, on the lower side of
the upper Si.sub.3N.sub.4 layer. Therefore, the vast majority of
the Ni is located in the NiCr layer and the vast majority of the Si
and N from the upper Si.sub.3N.sub.4 layer is located in that
layer. However, FIG. 16 illustrates that when the FIG. 15 coated
article of Example 7 is heat treated (HT) for 10 minutes as
discussed above, a significant portion of the Ni from the NiCr
layer migrates into the upper Si.sub.3N.sub.4 layer. Additionally,
upon HT a significant portion of the Si and N from the upper
Si.sub.3N.sub.4 layer migrates into the NiCr layer. In other words,
the interface between the metal NiCr layer and the upper
Si.sub.3N.sub.4 layer becomes blurred and non-distinct. This is
evidenced in FIG. 16 by the less steep slope 3a of the Ni on the
upper/outer side of the NiCr layer, and by the less steep slopes 5a
and 7a of the Si and N on the lower side of the upper
Si.sub.3N.sub.4 layer. Still further, it can be seen by comparing
FIGS. 15 and 16 that HT causes a significant amount of the Cr in
the NiCr layer to migrate within that layer toward the upper side
thereof so that it is not as uniformly distributed compared to
pre-HT.
[0008] Unfortunately, the aforesaid migrations of the Si, N, Ni and
Cr from their FIG. 15 positions to their respective FIG. 16
positions due to HT causes significant color shifting to occur and
thus explains the large transmissive .DELTA.E* value associated
with the coating of Ex. 7, and thus with coatings of the '585
patent when exposed to lengthy heat treatments.
[0009] In view of the above, it will be apparent to those skilled
in the art that there exists a need for a coating or layer system
that has a low .DELTA.E (or .DELTA.E*) value(s) (transmissive
and/or glass side reflective) and thus good color matchability
characteristics after at least five (5) minutes of heat treatment
(HT). It is a purpose of this invention to fulfill the above-listed
need, and/or other needs which will become more apparent to the
skilled artisan once given the following disclosure.
SUMMARY OF THE INVENTION
[0010] An object of this invention is to provide a coating or layer
system that has good color stability (i.e., a low .DELTA.E*
value(s)) with heat treatment (HT).
[0011] Another object of this invention is to provide a coating or
layer system having a .DELTA.E* value (transmissive and/or glass
side reflective) no greater than 5.0 (more preferably no greater
than 4.0, and most preferably no greater than 3.0) upon heat
treatment (HT) at a temperature of at least about 600 degrees C.
for a period of time of at least 5 minutes (more preferably at
least 7 minutes, and most preferably at least 9 minutes).
[0012] Another object of this invention is to nitride a Ni and/or
Cr inclusive layer (e.g., a NiCr layer) to an extent so as to
enable the resulting coated article to have the aforesaid low
.DELTA.E value(s).
[0013] Another object of this invention is to fulfill one or more
of the above-listed objects.
[0014] Generally speaking, certain example embodiments of this
invention fulfill one or more of the above listed objects and/or
needs by providing a coated article comprising:
[0015] a layer system supported by a glass substrate, said layer
system comprising a metal nitride inclusive layer located between
first and second dielectric layers, wherein the second dielectric
layer is at least partially nitrided and positioned so that the
metal nitride inclusive layer is between the second dielectric
layer and the glass substrate; and
[0016] wherein said coated article has a transmissive
.DELTA.E*.sub.T value no greater than 5.0 after at least about 5
minutes of heat treatment at a temperature(s) of at least about 600
degrees C.
[0017] Certain other example embodiments of this invention fulfill
one or more of the above-listed objects and/or needs by providing a
coated article comprising:
[0018] a layer system supported by a glass substrate, said layer
system comprising a metal nitride inclusive layer located between
said glass substrate and an at least partially nitrided dielectric
layer, wherein the metal nitride comprises at least one of
NiN.sub.x and CrN.sub.x and contacts said dielectric layer; and
[0019] wherein said coated article has a glass side reflective
.DELTA.E*.sub.G value no greater than 5.0 in view of thermal
tempering including heat treating for at least about 5 minutes.
[0020] Certain other example embodiments of this invention fulfill
one or more of the above-listed objects and/or needs by providing a
coated article comprising:
[0021] a layer system supported by a glass substrate, said layer
system comprising a NiCrN.sub.x inclusive layer wherein at least
50% of the Cr is nitrided, said NiCrN.sub.x inclusive layer being
located between and contacting first and second dielectric layers,
wherein the second dielectric layer is at least partially nitrided
and positioned so that the NiCrN.sub.x inclusive layer is between
the second dielectric layer and the glass substrate; and
[0022] wherein said coated article has a transmissive
.DELTA.E*.sub.T value no greater than 5.0 following or due to heat
treatment.
[0023] Still further example embodiments of this invention fulfill
one or more of the above-listed objects and/or needs by providing a
method of making a coated article, the method comprising:
[0024] providing a glass substrate;
[0025] depositing (e.g., via sputtering or any other suitable
method/technique) a metal on the substrate in an atmosphere
including a significant amount of nitrogen in order to form a metal
nitride inclusive layer on the glass substrate;
[0026] depositing (e.g., via sputtering or any other suitable
method/technique) a dielectric nitride inclusive layer on the
substrate over the metal nitride inclusive layer; and
[0027] heat treating the article which includes at least the metal
nitride inclusive layer and the dielectric nitride inclusive layer
for at least 5 minutes, the metal nitride inclusive layer being
nitrided to an extent so that after said heat treating the article
has a .DELTA.E value of no greater than 5.0.
[0028] This invention will now be described with respect to certain
embodiments thereof as illustrated in the following drawings,
wherein:
IN THE DRAWINGS
[0029] FIG. 1 is a partial side cross sectional view of an
embodiment of a coated article (heat treated or not heat treated)
according to an example embodiment of this invention.
[0030] FIG. 2 is a partial cross-sectional view of an IG unit as
contemplated by this invention, in which the coating or layer
system of FIG. 1 may be used.
[0031] FIG. 3 is an x-ray photoelectron spectroscopy (XPS) graph
illustrating the atomic % of components N, O, Na, Al, Si, Ca, Cr,
and Ni throughout the thickness of a layer system according to
Example 1 of this invention (before heat treatment), where the
"depth" axis refers to the depth into the coating and/or substrate
from the exterior surface thereof as compared to the depth into a
conventional SiO.sub.2 layer that would have been achieved over the
same period of time (i.e., the {acute over (.ANG.)} depth is not
actual depth, but instead is how deep into a reference SiO.sub.2
layer sputtering would have reached over the corresponding
time).
[0032] FIG. 4 is an XPS graph illustrating the atomic % of
components N, O, Na, Al, Si, Ca, Cr, and Ni throughout the
thickness of the layer system according to Example 1 of this
invention after heat treatment at 625 degrees C. for 10
minutes.
[0033] FIG. 5 is an x-ray photoelectron spectroscopy (XPS) graph
illustrating the atomic % of components N, O, Na, Al, Si, Ca, Cr,
and Ni throughout the thickness of a layer system according to
Example 2 of this invention (before heat treatment), where the
"depth" axis refers to the depth into the coating and/or substrate
from the exterior surface thereof as compared to the depth into a
conventional SiO.sub.2 layer that would have been achieved over the
same period of time.
[0034] FIG. 6 is an XPS graph illustrating the atomic % of
components N, O, Na, Al, Si, Ca, Cr, and Ni throughout the
thickness of the layer system according to Example 2 of this
invention after heat treatment at 625 degrees C. for 10
minutes.
[0035] FIG. 7 is an x-ray photoelectron spectroscopy (XPS) graph
illustrating the atomic % of components N, O, Na, Al, Si, Ca, Cr,
and Ni throughout the thickness of a layer system according to
Example 3 of this invention (before heat treatment), where the
"depth" axis refers to the depth into the coating and/or substrate
from the exterior surface thereof as compared to the depth into a
conventional SiO.sub.2 layer that would have been achieved over the
same period of time.
[0036] FIG. 8 is an XPS graph illustrating the atomic % of
components N, O, Na, Al, Si, Ca, Cr, and Ni throughout the
thickness of the layer system according to Example 3 of this
invention after heat treatment at 625 degrees C. for 10
minutes.
[0037] FIG. 9 is an x-ray photoelectron spectroscopy (XPS) graph
illustrating the atomic % of components N, O, Na, Al, Si, Ca, Cr,
and Ni throughout the thickness of a layer system according to
Example 4 of this invention (before heat treatment), where the
"depth" axis refers to the depth into the coating and/or substrate
from the exterior surface thereof as compared to the depth into a
conventional SiO.sub.2 layer that would have been achieved over the
same period of time.
[0038] FIG. 10 is an XPS graph illustrating the atomic % of
components N, O, Na, Al, Si, Ca, Cr, and Ni throughout the
thickness of the layer system according to Example 4 of this
invention after heat treatment at 625 degrees C. for 10
minutes.
[0039] FIG. 11 is an x-ray photoelectron spectroscopy (XPS) graph
illustrating the atomic % of components N, O, Na, Al, Si, Ca, Cr,
and Ni throughout the thickness of a layer system according to
Example 5 of this invention (before heat treatment), where the
"depth" axis refers to the depth into the coating and/or substrate
from the exterior surface thereof as compared to the depth into a
conventional SiO.sub.2 layer that would have been achieved over the
same period of time.
[0040] FIG. 12 is an XPS graph illustrating the atomic % of
components N, O, Na, Al, Si, Ca, Cr, and Ni throughout the
thickness of the layer system according to Example 5 of this
invention after heat treatment at 625 degrees C. for 10
minutes.
[0041] FIG. 13 is an x-ray photoelectron spectroscopy (XPS) graph
illustrating the atomic % of components N, O, Na, Al, Si, Ca, Cr,
and Ni throughout the thickness of a layer system according to
Example 6 of this invention (before heat treatment), where the
"depth" axis refers to the depth into the coating and/or substrate
from the exterior surface thereof as compared to the depth into a
conventional SiO.sub.2 layer that would have been achieved over the
same period of time.
[0042] FIG. 14 is an XPS graph illustrating the atomic % of
components N, O, Na, Al, Si, Ca, Cr, and Ni throughout the
thickness of the layer system according to Example 6 of this
invention after heat treatment at 625 degrees C. for 10
minutes.
[0043] FIG. 15 is an x-ray photoelectron spectroscopy (XPS) graph
illustrating the atomic % of components N, O, Na, Al, Si, Ca, Cr,
and Ni throughout the thickness of a layer system according to
Example 7 of this invention (before heat treatment), where the
"depth" axis refers to the depth into the coating and/or substrate
from the exterior surface thereof as compared to the depth into a
conventional SiO.sub.2 layer that would have been achieved over the
same period of time.
[0044] FIG. 16 is an XPS graph illustrating the atomic % of
components N, O, Na, Al, Si, Ca, Cr, and Ni throughout the
thickness of the layer system according to Example 7 of this
invention after heat treatment at 625 degrees C. for 10
minutes.
[0045] FIG. 17 is an x-ray photoelectron spectroscopy (XPS) graph
illustrating the atomic % of components N, O, Na, Al, Si, Ca, Cr,
and Ni throughout the thickness of a layer system according to
Example 8 of this invention (before heat treatment), where the
"depth" axis refers to the depth into the coating and/or substrate
from the exterior surface thereof as compared to the depth into a
conventional SiO.sub.2 layer that would have been achieved over the
same period of time.
[0046] FIG. 18 is an XPS graph illustrating the atomic % of
components N, O, Na, Al, Si, Ca, Cr, and Ni throughout the
thickness of the layer system according to Example 8 of this
invention after heat treatment at 625 degrees C. for 10
minutes.
[0047] FIG. 19 is an x-ray photoelectron spectroscopy (XPS) graph
illustrating the atomic % of components N, O, Na, Al, Si, Ca, Cr,
and Ni throughout the thickness of a layer system according to
Example 9 of this invention (before heat treatment), where the
"depth" axis refers to the depth into the coating and/or substrate
from the exterior surface thereof as compared to the depth into a
conventional SiO.sub.2 layer that would have been achieved over the
same period of time.
[0048] FIG. 20 is an XPS graph illustrating the atomic % of
components N, O, Na, Al, Si, Ca, Cr, and Ni throughout the
thickness of the layer system according to Example 9 of this
invention after heat treatment at 625 degrees C. for 10
minutes.
[0049] FIG. 21 is an x-ray photoelectron spectroscopy (XPS) graph
illustrating the atomic % of components N, O, Na, Al, Si, Ca, Cr,
and Ni throughout the thickness of a layer system according to
Example 10 of this invention (before heat treatment), where the
"depth" axis refers to the depth into the coating and/or substrate
from the exterior surface thereof as compared to the depth into a
conventional SiO.sub.2 layer that would have been achieved over the
same period of time.
[0050] FIG. 22 is an XPS graph illustrating the atomic % of
components N, O, Na, Al, Si, Ca, Cr, and Ni throughout the
thickness of the layer system according to Example 10 of this
invention after heat treatment at 625 degrees C. for 10
minutes.
DETAILED DESCRIPTION OF CERTAIN EXAMPLE EMBODIMENTS OF THE
INVENTION
[0051] Certain embodiments of this invention provide a coating or
layer system that may be used in applications such as IG units,
vehicle windows, architectural windows, and/or other suitable
applications. Certain embodiments of this invention provide a layer
system that has excellent color stability (i.e., a low value of
.DELTA.E* and/or a low value of .DELTA.a*; where .DELTA. is
indicative of change in view of HT) with heat treatment (e.g.,
thermal tempering, bending, or thermal heat strengthening)
monolithically and/or in the context of dual pane environments such
as IG units or windshields. Such heat treatments often necessitate
heating the coated substrate to temperatures from about 600.degree.
C. up to about 800.degree. C. for at least about 5 minutes.
[0052] FIG. 1 is a side cross sectional view of a coated article
according to an example embodiment of this invention. The coated
article includes substrate 11 (e.g., clear, green, bronze, grey,
blue, or blue-green glass substrate from about 1.0 to 12.0 mm
thick), optional first dielectric layer 13 (e.g., of or including
silicon nitride (e.g., Si.sub.3N.sub.4), titanium dioxide, titanium
nitride, zirconium nitride, silicon oxynitride, or the like), IR
reflecting nickel (Ni) or nickel-chrome inclusive layer 15 that is
nitrided (e.g., NiCrN.sub.x), and second nitrided dielectric layer
17 (e.g., of or including silicon nitride (e.g., Si.sub.3N.sub.4),
titanium nitride, zirconium nitride, silicon oxynitride, aluminum
nitride, or the like). Thus, the coating system 19 includes metal
nitride layer 15 located between (directly or indirectly) a pair of
dielectric anti-reflection layers 13 and 17. Underlayer 13 is
optional, and upper dielectric layer 17 is preferably at least
partially nitrided.
[0053] Surprisingly, it has been found that coatings according to
this invention can be made more color stable with heat treatment
(HT) if layer 15 is nitrided during the deposition process (e.g.,
the layer is nitrided so as to be deposited as NiCrN.sub.x). It is
believed that by at least partially nitriding layer 15 during the
deposition process (i.e., so that it is nitrided to some
significant extent prior to HT), migration of N, Cr, and/or Ni can
be reduced during HT thereby enabling the resulting coated article
to be more color-stable with HT (i.e., have a lower .DELTA.E*
value(s)). Metal in metal nitride layer 15 may or may not be fully
nitrided in different embodiments of this invention. For example,
metal such as Cr in layer 15 may be at least about 40% nitrided in
certain embodiments of this invention, more preferably at least
about 50% nitrided, even more preferably at least about 60%
nitrided, and most preferably at least about 75% nitrided. When
layer 15 is NiCrN.sub.x, it is believed that the layer includes at
least Ni and CrN.sub.x. In alternative embodiments of this
invention, layer 15 may be an oxynitride layer (e.g., a metal
oxynitride). Thus, metal nitride layer 15 may or may not include
amounts of oxide in different embodiments of this invention.
[0054] In certain preferred embodiments of this invention,
dielectric anti-reflection layers 13 and 17 each have an index of
refraction less than that of metal nitride layer 15 for
anti-reflective purposes (e.g., silicon nitride layers 13 and 17
may have an index of refraction "n" of from about 1.9 to 2.1, while
the metal nitride layer 19 has an index "n" higher than that).
[0055] Other layer(s) below or above the illustrated coating system
19 may also be provided. Thus, while the layer system 19 is "on" or
"supported by" substrate 11 (directly or indirectly), other
layer(s) may be provided therebetween. Thus, for example, the layer
system 19 of FIG. 1 is considered "on" the substrate 11 even when
other layer(s) are provided therebetween.
[0056] In embodiments of this invention where layers 13 and 17
comprise silicon nitride (e.g., Si.sub.3N.sub.4), sputtering
targets including Si employed to form these layers may be admixed
with up to 6-20% by weight aluminum or stainless steel (e.g.
SS#316), with about this amount then appearing in the layers so
formed. Moreover, while layer 15 may be NiCrN.sub.x, NiN.sub.x, or
CrN.sub.x in certain embodiments of this invention, these materials
are not limiting and other IR reflecting metal nitrides may instead
be used. In NiCrN.sub.x embodiments, any suitable ratio of Ni:Cr
may be used. For example, the Ni:Cr ratio in this layer may be
50:50 in certain embodiments, may be 80:20 in other embodiments,
and may be 90:10 or any other suitable ratio in still other
embodiments.
[0057] FIG. 2 illustrates the coating or layer system 19 of FIG. 1
being utilized on surface #2 of an IG (insulating glass) window
unit. In order to differentiate the "inside" of the IG unit from
its "outside", the sun 21 is schematically presented on the
outside. The IG unit includes outside glass pane or sheet 11 and
inside glass pane or sheet 23. These two glass substrates (e.g.,
float glass 2 mm to 12 mm thick) are sealed at their peripheral
edges by a conventional sealant (not shown) and are provided with a
conventional desiccant strip (not shown). The panes are then
retained in a conventional window or door retaining frame. By
sealing the peripheral edges of the glass sheets and replacing the
air in insulating space (or chamber) 25 with a gas such as argon, a
high insulating value IG unit is formed. Optionally, insulating
space 25 may be at a pressure less than atmospheric pressure in
certain alternative embodiments, although this of course is not
necessary in all IG embodiments. Coating 19 may be provided on the
inner wall of substrate 11 in certain embodiments of this invention
(as in FIG. 2), and/or on the inner wall of substrate 23 in other
embodiments of this invention.
[0058] Turning back to FIG. 1, while various thicknesses may be
used consistent with one or more of the objects and/or needs
discussed herein, according to certain exemplary embodiments of
this invention, the preferred thicknesses and materials for the
respective layers on the glass substrate 11 are as follows:
1TABLE 1 (Thicknesses) Layer Preferred Range (.ANG.) More Preferred
(.ANG.) Si.sub.3N.sub.4 (layer 13) 30-250 .ANG. 50-120 .ANG.
NiCrN.sub.x (layer 15) 20-600 .ANG. 50-350 .ANG. Si.sub.3N.sub.4
(layer 17) 100-500 .ANG. 210-310 .ANG.
[0059] In certain exemplary embodiments, the color stability with
lengthy HT due at least to the nitriding of layer 15 results in
substantial matchability between heat-treated and non-heat treated
versions of the coating or layer system. In other words, in
monolithic and/or IG applications, in certain embodiments of this
invention two glass substrates having the same coating system
thereon (one HT after deposition and the other not HT) appear to
the naked human eye to look substantially the same.
[0060] The values .DELTA.E* and .DELTA.a* are important in
determining whether or not there is matchability, or substantial
color matchability upon HT, in the context of this invention. Color
herein is described by reference to the conventional a*, b* values.
The term .DELTA.a* is simply indicative of how much color value a*
changes due to HT.
[0061] The term .DELTA.E* (and .DELTA.E) is well understood in the
art and is reported, along with various techniques for determining
it, in ASTM 2244-93 as well as being reported in Hunter et. al.,
The Measurement of Appearance, 2.sup.nd Ed. Cptr. 9, page 162 et
seq. [John Wiley & Sons, 1987]. As used in the art, .DELTA.E*
(and .DELTA.E) is a way of adequately expressing the change (or
lack thereof) in reflectance and/or transmittance (and thus color
appearance, as well) in an article after or due to HT. .DELTA.E may
be calculated by the "ab" technique, or by the Hunter technique
(designated by employing a subscript "H"). .DELTA.E corresponds to
the Hunter Lab L, a, b scale (or L.sub.h, a.sub.h, b.sub.h).
Similarly, .DELTA.E* corresponds to the CIE LAB Scale L*, a*, b*.
Both are deemed useful, and equivalent for the purposes of this
invention. For example, as reported in Hunter et. al. referenced
above, the rectangular coordinate/scale technique (CIE LAB 1976)
known as the L*, a*, b* scale may be used, wherein:
[0062] L* is (CIE 1976) lightness units
[0063] a* is (CIE 1976) red-green units
[0064] b* is (CIE 1976) yellow-blue units
[0065] and the distance .DELTA.E* between L*.sub.oa*.sub.ob*.sub.o
and L*.sub.1a*.sub.1b*.sub.1 is:
.DELTA.E*=[(.DELTA.L*).sup.2+(.DELTA.a*).sup.2+(.DELTA.b*).sup.2].sup.1/2
(1)
[0066] where:
.DELTA.L*=L*.sub.1-L*.sub.o (2)
.DELTA.a*=a*.sub.1-a*.sub.o (3)
.DELTA.b*=b*.sub.1-b*.sub.o (4)
[0067] where the subscript "o" represents the coating (or coated
article) before heat treatment and the subscript "1" represents the
coating (coated article) after heat treatment; and the numbers
employed (e.g., a*, b*, L*) are those calculated by the aforesaid
(CIE LAB 1976) L*, a*, b* coordinate technique. In a similar
manner, .DELTA.E may be calculated using equation (1) by replacing
a*, b*, L* with Hunter Lab values a.sub.h, b.sub.h, L.sub.h. Also
within the scope of this invention and the quantification of
.DELTA.E* are the equivalent numbers if converted to those
calculated by any other technique employing the same concept of
.DELTA.E* as defined above.
[0068] In certain example non-limiting embodiments of this
invention, coatings or layer systems herein provided on clear
monolithic glass substrates have reflective color as follows before
heat treatment, as viewed from the glass side of the coated article
(R.sub.G %):
2TABLE 2a Glass Side Reflective Color (R.sub.G) Before Heat
Treatment General Preferred a* +2.0 to -8.0 0.0 to -2.5 b* -2.0 to
+8.0 0.0 to +3.0 L* 10.0 to 75.0 20.0 to 70.3
[0069] Regarding transmissive color, in certain non-limiting
embodiments of this invention, coatings or layer systems herein
provided on clear monolithic glass substrates have transmissive
color as follows before heat treatment:
3TABLE 2b Transmissive Color Before Heat Treatment General
Preferred a* 0.0 to -5.0 0.0 to -2.0 b* -2.0 to -15.0 -3.0 to -9.0
L* 10.0 to 70.0 20.0 to 50.0
[0070] After heat treatment (HT), in certain embodiments of this
invention layer systems-provided on clear monolithic glass
substrates have color characteristics .DELTA.E*, and .DELTA.a*, and
.DELTA.b* as follows, when viewed from the glass (G) side (as
opposed to the layer side) of the coated article:
4TABLE 3a Reflective Glass Side Color
(.DELTA.E*.sub.G.DELTA.a*.sub.G & .DELTA.b*.sub.G After Heat
Treatment General Preferred Most Preferred .DELTA.E*.sub.G is
<=5.0 <=4.0 <=3.0 .DELTA.a*.sub.G is <=1.0 <=0.6
<=0.3 .DELTA.b*.sub.G is <=1.1 <=0.7 <=0.4
[0071] As for transmissive color characteristics, after HT in
certain embodiments of this invention layer systems provided on
clear monolithic glass substrates have transmissive color
characteristics .DELTA.E*, .DELTA.a* and .DELTA.b* as follows:
5TABLE 3b Transmissive Color Characteristics (.DELTA.E*.sub.T &
.DELTA.a*.sub.T) After HT General Preferred Most Preferred
.DELTA.E*.sub.T is <=5.0 <=4.0 <=3.0 .DELTA.a*.sub.T is
<=1.3 <=1.1 <=0.8 .DELTA.b*.sub.T is <=6.0 <=4.0
<=3.0
[0072] Accordingly, as shown in Table 3 above, coated articles
according to certain embodiments of this invention have a
.DELTA.E*.sub.G value (glass side) of no greater than 5.0, more
preferably no greater than 4.0, and even more preferably no greater
than 3.0; and have a .DELTA.a*.sub.G value (glass side) of no
greater than about 1.0, more preferably no greater than 0.6 and
most preferably no greater than 0.3. Also, in certain example
embodiments and as shown in Table 3 above, coated articles
according to certain embodiments of this invention have a
.DELTA.E*.sub.T value (transmissive) of no greater than 5.0, more
preferably no greater than 4.0, and even more preferably no greater
than 3.0; and have a .DELTA.a*.sub.T value (transmissive) of no
greater than about 1.3, more preferably no greater than 1.1, and
most preferably no greater than 0.8. When one or more of these are
achieved, matchability may result.
EXAMPLES 1-10
[0073] The following ten Example coated articles (each ultimately
annealed and heat treated) were made, with Examples 1-6 and 8-10
being made in accordance with certain example embodiments of this
invention and Example 7 being made for purposes of comparison where
the NiCr layer was not nitrided. For Examples 1-6 and 8-10, the
layer system on about 6.0 mm thick clear soda-lime-silica glass
substrate was: silicon nitride/NiCrN.sub.x/silicon nitride (e.g.,
see FIG. 1). For comparative Example 7, the layer system on about
6.0 mm thick clear soda-lime-silica glass substrate was: silicon
nitride/NiCr/silicon nitride (i.e., the NiCr layer was not nitrided
in comparative Ex. 7). The coater/process setups for the Examples
were as follows.
[0074] For each example, a Leybold Terra-G six-chamber sputter
coating apparatus was used to sputter the coatings onto the glass
substrates. Five cathodes were in each chamber, so there were a
total of 30 cathode targets in the sputter coater (not all were
used). Cathode numbering utilizes the first digit to refer to the
coater chamber, and the second digit to refer to the cathode
position in that chamber. For example, cathode #42 was the second
cathode (second digit) in the fourth (first digit) sputter chamber.
Cathode #s 42, 55 and 61 were dual C-Mag type cathodes; and cathode
#s 44 and 45 were planar cathodes. Below, "*" means Al content of
approximately 10%. The line speed for Examples 5-10 was 3.5 meters
per minute (m/min.), and was about 2.5 m/min. for Examples 1-4. All
gas flows in Table 4 (e.g., Ar and N) are presented in units of
sccm. Voltage is measured in terms of volts, and frequency in terms
of kHz. Pressure is measured in hPa, and power in kW. T-gas refers
to trim gas used to individually adjust gas flows along cathode
length to make corrections regarding layer thickness uniformity
(all T-gas was at 100 sccm). C% refers to the percentage (%) of
trim gas introduced at the center, while PS% refers to the
percentage of the trim gas introduced at the pump side, and VS %
refers to the percentage of the trim or tuning gas introduced at
the viewer side. The NiCr targets were approximately 80/20
NiCr.
6TABLE 4 Coater Setup/Processes for Examples Cathode Target Power
Voltage Pressure Ar N.sub.2 Freq. T-Gas C% PS% VS% EXAMPLE #1 #42
Si/Al* 11.0 192 2.11 E-03 200 71.4 24.3 N 5% 45% 50% #44 Ni/Cr
38.46 411 3.15 E-03 200 115.4 DC Ar 80% 10% 10% #45 Ni/Cr 38.30 412
2.79 E-03 200 114.9 DC Ar 70% 20% 10% #55 Si/Al* 44.68 308 3.40
E-03 200 268.1 27.1 N 5% 45% 50% #61 Si/Al* 44.72 299 3.98 E-03 202
268.3 27.2 N 5% 45% 50% EXAMPLE #2 #42 Si/Al* 11.0 192 2.11 E-03
200 71.4 24.3 N 5% 45% 50% #44 Ni/Cr 38.46 411 3.15 E-03 200 153.8
DC Ar 80% 10% 10% #45 Ni/Cr 38.30 412 2.79 E-03 200 153.2 DC Ar 70%
20% 10% #55 Si/Al* 44.68 308 3.40 E-03 200 268.1 27.1 N 5% 45% 50%
#61 Si/Al* 44.72 299 3.98 E-03 202 268.3 27.2 N 5% 45% 50% EXAMPLE
#3 #42 Si/Al* 11.0 192 2.11 E-03 200 71.4 24.3 N 5% 45% 50% #44
Ni/Cr 38.46 411 3.15 E-03 200 192.3 DC Ar 80% 10% 10% #45 Ni/Cr
38.30 412 2.79 E-03 200 191.5 DC Ar 70% 20% 10% #55 Si/Al* 44.68
308 3.40 E-03 200 268.1 27.1 N 5% 45% 50% #61 Si/Al* 44.72 299 3.98
E-03 202 268.3 27.2 N 5% 45% 50% EXAMPLE #4 #42 Si/Al* 11.0 192
2.11 E-03 200 71.4 24.3 N 5% 45% 50% #44 Ni/Cr 38.46 411 3.15 E-03
200 230.8 DC Ar 80% 10% 10% #45 Ni/Cr 38.30 412 2.79 E-03 200 229.8
DC Ar 70% 20% 10% #55 Si/Al* 44.68 308 3.40 E-03 200 268.1 27.1 N
5% 45% 50% #61 Si/Al* 44.72 299 3.98 E-03 202 268.3 27.2 N 5% 45%
50% EXAMPLE #5 #42 Si/Al* 11.0 192 2.11 E-03 200 71.4 24.3 N 5% 45%
50% #44 Ni/Cr 38.46 411 3.15 E-03 200 51.9 DC Ar 80% 10% 10% #45
Ni/Cr 38.30 412 2.79 E-03 200 51.7 DC Ar 70% 20% 10% #55 Si/Al*
44.68 308 3.40 E-03 200 268.1 27.1 N 5% 45% 50% #61 Si/Al* 44.72
299 3.98 E-03 202 268.3 7.2 N 5% 45% 50% EXAMPLE #6 #42 Si/Al* 11.0
192 2.11 E-03 200 71.4 24.3 N 5% 45% 50% #44 Ni/Cr 38.46 411 3.15
E-03 200 31.2 DC Ar 80% 10% 10% #45 Ni/Cr 38.30 412 2.79 E-03 200
31.0 DC Ar 70% 20% 10% #55 Si/Al* 44.68 308 3.40 E-03 200 268.1
27.1 N 5% 45% 50% #61 Si/Al* 44.72 299 3.98 E-03 202 268.3 27.2 N
5% 45% 50% EXAMPLE #7 (Comparative Example) #42 Si/Al* 11.0 192
2.11 E-03 200 71.4 24.3 N 5% 45% 50% #44 Ni/Cr 38.46 411 3.15 E-03
200 0 DC Ar 80% 10% 10% #45 Ni/Cr 38.30 412 2.79 E-03 200 0 C Ar
70% 20% 10% #55 Si/Al* 44.68 308 3.40 E-03 200 268.1 27.1 N 5% 45%
50% #61 Si/Al* 44.72 299 3.98 E-03 202 268.3 27.2 N 5% 45% 50%
EXAMPLE #8 #42 Si/Al* 11.0 192 2.11 E-03 200 71.4 24.3 N 5% 45% 50%
#44 Ni/Cr 38.46 411 3.15 E-03 200 36.5 DC Ar 80% 10% 10% #45 Ni/Cr
38.30 412 2.79 E-03 200 36.4 DC Ar 70% 20% 10% #55 Si/Al* 44.68 308
3.40 E-03 200 312.8 27.1 N 5% 45% 50% #61 Si/Al* 44.72 299 3.98
E-03 202 313.0 27.2 N 5% 45% 50% EXAMPLE #9 #42 Si/Al* 11.0 192
2.11 E-03 200 71.4 24.3 N 5% 45% 50% #44 Ni/Cr 38.46 411 3.15 E-03
200 36.5 DC Ar 80% 10% 10% #45 Ni/Cr 38.30 412 2.79 E-03 200 36.4
DC Ar 70% 20% 10% #55 Si/Al* 44.68 308 3.40 E-03 200 223.4 27.1 N
5% 45% 50% #61 Si/Al* 44.72 299 3.98 E-03 202 223.6 27.2 N 5% 45%
50% EXAMPLE #10 #42 Si/Al* 11.0 192 2.11 E-03 200 71.4 24.3 N 5%
45% 50% #44 Ni/Cr 38.46 411 3.15 E-03 200 36.5 DC Ar 80% 10% 10%
#45 Ni/Cr 38.30 412 2.79 E-03 200 36.4 DC Ar 70% 20% 10% #55 Si/Al*
44.68 308 3.40 E-03 200 178.7 27.1 N 5% 45% 50% #61 Si/Al* 44.72
299 3.98 E-03 202 178.9 27.2 N 5% 45% 50%
[0075] As can be seen above, Examples 1-6 and 8-10 were all
deposited on respective glass substrates in a manner so that layer
15 (i.e., the NiCrN.sub.x) layer was nitrided as deposited (due to
intentional introduction of N gas into the sputter chamber
including cathode(s) #s 44 and 45). However, in comparative Example
7 layer 15 (NiCr) was not nitrided, in order to illustrate the
benefits of nitriding layer 15 according to this invention.
Examples 1-6 and 8-10 illustrate that layer 15 can be nitrided (via
cathodes/targets 44-45) to various degrees (i.e., the nitrogen (N)
flow ranged from 31 sccm in Example 6 up to about 230 sccm in
Example 4). It will be shown below that each of these had better
characteristics with regard to color stability upon HT than
comparative Example 7 where no nitriding was done to the NiCr
layer. Generally, the more nitriding of layer 15, the lower the
.DELTA.E value and thus the better the color stability upon HT.
Moreover, it can be seen that Examples 9-10 each had a Si-rich
overcoat silicon nitride layer relative to the other Examples.
Examples 8-10 show the effect of N gas flow (mL/kW) on coating
stability; e.g., the higher the N gas flow, the less Ni migration
and more color stability with HT. While Si-rich overcoat silicon
nitride layers 17 are appropriate according to certain embodiments
of this invention, it will be shown below that the Si-rich nature
of the overcoat 17 tends to cause sheet resistance (R.sub.s) to
increase upon HT which is sometimes not desirable. Thus, it can be
seen that by increasing N gas flow for layer 15, Ni
diffusion/migration into the upper silicon nitride layer can be
reduced and/or prevented in order to provide a coating with more
color stability upon HT.
[0076] After being sputtered onto glass substrates as set forth
above, Examples 1-10 were tested and were found to have the
following characteristics monolithically (not in an IG unit), where
the heat treatment (HT) involved heating the respective monolithic
products at about 625 degrees C. for about 10 minutes. It is noted
that a* and b* color coordinate values are in accordance with CIE
LAB 1976, Ill. C 2 degree observer technique, .DELTA.a* and
.DELTA.b* are in terms of absolute value. Moreover, sheet
resistance (R.sub.s) is in units of ohms per square as is known in
the art.
7TABLE 5 Characteristics of Examples 1-10 (Monolithic: Before/After
HT) EXAMPLES 1-2 Value/Measurement Ex. 1 (pre-HT) Ex. 1 (post-HT)
Ex. 2 (pre-HT) Ex. 2 (post-HT) Transmission (TY) %: 9.83 10.57
10.58 11.13 L*.sub.T: 37.54 38.85 38.87 39.79 a*.sub.T: -0.42 -0.69
-0.59 -0.66 b*.sub.T: -7.04 -3.81 -6.72 -4.35 .DELTA.a*.sub.T
(transmissive): 0.27 0.07 .DELTA.E*.sub.T (transmissive): 3.5 2.5
Glass side Reflectance (R.sub.GY %): 40.29 36.45 39.62 35.66
L*.sub.G: 69.68 66.86 69.19 66.26 a*.sub.G: -1.71 -1.80 -1.68 -1.72
b*.sub.G: 2.26 1.88 1.84 1.61 .DELTA.a*.sub.G (glass side): 0.09
0.04 .DELTA.E*.sub.G (glass side): 2.8 2.9 .DELTA.b*.sub.G: 0.38
0.23 Film side Reflectance (R.sub.FY %): 35.13 35.02 32.77 34.61
L*.sub.F: 65.85 65.76 63.98 65.44 a*.sub.F: 0.05 0.04 0.32 -0.01
b*.sub.F: 20.91 15.31 22.32 16.28 R.sub.S (ohms/sq.): n/a n/a n/a
n/a EXAMPLES 3-4 Value/Measurement Ex. 3 (pre-HT) Ex. 3 (post-HT)
Ex. 4 (pre-HT) Ex. 4 (post-HT) Transmission (TY) %: 10.66 11.26
10.58 11.42 L*.sub.T: 39.0 40.01 n/a n/a a*.sub.T: -0.7 -0.69 n/a
n/a b*.sub.T: -6.07 -4.78 n/a n/a .DELTA.a*.sub.T (transmissive):
0.01 n/a .DELTA.E*.sub.T (transmissive): 1.6 n/a Glass side
Reflectance (R.sub.GY %): 39.3 35.33 38.69 35.71 L*.sub.G: 68.97
66.0 68.52 66.29 a*.sub.G: -1.71 -1.64 -1.68 -1.58 b*.sub.G: 1.72
1.47 1.74 1.47 .DELTA.a*.sub.G (glass side): 0.07 0.10
.DELTA.E*.sub.G (glass side): 3.0 2.2 .DELTA.b*.sub.G (glass side):
0.25 0.27 Film side Reflectance (R.sub.FY %): 32.71 34.29 33.73
33.92 L*.sub.F: 63.93 65.19 64.75 64.9 a*.sub.F: 0.3 -0.03 0.15
0.03 b*.sub.F: 21.58 17.58 19.93 17.86 R.sub.s (ohms/sq.): n/a n/a
n/a n/a EXAMPLES 5-6 Value/Measurement Ex. 5 (pre-HT) Ex. 5
(post-HT) Ex. 6 (pre-HT) Ex. 6 (post-HT) Transmission (TY) %: 10.48
11.54 9.5 10.68 L*.sub.T: 38.69 40.48 n/a 39.03 a*.sub.T: -0.45
-0.96 n/a -1.32 b*.sub.T: -7.78 -3.61 n/a -3.63 .DELTA.a*.sub.T
(transmissive): 0.51 n/a .DELTA.E*.sub.T (transmissive): 4.6 n/a
Glass side Reflectance (R.sub.GY %): 39.58 35.39 40.8 36.29
L*.sub.G: 69.17 66.05 70.0 66.74 a*.sub.G: -1.93 -1.98 -2.0 -1.8
b*.sub.G: 1.46 0.72 1.9 1.15 .DELTA.a*.sub.G (glass side): 0.05
0.20 .DELTA.E*.sub.G (glass side): 3.2 3.4 .DELTA.b*.sub.G (glass
side): 0.74 0.75 Film side Reflectance (R.sub.FY %): 33.39 32.32
35.3 33.4 L*.sub.F: 64.47 63.61 66 64.48 a*.sub.F: 0.07 0.24 -0.1
0.52 b*.sub.F: 22.23 15.26 21.6 14.96 R.sub.s (ohms/sq.): 41.4 36.0
40.4 39.5 EXAMPLES 7-8 (Ex. 7 provided for purposes of comparison
to other examples) Value/Measurement Ex. 7 (pre-HT) Ex. 7 (post-HT)
Ex. 8 (pre-HT) Ex. 8 (post HT) Transmission (TY) %: 8.02 9.71 9.87
11.37 L*.sub.T: 34.02 37.32 37.61 40.2 a*.sub.T: 0.03 -1.5 -0.28
-0.92 b*.sub.T: -8.21 -3.52 -7.61 -3.14 .DELTA.a*.sub.T
(transmissive): 1.53 0.64 .DELTA.E*.sub.T (transmissive): 5.9 5.2
Glass side Reflectance (R.sub.GY %): 43.58 38.41 40.19 35.52
L*.sub.G: n/a 71.94 69.61 66.15 a*.sub.G: n/a -2.06 -1.89 -1.91
b*.sub.G: n/a 2.18 1.85 0.8 .DELTA.a*.sub.G (glass side): n/a 0.02
.DELTA.E*.sub.G (glass side): n/a 3.6 .DELTA.b*.sub.G (glass side):
n/a 1.05 Film side Reflectance (R.sub.FY %): 38 30.1 35.72 33.22
L*.sub.F: 68.02 61.74 66.31 64.34 a*.sub.F: -0.32 1.12 -0.15 0.21
b*.sub.F: 21.0 18.65 20.13 13.68 R.sub.s (ohms/sq.): 38.8 41.9 41.4
34.5 EXAMPLES 9-10 Value/Measurement Ex. 9 (pre-HT) Ex. 9 (post-HT)
Ex. 10 (pre-HT) Ex. 10 (post-HT) Transmission (TY) %: 9.74 11.05
9.41 10.08 L*.sub.T: 37.36 39.67 36.76 37.98 a*.sub.T: -0.25 -1.2
-0.42 -1.52 b*.sub.T: -7.9 -3.78 -7.29 -3.2 .DELTA.a*.sub.T
(transmissive): 0.95 1.10 .DELTA.E*.sub.T (transmissive): 4.8 4.4
Glass side Reflectance (R.sub.GY %): 40.34 35.69 40.2 35.35
L*.sub.G: 69.71 66.29 69.61 66.02 a*.sub.G: -1.86 -1.63 -1.79 -1.33
b*.sub.G: 1.89 0.99 1.76 1.61 .DELTA.a*.sub.G (glass side): 0.23
0.46 .DELTA.E*.sub.G (glass side): 3.5 3.6 .DELTA.b*.sub.G (glass
side): 0.90 0.15 Film side Reflectance (R.sub.FY %): 35.91 33.57
37.27 37.22 L*.sub.F: 66.45 64.62 67.48 67.44 a*.sub.F: -0.21 0.41
-0.54 0.6 b*.sub.F: 20.6 15.14 20.61 11.42 R.sub.s (ohms/sq.): 40.7
39.8 41 47
[0077] As can be seen from the above, each of Examples 1-6 and 8-10
had good matchability (i.e., transmissive and/or glass side
reflective .DELTA.E* no greater than 5.0) because layer 15 was
nitrided. However, in Example 7 where layer 15 was not nitrided,
bad matchability and thus significant color shift with HT resulted
(i.e., .DELTA.E.sub.T was very high in Ex. 7 at 5.9). For the other
Examples where nitriding of layer 15 was done, .DELTA.E* was no
greater than 5.0, more preferably no greater than 4.0 and in
certain most preferred instances no greater than 3.0. Meanwhile, it
can also be seen that Example 7 experienced a very high .DELTA.a*
value of 1.53. In contrast, in the other Examples where nitriding
of layer 15 was conducted according to this invention the .DELTA.a*
values were much lower thereby illustrating significantly more
color stability upon HT. Accordingly, it can clearly be seen that
nitriding of layer 15 according to certain embodiments of this
invention enables the resulting coated article to have much
improved color stability upon lengthy HT (e.g., HT of at least 5
minutes).
[0078] For purposes of illustrating how certain color stability
numbers were calculated above, consider Example 3 which had the
following transmissive values:
8 L* (before HT): 39.0; L* (after HT): 40.01; .DELTA.L* = 1.01 a*
(before HT): -0.70; a* (after HT): -0.69 .DELTA.a* = 0.01 b*
(before HT): -6.07; b* (after HT): -4.78 .DELTA.b* = 1.29
[0079] Thus, using the equation
.DELTA.E*=[(.DELTA.L*).sup.2+(.DELTA.a*).s-
up.2+(.DELTA.b*).sup.2].sup.{fraction (1/12)}, (i.e., equation (1)
above), it can be determined that
[(1.01).sup.2+(0.01).sup.2+(1.29).sup.2].sup.1/-
2=(2.6843).sup.1/2=1.6=.DELTA.E*.sub.T. This relatively low
transmissive .DELTA.E* value indicates good matchability (before
versus after heat treatment), and is much better (i.e., much lower)
than the 5.9 value for Example 7.
[0080] FIGS. 3-4 are XPS plots of Example 1, before and after HT,
respectively. In a similar manner, FIGS. 5-6 are XPS plots of
Example 2 before and after HT, respectively; FIGS. 7-8 are XPS
plots of Example 3 before and after HT, respectively; FIGS. 9-10
are XPS plots of Example 4 before and after HT, respectively; FIGS.
11-12 are XPS plots of Example 5 before and after HT, respectively;
FIGS. 13-14 are XPS plots of Example 6 before and after HT,
respectively; FIGS. 15-16 are XPS plots of Example 7 before and
after HT, respectively; FIGS. 17-18 are XPS plots of Example 8
before and after HT, respectively; FIGS. 19-20 are XPS plots of
Example 9 before and after HT, respectively; and FIGS. 21-22 are
XPS plots of Example 10 before and after HT, respectively. As will
be appreciated by those skilled in the art, the nitrogen (N)
signals reported in these Figures are taken from the 1s orbital of
N as shown, and so forth. It is noted that the interface of the
coating system with the underlying glass substrate can be seen in
these FIGS. where Ca and Na begin to rise (e.g., around 750 {acute
over (.ANG.)} in FIGS. 3-4).
[0081] By comparing FIGS. 15-16 (comparative Example 7) with the
XPS plots for other examples, it can be seen that when layer 15 is
significantly nitrided there is significantly less migration of
nitrogen (N) from the upper silicon nitride layer into the NiCr
inclusive layer upon HT (as compared to FIG. 16). This is
illustrated, for example, by the fact that the N slope 7a on the
lower side of layer 17 is much more steep in FIGS. 4, 6, 8, 10, 12,
14, 18 and 20 (after HT) than in FIG. 16. Moreover, it can be seen
in these same Figures that the Ni slope 3a at the upper side of
layer 15 is much more steep in FIGS. 4, 6, 8, 10, 12, 14, 18 and 20
than in FIG. 16; thereby indicating that according to certain
embodiments of this invention there is much less Ni migration out
of layer 15 upon lengthy HT as compared to Example 7. Reduction in
such migrations enables .DELTA.E values to be reduced, thereby
permitting better color stability upon lengthy HT according to this
invention.
[0082] In Table 5 above, it can also be seen that in comparative
Example 7 the sheet resistance (R.sub.s) increased upon HT (this is
not desirable in certain instances). This increase in sheet
resistance in Example 7 is believed to at least partially result
from the Ni migrating from layer 15 into layer 17 upon HT as shown
in FIG. 16. Thus, another surprising advantage associated with
certain example embodiments of this invention is that sheet
resistance decreases upon HT (e.g., see Examples 5, 6, 8 and 9
above). This can be explained by at least the fact that the Ni
slope 3a is much more steep at the upper side of layer 15 in FIGS.
4, 6, 8, 10, 12, 14, 18 and 20 than in FIG. 16. However, it is
noted that while layer 17 may be a Si-rich form of silicon nitride
in certain embodiments of this invention, this may cause
significant Ni migration thereby causing sheet resistance to rise
upon HT as shown in Example 10 (note the less steep Ni slope 3a in
FIG. 22, and the increase in R.sub.s upon HT in Table 5). Thus,
increasing nitrogen (N) gas flow proximate the cathode target(s)
which form the upper silicon nitride layer enables production of a
coated glass article which will more likely experience a decrease
in sheet resistance upon HT.
[0083] In certain embodiments of this invention, coated articles
have a sheet resistance (R.sub.s) of no greater than 500 ohms/sq.
after HT, more preferably no greater than 250 ohms/sq. after HT,
even more preferably no greater than about 100 ohms/sq., and most
preferably no greater than about 41 ohms/sq. after HT. Moreover, in
certain preferred embodiments of this invention, coated articles
herein experience a reduction in sheet resistance upon HT (in
contrast to Example 7). Coated articles herein in certain example
embodiments also have a hemispherical emissivity (E.sub.h) of no
greater than about 1.0, more preferably no greater than about 0.5,
and most preferably no greater than about 0.4 before and/or after
HT.
[0084] Another surprising result of certain example embodiments of
this invention is that nitriding layer 15 results in a more
mechanically durable (e.g., scratch resistant) coated article after
HT. This is believed to be because or the chrome nitride present in
layer 15. Coated articles of certain embodiments of this invention
are both chemically and mechanically durable. Additionally,
monolithic coated articles according to certain embodiments of this
invention preferably have a visible transmittance (TY%) of from
5-80% (more preferably from 7-20%) before and/or after HT.
Additionally, monolithic coated articles according to certain
embodiments of this invention preferably have a glass side
reflectance value (R.sub.GY %) of at least 15%, and more preferably
from 20-42% before and/or after HT.
[0085] The aforesaid characteristics may be measured at a clear
float glass nominal substrate thickness of about 6 mm, or any other
suitable substrate thickness from 1-12 mm. Moreover, it is noted
that the units of Examples 1-6 and 8-10 may ultimately be utilized
in the context of an IG unit, a vehicle window, or the like.
[0086] Certain terms are prevalently used in the glass coating art,
particularly when defining the properties and solar management
characteristics of coated glass. Such terms are used herein in
accordance with their well known meaning. For example, as used
herein:
[0087] Intensity of reflected visible wavelength light, i.e.
"reflectance" is defined by its percentage and is reported as
R.sub.xY (i.e. the Y value cited below in ASTM E-308-85), wherein
"X" is either "G" for glass side or "F" for film side. "Glass side"
(e.g. "G") means, as viewed from the side of the glass substrate
opposite that on which the coating resides, while "film side" (i.e.
"F") means, as viewed from the side of the glass substrate on which
the coating resides.
[0088] Color characteristics are measured and reported herein using
the CIE LAB a*, b* coordinates and scale (i.e. the CIE a*b*
diagram, Ill. CIE-C, 2 degree observer). Other similar coordinates
may be equivalently used such as by the subscript "h" to signify
the conventional use of the Hunter Lab Scale, or Ill. CIE-C,
10.sup.0 observer, or the CIE LUV u*v* coordinates. These scales
are defined herein according to ASTM D-2244-93 "Standard Test
Method for Calculation of Color Differences From Instrumentally
Measured Color Coordinates" Sep. 15, 1993 as augmented by ASTM
E-308-85, Annual Book of ASTM Standards, Vol. 06.01 "Standard
Method for Computing the Colors of Objects by 10 Using the CIE
System" and/or as reported in IES LIGHTING HANDBOOK 1981 Reference
Volume.
[0089] The terms "emittance" and "transmittance" are well
understood in the art and are used herein according to their well
known meaning. Thus, for example, the term "transmittance" means
solar transmittance, which is made up of visible light
transmittance (TY), infrared radiation transmittance, and
ultraviolet radiation transmittance. Total solar energy
transmittance (TS) is then usually characterized as a weighted
average of these other values. With respect to these
transmittances, visible transmittance (TY), as reported herein, is
characterized by the standard CIE Illuminant C, 2 degree observer,
technique at 380-720 nm; near-infrared is 720-2500 nm; ultraviolet
is 300-800 nm; and total solar is 300-2500 nm. For purposes of
emittance, however, a particular infrared range (i.e. 2,500-40,000
nm) is employed.
[0090] Visible transmittance can be measured using known,
conventional techniques. For example, by using a spectrophotometer,
such as a Perkin Elmer Lambda 900 or Hitachi U4001, a spectral
curve of transmission is obtained. Visible transmission is then
calculated using the aforesaid ASTM 308/2244-93 methodology. A
lesser number of wavelength points may be employed than prescribed,
if desired. Another technique for measuring visible transmittance
is to employ a spectrometer such as a commercially available
Spectrogard spectrophotometer manufactured by Pacific Scientific
Corporation. This device measures and reports visible transmittance
directly. As reported and measured herein, visible transmittance
(i.e. the Y value in the CIE tristimulus system, ASTM E-308-85)
uses the Ill. C.,2 degree observer.
[0091] "Emittance" (E) is a measure, or characteristic of both
absorption and reflectance of light at given wavelengths. When
transmittance is zero, which is approximately the case for float
glass with wavelengths longer than 2500 nm, the emittance may be
represented by the formula:
E=1-Reflectance.sub.film
[0092] For architectural purposes, emittance values become quite
important in the so-called "mid-range", sometimes also called the
"far range" of the infrared spectrum, i.e. about 2,500-40,000 nm.,
for example, as specified by the WINDOW 4.1 program, LBL-35298
(1994) by Lawrence Berkeley Laboratories, as referenced below. The
term "emittance" as used herein, is thus used to refer to emittance
values measured in this infrared range as specified by ASTM
Standard E 1585-93 for measuring infrared energy to calculate
emittance, entitled "Standard Test Method for Measuring and
Calculating Emittance of Architectural Flat Glass Products Using
Radiometric Measurements". This Standard, and its provisions, are
incorporated herein by reference. In this Standard, emittance is
reported as hemispherical emittance (E.sub.h) and normal emittance
(E.sub.n). The actual accumulation of data for measurement of such
emittance values is conventional and may be done by using, for
example, a Beckman Model 4260 spectrophotometer with "VW"
attachment (Beckman Scientific Inst. Corp.). This spectrophotometer
measures reflectance versus wavelength, and from this, emittance is
calculated using the aforesaid ASTM E 1585-93 which has been
incorporated herein by reference.
[0093] Another term employed herein is "sheet resistance". Sheet
resistance (R.sub.s) is a well known term in the art and is used
herein in accordance with its well known meaning. It is here
reported in ohms per square units. Generally speaking, this term
refers to the resistance in ohms for any square of a layer system
on a glass substrate to an electric current passed through the
layer system. Sheet resistance is an indication of how well the
layer or layer system is reflecting infrared energy, and is thus
often used along with emittance as a measure of this
characteristic. "Sheet resistance" may for example be conveniently
measured by using a 4-point probe ohmmeter, such as a dispensable
4-point resistivity probe with a Magnetron Instruments Corp. head,
Model M-800 produced by Signatone Corp. of Santa Clara, Calif.
[0094] "Chemical durability" or "chemically durable" is used herein
synonymously with the term of art "chemically resistant" or
"chemical stability". Chemical durability is determined by boiling
a 2".times.5" sample of a coated glass substrate in about 500 cc of
5% HCl for one hour (i.e. at about 220.degree. F.). The sample is
deemed to pass this test (and thus the layer system is "chemically
resistant" or is deemed to be "chemically durable" or to have
"chemical durability") if the sample's layer system shows no
visible discoloration or visible peeling, and no pinholes greater
than about 0.003" in diameter after this one hour boil.
[0095] "Mechanical durabilility" as used herein is defined by the
following tests. The test uses a Pacific Scientific Abrasion Tester
(or equivalent) wherein a 2".times.4"1" nylon brush is cyclically
passed over the layer system in 500 cycles employing 150 gm of
weight, applied to a 6".times.17" sample. In this test, if no
substantial, noticeable scratches appear when viewed with the naked
eye under visible light, the test is deemed passed, and the article
is said to be "mechanically durable" or to have "mechanical
durability".
[0096] The terms "heat treatment" and "heat treating" as used
herein mean heating the article to a temperature sufficient to
enabling thermal tempering, bending, or heat strengthening of the
glass inclusive article. This definition includes, for example,
heating a coated article to a temperature of at least about 600
degrees C. for a sufficient period to enable tempering.
[0097] Once given the above disclosure many other features,
modifications and improvements will become apparent to the skilled
artisan. Such other features, modifications and improvements are
therefore considered to be a part of this invention, the scope of
which is to be determined by the following claims:
* * * * *