Stock material or miscellaneous articles – Composite – Of quartz or glass
Reexamination Certificate
2002-12-13
2004-04-06
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Composite
Of quartz or glass
C428S432000, C428S448000, C428S450000, C428S666000, C428S680000, C428S697000, C428S698000, C428S699000, C428S701000, C428S702000, C428S704000
Reexamination Certificate
active
06716532
ABSTRACT:
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
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.
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. 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 &Dgr;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, &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 Example 7 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 (the NiCr layer is not nitrided as deposited as can be seen in FIG.
15
), and the overcoat of Si
3
N
4
is about 210-310 Å thick. As explained in Example 7 below, this coated article has a rather high transmissive &Dgr;E* value of about 5.9 after a 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. This is not desirable.
The instant inventor believes that the high &Dgr;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
3
N
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
3
N
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
3
N
4
layer. Additionally, upon HT a significant portion of the Si and N from the upper Si
3
N
4
layer migrates into the NiCr layer. In other words, the interface between the metal NiCr layer and the upper Si
3
N
4
layer becomes blurred and non-distinct. This is evidenced in
FIG. 16
by the less steep slope
3
a
of the Ni on the upper/outer side of the NiCr layer, and by the less steep slopes
5
a
and
7
a
of the Si and N on the lower side of the upper Si
3
N
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.
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 &Dgr;E* value associated with the coating of Ex. 7, and thus with coatings of the '585 patent when exposed to lengthy heat treatments.
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 &Dgr;E (or &Dgr;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
An object of this invention is to provide a coating or layer system that has good color stability (i.e., a low &Dgr;E* value(s)) with heat treatment (HT).
Another object of this invention is to provide a coating or layer system having a &Dgr;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).
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 &Dgr;E value(s).
Another object of this invention is to fulfill one or more of the above-listed objects.
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:
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 articl
Neuman George
Stachowiak Grzegorz
Wang Hong
Guardian Industries Corp.
Jones Deborah
Nixon & Vanderhye P.C.
Piziali Andrew T
LandOfFree
Heat treatable coated articles with metal nitride layer and... 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 articles with metal nitride layer and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Heat treatable coated articles with metal nitride layer and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3224861