Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
2001-11-29
2003-12-23
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S428000, C428S432000, C428S448000, C428S469000, C428S472000, C428S680000, C428S666000, C428S697000, C428S698000, C428S701000, C428S702000, C428S704000
Reexamination Certificate
active
06667121
ABSTRACT:
This invention relates to coated articles including a layer structure of barrier/metal(or mostly metal)/barrier, and a method of making the same. This layer structure may be used by itself, or more preferably as only a component of an overall coating or layer system. In certain embodiments, a single sputtering target (e.g., cathode target) is used to make this layer structure. In these and/or other embodiments of the invention, the resulting coated article has approximately the same color characteristics as viewed by the naked eye before and after heat treatment (e.g., thermal tempering). Such coated articles may be used in insulating glass (IG) window units, vehicle windows, and/or other suitable applications.
BACKGROUND AND SUMMARY OF THE INVENTION
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 typically employ IG units and/or laminates for safety and/or thermal control. It is 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.
U.S. Pat. No. 5,376,455 discloses a coated article including: glass/Si
3
N
4
/NiCr/Ag/NiCr/Si
3
N
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 &Dgr;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.
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.
However, commonly owned U.S. Pat. No. 5,688,585 discloses a solar control coated article including glass/Si
3
N
4
/NiCr/Si
3
N
4
, wherein matchability is achieved with a single layer system. 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, it has been found that with longer HT times the coatings of the '585 patent cannot maintain low &Dgr;E values and thus lose color matchability. In particular, it has been found that in coatings such as those of the '585 patent, &Dgr;E values jump significantly upward after HT for 4-5 minutes at a temperature of from about 600 to 800 degrees C.
Consider the following layer stack (see Comparative Example below): glass/Si
3
N
4
/NiCr/Si
3
N
4
, where the underlayer of Si
3
N
4
is about 50-70 Å (angstroms) thick, the NiCr layer is about 325 Å thick, and the overcoat of Si
3
N
4
is about 210-310 Å thick. As explained in the Comparative Example below, this coated article has a rather high transmissive &Dgr;E* value of about 5.9 after heat treatment (HT) at 625 degrees C for ten (10) minutes. This high transmissive &Dgr;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.
COMPARATIVE EXAMPLE
The following Comparative Example layer system was provided on about a 6.0 mm thick clear soda-lime-silica glass substrate
1
, and was: silicon nitride/NiCr/silicon nitride. A Leybold Terra-G six-chamber sputter coating apparatus was used to sputter the coating onto the glass substrate. 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 was 3.5 meters per minute (m/min.). All gas flows (i.e., 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 (or tuning) 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 80/120 NiCr.
Comparative Example Sputtering Data
Cathode
Target
Power
Voltage
Pressure
Ar
N
2
Freq.
T-Gas
C %
PS %
VS %
#42
Si/Al*
11.0
192
2.11E−03
200
71.4
24.3
N
5%
45%
50%
#44
Ni/Cr
38.46
411
3.15E−03
200
0
DC
Ar
80%
10%
10%
#45
Ni/Cr
38.30
412
2.79E−03
200
0
C
Ar
70%
20%
10%
#55
Si/Al*
44.68
308
3.40E−03
200
268.1
27.1
N
5%
45%
50%
#61
Si/Al*
44.72
299
3.98E−03
202
268.3
27.2
N
5%
45%
50%
After being sputtered onto glass substrate
1
as set forth above, the resulting coated article of the Comparative Example was tested and found to have the following characteristics monolithically (not in an IG unit), where the heat treatment (HT) involved heating the monolithic product 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, and &Dgr;a* and &Dgr;b* are in terms of absolute value. Moreover, sheet resistance (R
s
) is in units of ohms per square as is known in the art.
Comparative Example (measurements before/after HT)
Value/Measurement
(Pre-HT)
(Post-HT)
Transmission (TY) %:
8.02
9.71
L*
T
:
34.02
37.32
a*
T
:
0.03
−1.5
b*
T
:
−8.21
−3.52
&Dgr;a*
T
(transmissive):
1.53
&Dgr;E*
T
(transmissive):
5.9
Glass side
Reflectance (R
G
Y %):
43.58
38.41
L*
G
:
n/a
71.94
a*
G
:
n/a
−2.06
b*
G
:
n/a
2.18
Film side
Reflectance (R
F
Y %):
38
30.1
L*
F
:
68.02
61.74
a*
F
:
−0.32
1.12
b*
F
:
21.0
18.65
&Dgr;E* (film side)
6.86
R
s
(ohms/sq.):
38.8
41.9
As can be seen above, the Comparative Example experienced a rather high transmissive &Dgr;E* value of 5.9 and a rather high film side reflective &Dgr;E* value of 6.86 (evidencing that the coating is not color stable upon HT). It is believed that these high &Dgr;E* value(s) associated with the coating of the Comparative Example are caused for at least the following reasons. Prior to heat treatment (HT), 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
3
N
4
layer is located in that upper layer. However, when the Comparative Example coated article is heat treated (HT) as discussed above, a significant portion of the Ni from the NiCr layer migrates (of diffuses) into the upper Si
3
N
4
layer (see parent application). Additiona
Guardian Industries Corp.
Jones Deborah
Nixon & Vanderhye P.C.
Piziali Andrew T
LandOfFree
Heat treatable coated article with anti-migration barrier... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Heat treatable coated article with anti-migration barrier..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Heat treatable coated article with anti-migration barrier... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3154418